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IEEE Journal of Emerging and Selected Topics in Power Electronics
Journal Prestige (SJR): 1.657
Citation Impact (citeScore): 7
Number of Followers: 56  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2168-6777 - ISSN (Online) 2168-6785
Published by IEEE Homepage  [228 journals]
  • IEEE Journal of Emerging and Selected Topics in Power Electronics
           Publication Information

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      Pages: C2 - C2
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • IEEE Industry Applications Society Information

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      Pages: C3 - C3
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Guest Editorial Special Issue on Integrated Control and Modulation for
           Electric Drives

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      Authors: Jorge Rodas;Luca Zarri;Antonio J. Marques Cardoso;
      Pages: 1287 - 1290
      Abstract: Green energies and electric mobility are considered exciting solutions to help reduce the emissions of greenhouse gases into the atmosphere. This scenario has significantly promoted the use of electric drives; consequently, higher technical requirements are assumed as mandatory. Focusing on the required high-performance electric drives, the direct control of power converters and the use of integrated modulators, namely, control techniques that avoid the pulse-width modulation stage, can be an attractive alternative to conventional linear controllers. For example, Model Predictive Control (MPC) presents inherent flexibility in defining control objectives, while Direct Torque Control (DTC) provides a fast dynamic response. Unfortunately, unacceptable harmonic distortion can appear in the system if single control action is applied per control cycle. This scenario promotes a higher current ripple in three-phase electric drives when a control scheme using a standard integrated modulator is implemented. The situation is even worse when multiphase drives are used since several orthogonal subspaces need to be regulated with a single control action. In addition, the characteristic low value of the equivalent impedance of the secondary subspaces may lead to enormous harmonic currents. Considering the previous scenario, although the dynamic response is very fast in direct controllers (control scheme based on integrated modulators), these control strategies could be discarded due to their high harmonic distortion. Fortunately, the disadvantages of direct control strategies can be mitigated by using enhanced integrated modulators, such as multi-vector solutions as control actions. On the other hand, as these control techniques’ performance is founded on the nature of the available voltage vectors, the use of some specific electric drives, such as symmetrical six-phase machines, can allow taking advantage of their desirable skills.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Direct Model Predictive Control Strategy With an Implicit Modulator for
           Six-Phase PMSMs

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      Authors: Yitong Wu;Zhen Zhang;Qifan Yang;Wei Tian;Petros Karamanakos;Marcelo Lobo Heldwein;Ralph Kennel;
      Pages: 1291 - 1304
      Abstract: This article proposes a direct model predictive control (MPC) scheme for asymmetric six-phase permanent magnet synchronous machines (PMSMs), which combines control and modulation in one computation stage. By emulating the switching pattern of space vector modulation (SVM), the MPC problem is formulated as a 4-D current control problem where the switching sequences and instants are computed and directly applied to the inverters. This implicit modulation addresses the issue of a variable switching frequency and spread harmonic spectra of conventional direct MPC methods. Moreover, the effect of the modulation constraints and controller bandwidth on the system performance is investigated as well. To verify the effectiveness of the proposed control strategy, experiments are carried out with an asymmetric six-phase PMSM driven by two three-phase two-level inverters.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Low-Complexity Modulated Model Predictive Torque and Flux Control
           Strategy for PMSM Drives Without Weighting Factor

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      Authors: Ahmed Nasr;Chunyang Gu;Giampaolo Buticchi;Serhiy Bozhko;Chris Gerada;
      Pages: 1305 - 1316
      Abstract: This article proposes a modulated model predictive torque and flux control (M2PTFC) method with low complexity for a two-level voltage source inverter (2L-VSI)-fed permanent magnet synchronous motor (PMSM). The proposed strategy aims to reduce the computation burden and simplify the control implementation of the conventional M2PTFC scheme by reducing the number of candidate voltage vectors at every control sample to the minimum (i.e., only two candidates) and eliminating the weighting factor of the cost function and its corresponding tuning procedures. For these purposes, the proposed method devotes different control objectives to the duty modulation and the cost function evaluation processes while executing them sequentially. First, aiming at torque ripple reduction, a duty modulation strategy is proposed based on the analysis of torque deviations produced by different voltage vectors, which ensures proper selection of the two candidates and restricts active voltage vectors (AVVs) that cause high deviations. Then, these candidates are evaluated based on a cost function assigned to achieve the stator flux control objective. The effectiveness of the proposed control scheme is verified through comparative assessment with the conventional M2PTFC and two existing simplified methods by means of simulation and experimental results.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Adjacent-Vector-Based Model Predictive Control for Permanent Magnet
           Synchronous Motors With Full Model Estimation

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      Authors: Zhuoyi Chen;Jianqi Qiu;
      Pages: 1317 - 1331
      Abstract: The finite-control-set model predictive control (FCS-MPC) shows appealing features in permanent magnet synchronous motor control but suffers from high current ripples. Multiple-vector-based MPC (MVB-MPC) methods reduce the ripples but may lose some of the merits possessed by the FCS-MPC. Furthermore, the performance of both the FCS-MPC and the MVB-MPC is dependent on the accurate knowledge of the system parameters. This article proposes an adjacent-vector-based MPC (AVB-MPC) combining the FCS-MPC and the MVB-MPC. Instead of finding a solution with minimum cost, the AVB-MPC searches from a lookup table of adjacent vectors for the solution with the least switching actions to keep the cost within a tolerable band. Hence, the current ripple is reduced under the same switching frequency, while the merits of fast dynamic responsiveness and inherent overmodulation ability are retained. In addition, a full model estimation method is proposed so that the knowledge of the machine parameters is not required. The rank deficiency problem of multiparameter identification is also solved by the tolerable band. And these benefits are gained without adding much computational effort. Finally, the effectiveness and benefits of the AVB-MPC are validated by comparative experimental results comparing with several other typical predictive controllers.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Computationally Efficient Model-Free Predictive Control of Zero-Sequence
           Current in Dual Inverter Fed Induction Motor

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      Authors: Mahdi S. Mousavi;S. Alireza Davari;Vahab Nekoukar;Cristian Garcia;Jose Rodriguez;
      Pages: 1332 - 1344
      Abstract: A model-free predictive zero-sequence current (ZSC) control is presented in this article for the dual-inverter-fed open-end winding induction motor (OEWIM). The proposed method is performed in a cascaded finite set predictive control approach to decrease the computational burden. In the proposed method, a state observer estimates the ZSC and its disturbances. The estimated ZSC is suppressed by a disturbance rejecting control loop that produces the reference of common-mode voltage (CMV). As a benefit, the motor parameters have not appeared in this process, which improves the robustness of the whole control system. To reduce the computational burden, the model-free predictive control (MFPC) is implemented in two cascaded stages. First, the predictive algorithm is performed for the voltage vectors (VVs) with zero CMV to detect the optimum zone of the space vector locations. In the second stage, the proposed MFPC is implemented with the VVs of the selected zone, and the optimum VV is achieved. In this way, the predictive algorithm is iterated 13 times. On the contrary, the conventional predictive algorithm is iterated 27 times for the VVs of the dual inverter. So, the calculation of the proposed method is reduced almost 50%. This feature is achieved without neglecting any of the VVs. Therefore, the performance of the proposed method is not degraded by reducing the calculations. A comparative analysis is carried out through simulations and experimental tests. The results confirm that while the proposed MFPC method is computationally efficient, its performance and robustness are also improved.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Computationally Efficient Predictive Current Control With Finite Set
           Extension Using Derivative Projection for IM Drives

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      Authors: Haotian Xie;Fengxiang Wang;Qing Chen;Yingjie He;José Rodríguez;Ralph Kennel;
      Pages: 1345 - 1357
      Abstract: This article proposes a computationally efficient predictive current control (PCC) combined with an extension of a finite set using current derivative projection, to solve the challenges experienced by finite control set PCC (FCS-PCC), that is, unsatisfied steady-state performance and high computational burden. Since only one switching sequence is utilized in the entire sampling period, FCS-PCC is inevitably penalized by the high torque and current deviations. More specifically, FCS-PCC suffers from the high computational burden caused by the exhaustive search in the optimization stage. To tackle the aforementioned issues, a reformulated objective function using current derivative projection with least-squares (LSs) optimization in PCC is presented in this work. First, PCC is geometrically described as a quadratic programming (QP) problem. To minimize the deviation between the selected and desired current derivative, the objective function is rearranged as the quadratic Euclidean norm of the derivative deviation. The exhaustive search in the optimization stage is avoided by a preselection principle. Based on the above, the optimal stator current derivatives in the consecutive sampling intervals combined with their duty cycles are optimized by the LS method. The effectiveness of the proposed method is verified by the experimental results based on a 2.2-kW IM drive platform.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Decoupled Discrete Current Control for AC Drives at Low
           Sampling-to-Fundamental Frequency Ratios

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      Authors: Meiqi Wang;Giampaolo Buticchi;Jing Li;Chunyang Gu;David Gerada;Michele Degano;Lie Xu;Yongdong Li;He Zhang;Chris Gerada;
      Pages: 1358 - 1369
      Abstract: Implementation of proportional–integral (PI) controllers in the synchronous reference frame (SRF) is a well-established current control solution for electric drives. It is a general and effective method in digital control as long as the ratio of sampling-to-fundamental (S2F) frequency ratio, $r_{mathrm {S2F}}$ , remains sufficiently large. When the aforesaid condition is violated, such as operations in high-speed or high-power drives, the performance of the closed-loop system becomes incrementally poor or even unstable. This is due to the cross-coupling of the signal flow between $d$ - and $q$ -axes, which is introduced by the SRF. In this article, an accurate model of current dynamics, which captures the computational delay and PWM characteristics in the discrete-time domain, is developed. This motivates the investigation of eliminating cross-coupling effects in permanent magnet synchronous motor (PMSM) drive systems. A new current control structure in the discrete-time domain is proposed targeting full compensation of cross-coupling effects of SRF while improving dynamic stiffness at low S2F ratios. The matching simulation and experimental results carried out on a 5-kW high-speed drive corroborate the theoretical analysis.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Grid Current Control for Active-Front-End Electric Propulsion Systems in
           AC Ship Microgrids

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      Authors: Diego Pérez-Estévez;Jesús Doval-Gandoy;Alberto Crego-Lourido;
      Pages: 1370 - 1384
      Abstract: This article proposes a finite control set (FCS) current controller for grid-tied converters, specifically tailored to meet the characteristics of ac ship microgrids in all-electric ships (AESs). Contrary to a pulsewidth modulator (PWM)-based design, which often employs an LCL filter, the proposal is able to meet applicable harmonic regulations using an L filter with the same total inductance as the LCL filter and the same switching frequency required by PWM-based solutions. Moreover, the proposed design provides a low sensitivity in a wide frequency range from dc to the switching frequency of the power converter. This low sensitivity permits to quickly attenuate low-order disturbances and it is particularly convenient in marine applications with a weak grid, where the frequent connection and disconnection of high power nonlinear loads can significantly affect the voltage waveform quality.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Improved Flux-Weakening Method With Excitation Current Distribution for
           Hybridly Excited Asymmetric Stator Pole Doubly Salient Machine Based on
           Electrical Vehicle

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      Authors: Wei Xu;Chen Cao;Yishu Zhang;Shoudao Huang;Jian Gao;
      Pages: 1385 - 1396
      Abstract: The hybridly excited asymmetric stator pole doubly salient machine (HEASPDSM) has demonstrated great attraction to electrical vehicle (EV) for its strong robustness, while it suffers poor torque capability during the high-speed operation range. In order to solve such a problem, an improved flux-weakening method with excitation current distribution is proposed for the HEASPDSM in this article. First, the machine topology and the operating principle are briefly introduced. Second, the mathematical model is established, and the flux-weakening analysis is given out. Third, an excitation current distribution method has been put forward to the whole speed range along with the maximum torque per ampere (MTPA), the current and voltage limit (CVL), and the maximum torque per voltage (MTPV) from low to high operation automatically, which can widen the speed range and strengthen the torque capability. Finally, the feasibility of the proposed algorithm has been fully validated by both simulation and experimental results.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Integrated Control Strategy for Distortion Current Elimination of
           Fault-Tolerant Open-End Winding Permanent Magnet Synchronous Machine With
           Topology Reconfiguration

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      Authors: Jiadan Wei;Xianghao Kong;Ying Hong;Zhuoran Zhang;Bo Zhou;Wei An;
      Pages: 1397 - 1406
      Abstract: This article proposes a reconfigured topology of a five-leg inverter for the open-end winding permanent magnet synchronous machine (OW-PMSM) driving system after the device fault condition. Due to the asymmetric structure and common dc bus of the reconfigured fault-tolerant five-leg inverter, the zero-sequence current generated by the dead-time effect and inherent third harmonic voltage of the open-end winding will deteriorate the output torque and the efficiency of the driving system. Thus, the asymmetric property and dead-time effect of the five-leg inverter on the distortion currents of OW-PMSM are analyzed, and an integrated control method with the closed-loop of zero-sequence current and the compensation of dead-time effect and third harmonic voltage are employed to suppress the distortion current for the low-current total harmonic distortion (THD) of the OW-PMSM. The effectiveness and validity of the high-performance OW-PMSM driving system based on the five-leg inverter were verified by the simulation and experimental results.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Integration of Reference Current Slope Based Model-Free Predictive Control
           in Modulated PMSM Drives

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      Authors: Chenwei Ma;Jose Rodriguez;Cristian Garcia;Frederik De Belie;
      Pages: 1407 - 1421
      Abstract: Conventional model-based predictive current control (MBPCC) suffers from high current ripple and system parameter dependence problem. To address these issues, a novel reference current slope-based modulated model-free predictive control (MFPC) is proposed in this article. In the proposed method, a reference current slope is obtained based on the current deadbeat solution. A reduced amount of active voltage vectors can then be determined in a straightforward way according to the reference current slope and the current slopes for the possible voltage vectors, thus avoiding enumerating operation in the conventional MBPCC. To reduce the current ripples, a two-vector modulation strategy is introduced to the proposed method. In addition, the current slopes for the possible voltage vectors are obtained in a model-free manner based on online measured data only to reduce the influence of parameter uncertainties on the controller. Here, the principles of the two-vector modulation are well-considered, and the current variations with the input voltage vectors from two sampling time intervals are used to estimate the current slopes for all the voltage vectors. As a result, even though two voltage vectors with variable time durations are applied in each control period, the current slope information can be refreshed every half control period, thus guaranteeing the reliability and accuracy of current predictions. The proposed method is verified on a permanent magnet synchronous machine (PMSM) setup to demonstrate its improved parameter robustness and steady-state performance.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Model Predictive Control With Duty Cycle Optimization and Virtual Null
           Vector for Induction Generator With Six Switch Converter

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      Authors: Paulo Roberto Ubaldo Guazzelli;Stefan Thiago Cury Alves dos Santos;José Roberto Boffino de Almeida Monteiro;Manoel Luís de Aguiar;
      Pages: 1422 - 1431
      Abstract: The incorporation of duty cycle optimization in the finite control set model predictive control increased its advantages, improving its steady-state performance and maintaining its fast dynamics. However, duty cycle optimization depends on the application of a null vector alongside the optimal vector, and some converters do not have a null voltage vector inherently. This is the case of the six-switch converter, a reduced switch count converter that replaces the back-to-back converter with only 50% of the number of switches, and whose union with predictive control has been little exploited. This article develops a model predictive control with duty cycle optimization for a variable speed turbine wind power system with the six-switch converter (SSC) connected to the grid and a squirrel cage induction generator (SCIG). Calculations are performed by the means of a virtual null voltage vector properly applied to the system. Experimental results show the proposed control technique improved the steady-state performance of the system, with lower torque ripples, active power ripples, and current total harmonic distortion, certifying the controller as a feasible technique for the application.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Model-Free Predictive Current and Disturbance Rejection Control of Dual
           Three-Phase PMSM Drives Using Optimal Virtual Vector Modulation

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      Authors: Sodiq Agoro;Iqbal Husain;
      Pages: 1432 - 1443
      Abstract: Model-based predictive current control (MBPCC) relies heavily on adequate system modeling and accurate parameters. The detailed models of dual three-phase permanent magnet synchronous motors (PMSMs) contain mutual cross-coupling dynamics which make it difficult to extract accurate parameters. Also, some of the physical parameters of PMSMs are generally nonlinear functions of current and rotor position. In this article, a model-free predictive current control (MFPCC) based on an ultralocal model and an extended state observer is proposed for an asymmetrical dual three-phase (ADTP) PMSM. The MFPCC method is shown to provide superior current regulation when compared to the standard MBPCC approach under uncertain parameter conditions. Furthermore, the harmonic currents and the current ripple in the ADTP PMSM drive have been regulated to near-zero values by using optimized voltage vectors comprised of virtual vectors and null vectors. A generalized center-aligned pulsewidth modulation (PWM) scheme is presented to facilitate the synthesis of the optimal virtual voltage vectors for implementation on a low-cost digital signal processing platform. The performance improvements of the MFPCC with optimal virtual vector modulation are verified and compared with the conventional MBPCC method in both simulations and experiments on a surface-mount type dual three-phase PMSM.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Predictive Stator Current Control of a Five-Phase Motor Using a Hybrid
           Control Set

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      Authors: Manuel R. Arahal;Federico Barrero;Mario Bermúdez;Manuel G. Satué;
      Pages: 1444 - 1453
      Abstract: Finite state model predictive control (FSMPC) of multiphase drives can use an extra number of inverter configurations compared with the three-phase case. This, however, requires more computing power for the optimization phase. The application time of each selected voltage vector (VV) is then increased, which can result in higher harmonic content. Reducing the allowed VVs can speed up the computations, thus ameliorating the current tracking/regulation in different orthogonal subspaces. However, the flexibility offered by the reduced set of VVs is less than that of the full set. Furthermore, a lower sampling time can result in an increase in the switching frequency, especially for some speed-load combinations. This article proposes the use of a hybrid scheme where the set of allowed VVs is not fixed but rather selected on-line according to the actual speed and torque producing stator current which are computed by the outer loop. A five-phase induction machine (IM) is used as a test bed for the proposal, showing improved results with respect to the nonhybrid case.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Speed Control for Variable Speed PMSM Drive System Using Nonlinear
           Variable-Horizon Predictive Functional Control

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      Authors: Taoming Wang;Guangzhao Luo;Chunqiang Liu;Zhe Chen;Wencong Tu;
      Pages: 1454 - 1465
      Abstract: Electrohydrostatic actuators (EHAs) adopted variable speed permanent magnet synchronous motor (PMSM) drive systems are widely used by surface actuation systems in more electrical aircraft. However, the dynamic performance and the antidisturbance performance of EHA need to be improved due to the limited dynamic response of variable speed PMSM drive systems and uncertain aerodynamic disturbance. To improve the transient-state operation, nonlinear variable-horizon predictive functional control (NVHPFC) is proposed for the speed controller of the variable speed PMSM drive system. By analyzing the relationship between the prediction horizon and the electromagnetic torque, a nonlinear variable predictive horizon strategy is presented, which replaces the fixed predictive horizon in classical PFC. Aiming to improve the prediction accuracy and antidisturbance performance of NVHPFC, a discrete prediction error compensation strategy is incorporated with the NVHPFC. Meanwhile, the stability of the proposed method is verified by the Lyapunov function in the discrete domain. Finally, simulation and experimental results of the proposed method show stronger antidisturbance, smaller overshoot, and shorter settling time performance compared with the classical PFC method based on a field-programmable gate array (FPGA) test bench.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Synchronous Optimal PWM With Continuous Switching-to-Fundamental Frequency
           Ratio

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      Authors: Kun He;Jian Li;Lifan Xiao;Yang Lu;Linghao Wu;Hongwu Chen;
      Pages: 1466 - 1476
      Abstract: In high-power applications, the synchronous optimal pulse width modulation (SOPWM) serves as a vital modulation method that achieves an excellent tradeoff between the switching losses and the current harmonic. However, the optimized pulse patterns of SOPWM are constrained due to the discrete pulse numbers, which leads to the underutilization of the allowable maximum switching frequency. Therefore, the corresponding current harmonic could not be reduced as low as possible. In response to this issue, the SOPWM with a continuous switching-to-fundamental frequency ratio is proposed in this article. First, the deduction of the traditional pulse patterns is introduced based on the symmetry of the voltage pulse waveform. Then, the principle of the proposed strategy is illustrated in detail, and an overall comparison with traditional SOPWM is given theoretically. With the proposed strategy, a considerable reduction of the current THD is achieved over almost the whole high-speed range, and the losses and efficiency of the system are analyzed by the finite element method (FEM). Finally, theoretical results are verified by simulation and experimental tests.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Parasitic Component Small-Signal Modeling and Control of a Practical CLLC
           Resonant Converter

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      Authors: Ashwin Chandwani;Ayan Mallik;
      Pages: 1477 - 1495
      Abstract: This article presents a comprehensive characterization of an asymmetric resonant CLLC dc/dc converter plant transfer function obtained using a generalized harmonic approximation (GHA)-based small-signal modeling approach. The effect of circuit parasitic components is comprehensively considered while deriving this model, and a quantified comparison of the resultant plant frequency response with a conventional first harmonic approximation (FHA)-based model is presented, which provides the designer insightful findings to design a robust and noise immune closed-loop compensator. Furthermore, a thorough explanation of a sliding mode control (SMC) along with detailed parameterization of the controller coefficients is provided by analyzing the system’s dynamic behavior and comparing the response with a conventional proportional–integral (PI)-based controller. In addition to the objective of designing a robust SMC controller, a phase shift-based secondary side modulation is introduced, which facilitates a significant reduction in the secondary side switching losses, thus enhancing the steady-state efficiency of the overall system. To validate and benchmark the open-loop plant response and controller dynamics, detailed steady-state results are elucidated for a 400–28- and 400–24-V voltage conversion at a rated load of 1 kW, with a resonant frequency of 500 kHz. Furthermore, a comprehensive experimental comparison between the proposed hybrid control scheme and the conventional PI controller is shown for two dynamic load changes corresponding to 10%–90% load step-up and 90%–10% load step-down. Quantification of dynamic response portrays a settling time reduction of 46.4% and an over/undershoot reduction of 33%, thus validating the robustness of the pro-osed control scheme.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • The Stability of LCL-Type Grid-Tied Inverter Based on Repetitive Control
           and Grid Voltage Feed-Forward

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      Authors: Feng Xu;Mingzhe Zhu;Yongqiang Ye;
      Pages: 1496 - 1506
      Abstract: The grid voltage feed-forward can improve the dynamic performance of the repetitive controller (RC), but it will seriously weaken the stability under non-ideal grid conditions. This article focuses on the stability and dynamic characteristics of a grid-tied inverter with RC and grid voltage feed-forward. The internal model filter of RC uses an infinite impulse response (IIR) filter to improve the steady-state performance. First, an equivalent digital control model with RC and feed-forward is established, the parameters of RC are designed, and the system’s stability is analyzed based on the small gain theorem. Then, it is verified that the stability of RC in the presence of grid impedance can be weakened by the feed-forward term, thus a better feed-forward scheme is required. In addition, the solution for weak grid condition is proposed, and different feed-forward algorithms are compared from various perspectives, which is concluded that the improved proportional and first-order differential feed-forward scheme has a better performance. Finally, the validity of the controller is verified by the experimental prototype of a single-phase $LCL$ -type grid-tied inverter.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Artificial Neural Network-Based Constrained Predictive Real-Time Parameter
           Adaptation Controller for Grid-Tied VSCs

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      Authors: Mohammad Mehdi Mardani;Radu Dan Lazar;Nenad Mijatovic;Tomislav Dragičević;
      Pages: 1507 - 1517
      Abstract: This article proposes a real-time algorithm for identifying the grid parameters, which is concurrently used for online tuning of the predictive controller in each iteration, in a grid-tied active front end (AFE) voltage source converter (VSC) applications. The algorithm is designed by inspiring from the concepts of the extended Kalman filter (EKF) and the model predictive control (MPC). The performance of the algorithm highly depends on the weighting factors of the algorithm. The artificial neural network (ANN)-based algorithm is used to find the optimal set of weighting factors among the ones in a parameter search block. An offline particle swarm optimization (PSO) is run to provide the data source for the parameter search block. The algorithm identifies not only the inductance but also the resistance of the grid. In addition, the hard constraints on the amplitude of the input and output variables are guaranteed. The validation of the proposed approach is performed experimentally and compared with the state-of-the-art conventional methods. The experimental results show that the proposed method could effectively stabilize the system in weak grid conditions and under wide impedance variations. In addition, the accuracy of the proposed impedance identification method is 96%.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Switching Loss Reduction Method for Instantaneous Reactive Power
           Compensator in Three-Phase Rectifier System

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      Authors: Nuilers Surasak;Hideaki Fujita;
      Pages: 1518 - 1529
      Abstract: This article discusses a switching loss reduction method for an instantaneous reactive power compensator (IRPC) of a rectifier system that consists of a three-phase synchronous rectifier and a buck converter. The compensator generates a compensating current to suppress the instantaneous reactive power produced by the rectifier, resulting in a sinusoidal three-phase grid current. Zero-voltage switching (ZVS) and discontinuous pulsewidth modulation are used to reduce the switching power loss caused by the high peak of the compensating current in the compensator. A new dead-time compensation method is developed based on switching current estimation to reduce the harmonic distortion of the grid current. A 4.5-kW experimental setup was used to verify the effectiveness of the proposed methods. These methods are found to improve the grid current with a total harmonic distortion (THD) of around 3% and a peak efficiency of 99.2%.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • An Improved Master-Slave Control Strategy for Automatic DC Voltage Control
           Under the Master Station Failure in MTDC System

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      Authors: Min Yang;Xuejun Pei;Man Zhang;Youwen Zhang;Hanyu Wang;
      Pages: 1530 - 1541
      Abstract: The master-slave (MS) control is often used in multi-terminal direct current (MTDC) system due to its stable dc voltage control and precise power regulation. However, the MS switching, which aims to maintain dc voltage control under the master station failure, relies heavily on the high-speed communication between the power dispatch center and each station. Some methods in existing works are proposed to address the high communication dependence, at the cost of steady-state control performance. In this article, an improved MS control including five-state control process is proposed to realize the automatic MS switching without communication participation. Based on logic judgment, the multilayer dc voltage clamping mechanism is created to enhance the redundancy of the dc voltage control, and a reasonable dc voltage recovery process is included to eliminate the dc voltage deviation caused by the master station failure. Furthermore, the power and dc voltage hybrid controller are developed to improve the dynamic performance of each station during the MS switching. Simulation and experimental results demonstrate the effectiveness and advantages of proposed method.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Low-Frequency Passivity-Based Analysis and Damping of
           Power-Synchronization Controlled Grid-Forming Inverter

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      Authors: Fangzhou Zhao;Xiongfei Wang;Tianhua Zhu;
      Pages: 1542 - 1554
      Abstract: This article presents a passivity-based analysis and damping method for the low-frequency dynamics of grid-forming (GFM) control. A closed-form analytical solution to the positive realness of control input admittance is developed, which reveals the inherent nonpassive property of GFM control. This feature gives rise to the risk of instability, especially in connection with a nearby nonpassive GFM inverter, which may induce undesired control interactions. It is further revealed that the passivity index is determined by a low-frequency resonance around 10 Hz in the dq -frame, and this resonance can be better dampened, therefore, with enhanced passivity index, by using a virtual reactance (VRA) than using a virtual resistance (VRS). Finally, the theoretical findings are verified by the experimental results.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Fixed-Frequency PWM Control and Stability of Series-Stacked Buffer for
           2ω-Power Decoupling

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      Authors: Anwesha Mukhopadhyay;Vinod John;
      Pages: 1555 - 1567
      Abstract: Active second-harmonic ( $2omega $ ) filters have become an integral technology for single-phase power converters in high-power density designs. The series-stacked buffer (SSB) has emerged as an attractive topology among the existing solutions due to its low power, high efficiency, and compact design. However, one of the challenges in adopting SSB lies in its control, where hysteresis current control has been adopted conventionally. This results in a wide variation in the switching frequency, making the digital control implementation and filter design complex. On the other hand, fixed-frequency pulsewidth modulation (PWM) control necessitates developing a model for the systematic controller design to ensure stability and desired filtering performance. The assumption of SSB modeled as a second-harmonic current source, independent of the dc bus circuit components, fails to capture the dc bus loading effect on the SSB. In this work, a dynamic model of SSB is developed where the main dc bus and its passive elements are considered. The derived model enables a systematic approach for the controller design while ensuring the desired $2omega $ filtering. The stability limits and parameter sensitivities of the model are studied analytically and in simulations. The analytical model is validated, and the proposed controller performance and stability limit are verified experimentally on a hardware prototype. A video demonstrating the transition from stable to unstable operation is provided.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Closed-Form Implicit Models for Efficient Simulation of Power Electronics

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      Authors: Andrew S. Wunderlich;Enrico Santi;
      Pages: 1568 - 1577
      Abstract: This document describes novel closed-form implicit (CF-implicit) models of switched-mode power converters, which feature implicit integration but require no iterative numerical solving algorithm for evaluation because they are explicitly solved in CF prior to model execution. The derived models capture the large-signal dynamic behavior of the power converters, so their use and accuracy are not limited to any one set of operating conditions. These models can be directly implemented in any computational environment, including directly on an existing embedded controller. Since no iterative solver is required, the models are highly computationally efficient and have a very predictable worst case execution time (WCET), which makes them especially suitable for real-time (RT) modeling applications, such as hardware-in-the-loop (HIL) simulation or digital twins (DTs). The model derivation process is demonstrated by example on a two-stage power converter, and computational expense is analyzed. A discussion of model error is also included.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Distinguishing Between Cyber Attacks and Faults in Power Electronic
           Systems—A Noninvasive Approach

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      Authors: Kirti Gupta;Subham Sahoo;Rabindra Mohanty;Bijaya Ketan Panigrahi;Frede Blaabjerg;
      Pages: 1578 - 1588
      Abstract: With the increased cyberinfrastructure in large power systems with inverter-based resources (IBRs), it remains highly susceptible to cyber-attacks. Reliable and secure operations of such a system under a large signal disturbance necessitate an anomaly diagnosis scheme, which is substantial for either selective operation of relays (during grid faults) or cybersecurity (during cyber-attacks). This becomes a challenge for power electronic systems, as their characteristic response to such large-signal disturbances is very fast. Hence, we accumulate our efforts in this article to characterize them accurately within a short time frame. A novel noninvasive anomaly diagnosis mechanism for IBRs is presented, which only requires locally measured voltage and frequency as inputs. Mapping these inputs in a $XY$ -plane, the characterization process is able to classify between the anomalies within 5 ms. To the best of our knowledge, this mechanism provides the fastest decision in comparison to the existing techniques, which also assists the equipped protection/cybersecurity technology to take corresponding decisions without enforcing any customization. The proposed scheme is validated on many systems using real-time (RT) simulations in OPAL-RT environment with HYPERSIM software and also on a hardware prototype. The results verify the effectiveness, scalability, and accuracy of the proposed mechanism under different scenarios.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • An Improved Deadbeat Control Scheme for Unipolar Sinusoidal Current
           Excited Switched Reluctance Motor Drives

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      Authors: Jian Liu;Guofeng Wang;Di Liu;Yunsheng Fan;
      Pages: 1589 - 1603
      Abstract: This article reports on a novel deadbeat control (DBC) scheme to improve the current regulation performance of the unipolar sinusoidal excited control strategy for switched reluctance motors (SRMs). In this scheme, the deadbeat controller with delay compensation is first designed by using a second-order inductance-based SRM model in the rotating reference frame. This developed model can provide a more accurate description of the torque and electromagnet characteristics compared with the existing model. However, ignoring the magnetic saturation during the modeling inevitably leads to uncertainties in the proposed DBC system. To further estimate the disturbance caused by these uncertainties and improve robustness, a simple adaptive disturbance observer (ADO) based on the steepest descent method is embedded in the deadbeat controller. Then, a stability analysis based on the discrete-time Lyapunov function is used to guarantee convergence and tune the adaption gain of the proposed ADO. Finally, comparative experiments under different operation conditions are carried out on a three-phase 12/8 SRM prototype to verify the effectiveness of the proposed scheme.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Finite-Time Disturbance Observer of Active Power Filter With Dynamic
           Terminal Sliding Mode Controller

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      Authors: Juntao Fei;Lunhaojie Liu;Yun Chen;
      Pages: 1604 - 1615
      Abstract: This article proposes an adaptive dynamic terminal sliding mode control (ADTSMC) based on a finite-time disturbance observer (FTDO) for a single-phase active power filter (APF). Aiming at the internal parameter fluctuations and external unknown disturbances in the APF system, an FTDO is designed to compensate for the unknown uncertainties. Then, the proposed dynamic terminal sliding mode control (DTSMC) method combines the dynamic sliding mode control and the terminal sliding mode control to achieve finite-time convergence and weaken system chattering. In order to ensure the organic combination of FTDO and DTSMC, a dual-hidden-layer recurrent neural network (DHLRNN) is used to estimate the gain of sliding mode switching term adaptively so that FTDO can achieve the maximum disturbance estimation. Hardware experiments verify that the designed ADTSMC method has satisfactory robustness and harmonic compensation property under different nonlinear loads.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Control Study for Compensating Rotor Vibration of Four-DOF Six-Pole Hybrid
           Magnetic Bearings Based on Variable Step Size LMS Algorithm

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      Authors: Jiaming Shi;Huangqiu Zhu;
      Pages: 1616 - 1626
      Abstract: In order to solve the problem that the unbalance vibration caused by rotor mass eccentricity of the four-degree-of-freedom (four-DOF) six-pole hybrid magnetic bearings (HMBs), a feed-forward compensation control strategy based on variable step size least-mean-square (LMS) adaptive filter is proposed. First, the structure, operation principle and mathematical model of the four-DOF six-pole HMBs are introduced, the motion law of rotor vibration is analyzed, and the dynamic equation is derived. Second, the variable step size LMS adaptive filter is improved by using the Versoria function. The step size of LMS algorithm is adjusted adaptively by using Versoria function model and Takagi–Sugeno (TS) fuzzy inference machine. The LMS adaptive filter can generate a signal with the same frequency, amplitude, and phase as the rotating speed to offset the vibration signal, so as to realize the vibration compensation control of the four-DOF six-pole HMB rotor. Finally, the simulations and experiments not only prove the effectiveness of this method but also show that the method has good compensation accuracy. The result shows that the Versoria function used in variable step size LMS adaptive filter for vibration compensation is better than the traditional variable step size filtering algorithm based on Sigmoid function.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Compact MV-Insulated MHz Transformer-Coupled Gate Driver With Staged
           Turn-Off Scheme for Series-Connected Power Devices in DC Circuit Breaker
           Applications

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      Authors: Jian Liu;Lakshmi Ravi;Rolando Burgos;Steve C. Schmalz;Andy Schroedermeier;Dong Dong;
      Pages: 1627 - 1638
      Abstract: The short-circuit protection equipment of dc circuit breaker (DCCB) is important for the dc grid. Also, the series-connected power devices are usually employed in the solid-state circuit breaker (SSCB) or hybrid circuit breaker (HCB) to meet the clamping voltage requirement. A simple passive gate driver and power supply solution is a critical component to drive the circuit breakers more cost-effective and reliable. This article proposed a novel compact MV-insulated transformer-coupled gate driver method, which combines the auxiliary power and gate signal together. The proposed high-frequency-modulated multilevel transformer voltage enables both the simultaneous and the staged turn-off schemes. Besides, the cascade high- and low-voltage transformer structures simplify the insulation design and demonstrate better scalability. The common-mode current could be suppressed as well using this structure. The design example of a compact 2-MHz high-voltage planar transformer with >13-kV partial-discharge-free insulation capability is illustrated. Finally, the simulation and experimental results are also given to demonstrate the feasibility of the proposed gate driver method.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Droop-Based Adaptive Power Management System for Energy Storage
           Integration to DC Grid Using a Modified Dual Active Bridge Converter

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      Authors: Sanjib Kumar Mitra;Srinivas Bhaskar Karanki;
      Pages: 1639 - 1649
      Abstract: This article proposes an adaptive power management system (APMS) for energy storage integration to the dc grid using a modified dual active bridge (DAB) bi-directional dc–dc converter (BDC). The converter can achieve high voltage (HV) gain and zero voltage switching (ZVS) for a wide range of loading conditions with distributed voltage stress. An APMS is designed with a voltage droop control-based model reference adaptive control (MRAC). A reduced-order harmonic model of the converter is used for the APMS design. The proposed APMS does not require detailed knowledge of the system parameters and is also robust to uncertainty and multiple disturbances. The proposed converter and its control technique are verified in MATLAB/SIMULINK platform. An experimental laboratory prototype is also developed for 500 W rating, and the results are presented to validate the system’s efficacy by comparing it with conventional proportional-integral (PI) and sliding mode controllers.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Variable Self-Tuning Horizon Mechanism for Generalized Dynamic
           Predictive Control on DC/DC Boost Converters Feeding CPLs

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      Authors: Chuanlin Zhang;Mingdi Li;Liwen Zhou;Chenggang Cui;Long Xu;
      Pages: 1650 - 1660
      Abstract: In high-power electronic industrial systems, constant power loads (CPLs) can affect the system performance or even cause instability due to its inherent negative impedance characteristics. Regarding this control issue, model predictive control (MPC) methods are generally applied to dc/dc converters feeding CPLs, aiming to achieve satisfactory control performance. However, they are mostly based on a fixed horizon design, whose optimal performance may be far from the desired one due to the change of operating conditions, e.g., different variation levels of CPLs. In this context, a novel generalized dynamic predictive control (GDPC) strategy employing a simple self-tuning horizon mechanism is proposed for the first time, allowing the controller to adaptively optimize the system transient-time performance even under largely-varied operating conditions. First, a disturbance observer is utilized to reconstruct the lumped disturbances within the system, which are subsequently brought into the control design through feedforward compensation loops. Second, an adaptive horizon is introduced into the generalized predictive control (GPC) design and rigorous stability analysis based on Lyapunov theorem is given. The effectiveness and performance improvement of the proposed regulation methodology are verified by both simulation and experimental studies in reference to the double-loop proportional-integral (PI) control and a benchmark GPC algorithm.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Graphic Weighting Factor Design Method for Finite Control Set Model
           Predictive Control of Power Converters

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      Authors: Linqiang Hu;Wanjun Lei;Ruixiang Li;Yichao Gao;
      Pages: 1661 - 1671
      Abstract: Finite control set model predictive control (FCS-MPC) has been widely used in the control of power converters. However, for converters with multiple optimization objectives, the design of the weighting factors in the cost function is a tricky problem. To solve the weighting factor design problem in multiobjective FCS-MPC, a graphic weighing factor design method is proposed in this article. First, the discrete control variables are taken into the prediction model to determine the state boundaries of each control objective under all the system states. Then, the priorities and weighting factors of the control objectives are determined and designed by adjusting the intersection area of these state boundaries, so as to optimize the system performance. Finally, the operating condition feedback is introduced to realize an adaptive adjusting of the weighting factors so that the relationship of the state boundaries between different control objectives will not be affected by the change of system operating condition, and the controller robustness can be guaranteed. Analysis and experiment are carried out based on the parallel three-level dc–dc system. The results show that the proposed method can effectively solve the weighting factor design problem of multiobjective FCS-MPC. It is simple, efficient, and robust.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Novel Robust Adaptive Nonsingular Fast Integral Terminal Sliding Mode
           Controller for Permanent Magnet Linear Synchronous Motors

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      Authors: Dongxue Fu;Ximei Zhao;
      Pages: 1672 - 1683
      Abstract: To realize the high-precision tracking control of permanent magnet linear synchronous motor (PMLSM) in complex working conditions, a control system with strong robustness must be equipped for PMLSM, so this article proposes a novel robust adaptive nonsingular fast integral terminal sliding mode control (ANFITSMC) strategy. First, a dynamical mathematical model of PMLSM is established to describe the thrust and unknown uncertainty in the motion process. Second, considering that the uncertain factors, such as external disturbances and high-frequency noises in the system, may cause the degradation of position tracking accuracy, a nonsingular fast integral terminal sliding mode control (NFITSMC) method that only requires position and velocity information to estimate the lumped uncertainty of the system is designed. Meanwhile, the adaptive control algorithm is used to estimate the lumped uncertainty dynamically in real time, thus weakening the chattering and improving the tracking accuracy. Also, the stability of this control system is proven by utilizing the Lyapunov stability theory. Finally, the high-precision positioning experimental platform is used to carry out experimental tests with different position trajectory commands. The experimental results show that the proposed ANFITSMC method not only enables the system to have higher control accuracy but also ensures a more robust performance.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Improved ROGI-FLL-Based Sensorless Model Predictive Current Control With
           MRAS Parameter Identification for SPMSM Drives

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      Authors: Xuliang Yao;Shengqi Huang;Jingfang Wang;He Ma;Guowang Zhang;Yujian Wang;
      Pages: 1684 - 1695
      Abstract: This article presents a sensorless finite control set model predictive current control (FCS-MPCC) for surface-mounted permanent magnet synchronous motor drives based on an improved reduced-order generalized integrator-frequency-locked loop (IROGI-FLL). To simplify the structure of the sensorless FCS-MPCC and avoid control performance degradation caused by the rotor position estimation error, an instantaneous power theory-based given current calculation method is designed. Accordingly, the whole algorithm can be realized without using rotor position. IROGI-FLL is adopted for filtering the estimated back electromotive force and estimating motor speed. To enhance its dynamic speed tracking performance, a speed tracking deviation compensation term is designed for FLL. With the feedforward compensation term, speed static tracking deviation in acceleration and deceleration states can be eliminated. Moreover, to avoid the adverse effect of parameter mismatch on control performance, an incremental adjustable model-based model reference adaptive system (MRAS) is introduced to identify the resistance and inductance parameters. The incremental adjustable model can avoid identification error caused by the rank deficiency issue. Finally, the effectiveness of the proposed method is investigated by experiments.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Robust Loop Correction Scheme Based on Reference Model for Inverters in
           Weak Grids

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      Authors: Ningbo Dong;Mengfei Li;Xiaofei Chang;Huan Yang;Rongxiang Zhao;
      Pages: 1696 - 1704
      Abstract: Grid-connected inverters are widely used to interface renewable energy and energy storage resources into power grids. However, the impedance of the power transmission line is relatively large in weak grids, which can affect the stability of grid-connected inverters. In order to improve the stability of inverters in weak grids, a robust loop correction method is proposed in this article. First, a reference model with good stability is designed. Then, a high-pass filter is used to obtain the high-frequency components of the reference model response, and a low-pass filter is used to obtain the low-frequency components of the actual system response. The outputs of the two filters are added together to form the actual feedback current. Consequently, this method can correct the frequency characteristics of an inverter in high-frequency range, so that the inverter still has a good stability margin in a weak grid. The effectiveness of the proposed method is verified by both simulation and experimental results.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Novel Random High-Frequency Square-Wave and Pulse Voltage Injection
           Scheme-Based Sensorless Control of IPMSM Drives

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      Authors: Shuo Chen;Wen Ding;Xiang Wu;Ruiming Hu;Shuai Shi;
      Pages: 1705 - 1721
      Abstract: Signal injection-based sensorless control schemes for interior permanent magnet synchronous machine (IPMSM) drives at zero and low speed are generally troubled by the audible noise induced by the fixed-frequency injected signals and the control performance sensitive to voltage distortions. Aiming at that, a novel random high-frequency square-wave and pulse voltage injection (RHFSPVI) with novel signal demodulation method-based sensorless control of IPMSM drives is proposed. First, the power spectra density (PSD) analyses of conventional high-frequency square-wave voltage injection (HFSVI) and high-frequency pulse voltage injection (HFPVI) methods are carried out. On the basis of the analysis results, the simple form of random square-wave and pulse voltage injection is analyzed and designed to eliminate discrete harmonics in the current PSD spectrum for the audible noise reduction. Moreover, a signal demodulation scheme matched with the proposed injected form is designed to prevent the impact of voltage distortions on the position estimation accuracy. The capability of the proposed sensorless control scheme is verified on a 750-W IPMSM drive platform.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Highly Integrated Multichip SiC MOSFET Power Module With Optimized
           Electrical and Thermal Performances

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      Authors: Dingkun Ma;Guochun Xiao;Tongyu Zhang;Fengtao Yang;Mengyu Zhu;Tianshu Yuan;Liangjun Ma;Yongmei Gan;Laili Wang;
      Pages: 1722 - 1736
      Abstract: This paper proposes a highly integrated multichip silicon carbide (SiC) MOSFET power module packaging with optimized electrical and thermal performances. The structure of the module is to stack the two power switches up and down with the cooling system and the decoupling circuit integrated inside the module. The structural characteristics of the module realize the co-optimization of the switching performance, thermal management, and electromagnetic interference (EMI) issue of the multichip SiC module, which effectively solve the contradiction in the optimization of the electrical and thermal performance. In addition, by optimizing the process flow and designing a variety of soldering fixtures, the feasibility of the process and the engineering margin is increased. Experiments and simulations show that the proposed SiC power module has good electrical and thermal performance. The loop parasitic inductance is reduced to 2.02 nH and the common-mode (CM) current is eliminated. The drain–source voltage overshoot during the turn-off transient is reduced by 76.5%, and the voltage oscillation is significantly improved due to the integration of the decoupling circuit. At the same time, the integrated liquid-cooling heatsink greatly improves the cooling efficiency of the module on the premise of ensuring the insulation performance of the module.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Hybrid Si/SiC Switches: A Review of Control Objectives, Gate Driving
           Approaches and Packaging Solutions

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      Authors: Dereje Woldegiorgis;Md Maksudul Hossain;Zahra Saadatizadeh;Yuqi Wei;H. Alan Mantooth;
      Pages: 1737 - 1753
      Abstract: Hybrid silicon (Si)/silicon carbide (SiC) switches are gaining increased attention for designing high-efficiency and high-power density energy conversion systems. They offer very good conduction and switching power loss performance compared to using only Si insulated gate bipolar transistor (IGBT) or SiC metal–oxide–semiconductor field effect transistor (MOSFET) devices as a result of combining the best properties of both devices. Several Si/SiC gate control strategies, gate driving approaches, and packaging considerations have been proposed in the literature. This article presents a comprehensive review and performance comparison of different Si/SiC gate control strategies, gate driver solutions, and packaging approaches that are already proposed in the literature. In addition, it aims to provide a general guideline for selecting the appropriate Si/SiC gate control approach that is suitable for different applications considering several Si/SiC switch design properties. It also aims to establish a general metrics for evaluating the performance of different Si/SiC gate driver solutions that are proposed in the literature in order to help the designer choose a suitable gate driver solution for different applications. Moreover, it highlights future research and development needs of hybrid Si/SiC switches in terms of gate control techniques, gate driver approaches, and packaging solutions in order to achieve further performance improvements and fully exploit their benefits.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Analytical Modeling and Sensitivity Analysis on Plasma Extraction Transit
           Time (PETT) Oscillations in High-Voltage NPT p-i-n Diode

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      Authors: Ankang Zhu;Shuoyu Ye;Jianlong Kang;Zhen Xin;Haoze Luo;Francesco Iannuzzo;Wuhua Li;Xiangning He;
      Pages: 1754 - 1766
      Abstract: A comprehensive research on the analytical model and influence factors of plasma extraction transit time (PETT) oscillation during reverse recovery process of non-punchthrough (NPT) p-i-n diode is presented in this article. First, the experimental platform is setup to evaluate PETT oscillation under various conditions, and the result demonstrates that the oscillation on gate voltage is induced by the mutual inductance with oscillation loop. In addition, a physical model is established to investigate the features and occurrence condition of PETT oscillation based on the operating rule of electrical field and excess carrier inside diode. Furthermore, the time and frequency characteristics are defined, and the influence of load current, bus voltage, junction temperature, and switching speed is investigated based on the experimental waveforms. The analytical model illustrates that the time features increase with current logarithm and reciprocal of bus voltage, which is consistent with experimental results.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Steady-State Performance Optimization of Dual-Bridge Series Resonant DC/DC
           Converters

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      Authors: Wensheng Song;Shuai Yin;Yaru Deng;Ming Zhong;
      Pages: 1767 - 1777
      Abstract: By establishing the mathematical model of the resonant-tank root-mean-square (rms) current of the dual-bridge series resonant dc/dc converter (DBSRC), this article comparatively analyzes the performance of the DBSRC under asymmetric-phase shift (APS) control. This article analyzes the influence of the dead-time gap on APS control. Then, a steady-state performance optimization strategy is proposed in this article for DBSRC under APS control considering the dead-time gap, and the proposed control scheme is analyzed and implemented. The steady-state performance optimization strategy can minimize the resonant tank rms current, extend the zero voltage switching (ZVS) range, eliminate the influence of the dead-time gap and enhance the transmission efficiency of the DBSRC. Besides, the resonant tank parameters sensitivity of the proposed optimization strategy is discussed, and a simple parameters estimation strategy is proposed. At last, the excellent performance and theoretical analysis of the steady-state optimization strategy have been verified in this article.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Optimal Design of a Matrix Planar Transformer in an LLC Resonant Converter
           for Data Center Applications

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      Authors: Mingxiao Li;Chang Wang;Ziwei Ouyang;Michael A. E. Andersen;
      Pages: 1778 - 1787
      Abstract: The 48-V bus converter has been gradually adopted in intermediate bus architecture. The ever-growing development of data centers consumes significant power, thereby pushing power converters to be more efficient. This article focuses on the optimization of the transformer for an LLC resonant converter used in data centers, which is the second stage operating as a dc transformer to realize the isolation and a fixed voltage step-down ratio. The front stage is a multiphase buck converter. The magnetic core geometry reported in this article for the LLC enables a single turn for both primary and secondary windings. Compared with the previous research, the improved interleaving winding scheme benefits from reduced conduction path, lower ac resistance, and smaller core volume. Ansys 3D simulation performs the design and optimization of the magnetic core. The proposed magnetic core, winding layout, and design optimization are verified in the 30-/5-V 660-W LLC resonant converter. It has higher current stress but achieves a higher efficiency of 97.7%, better thermal performance, and lower components count than the state of the art.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Matrix Converter Based on Trapezoidal Current Injection

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      Authors: Jiaxing Lei;Xinlin Huang;Patrick Wheeler;Yihui Xia;Jianfeng Zhao;Wu Chen;
      Pages: 1788 - 1800
      Abstract: The matrix converter (MC) is a direct ac–ac power converter featuring high power density and high efficiency. However, the conventional MC (CMC) topologies require high control complexity and high transistor capacity, hindering the wide applications. An emerging MC topology (3CI-MC) based on the third-harmonic current injection (3CI) reduces the control complexity, but requires more transistors and a complex clamping circuit. This article proposes the trapezoidal current injection (TCI) technique to form a novel MC topology (TCI-MC), which consists of a line-commutated converter (LCC), a TCI circuit, and a voltage source converter (VSC). Compared with the 3CI-MC, the proposed TCI-MC not only maintains the advantages of simple modulation and independent voltage control but also achieves lower current stress on the LCC part of the circuit. The total transistor capacity (TTC) of the proposed TCI-MC is the lowest among all the considered MC topologies. The clamping circuit is also simplified and the bidirectional switches are eliminated, reducing the implementation cost. Simulation and experimental results have verified the validity of the proposed topology.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Flattop Modulation Technique for a Low-Device Count Single-Stage AC-DC DAB
           Converter to Improve Its Overall Efficiency

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      Authors: Akhil Chambayil;Souvik Chattopadhyay;
      Pages: 1801 - 1814
      Abstract: This article proposes a flattop modulation technique for a single-stage, single-phase bidirectional ac-dc dual-active-bridge (DAB) converter for achieving a flattopped DAB inductor current. The flattopped DAB inductor current has a low root mean square (rms) value, and it improves the soft-switching performance of the converter. The novelty of the proposed technique is that it guarantees flattopped DAB inductor current throughout the ac line cycle and has direct control over the ac current. In this technique, sinusoidal pulse width modulation (PWM) is performed at the ac side bridge for direct ac current control. Sinusoidal phase shift modulation is performed at the dc side to generate a bridge output voltage with a pulsewidth identical to the ac side bridge. The high-frequency (HF) transformer turns ratio is appropriately selected to match the voltages at the DAB inductor’s ends. Thereby, flattop DAB inductor current is achieved throughout the line cycle. The proposed modulation technique ensures a regulated dc bus at the ac side and provides a ripple-free ac current by interleaving. The operation of the converter under the flattop modulation technique is analyzed in detail, and parameter design guideline is provided. Experimental results from a 2-kW converter prototype support the theoretical claims.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Single-Stage Isolated AC/AC Converter With Phase-Shifted Controller

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      Authors: Mohamed Atef Tawfik;Muhammad Ehab;Ashraf Ahmed;Joung-Hu Park;
      Pages: 1815 - 1826
      Abstract: This article proposes a single-stage ac/ac converter with a high-frequency link, which is suitable for multilevel converters. The proposed topology is a direct ac/ac converter without commutation problems, which solves the common issue of direct ac/ac converters. Moreover, four-quadrant switches commonly used in matrix converters, and unfolding bridges normally essential in conventional circuits, are unnecessary in the proposed circuit, which enhances the efficiency and cost. The converter control strategy is adapted based on a single-phase shift technique with constant switching frequency and 50% duty cycle. The control strategy achieves a wide range of zero-voltage-switching (ZVS) turn-on without any auxiliary circuit. Furthermore, the high-frequency transformer (HFT) is free from line-frequency components with minimized rms value of current. Hence, an HFT with reduced size can be realized. The converter also has a low total harmonic distortion (THD) load current. A new continuous-time transient model of the proposed converter is proposed based on the generalized average model (GAM). The derived model is used to design the proposed phase shift controller. Moreover, a detailed closed-loop transient analysis is presented. A prototype circuit is implemented to validate the theoretical analysis and the feasibility of the proposed converter.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • PESNet 3.0: A WRN-Based Communication Network With ±0.5 ns
           Synchronization Error for Large-Scale Modular Power Converters

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      Authors: Yu Rong;Zhiyu Shen;Jun Wang;Jianghui Yu;Boran Fan;Slavko Mocevic;Dushan Boroyevich;Rolando Burgos;
      Pages: 1827 - 1837
      Abstract: Emerging large-scale silicon-carbide (SiC)-based modular power converters are pursuing high-performance distributed control systems (DCSs). In particular, fast-switching-enabled novel control schemes raise the need for minimal synchronization error (SE) of communication networks. This article presents the development of a proposed power electronics system network (PESNet) 3.0 that features a sub-nanosecond (ns) SE and gigabits-per-second data rate. The White Rabbit Network (WRN) technology, originally developed for particle accelerators, has been embedded in PESNet 3.0 and tailored to be suited for large-scale high-frequency modular power converters. A simplified node-to-node phase-locked loop (N2N-PLL) and an improved precision time protocol (PTP) model has been proposed to lock both the frequency and phase of two independent clocks on two adjacent nodes. Subsequently, the stability analysis of the N2N-PLL is carried out with its closed-loop transfer function verified by digital perturbation injection (DPI). Finally, the experimental validation of PESNet 3.0 is demonstrated at both controller and converter levels. The latter is on a first-of-it-kind 10-kV SiC-MOSFET-based modular converter prototype operating at 12-kV dc-link voltage, 10-kHz switching frequency, and above 100-V/ns slew rate, verifying ±0.5 ns SE at 5 Gb/s data rate.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Multimode Control Scheme for Output Regulation and Voltage Balancing in
           a Stacked-Switch Resonant Converter With Extended High Efficiency for Wide
           Gain Range Applications

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      Authors: Reza Emamalipour;Siamak Derakhshan;John Lam;
      Pages: 1838 - 1853
      Abstract: In this article, a new hybrid comprehensive multimode control system is proposed for a stacked-switch bidirectional CLLC resonant converter for wide voltage gain applications. By configuring the presented leg with different switching patterns, the presented leg in the converter can operate in different modes: full-wave (FW), half-wave (HW), or voltage-doubler (VD) through the converter’s built-in circuit redundancy. The proposed hybrid control scheme consists of different control modes: variable frequency modulation, pulse-width modulation (PWM), and asymmetric PWM (APWM) control. Correspondingly, four voltage gain curves are derived from the proposed converter. With the proposed approach, the converter is able to achieve constant voltage regulation while constraining the range of switching frequency, allowing very high efficiencies to be realized for a wide range of input voltages. Soft-switching is achieved for all the semiconductor devices for the entire operating range. The steady-state and dynamic performances of the proposed hybrid comprehensive control system are verified through a proof-of-concept 400-V $sim ~1$ -kV/ 700-V, 1-kW laboratory prototype. Results confirmed that the efficiency is maintained between 95.03% and 96.97% throughout the specified input voltage range.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Novel Multilevel Inverter With Self-Balancing Capability of Capacitors
           Voltage; Structure, Modulation, and Operation

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      Authors: Shayan Pourfarrokh;Jafar Adabi;Firuz Zare;
      Pages: 1854 - 1864
      Abstract: This article presents a 17-level asymmetrical multilevel inverter (MLI) with a reduced number of components. This structure can also be used symmetrically to increase redundancy. It can be extended in a modular fashion to increase the number of output voltage levels. Moreover, the capacitor voltages are self-balanced and do not require a sensor to stabilize the voltage. Due to the application of a level-shifted modulation (LSM), most power switches are turned on and off at low and fundamental frequencies, which will significantly reduce losses. Other benefits of this topology are the inherent production of negative levels without H-bridge, reduced total standing voltage (TSV), and low total harmonic distortion (THD). Power loss analysis is also presented as well as calculation of capacitances. MATLAB simulation results and laboratory implementation are carried out to evaluate circuit performance in different operational conditions.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Design and Qualification of a 100-kW Three-Phase SiC-Based Generator
           Rectifier Unit Rated for 50 000-Ft Altitude

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      Authors: Jiewen Hu;Xingchen Zhao;Lakshmi Ravi;Rolando Burgos;Dong Dong;Richard Eddins;Sriram Chandrasekaran;Saeed Alipour;
      Pages: 1865 - 1878
      Abstract: Featuring higher blocking voltage, smaller parasitic elements, faster-switching speed, and a more compact package, wide bandgap (WBG) semiconductor devices like silicon carbide devices (SiC), can enable compact aircraft generator-rectifier units (GRUs) thus making them highly desirable. Yet, the combination of the increased voltages, high-power density, and the lower pressure environment associated with aircrafts can pose a significant threat to the converter operation due to the increased sensitivity to electric field ( $E$ -field) intensity inside the GRU components and their assembly. To this end, a comprehensive design and qualification of a 100-kW three-phase SiC-based GRU rated for a flight altitude of 50000 ft (11.6 kPa) is presented in this article. First, an insulation coordination based on Paschen-curve is proposed to improve the power density. High $E$ -field areas of the GRU are determined and preemptively solved with the use of an $E$ -field control methodology to prevent partial discharge (PD) under normal operating conditions. Second, the gate driver and electromagnetic interference (EMI) filter components are optimized for operation at 70 kHz. Finally, the insulation design is qualified through low-pressure PD tests, and it is verified that the unit successfully operates at rated conditions to achieve 33.3-kW/l power density, 99.2% efficiency, and PD-free operation at 50000 ft.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • High-Efficiency Interleaved Totem-Pole PFC Converter With Voltage Follower
           Characteristics

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      Authors: Jefferson Wilhelm Meyer Soares;Alceu André Badin;
      Pages: 1879 - 1887
      Abstract: High power density, efficiency, control simplification, and robustness are highly demanded for power factor correction (PFC) converters. This article proposes a totem-pole rectifier based on the switching cell with switching frequency modulation (SC-SFM). The SC-SFM features interleaved operation, soft commutation, and resistive characteristics with continuous conduction in the input inductor. The converter operates without needing sensors and a control loop for the current. Unlike conventional solutions or some sensorless converters, the converter does not require a fast control loop to shape the current since the current naturally follows the input voltage. Only one output voltage sensor and one input half-line cycle detector are required to achieve unitary power factor (PF) and regulated dc output voltage. A detailed analysis of the converter operation, including the operating principle, mathematical analysis, a small signal model, and control method, is presented, including the differences in operation from the conventional PFC rectifier with the diode bridge. Experimental results evaluate a 1-kW prototype with different switch technologies [insulated-gate bipolar transistor (IGBT), silicon carbide (SiC), and gallium nitride (GaN)].
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Burst Mode and Variable Frequency Voltage Sharing Control Mechanism for
           an Adjustable High Voltage Pulsed Converter

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      Authors: Chang-Hua Lin;Javed Ahmad;Ren-Hao Li;Hwa-Dong Liu;
      Pages: 1888 - 1900
      Abstract: This article presents a modular adjustable high-voltage pulse (MAHVP) generation system. The proposed MAHVP generation system uses a combination of full-bridge LLC resonant converters whose input terminals are connected in parallel and whose output terminals are in series to boost the output voltage; input parallel output series configuration efficiently increases the power holding capabilities of the overall system. The MAHVP generation system uses a novel burst mode and variable frequency voltage sharing (BMVFVS) control mechanism, the BMVFVS control mechanism senses the type of load if the MAHVP generation system needs to operate at a heavy load, it uses the variable frequency voltage sharing method to divide the power equally between the modules to enhance the overall performance. For light load conditions, the MAHVP generation system operates in burst mode, and the BMVFVS control mechanism combined with the frequency modulation technique is used to control the amplitude and pulsewidth of the output voltage smoothly and efficiently. A hardware prototype of 2.4 kW is developed, and experimental results are taken to verify the feasibility and validity of the proposed system, the maximum output voltage of the developed two-module prototype is tested up to 6 kV at the high efficiency of 97%.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Multiconstraint Design of Single-Switch Resonant Converters Based on
           Extended Impedance Method

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      Authors: Yifan Jiang;Heyuan Li;Yichao Liu;Junrui Liang;Haoyu Wang;Minfan Fu;
      Pages: 1901 - 1912
      Abstract: The single-switch resonant converter is attractive for low-cost high-frequency power conversion applications. However, the exiting design method needs complicated derivations to meet various practical demands, and it would become impossible as the circuit order increases. This article incorporates the extended impedance method to evaluate the potential designs. The practical demands can be mathematically represented by the inequality constraints. Given the design variables, the proposed design is able to improve the steady-state performance (like the system robustness, voltage gain, load insensitivity, efficiency, current stress, and voltage stress) for the existing resonant converters. A family of Class E inverters is designed to justify the generality and validity of the proposed design. The first case is a classical Class E inverter. The EIM-based design is able to improve the system robustness under 6% parameter variation. The second case is a Class E inverter with resonant input inductor. The EIM-based design is able to offer a wider voltage gain compared to the benchmark method. The last case is a Class E inverter using $pi $ network. Compared to the previous design approach, the proposed method is able to find a better design point, whose light-load efficiency is improved by 5%.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Transformer-Less Soft-Switching High-Gain PWM Boost Converter With Reduced
           Components and Increased Effective Duty Cycle

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      Authors: Ling Qin;Lei Zhou;Waqas Hassan;John Long Soon;Min Tian;Jingfeng Mao;Lei Ren;
      Pages: 1913 - 1928
      Abstract: A transformer-less soft-switching high-gain pulsewidth-modulation (PWM) converter is proposed in this article. The proposed converter is derived from a single-switch dual-inductor transformer-less boost converter by replacing the complementary diode connected to the switch with a synchronous rectifier switch. Moreover, the peak value of the reverse current of the rear-end inductor in continuous bidirectional conduction mode (CBCM) is regulated to exceed the input inductor valley current. Based on these two measures, the zero-voltage switching (ZVS) for all switches and the natural turn-off for the output diode are realized, and the effective duty cycle is enhanced. Besides, the proposed ZVS converter has the merits of fewer power components count, reduced voltage stress, and lower cost. Furthermore, the ringing issue in the original topology under light load or high input voltage conditions is eliminated. The operation principle, steady-state characteristics, dynamic model, soft-switching operation, and realization conditions are analyzed in detail, and subsequently, the parameter design method is elaborated. The proposed topology demonstrates an enhanced efficiency performance over wide operating operations with a maximum efficiency of 97.1%.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • An Active Power Decoupling-Integrated Reduced-Switch Current-Fed Switched
           Inverter

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      Authors: Pramit Nandi;Ravindranath Adda;
      Pages: 1929 - 1942
      Abstract: In recent literature, high-gain dc–ac inverters are employed in grid-connected photovoltaic (PV) systems. These inverters can have several features, such as shoot-through immunization and buck/boost capabilities achieving a wide range of operations with reliability and minimum distortion. One such example is the single-phase reduced-switch current-fed switched inverter (RSCFSI). This article proposes the enhanced boost control-based pulsewidth modulation (EBC-PWM) strategy for RSCFSI to improve the inverter’s dc–ac gain. Being a single-phase inverter, RSCFSI suffers from the double-line frequency ripple problem. However, a low-frequency (LF) ripple analysis reveals that the RSCFSI is also plagued with fundamental frequency ripple, which poses additional challenges for the active power decoupling (APD) integration and corresponding closed-loop controllers. Although both LF ripples can be alleviated using markedly large passive elements, the power density and reliability of the inverter worsen. In this article, an APD-integrated RSCFSI (APDRSCFSI) is introduced as a solution that deflects the aforementioned LF ripple energy to an auxiliary capacitor without adding more active switches. As a result, the inverter can employ smaller passive elements. In addition, the EBC-PWM strategy is also extended for APDRSCFSI, improving its dc–ac voltage gain and voltage stress. A closed-loop control technique that combines output voltage control and APD functionality is also illustrated. A hardware prototype is used to corroborate the advantages of APDRSCFSI.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Closed-Loop High-Frequency Current Shaping Method to Achieve Trapezoidal
           Transformer Current in a Current-Fed Dual Active Half-Bridge Converter for
           Minimum RMS Current and Wide-Range ZVS

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      Authors: Souvik Chattopadhyay;Bharath T;Sayan Samanta;
      Pages: 1943 - 1952
      Abstract: This article proposes the use of primary and secondary side duty ratio control along with the phase shift control in a current-fed dual active half-bridge (DAHB) converter to achieve trapezoidal transformer current, which results in zero voltage switching (ZVS) of all the switches and minimum rms current even at light loads, for a wide range of input voltage. The high-frequency transformer current is directly sensed at specific transition instants by a delay-adjusted sampling strategy to be used as control variables in a current control structure. This is better because the voltage control of capacitor voltages would have required more expensive sensors. A simple and accurate small-signal model of the converter is developed, and the relevant transfer functions are derived. The controller design details are provided. Finally, experimental results on a 1-kW laboratory prototype demonstrate the effectiveness of the closed-loop duty ratio control in achieving trapezoidal transformer current resulting in improved efficiency and ZVS of the switches, compared to a simple phase shift control.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Quasi-Resonant Switched-Capacitor-Based Seven-Level Inverter With Reduced
           Capacitor Spike Current

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      Authors: Ashutosh Kumar Singh;Rajib Kumar Mandal;Ravi Anand;
      Pages: 1953 - 1965
      Abstract: This article proposes a novel seven-level multilevel inverter (MLI) with integrated output voltage boosting functions. The inverter uses switched capacitors (SCs), a key component of a voltage-boosting approach, to achieve the goal of increasing the output voltage at the load end. Additionally, the MLI has the ability to automatically balance the capacitor voltages. The proposed inverter is more cost-effective and has lower conduction losses than those of its rivals since it has fewer components than competing designs. An inductor is used in the capacitor charging loop to both minimize dc source current spikes and enable quicker charging of the capacitor, thereby increasing the capacitor’s lifespan. This article provides a number of waveforms, including output voltage and current, under various loading conditions and modulation indices. A laboratory model is also employed to support the viability of the proposed topology. The performance of the system is verified using MATLAB/Simulink. At long last, the maximum achievable experimental efficiency of 98.77% and total harmonic distortion (THD) for output voltage and current were 20.44% and 0.54%, respectively, at 300 V and 1.2 kW load.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Novel Version of the Ripple-Modulation Technique for Enabling the Use of
           Single-Phase Buck Converters in VLC Applications

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      Authors: Juan Rodríguez;Juan R. García-Meré;Diego G. Lamar;Javier Sebastián;
      Pages: 1966 - 1978
      Abstract: Visible light communication (VLC) has recently emerged as a promising technology for alleviating the saturation of the radio frequency (RF) spectrum. VLC uses high-brightness light-emitting diodes (HB-LEDs) both for lighting and communication. In particular, the information transmission is carried out by performing fast changes of the light intensity emitted by the HB-LEDs. The conventional VLC driver includes a linear power amplifier (LPA) for reproducing the communication signal. Unfortunately, this approach penalizes the efficiency. During the last years, a wide variety of VLC drivers fully based on the use of switching-mode power converters (SMPCs) have been proposed to overcome the efficiency limitation. One of the most promising approaches is the ripple-modulation (RM) technique, which consists in using the output voltage ripple of an SMPC to reproduce the communication signal. However, the conventional RM technique has a major drawback: it can only be applied to multiphase buck converters. This work is focused on overcoming that limitation by introducing a novel version of the RM technique that enables the use of a single-phase buck converter. In this way, the work aims to reduce the required power-stage complexity, which is a critical parameter of HB-LED bulbs. Moreover, a novel output filter structure is proposed to reduce the total harmonic distortion of the reproduced signal. A ripple-modulated buck converter prototype was built with an output power and a switching frequency of 8 W and 2 MHz, respectively. Moreover, the reproduced passband modulation scheme provides a bit rate of up to 1.25 Mb/s with a communication range of 100 cm and a peak efficiency of 94%.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Voltage-Mode Variable-Frequency Controlled LLC Resonant Power Factor
           Correction Converter and Its Accurate Numerical Calculation Analysis

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      Authors: Huan Luo;Buxiang Zhou;Gao Liu;Tianlei Zang;Shi Chen;Xiang Zhou;Jianping Xu;
      Pages: 1979 - 1994
      Abstract: LLC resonant converter is a good candidate for single-stage ac–dc converter, which can realize both functions of power factor correction (PFC) and output voltage regulation, and contribute to the improvement of conversion efficiency and power density. However, voltage mode (VM) controlled single-stage half-bridge LLC PFC converter has the disadvantages of large dead-zone of input current and hard-switching operation, since there is no current control. Besides, the voltage ripple of input filter brings asymmetrical operation of the converter between the positive and the negative half-switching cycle. In order to solve these problems, this article presents a modified numerical calculation method, which can realize accurate characterization of the asymmetrical behavior of resonant current and voltage. Based on that, the switching frequency of LLC resonant converter for unity power factor (PF) is derived. A method of fitting the switching frequency is proposed to simplify the circuit implementation. A 250-W/48-V prototype has been built to verify the analysis results. Experimental results show that the proposed voltage-mode variable-frequency (VM-VF) controlled LLC resonant PFC converter can achieve high efficiency of up to 94.08% and power factor of 0.95 over the input voltage range of 180–260 VAC.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Single-Phase 5-Level Split-Midpoint Cross-Clamped (5L-SMCC) Inverter: An
           Alternative to the Two-Stage ANPC Topology

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      Authors: Sze Sing Lee;Shuyu Cao;Reza Barzegarkhoo;Majid Farhangi;Yam P. Siwakoti;
      Pages: 1995 - 2003
      Abstract: The conventional active neutral-point-clamped (ANPC) multilevel inverters are popular for single-phase applications owing to their advantage of mitigating high-frequency common-mode voltage (CMV). With the ac neutral connected to the midpoint of dc link, their voltage gain is restricted to only half. For boosting output voltage, a two-stage structure by adding a frontend dc–dc boost converter is commonly used. This article investigates the performance of the conventional two-stage 5-level ANPC inverter and proposes an improved topology by splitting the dc-link midpoint and cross clamping them to the dc-link capacitors. While using the same number of power devices and retaining the advantages of the conventional two-stage 5-level ANPC topology, such as high-frequency CMV mitigation and continuous dc source current, the proposed 5-level split-midpoint cross-clamped (5L-SMCC) inverter achieves several advantages, such as higher voltage gain, lower voltage across dc-link capacitors, lower inverter voltage stress, and natural voltage balancing for all capacitors without requiring any balancing controller or sensor. In addition, it saves one capacitor by eliminating the flying capacitor of the conventional 5-level ANPC inverter. The operation of the proposed 5L-SMCC inverter is thoroughly analyzed. For validation, simulation and experimental results are presented.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Novel Planar Nonlinear Coupled Inductor for Improving Light and
           Intermediate Load Efficiency of DC/DC Converters

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      Authors: Fei Li;Laili Wang;Bin Wu;Longyang Yu;Kangping Wang;
      Pages: 2004 - 2014
      Abstract: With the development of data center, the two-stage voltage regulator module (VRM) is paid considerable attention. Since CPU goes into sleep mode frequently and spends a lot of time working at intermediate load in our daily use, it is important to have high light and intermediate load efficiency. This article proposes a novel planar nonlinear coupled inductor with a three-layer sandwiched structure, in which a middle layer made of high permeability material is sandwiched between two side layers made of low permeability material. Its nonlinearity can be controlled by configuring permeability, saturation flux density, and thickness of the high permeability middle layer. Benefitting from the structure, it can improve light and intermediate load efficiency, due to high self-inductance and low coupling coefficient. Besides, an analytic model is derived to calculate self-inductance and coupling coefficient for quick design, and design guidelines are summarized. A nonlinear coupled inductor and a conventional inductor with constant coupling coefficient are fabricated to compare the performance. Compared with the conventional constant coupling coefficient inductor, the proposed nonlinear coupled inductor could effectively improve the efficiency at light and intermediate load.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Forced Air-Cooling Thermal Design Methodology for High-Density,
           High-Frequency, and High-Power Planar Transformers in 1U Applications

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      Authors: Minh Ngo;Yuliang Cao;Dong Dong;Rolando Burgos;Khanh Nguyen;Agirman Ismail;
      Pages: 2015 - 2028
      Abstract: Due to increased loss per unit volume in power transformers when operating at higher frequency, the increase in cooling system size can outweigh high-frequency transformer (HFT) size reduction benefits. Conventional air-cooling approach simply adopts oversized cooling fans with high airflow to keep the transformer below a temperature limit, resulting in a large footprint and high power consumption. For many applications using air cooling, more challenges arise when multiple transformers are placed in a dimension-constrained space in which free airflow from the cooling system is easily disrupted. This work seeks to address this tradeoff by presenting a high-density, low-profile, forced air-cooling system for HFTs. The combination of an epoxy resin cast transformer winding and converging air duct is proposed to minimize the heat transfer barrier from both the internal and external structures of the high-frequency power transformer. The air-cooling system design process is demonstrated with a 15-kW load test featuring two 500-kHz planar Litz-wire transformers. The proposed transformer cooling system achieves a power density of 635 W/in3, a peak height of 43 mm, and a cooling power consumption of 6.8 W. Compared to using a 120 $times120$ mm cooling fan, peak winding temperature is reduced to 8%, the cooling system volume is reduced to $3times $ , and a $4times $ reduction of cooling power consumption is achieved.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Modifications to PM-Assisted Synchronous Reluctance Machine to Achieve
           Rare-Earth Free Heavy-Duty Traction

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      Authors: M. Al-ani;A. Walker;G. Vakil;D. Gerada;C. Gerada;K. Paciura;
      Pages: 2029 - 2038
      Abstract: Automotive applications require electrical machines designed for high torque density, wide speed range, and low cost. NdFeB magnets can achieve a high torque density and wide speed range, and however, they have a high cost. Therefore, this article explores the capability of rare-earth-free (REF) design through a PM-assisted synchronous reluctance (PM-SynRel) motor. A PM-SynRel design with NdFeB has been used in this study where the NdFeB magnets have been replaced with ferrite magnets. Then, several modifications on the rotor have been made to ensure mechanical safety. Thermal analysis has been conducted last to evaluate the temperatures in the different machine parts to avoid exceeding the required limits. Finally, a prototype has been made and tested to validate the simulation results.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Phase Current Reconstruction Technique for Four-Phase Switched Reluctance
           Generator With Two Current Sensors

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      Authors: Vaibhav Shah;Gautam Kumawat;Saifullah Payami;
      Pages: 2039 - 2050
      Abstract: This article proposes a novel current reconstruction technique with two current sensors to reconstruct the phase currents in a four-phase switched reluctance generator (SRG). Conventionally with the asymmetric half-bridge (AHB) converter, four current sensors are employed, one in each phase for measuring the phase currents in SRG. In the proposed work, the AHB converter’s dc bus is split into the excitation bus and the generating bus. Two current sensors are employed, first in the excitation bus, measuring the energization current of the respective active phase during phase excitation. Also, the second current sensor is placed in the generating bus, measuring the generating current. The switching functions of the AHB converter are redesigned such that the phase current during free wheeling and deenergization flows through the generating bus. The proposed current reconstruction technique using linear algebraic equations facilitates the reconstruction of phase currents from two current sensors only. This is the first time that an article experimentally verifies the proposed phase current reconstruction technique for four-phase SRG, in which multiple phases are conducting simultaneously. Also, during power electronics switch fault, the proposed current reconstruction method successfully reconstructs healthy phase currents after isolating the faulty phase.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Variable Switching Frequency Space Vector Pulsewidth Modulation
           Technique Using Virtual Flux Ripple

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      Authors: Zhihuang Ruan;Wenxiang Song;Yunpeng Zhang;Gang Yao;Youguang Guo;
      Pages: 2051 - 2060
      Abstract: The variable switching frequency space vector pulsewidth modulation (PWM) technique based on current ripple prediction (CRP-VSFSVPWM) can effectively suppress electromagnetic noise, but its effectiveness depends on the accuracy of load parameters. In this article, a virtual flux ripple (VFR) prediction model is developed. Similar to the current ripple prediction model, it is also a time-domain ripple prediction model, but it does not require load parameters and has low complexity. Furthermore, a variable switching frequency space vector modulation strategy based on three-phase VFR is designed in this article. The proposed method is fully validated by comparison with the fixed switching frequency space vector modulation and CRP-VSFSVPWM on a three-phase inverter. Experimental results confirm that the proposed technique can significantly suppress electromagnetic noise while maintaining current harmonic performance, and its performance is not affected by load parameters.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Current Control Scheme for LC-Equipped PMSM Drive Considering Decoupling
           and Resonance Suppression in Synchronous Complex-Vector Frame

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      Authors: Zekai Lyu;Lijian Wu;
      Pages: 2061 - 2073
      Abstract: Permanent-magnet synchronous machine drive with sine wave filter has features of low insulation stress and current harmonics. However, the filter can affect the current control of machine. Specifically, the increased axes cross-coupling degrades the response performance in the transient state, and the introduced resonant frequency oscillations can make the system unstable. To solve the issues, a complex-vector frequency-domain model of LC -equipped permanent-magnet synchronous machine drive is established in this article. Moreover, a quantitative index related to the symmetrical extent of double-sided frequency responses is introduced to evaluate the performance. A decoupling strategy based on the modified complex-vector controller is proposed and compared against conventional methods in terms of decoupling performance and parameter robustness based on the aforementioned evaluation index. Furthermore, an active damping method based on virtual impedance in parallel with the stator inductance is proposed to suppress the resonance. The quantified double-sided frequency-domain analysis is performed to illustrate the relationship between cross-coupling and system stability. Then, the systematic codesign procedure of decoupling controller and active damping link in the $z$ -domain is proposed. Finally, the experimental results show that the proposed scheme can improve the overall control performance in both transient and steady states.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Double-Objective Global Optimal Model-Free Predictive Control for SMPMSM
           Drive System Based on DSVM

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      Authors: Rundong Liu;Hongmei Li;Yanan Zhou;Bin Chen;Peng Zhang;
      Pages: 2074 - 2083
      Abstract: To achieve the global optimization of stator current and inverter switching frequency, a double-objective global optimal model-free predictive control (MFPC) is proposed based on discrete space vector modulation (DSVM) for surface-mounted permanent magnet synchronous motor (SMPMSM) drive system. First, the double-objective invalid optimization area of the conventional DSVM-based finite control set (FCS) model predictive control (MPC) is revealed, and the reason is analyzed that the global optimal voltage vector cannot be achieved. Then, according to the distribution of the double-objective invalid optimization area, the voltage hexagon is divided into three subareas. In each subarea, the candidate voltage vector with the best current control performance (BC-CVV) is obtained. Moreover, the inverter switching number of the three BC-CVVs is used as a criterion, and the number of voltage vectors evaluated online is significantly reduced. As a result, the double-objective global optimal voltage vector is achieved without enumerating all the feasible voltage vectors. Finally, experiments under different operating conditions are implemented and the effectiveness of the proposed method is confirmed.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Fault-Tolerant Predictive Current Control of Six-Phase PMSMs With Minimal
           Reconfiguration Requirements

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      Authors: Pedro F. C. Gonçalves;Sérgio M. A. Cruz;André M. S. Mendes;
      Pages: 2084 - 2093
      Abstract: By manipulating the additional degrees of freedom of multiphase machines, inherent to this type of machine, fault-tolerant control strategies are able to keep multiphase drives in service after one or more open-phase faults (OPFs). Therefore, multiphase machines controlled by finite control set model predictive control (FCS-MPC) strategies are an excellent fit for critical systems, where reliability and excellent dynamic performance are necessary. However, the existing fault-tolerant FCS-MPC strategies typically require considerable changes to the structure of the control algorithm when transitioning between healthy and fault-tolerant modes of operation. Therefore, this article proposes a novel fault-tolerant predictive current control (FT-PCC) strategy with minimal reconfiguration requirements for the six-phase permanent magnet synchronous machine (PMSM) drives. The proposed method only requires the adjustment of current references during fault-tolerant operation and keeps the structure of the control algorithm unchanged. To validate this FT-PCC strategy, several simulation and experimental results are presented for different OPF scenarios, in which the excellent performance obtained with the proposed method is demonstrated.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Torque Ripple Minimization of Low-Speed Gimbal Servo System Using
           Parameter-Optimized ESO

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      Authors: Haitao Li;Siyi Yang;Yun Le;
      Pages: 2094 - 2103
      Abstract: Torque ripple of permanent magnet synchronous motor (PMSM) and load disturbances are the main influencing factors that restrict the application of PMSM in low-speed tracking systems. To improve the speed tracking precision of the gimbal servo system in control moment gyro (CMG) with multisource disturbances, this article proposes a composite control method based on parameter-optimized extended state observers (ESOs) with sliding mode control in the speed loop and PI control with a feed-forward compensation in the current loop. Three ESOs are employed to estimate the disturbances on the $d$ -axis current, the $q$ -axis current, and the load torque so that the controller can have the corresponding parts to compensate for the disturbances. In particular, aiming at the contradiction between the estimation quality of the observer and the sensitivity to the measurement noise, an appropriate cost function is designed to take a compromise between the lumped disturbances and measurement noise and optimize the parameters of the ESOs. Finally, simulation and experimental results on the gimbal servo system of magnetically suspended control moment gyroscope (MSCMG) show the effectiveness of the proposed methods.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Generalized Multilevel Inverter With Extended Linear Modulation Range
           and Instantaneously Balanced DC-Link Series Capacitors for an Induction
           Motor Drive

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      Authors: Tutan Debnath;K. Gopakumar;L. Umanand;Kaushik RajaShekara;Dariusz Zielinski;
      Pages: 2104 - 2113
      Abstract: The voltage drift control of series-connected capacitors across a single dc-link is the major challenge for a multineutral point-clamped (NPC) converter. This drifting is caused due to uneven currents drawn from the neutral points (NPs) during the PWM operation. This work presents the working principle of instantaneous voltage control of “ $n$ ” dc-link series-connected capacitors for an induction machine load. The mechanism of instantaneous voltage balancing is realized by ensuring zero instantaneous currents at each dc-link NP. To get zero instant currents at a dc-link NP branch, the phase terminals tapping on the dc-link are manipulated with the help of cascaded hybrid bridges (CHBs). Charge balancing of CHB capacitors is also taken care of by proper utilization of pole voltage redundancies. The detailed results are presented for a small-scaled inverter (nine-level) with three NPs (four dc-link capacitors). The simulation and experimental results reflect the capability and limitations of such inverters. The results are presented at all modulation indexes operated under low-power-factor (LPF) and high-power-factor (HPF) load conditions. It is found that the linear modulation range (LMR) can be increased to full base speed even for an HPF load.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Open-Phase Fault-Tolerant DTC Technique for Three-Level NPC VSI-Fed
           Five-Phase Induction Motor Drives

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      Authors: Bheemaiah Chikondra;Alejandro G. Yepes;Omar Al Zaabi;Khalifa Al Hosani;Jesus Doval Gandoy;Ranjan Kumar Behera;
      Pages: 2114 - 2125
      Abstract: The demand for motor drives based on multiphase machines (MMs) is increasing due to their inherent fault-tolerant capabilities. To achieve satisfactory post-fault operation, a proper fault-tolerant controller is needed. Some direct-torque-control (DTC) techniques have been reported for five-phase induction motor (FPIM) drives under an open-phase fault (OPF). DTC offers simplicity, fast response, and less parameter sensitivity. However, the existing fault-tolerant DTC methods were designed for two-level voltage-source inverters (VSIs). A three-level neutral-point-clamped (NPC) VSI allows greater flexibility in the switching states, lower current and torque ripple, and reduced common-mode voltage (CMV). However, the increased number of switching states requires the design of new DTC methods, able to tolerate OPFs while providing satisfactory performance in various aspects. In this article, two fault-tolerant DTC techniques are developed for three-level NPC VSI-fed FPIM drives under an OPF. The possible switching states are synthesized with suitable virtual vectors (VVs), addressing the dc-link voltage balance, ${text {d}v/text {d}t}$ , CMV, and dc-link utilization. The two methods are compared under an OPF in these terms, as well as regarding the average switching frequency. Comparative experimental results are provided to assess the viability of the developed DTC schemes at steady-state and dynamic conditions.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • An Accurate Inverter Nonlinearity Compensation Method for IPMSM Torque
           Estimation Based on Numerical Fitting

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      Authors: Zhiwei Chen;Tingna Shi;Yanfei Cao;Chen Li;Yan Yan;
      Pages: 2126 - 2138
      Abstract: The accurate compensation of inverter nonlinear voltages error (INVE) is of great significance in improving interior permanent magnet synchronous motor (IPMSM) field-oriented control system performance. In this article, the modeling and compensation of INVE are studied. First, the effect of parasitic capacitance between collector and emitter on INVE is divided into three cases, and specific mathematical models are given for different cases. Combining the INVE caused by the dead time, the turn-on and turn-off delay time of the switching device, and the voltage drop of the switching device and diode, an accurate INVE model is established. Second, to address the problem that it is difficult to deal with the relationship between $D(i_{X})$ and $D(i_{X}$ /2) in the INVE acquisition method based on self-commissioning, an accurate INVE acquisition method based on modeling and numerical fitting is proposed to realize the compensation of INVE. On this basis, torque estimation accuracy in steady-state operation is proposed as the criterion to judge the merits of INVE compensation. Finally, experiments verify the effectiveness and superiority of the proposed method.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • An Enhanced Predictive Current Control Scheme for Common Mode Voltage
           Alleviation and Improvement of Torque Response of PMSM Drive

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      Authors: M. L. Parvathy;Thippiripati Vinay Kumar;
      Pages: 2139 - 2150
      Abstract: Predictive current control (PCC) is an effective control scheme with provisions to handle multiple objectives and nonlinear constraints. In the conventional PCC (CPCC) scheme, the application of a zero-voltage vector (ZVV) leads to the generation of large common-mode voltage (CMV), which gradually leads to bearing damage. However, disregarding ZVV can suppress CMV at the expense of large distortions in stator current. To avoid this, the present work deploys synthesized voltage vectors (SVVs) obtained from adjacent active vectors (AAVs) for permanent magnet synchronous motor (PMSM) drive control. In this article, two techniques are proposed for alleviating the CMV. Two AAVs are applied for a fixed duration in the first proposed method. Thus, the effect of neglection of ZVV can be circumvented with the application of two AAVs. In the second method, multivectors are applied to ensure CMV suppression and improvement of the steady-state torque response. Furthermore, an effective voltage vector (VV) preselection scheme using the complex-plane concept is introduced. Unlike the conventional CMV reduction schemes, the proposed VV-preselection evades tangent inverse angle determination and complex transformations. This offers the advantage of reduced computational burden with improved steady-state torque performance. The effectiveness of the proposed schemes is validated by comparing them with CPCC and existing literature.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Novel SVPWM for Open Winding PMSM Drives With Simultaneous Common Mode
           Voltage Control and Full Frequency Zero Sequence Current Suppression

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      Authors: Lei Xu;Z. Q. Zhu;
      Pages: 2151 - 2163
      Abstract: Zero sequence voltage (ZSV) can cause zero sequence current (ZSC), while variation of common mode voltage (CMV) can cause bearing current in an open winding (OW) permanent magnet synchronous machine (PMSM) fed by common dc -bus dual two-level inverters. This article proposes a novel space vector pulsewidth modulation (SVPWM) strategy for simultaneously eliminating CMV variation and suppressing full frequency ZSC harmonics in either linear or over modulation region by optimal selection of switching combinations. The proposed SVPWM can reduce large ZSV ripples and number of switching actions in the conventional CMV control method for the common dc -bus OW drive. Thus, high-frequency ZSC harmonics and switching frequency can be significantly reduced in both linear and over modulation regions. Moreover, the proposed SVPWM can suppress large low-frequency ZSC harmonics induced by the conventional method in over modulation region. The superior performances of CMV variation elimination and full frequency ZSC suppression in the proposed SVPWM are verified by experiments.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Multiobjective Control Strategy for Harmonic Current Mitigation With
           Enhanced LVRT Operation of a Grid-Tied PV System Without PLL Under
           Abnormal Grid Conditions

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      Authors: Manash Kumar Mishra;Vivek Nandan Lal;
      Pages: 2164 - 2177
      Abstract: This article proposes a novel multiobjective control strategy (MOCS) for improving the performance of grid-tied photovoltaic (GTPV) system without phase-locked loop (PLL) operating under abnormal grid voltage conditions such as harmonically distorted voltages, grid faults, and weak grid. The proposed control strategy effectively mitigates the harmonics in grid injected current, eliminates the oscillations in grid injected power, and enhances the low-voltage ride-through (LVRT) capability simultaneously during abnormal grid conditions. The LVRT capability of the GTPV system is enhanced by incorporating an active power regulator (APR) with dynamic reactive power support (DRPS) controller in the proposed control strategy. The proposed MOCS is designed in the $alpha beta $ stationary reference frame. Furthermore, the proposed MOCS consists of an advanced phase compensated multiresonant (APCMR) current controller and a phase-shifted reference current generator (PSRCG) integrated with the APR with DRPS controller. The APCMR suppresses the grid current harmonics under weak and distorted grid voltages and the PSRCG eliminates active and reactive power oscillations at the grid side caused by grid faults. The synchronization mechanism of the GTPV system is included in the PSRCG, and therefore, the requirement of PLL is avoided. Consequently, the associated computational burden on the digital controller is reduced. The effectiveness of the proposed control strategy is validated using the OPAL-RT digital simulator and offers superior performance compared to the conventional control strategy (COCS).
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Recursive Selective Harmonic Elimination for Multilevel Inverters:
           Mathematical Formulation and Experimental Validation

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      Authors: Concettina Buccella;Maria Gabriella Cimoroni;Carlo Cecati;Antonino Oscar Di Tommaso;Rosario Miceli;Claudio Nevoloso;Giuseppe Schettino;
      Pages: 2178 - 2189
      Abstract: A recursive method that eliminates $n+1$ harmonics and their respective multiples from the output voltage of a cascaded H-bridge (CHB) multilevel inverters with $s=2^{n}$ dc sources $(n=1,2,3,ldots)$ is proposed. It solves $2 times 2$ linear systems with no singular matrices and always gives an exact solution with very low computational effort. Simulated results in three-phase five-, nine-, 17-, and 33-level CHB inverters, and experimental results in a five-level inverter demonstrate the validity of the method.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Practical Switch Condition Monitoring Solution for SiC Traction
           Inverters

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      Authors: Bhanu Teja Vankayalapati;Masoud Farhadi;Rahman Sajadi;Bilal Akin;Hui Tan;
      Pages: 2190 - 2202
      Abstract: As automotive manufacturers move toward silicon carbide (SiC) MOSFET-based traction inverters, practical online switch condition monitoring solutions are crucial to address potential reliability concerns. In this article, an end-to-end practical online condition monitoring (OCM) solution is proposed. An online sensing circuit is proposed, which enables online ON-state resistance ( $R_{text {ds-}mathrm{scriptscriptstyle ON}}$ ) measurement for all six switches of the inverter. To address the challenge of periodic data acquisition alongside higher priority motor control tasks, a fast, code-efficient out-of-order equivalent time sampling (ETS) technique is also proposed. The obtained periodic, high-resolution $R_{text {ds-}mathrm{scriptscriptstyle ON}}$ data are filtered by a Kalman filter stage. With the proposed measurement solution, $R_{text {ds-}mathrm{scriptscriptstyle ON}}$ obtained at the motor current peak has an error of ${< }1.5%$ . Furthermore, the symmetrical nature of the inverter’s operation is exploited to propose a Bayesian inference solution for independent online state-of-health (SoH) estimation for all six switches. This technique isolates aging-related $R_{text {ds-}mathrm{scriptscriptstyle ON}}$ change from operating conditions-related changes. In particular, by automatically accounting for device- and system-level variations in the model, the proposed Bayesian SoH estimation solution eliminates the need for extensive system/device specific calibration. The efficacy and robustness of the proposed solution are tested by inducing bond-wire failure -n several decapsulated discrete SiC MOSFETs.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Simple and Effective Open-Circuit-Fault Diagnosis Method for Grid-Tied
           Power Converters—A New Technique Based on Tellegen’s Theorem

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      Authors: Mingyuan Zhang;Zhenbin Zhang;Zhen Li;Jinyu Wang;Yongfeng Zhang;Shiming Liu;
      Pages: 2203 - 2213
      Abstract: Grid-tied power converters are widely adopted in renewable energy integration systems. Reliable operation of such power converters is highly desirable, which relies on effective fault diagnosis and ride-through techniques. In this work, we propose a new open-circuit fault diagnosis method for grid-tied power converters based on Tellegen’s theorem, which is fast in fault detection and accurate in faulty component location. We first developed a “quasi-power” concept to define the relationship between current and voltage magnitudes for the underlying power converter. The value of the afore-developed quasi-power in this proposal depends solely on the connection state (i.e., the switch position and status) of a power converter, resulting in its good features of robustness to parameter variations and immunity to operation changes. Thereafter, we propose a fault diagnosis method based on the quasi-power of a converter, which is able to identify any faulty component among all the semiconductor switches (i.e., the insulated gate bipolar translators (IGBTs) and freewheeling diodes) at a time-scale of only one sampling period. As a case study, the proposed technique is incorporated into a well-known model predictive control (MPC) framework of a grid-tied two-level (2L) power converter and tested at a lab-constructed test bench. Experimental results confirm its effectiveness.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A General Diode Open-Circuit Fault Diagnosis Method for Autotransformer
           Rectifier Unit Considering Grid Voltage Disturbance

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      Authors: Chao Yang;Fanghua Zhang;Long Cheng;Zhaorong Zhang;
      Pages: 2214 - 2226
      Abstract: It is crucial for the reliable operation of the autotransformer rectifier unit (ATRU) to accurately diagnose diode open-circuit (OC) fault. However, grid voltage disturbance may lead to misdiagnosis by existing methods. This article takes the 18-pulse ATRU as an example and first analyzes its sag-based fault feature in the dc-link output voltage (DLOV) caused by diode OC fault under no grid voltage disturbance. Then, the reason for misdiagnosis under grid voltage disturbance is discussed. Subsequently, a general diode OC fault diagnosis method with strong immunity to grid voltage disturbance is proposed. In the proposed method, the DLOV waveform is divided equally according to the number of rectified pulses. Hausdorff distance (HD) algorithm is employed to extract the sag-based fault feature by calculating the similarity between the DLOV sampling sequence and the constructed template sequence. To be immune to grid voltage disturbance, the template sequence is adaptively generated as per the sampling sequence in each interval. Also, the generalized minimum failure mode is defined to normalize two sequences for good universality. With the help of the phase of grid single-phase voltage, OC faults can be detected and located according to the interval positions with the sag. Finally, simulation and experimental results confirm the strong immunity of the proposed method to grid voltage disturbance and its good universality to the different ATRUs.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Reliability-Oriented Optimal DPWM Strategy for Single-Phase Five-Level
           T-Type Inverter in PV Systems

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      Authors: Taerim Ryu;Ui-Min Choi;
      Pages: 2227 - 2235
      Abstract: Many efforts have been devoted to improving the reliability of PV inverters with a focus on reliability-critical components such as power devices and capacitors. Discontinuous pulsewidth modulation (DPWM) methods are representative of improving the reliability of power devices by decreasing their thermal loadings. However, although the DPWM method affects the ripple current of the DC-link capacitor, prior-art research is only focusing on the power devices. There is a lack of study on the effect of applying the DPWM method on the reliability of the DC-link capacitor. It may have a negative effect on the reliability of the DC-link capacitor and thus affects the reliability of overall PV inverters. In this article, the influence of the DPWM method with different clamping periods on the reliability of power devices and DC-link capacitors of the single-phase five-level T-type inverter is investigated, where a 7-kW PV system and annual mission profile of PV system are considered as a case study. Then, a reliability-oriented optimal DPWM strategy is presented for the target lifetime of the T-type inverter by considering system-level reliability, including the lifetimes of both power devices and DC-link capacitors.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Active Power Decoupling Control for PWM Converter Considering Sensor
           Failures

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      Authors: Jian Xiong;Jianzhong Zhang;Zheng Xu;Zakiud Din;Yeming Zheng;
      Pages: 2236 - 2245
      Abstract: The power converters integrated with active power decoupling (APD) may handle the ripple power in dc link and then reduce the volume of the filter capacitor dramatically. Generally, voltage and current signals of the LC branch are required for the closed-loop APD control. However, sensor failures could degrade the control performance and even lead to the breakdown of the converter system. This article proposes a detection method for sensor failures in the APD circuit of the single-phase converter. The voltage and current of the LC branch in the APD circuit are estimated by a dual sliding mode observer (SMO). The residuals of the estimated and measured signals are calculated, and they have high sensitivity to specific sensor faults, namely, the current residual is sensitive to the fault of the current sensor and the voltage residual is sensitive to the fault of the voltage sensor, which could be employed to locate the faulty sensors. Finally, the effectiveness of the proposed method is verified by the simulation and experimental results.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • An Adaptive Temperature Observer for Electrothermal Analysis of IGBT Based
           on Temperature Characteristics

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      Authors: Xiuchen Xiao;Xinglai Ge;Qianxia Ke;Linjin Yong;Yongkang Liao;Huimin Wang;Yichi Zhang;
      Pages: 2246 - 2258
      Abstract: Most of the existing methods for electrothermal analysis of the aging insulated gate bipolar transistor (IGBT) modules have limitations on performing synchronous recognition and decoupling of two typical aging models, and failed to be low-invasive and real-time. To address this, two characteristic functions are developed in this article. The characteristic functions are derived from the temperature response under periodic power loss excitation and can be extracted in real-time and low-invasively from the negative temperature coefficient (NTC) thermistor sensor integrated into the IGBT module. Then, a temperature observer based on the 3-D state-space model of the IGBT module is designed, which is based on the feedback from the characteristic functions, to achieve the target of online electrothermal analysis for the IGBT module even with the significant deterioration of the IGBT module. Finally, the performance of the proposed method is thoroughly investigated by extensive experimental tests.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Implementation of Global Maximum Power Point Tracking in Photovoltaic
           Microconverters: A Survey of Challenges and Opportunities

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      Authors: Dmitri Vinnikov;Andrii Chub;Roman Kosenko;Vadim Sidorov;Andre Lindvest;
      Pages: 2259 - 2280
      Abstract: This survey focuses on photovoltaic (PV) module-level power electronic systems. The survey demonstrates that dc-dc converters with a wide input voltage range can enable global maximum power point tracking (GMPPT). It discusses the requirements and challenges in the design and implementation of these converters. A wide input voltage range allows for implementing different algorithms of the GMPPT, among which the $I$ – $V$ curve scanning or sweeping is the most robust one. Special attention is paid to buck–boost high step-up dc-dc converter topologies as the most promising solution for residential applications suffering from shading issues. An example of such a converter is presented along with the corresponding implementation of the GMPPT by $I$ – $V$ curve sweeping. Several case studies of partial shading conditions are synthesized to compare the performance of the local and GMPPT algorithms. The obtained results demonstrate that the GMPPT shows superior performance under partial shading, while its performance is comparable to the conventional local maximum power point tracking (MPPT) under regular operation. The case studies are compared in terms of harvested energy, MPPT efficiency, and converter efficiency. The latter allows for better comparison as the partial shading could result in operation at a reduced input voltage with a measurable efficiency drop.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Battery Lifetime Extension in a Stand-Alone Microgrid With Flexible Power
           Point Tracking of Photovoltaic System

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      Authors: Hein Wai Yan;Glen G. Farivar;Neha Beniwal;Hossein Dehghani Tafti;Salvador Ceballos;Josep Pou;Georgios Konstantinou;
      Pages: 2281 - 2290
      Abstract: In stand-alone dc microgrids (dcMGs), battery energy storage systems (BESSs) are conventionally used for regulating the dc-link voltage, causing a continuous battery operation. Though operating the photovoltaic (PV) system at its maximum power point (MPP) yields minimum battery discharge current, the opposite is true for battery charging current. Therefore, reducing the battery charging current based on its state-of-charge (SoC) and the amount of available PV surplus power (which can be treated as virtually stored energy) is an opportunity for improving the battery life. The main objective of the control strategy proposed in this article is to prolong the battery lifetime by reducing the charging current and keeping the battery SoC at lower values if the PV power is enough to supply the loads. Additionally, the PV system is used as the primary asset to regulate the microgrid voltage. The dynamic performance of the proposed control strategy is validated with experimental tests under various operating conditions. Furthermore, its effectiveness in prolonging the battery lifetime is evaluated using an aging model of a lithium-ion (Li-ion) battery (without loss of generality) by simulated case studies.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Normalized Least Means Absolute Third-Based Adaptive Control Algorithm
           Design for Grid-Connected PV System

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      Authors: Diptiman Dey;Bidyadhar Subudhi;
      Pages: 2291 - 2299
      Abstract: This article presents design and real-time control of a single-stage grid-connected photovoltaic (SSGCPV) system. A normalized least means absolute third (NLMAT) algorithm has been employed to design an adaptive controller to achieve effective grid synchronization. The objective is to mitigate harmonics generated by nonlinear load and inject active power to the utility grid with unity power factor (PF). A 20-kW PV system with the above controller has been simulated using MATLAB/Simulink and then verified with a 1.4-kW prototype. A comparison of the proposed controller with least means fourth, variable step size least means square (VSS-LMS), variable leaky least mean square(VLLMS), and NLMAT algorithms has been made. It is found out that although the total harmonic distortion (THD) of the grid current remains within the prescribed limit of the IEEE-519 standard for all the three algorithms, the proposed controller outperforms among all. It provides reduced THD even with unbalanced loading and change in irradiance conditions.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Battery-Friendly DC–DC Converter With Ripple-Free Current
           Modulation Strategy

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      Authors: Zhixing Yan;Shunli Sun;Bo Fu;Dehai Cen;Ningrui Yang;Haixia Qi;Renjun Hu;Jun Zeng;Junfeng Liu;
      Pages: 2300 - 2310
      Abstract: In this article, a battery-friendly dc–dc converter with a ripple-free current technique is proposed interfaced battery energy storage system (BESS). Two-phase interleaved circuits are adopted to cancel the current ripple on the BESS side. On the high voltage (HV) side, the circuit combined with a half-bridge circuit and full-bridge circuit is employed to achieve voltage-second balance control. With the associated control strategy, the power control variables can be decoupled. The voltage-second balance control on two ends of the leakage inductor is realized by the adjustment of the duty cycle. After that, the transferred power only changes monotonously along with the change of phase shift angle. The zero-voltage switching (ZVS) conditions are analyzed in detail to ensure that the ZVS of all switches can be achieved through parameter design. Moreover, a comparison is conducted to illustrate the merits of the proposed converter. The theoretical analysis has been fully validated experimentally by an experimental prototype of 40–60 V to 400 V/1 kW operating at 50 kHz. The accordance between the theoretical analysis and experimental verification further testifies to the effectiveness.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • H∞-Based Control Design for Grid-Forming Inverters With Enhanced Damping
           and Virtual Inertia

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      Authors: Dayan B. Rathnayake;Si Phu Me;Reza Razzaghi;Behrooz Bahrani;
      Pages: 2311 - 2325
      Abstract: Grid-forming inverters (GFMIs) are identified as an important asset for achieving renewable energy-rich power grids. GFMIs are attracting significant attention due to their superior characteristics over grid-following inverters in both grid-connected (GC) and standalone (SA) scenarios. In this article, a second-order discrete-time controller is proposed to achieve a well-damped step response for power reference commands and improved virtual inertia provision capability. In this article, a control design method based on $mathcal {H}_{infty} $ is proposed, which is based on the frequency response of the system, to tune the proposed controller. The proposed control design presents a methodical process to specify the desired performance indices through frequency-domain constraints. The performance of the controller is thoroughly validated analytically and through simulation results. The superior performance of the proposed controller over the virtual synchronous generator controller in terms of tracking performance and virtual inertia provision capability is verified through experimental results.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A High Step-Up, High Efficiency, and Low Switch Voltage Stress
           Coupled-Inductor DC–DC Converter With Switched-Capacitor and
           Coupled-Inductor Techniques

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      Authors: Min Zhang;Pengfei Xue;Chenggong Yuan;Ruiming Ye;Zhenwei Zhao;Chang Zhao;Zhen Guo;
      Pages: 2326 - 2339
      Abstract: This article proposed a high step-up, high efficiency, and low switch voltage stress coupled-inductor (CL) dc–dc converter with switched-capacitor (SC) and CL techniques. The design method of the converter is to replace the single switch in the single-switch dc–dc converter with an SC and then combine the CL. Compared to other typical dc–dc converters, the improved topology power switch has lower voltage stress, low diode current stress, fewer devices in total, and common grounding, and all diodes are capable of ZVZCT. The operation mode and steady-state analysis of the proposed converter are given. The device stress derivation, the theoretical efficiency analysis, and the comparison with other dc–dc converters are carried out. Finally, experiments on a 200-W dc–dc converter are carried out to verify the reliability of the converter.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • A Single-Phase Grid-Connected Boost/Buck–Boost-Derived Solar PV
           Micro-Inverter Topology Having Power Decoupling Capability

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      Authors: Arup Ratan Paul;Arghyadip Bhattacharya;Kishore Chatterjee;
      Pages: 2340 - 2349
      Abstract: A boost/buck–boost-derived solar photovoltaic (PV) micro-inverter suitable for interfacing a 35 V 220 W PV module to a 220 V single-phase ac grid is proposed in this article. It uses only six switches, of which two switches operate at high frequency (HF), two at line frequency (LF), and the remaining two switches at HF during either positive half cycle (PHC) or negative half cycle (NHC) of the grid voltage. To achieve high gain and negligible turn on losses for the HF switches, the micro-inverter is operated in discontinuous mode of conduction for all possible operating conditions. The negative terminal of the PV module is directly connected to the grid neutral, and hence the magnitude of leakage flow is zero. The instantaneous power mismatch between the dc side and the ac side is addressed by achieving inherent power decoupling in the proposed topology without incorporating any additional active power decoupling circuit (APDC). The detailed analyses of the proposed micro-inverter are carried out. A 220 W laboratory prototype of the proposed micro-inverter is fabricated, and experimental studies are carried out in detail to confirm the viability of the proposed scheme.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Active Power Backflow Suppression Strategy of Cascaded PV Solid-State
           Transformer Under Interphase Short-Circuit Fault Condition

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      Authors: Tao Zhao;Zhijian Feng;Mingda Wang;Mengze Wu;Xing Zhang;
      Pages: 2350 - 2363
      Abstract: Currently, the grid-tied guidelines all require large and medium-sized photovoltaic (PV) power stations to stay connected to the grid during low-voltage ride through (LVRT). However, three-phase cascaded PV solid-state transformer (SST) has the inherent active power backflow problem during asymmetric voltage sags, causing that H-bridge dc-bus voltages are out of control and that the converter will be disconnected from the grid because of overvoltage fault. The existing control strategy is capable of avoiding active power backflow in theory by injecting appropriate zero-sequence voltage, but the overmodulation range is larger during interphase short-circuit fault, weakening active power backflow suppression effect. For this issue, this article proposes a combined control method of positive–negative-sequence maximum–minimum harmonic zero-sequence voltage injection strategy and adaptive zero-sequence voltage compensation strategy, which can shrink effectively active power backflow range of three-phase cascaded PV SST, increasing its adaptability to different output powers and different grid drop depths, and then improving LVRT capability of the PV power generation system. Finally, a low-voltage and low-power experimental prototype is made to verify the effectiveness and feasibility of the proposed control strategy.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Indirect Control Strategy of Secondary Charging Voltage and Current and
           Transient Analysis of LCC-S WPT System

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      Authors: Yuchen Wei;Fengjiang Wu;Hongchen Liu;
      Pages: 2364 - 2376
      Abstract: In this article, the steady-state and transient models of the LCC-S compensated wireless power transfer system (LCC-S WPT) are built. From the steady-state model, the secondary charging voltage and current are, respectively, proportional to the primary inverter current and coil current. Then the indirect control strategy of the secondary charging voltage and current based on the dual primary current closed-loop control is proposed. From the transient model, the controller parameters design criteria are given. The transient characteristics of the both side variables of the indirect control strategy are originally analyzed. It is proven that a good secondary transient performance is ensured under the indirect way. Furthermore, the feedforward control of the input voltage is proposed to eliminate its transient effect. The feasibility and practicability of the proposed control strategy are verified by the experiments.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Dual-Frequency Modulation to Achieve Power Independent Regulation for
           Dual-Load Underwater Wireless Power Connector

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      Authors: Shui Pang;Jiayi Xu;Hongyu Li;Qingfeng Ma;Xingfei Li;
      Pages: 2377 - 2389
      Abstract: The power supply of underwater devices can be realized by the nonelectrical contact wireless power transfer (WPT) technology. The diversity and flexibility of devices carried by the remotely operated vehicle (ROV) can be increased by the WPT which can achieve convenient and safe device switching. Power independent regulation is a key for the underwater wireless power connector (UWPC) with multiload, and a superimposed dual-frequency modulation (SDFM) method is proposed in this article to achieve the load power independent regulation. The equal-area rule is first applied to SDFM, which can use one inverter to generate SDFM current at the transmitter. The theory of decoupled power transfer is analyzed in detail for the SDFM UWPC with dual-load (DL). All the above analyses are verified in a DL UWPC system prototype. The experimental results show that the SDFM current is generated using one inverter, and the load power can be independently regulated by adjusting the output voltage of the inverter. Furthermore, the load power is still independent and controllable under the conditions of load switching and mutual inductances changing. The DL UWPC system power can reach 50 W and dc–dc efficiency is about 68.73%.
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Women in Engineering

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      Pages: 2390 - 2390
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Connect. Support. Inspire.

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      Pages: 2391 - 2391
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
  • Create Change: IEEE Smart Village

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      Pages: 2392 - 2392
      PubDate: April 2023
      Issue No: Vol. 11, No. 2 (2023)
       
 
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