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  Subjects -> ELECTRONICS (Total: 207 journals)
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Journal of Power Electronics
Number of Followers: 6  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1598-2092 - ISSN (Online) 2093-4718
Published by Springer-Verlag Homepage  [2469 journals]
  • Simple symmetric switched inductor high step-down converter

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      Abstract: Abstract The voltage gain of a traditional buck converter is finite due to the high voltage across the semiconductor and reduced efficiency. A non-isolated high step-down DC–DC converter based on symmetric switched inductors is proposed in this paper. The connection of inductors in series or in parallel is controlled by switches to improve the conversion ratio. The converter has many beneficial characteristics, such as high step-down, reduced voltage stresses, and high efficiency. Moreover, it can realize voltage balance on the switches. The voltage on the switch does not oscillate and the loss of the switches is reduced. Therefore, the efficiency of the whole topology is improved. This paper discusses the operation principle, modes analysis, voltage gain analysis, voltage stress analysis, output ripple analysis, loss analysis, comparative analysis and design considerations. The correctness of the theoretical analysis of the proposed converter is verified by a laboratory prototype, and its peak efficiency reaches 96.5%.
      PubDate: 2022-10-01
       
  • Comparative analysis of switched inductor-based quasi-Z-source inverters

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      Abstract: Abstract A switched-inductor quasi-Z-source inverter (SI-qZSI) exhibits a higher gain than a quasi-Z-source inverter (qZSI) while keeping continuous input current. Like renewable power generation systems that result in low input voltage, SI-qZSI exhibits boosting ability that may not be adequate in some cases. A voltage-lifting unit can be formed by alternating one of the diodes in the switch inductor unit. A high step-up topology, such as qZSI with voltage-lifting unit (qZSI-VL), can be derived. The boosting factor of qZSI-VL can be enhanced further by retaining all the merits of the SI-qZSI. The overall conduction loss can be reduced under the same output and input voltage for the qZSI-VL, thereby enhancing efficiency. In this study, the analysis of the qZSI-VL and its operating principle are explained. The characteristic comparison of qZSI-VL with the SI-qZSI and qZSI is discussed in detail. Finally, the prototypes of qZSI-VL and SI-qZSI are designed in the lab. Simulation and experiments are performed to verify the analysis.
      PubDate: 2022-10-01
       
  • Position-independent wireless power transfer system delivering constant
           power

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      Abstract: Abstract A single-stage wireless power transfer (WPT) system based on the switching control capacitor (SCC) is proposed in this paper. Using the SCC instead of an ordinary capacitor gives the WPT system, an additional control degree of freedom. The proposed robust WPT system has a constant power (CP) output characteristic under a wide range of load resistance and coupling coefficient variations by adjusting the conduction angle of the SCC. When compared with constant current (CC) charging, CP charging can shorten the charging time and promote battery cycle life. Moreover, a primary side control method is proposed. It only needs to sample the primary current to identify the reflected impedance, which avoids wireless communication. When combined with the control strategy, the condition of zero-voltage switching (ZVS) is derived. Finally, a 125-W experimental prototype is built to verify the performance of the proposed method. Experimental results demonstrate that stable CP charging can be maintained during coil movement and load changes. In addition, soft switching is implemented in all situations.
      PubDate: 2022-10-01
       
  • Synthesis of multi-port converters based on series/parallel input
           pulsating cells and output pulsating cells

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      Abstract: Abstract Due to their advantages of reduced cost, integrated multi-port converters (MPCs) with fewer components have received extensive attention. In this article, by extracting the concept of series/parallel input pulsating cells (IPCs) and output pulsating cells (OPCs), a set of syntheses for generating MPCs composed of IPCs and OPCs is proposed. When compared with the existing synthesis method for non-isolated MPCs, the proposed approach employs only one inductor and features single-stage power conversion between any two ports, which offers benefits in terms of compact size and high efficiency. Two design examples are shown to demonstrate the worth of proposed methodology. The operation principles are first analyzed. The pulsewidth modulation (PWM) and power control schemes are explained and designed in detail. To design the controllers, small-signal models for each of the operation modes are also extracted. Meanwhile, the characteristics of pulsating cells with different configurations are discussed and compared. The theoretical analysis is validated by simulation and experimental results for different operation conditions.
      PubDate: 2022-10-01
       
  • Thermal-structural coupling analysis of motor rotor under extreme variable
           working conditions

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      Abstract: Abstract Extreme variable working conditions were proposed, and the thermal-structural coupling analysis of the rotor was conducted with an electric drive system as the research object to make the structural strength of the rotor of a vehicle motor satisfy all operating conditions as much as possible. The overall temperature rise characteristics of the electric drive system were obtained through simulation, and the accuracy of simulation results was verified through testing. On the basis of material tests at different temperatures, the interference fit, and the rotating centrifugal force as loads, a comparative analysis of the strength of the rotor was conducted for variable working conditions and single working conditions. Results show that the stress value in the variable working condition is 74.9 MPa greater than that in the single working condition. This finding indicates that the analysis of rotor stresses under variable working conditions has more engineering importance.
      PubDate: 2022-10-01
       
  • Electromagnetic torque and reactive torque control of induction motor
           drives to improve vehicle variable flux operation and torque response

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      Abstract: Abstract This paper investigates the decoupling and fast torque response for induction motor drives during vehicle operation with variable flux. A torque control method considering flux transient information is proposed, which takes the electromagnetic torque and reactive torque as state variables for modeling and feedback linearization control. Since the electromagnetic torque is aligned with the active power, and the reactive torque is aligned with the reactive power and perpendicular to the electromagnetic torque, the stator dq-axis current control of the field-oriented control (FOC) is replaced by the simultaneous control of the electromagnetic torque and reactive torque. The physical concept of the inner loop changes from the current to the torque, and the modulation signals from the voltage-type to the power-type. This strategy improves the decoupling performance under variable flux, and the fast response capability of the torque. In addition, it eliminates the complex rotation coordinate transformation. A comparative experiment was carried out between the proposed method and the FOC. Both methods have good steady-state performance. However, the proposed method has better torque response and decoupling.
      PubDate: 2022-10-01
       
  • Asymmetrical SPWM-based control scheme for BESS-integrated UPQC with
           hybrid connected configuration

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      Abstract: Abstract The unified power quality conditioner (UPQC) integrated with the battery energy storage system not only mitigates the power quality problems on the grid side and load side but also supplies active power to the load or the grid. The wide voltage variation of the battery and the high efficiency of the whole system can be achieved with the hybrid connected configuration, i.e., the battery is connected simultaneously to the series and shunt converters of the UPQC directly and indirectly through the dc–dc converter. However, the control and modulation strategies are the major challenges for this configuration. This study proposes a control scheme based on asymmetrical sinusoidal pulse width modulation (SPWM) to realize high-efficiency active power delivery, thereby addressing the issue above. The mechanism of the modulation scheme to regulate active power is revealed, and the voltage variation of the battery is considered. The modified SPWM strategy features easy implementation and a low computation burden. The effectiveness of the system with the proposed control and modulation schemes is verified by both simulation and experimental results.
      PubDate: 2022-10-01
       
  • Control stability of inverters with series-compensated transmission lines:
           analysis and improvement

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      Abstract: Abstract With the rapid development of renewable energy, large amounts of power need to be transmitted to load centers, and series-capacitor compensation (SCC) plays an important role in renewable power transmission. However, it has been pointed out that SCC interacts with inverters and threatens system stability. This paper investigates the influence of SCC on inverter control, and proposes strategies for enhancing system stability based on the instability mechanism. First, the impacts of SCC on inverter current control and synchronization control are analyzed. A current control model is established by a system transfer function, and a synchronization control model focusing on transient stability is established based on the traditional synchronous reference frame phase-locked loop (SRF-PLL). Bode and nonlinear analysis methods are utilized in the stability analysis of both current control and synchronization control. It is found that SCC has little effect on inverter current control. However, it seriously affects synchronization control. SCC reduces the stability range of synchronization control, and causes system instability when there is a large frequency disturbance. In order to improve system stability, two approaches have been proposed. These approaches are optimizing a PI controller, and designing a band-pass filter (BPF) inside the PLL. Finally, simulations and experiments are presented to verify the correctness of theories.
      PubDate: 2022-10-01
       
  • Experimental verification of interleaved hybrid DC/DC boost converter

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      Abstract: Abstract In this study, an improved interleaved hybrid DC/DC boost converter used for high-power applications with high voltage gain was proposed. The proposed DC/DC boost converter increases low-input voltage to the desired high-output voltage with a wide duty cycle range through the hybrid structure, thereby prolonging the lifetime of the proposed converter by decreasing the current on circuit components. An extra filter for input current ripples is unnecessary. The proposed converter is less complex and has easier control than the converters used for high voltage gain. The proposed converter was operated when the duty cycle (d) was larger and smaller than 0.5. It was also analyzed theoretically, and the average- and small-signal circuits were obtained to show its stability. The proposed converter was controlled with the conventional control method by using a modern digital signal processor TMS320F28379D board. The proposed converter and its controller were operated under different conditions.
      PubDate: 2022-10-01
       
  • Novel DQ transform and time delay module-based phase-locked loop

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      Abstract: Abstract The Phase-Locked-Loop (PLL) based on quadrature signal generation (QSG) is widely used in the synchronization units of power systems. Being one of the most popular QSG-PLLs, the time delay unit-based PLL (TD-PLL) is simple and easy to implement. However, when the frequency of the input signal deviates from its rated value, the orthogonality of the QSG output signal and the original input signal cannot be guaranteed, which leads to the generation of double frequency components. To solve this problem, this paper analyzes the generation mechanism for the double frequency component of the TD-PLL. Then, a quadrature signal generation and processing module is built based on a DQ transform and time delay unit to eliminate the double frequency component. This ability is the key part of the proposed PLL (DQ-TD-PLL). Finally, the performance of DQ-TD-PLL is evaluated with simulations and experiments. The obtained results show that the proposed DQ-TD-PLL can eliminate the influence of double frequency component. It can also be seen that the proposed method has better dynamic performance when compared with other methods in the literature.
      PubDate: 2022-10-01
       
  • A novel medium voltage five-level converter with minimized volume

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      Abstract: Abstract In applications such as ship propulsion and off-shore wind power generation, it is important to minimize the volume of medium voltage power converters. To make this possible, a novel five-level converter topology is proposed in this paper. This converter is realized by connecting two half-bridge (HB) cells with a three-level neutral point clamped (3L-NPC) unit. In each HB cell, the switches are directly clamped to DC side capacitors where the larger volume high-voltage flying capacitors are avoided. By adopting the 3L-NPC unit, the volume of the proposed converter is further reduced. A comprehensive comparison result shows that the volume of the proposed converter is more than 7% less than existing five-level converters. The operation principle and modulation method of this converter are also introduced. Based on the phase-shift pulse width modulation (PS-PWM) method, the capacitor voltages of the proposed converter can be self-balanced. Simulation and experiment results are shown to verify the performance of this converter and the validity of the theoretical analysis.
      PubDate: 2022-10-01
       
  • Power flow predictive model control to improve the efficiency of
           regenerative energy storage and utilization

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      Abstract: Abstract In dual-motor drive systems, a supercapacitor is connected to a common direct current (DC) bus through a DC/DC converter for the storage and utilization of regenerative energy, which is an effective energy saving method. However, the uncoordinated control of this type of system results in undesirable power circulation and reduced energy utilization efficiency. In this paper, an optimal power tracking control strategy based on a power flow predictive model is proposed. The power flow of the system is analyzed and a power flow predictive model is established. In addition, an objective function is deduced from the perspective of optimal performance tracking and minimum grid side energy consumption. The reference power of a supercapacitor is obtained in real time under constraints. The power flows among the grid side, the motors, and the energy storage unit are fully coordinated to realize a reasonable energy distribution. Experimental results indicate that the energy utilization efficiency of the system is improved by 25.4% in comparison with double closed-loop control in one working period.
      PubDate: 2022-10-01
       
  • Fault-tolerant converter and fault-tolerant methods for switched
           reluctance generators

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      Abstract: Abstract Aiming at improving the fault-tolerant performance of switched reluctance generators, a new power converter with fault-tolerance capability is proposed in this paper. The structure of the converter is simple and there is only one transistor in each of the working modes, which makes fault diagnosis easier. To obtain more fault information, an improved current measurement method is proposed. The phase current is obtained by solving current equations obtained by current sensors and rotor positions. Open-circuit and short-circuit faults can be determined by comparing the consistency of the current slope and gate signal. Fault locations can be determined by comparing the relationships among the magnitude of the bus current, the phase current, and the corresponding thresholds. Open-circuit transistors can be replaced by fault-tolerant strategy, which returns the power converter to normal and maintains the stable operation of the system. Simulations and experiments show that the open-circuit and short-circuit faults of transistors can be diagnosed by the proposed strategy.
      PubDate: 2022-10-01
       
  • Calculation and analysis of switching losses in IGBT devices based on
           switching transient processes

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      Abstract: Abstract Accurately revealing the generation mechanism and the mathematical relationship with system parameters of the power loss in the switching transients of high-voltage large power IGBT devices is very important for the device selection and circuit design of converter equipment. To reveal the mechanism of generating switching losses, this paper analyzes the switching transient processes of the IGBT devices in the basic commutation circuit in detail. Then this paper proposes an accurate calculation method based on a finite state machine (FSM) for the switching losses of IGBT devices, and verifies the correctness of this method. To further reveal the mathematical relationships among switching losses, device parameters, and loop parameters, approximate analytical formulas for the switching loss of different switching transient processes are mathematically derived, which can provide a theoretical basis for reducing the switching losses in converters.
      PubDate: 2022-10-01
       
  • Proper flying capacitor selection for performance enhancement of
           five-level hybrid active neutral-point-clamped inverters

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      Abstract: Abstract Flying capacitors (FCs) are very important in multilevel inverter systems when it comes to synthesizing additional voltage levels for various medium-voltage industrial applications, including renewable energy, motor drives, and power transmission. In particular, they are responsible for forming the five-level output pole voltages in five-level hybrid active neutral-point-clamped (ANPC) topologies. This is only possible when the FCs reach their reference values (i.e., 25% of the DC-link value). When a five-level hybrid ANPC inverter operates in the high-frequency (HF) range, the output three-phase current waveforms are less distorted when compared to the low-frequency (LF) performance. Instantaneously achieving a five-level output pole voltage during HF operation is a challenging task. This is due to the large capacitance of some existing types of FCs. In this study, a novel analysis of the effects of a FC on the performance of a five-level hybrid ANPC inverter is presented with simulation and experimental validations. Film capacitors significantly enhanced system performance when compared to electrolytic capacitors due to their many advantageous features, including the ability to charge and discharge quickly during HF operation. In addition, the total harmonic distortion of the output pole voltage is significantly suppressed. Consequently, the size of the required filter can be reduced. Therefore, the proposed system is highly desirable for various industrial applications.
      PubDate: 2022-10-01
       
  • Capacitor-assisted active-switched quasi-Z-source inverters with high
           voltage gain

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      Abstract: Abstract This paper presents a novel topology called the capacitor-assisted active-switched quasi Z-source inverter (CA/AS-qZSI). The proposed CA/AS-qZSI topology has a high ac voltage gain and low voltage and current stresses on the diodes and extra switch in the Z-network. The design guide of the passive elements used in the proposed topology and a comparative study of the proposed CA/AS-qZSI and four other topologies with an active-switched impedance network are addressed. A new pulse-width modulation (PWM) technique using a sawtooth carrier signal is also suggested to reduce the switching losses of the diodes and switches. Compared with the traditional simple boost control method, the efficiency of CA/AS-qZSI using the new PWM technique is improved by 4–4.6%. The experimental results utilizing a prototype made in the laboratory demonstrate the performance of the proposed CA/AS-qZSI and PWM technique.
      PubDate: 2022-09-29
       
  • Artificial neural network-based FCS-MPC for three-level inverters

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      Abstract: Abstract Finite control set model predictive control (FCS-MPC) stands out for fast dynamics and easy inclusion of multiple nonlinear control objectives. However, for long horizontal prediction or complex topologies with multiple levels and phases, the required computation burden surges exponentially as the increases of candidate switch states during one control period. This phenomenon leads to longer sample period to guarantee enough time for traverse progress of cost function minimization. In other words, the allowed highest switching frequency is bounded considerably far from the physical limits, especially for wide-band semiconductor applications. To overcome this issue, the parallel computing characteristic of artificial neural network (ANN) motivates the idea of an ANN-based FCS-MPC imitator (ANN-MPC). In this article, ANN-MPC is implemented on a neutral point clamped (NPC) converter using a shallow neural network. The expert (FCS-MPC) is initially designed, and the basic structure, including activation function selection, training data generation, and offline training progress, and online operation of the imitator (ANN-MPC) are then discussed. After the design of the expert and imitator, a comparative analysis is conducted by field programmable gate array (FPGA) in-the-loop implementation in MATLAB/Simulink environment. The verification results of ANN-MPC show highly similarly qualified control performance and considerably reduced computation resource requirement.
      PubDate: 2022-09-29
       
  • Anti-misalignment capability optimization for laminated magnetic couplers
           in wireless charging systems using balanced particle swarm optimization
           method

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      Abstract: Abstract To desensitize wireless charging systems (WCSs) to misalignment and to achieve a stable output voltage without using additional control methods, a laminated magnetic coupler (LMC) optimized by the balanced particle swarm optimization (BPSO) method is proposed to improve the performance of WCSs. First, the output characteristics of the LCC-S compensated WCS are analyzed to illustrate the working principle of the LMC. Next, the misalignment characteristics of the LMC, which employs the magnetic integration technique and coil self-decoupling method, are analyzed. Then, the operating principle of the BPSO method is analyzed and used to optimize the LMC in terms of the mutual inductance and anti-misalignment range. Finally, experimental results indicate that the optimized LMC achieves high-efficiency constant voltage charging within a reasonable horizontal misalignment range. When compared to commonly used methods (such as the exhaustive method) for optimizing magnetic couplers, the BPSO method avoids complex algorithms and a heavy computation burden.
      PubDate: 2022-09-26
       
  • Online cell-by-cell SOC/SOH estimation method for battery module employing
           extended Kalman filter algorithm with aging effect consideration

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      Abstract: Abstract As the number of series connections of battery cells increases, individual cells are operating in different temperature profiles, and the aging patterns of the cells become dissimilar from each other. Thenceforth, individual state-cell-characteristics should be tracked online for higher safety. Although Kalman-filter-based battery state estimation is one of the most popular methods, it is sensitive to the accuracy of the battery model parameters and difficult to be applied to every cell. This work proposes an online cell-by-cell state-of-charge (SOC)/state-of-health (SOH) estimation method to mitigate this limitation. The aging patterns of the individual cells are predicted by introducing a combination of a switch-matrix flying capacitor and electrochemical impedance spectroscopy (EIS) model parameter scanning techniques. Accordingly, the accuracy of the SOC estimation for individual cells is enhanced. The proposed method is verified by a real-time simulation platform, where the SOC and SOH levels of the cells are individually estimated within a 1.24% error.
      PubDate: 2022-09-26
       
  • Hybrid passivity-based control for stability and robustness enhancement in
           DC microgrids with constant power loads

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      Abstract: Abstract In a DC microgrid, the negative damping characteristics of a constant power load can deteriorate the stability of the whole system. To improve the robustness and stability of the DC microgrid, a hybrid passivity-based control of damping injection is presented in this paper. The stability of the closed-loop system is ensured by the energy dissipation property of the passivity-based control. A proportional-integral controller is integrated with the passivity-based controller to form a hybrid passivity-based control to improve control robustness. A small-signal model of a DC power system with constant power load is derived in detail, and the stability of the system is analyzed with the Lyapunov eigenvalue method. The proposed hybrid passivity-based control provides the system with a faster recovery and a larger power boundary when compared with the typical voltage-current dual-loop control. First, the proposed control is verified by simulation of the DC power system based on MATLAB/Simulink, and the feasibility and superiority of the proposed control are further verified by hardware-in-loop (HIL) experiments based on real-time laboratory (RT-Lab) and a TI DSP TMS320 F28335.
      PubDate: 2022-09-26
       
 
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