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  Subjects -> ELECTRONICS (Total: 155 journals)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 2)
Advances in Electronics     Open Access   (Followers: 4)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 5)
Advances in Microelectronic Engineering     Open Access   (Followers: 2)
Advances in Power Electronics     Open Access   (Followers: 7)
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 131)
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 13)
Annals of Telecommunications     Hybrid Journal   (Followers: 5)
APL : Organic Electronics and Photonics     Hybrid Journal   (Followers: 2)
APSIPA Transactions on Signal and Information Processing     Open Access   (Followers: 6)
Archives of Electrical Engineering     Open Access   (Followers: 9)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 5)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 10)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 15)
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 6)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 5)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 2)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access  
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 13)
China Communications     Full-text available via subscription   (Followers: 4)
Circuits and Systems     Open Access   (Followers: 10)
Consumer Electronics Times     Open Access   (Followers: 4)
Control Systems     Hybrid Journal   (Followers: 30)
Electronic Design     Partially Free  
Electronic Markets     Hybrid Journal   (Followers: 5)
Electronic Materials Letters     Hybrid Journal   (Followers: 3)
Electronics     Open Access   (Followers: 10)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 5)
Electronics Letters     Hybrid Journal   (Followers: 20)
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 23)
Energy Harvesting and Systems : Materials, Mechanisms, Circuits and Storage     Hybrid Journal   (Followers: 3)
EPJ Quantum Technology     Open Access  
EURASIP Journal on Embedded Systems     Open Access   (Followers: 9)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Frequenz     Hybrid Journal   (Followers: 3)
Frontiers of Optoelectronics     Hybrid Journal   (Followers: 2)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 20)
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 3)
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 15)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 13)
IEEE Consumer Electronics Magazine     Full-text available via subscription   (Followers: 18)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 13)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 3)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 7)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 13)
IEEE Transactions on Audio, Speech, and Language Processing     Hybrid Journal   (Followers: 14)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 27)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 17)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 8)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 14)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 21)
IEEE Transactions on Signal and Information Processing over Networks     Full-text available via subscription  
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 8)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 7)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 6)
IET Power Electronics     Hybrid Journal   (Followers: 14)
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 10)
IETE Journal of Education     Open Access   (Followers: 2)
IETE Journal of Research     Open Access   (Followers: 9)
IETE Technical Review     Open Access   (Followers: 4)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 3)
Informatik-Spektrum     Hybrid Journal  
Instabilities in Silicon Devices     Full-text available via subscription  
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 2)
International Journal of Advanced Electronics and Communication Systems     Open Access   (Followers: 5)
International Journal of Advanced Research in Computer Science and Electronics Engineering     Open Access   (Followers: 20)
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems     Open Access   (Followers: 3)
International Journal of Aerospace Innovations     Full-text available via subscription   (Followers: 13)
International Journal of Antennas and Propagation     Open Access   (Followers: 7)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 1)
International Journal of Biomedical Nanoscience and Nanotechnology     Hybrid Journal   (Followers: 6)
International Journal of Computational Vision and Robotics     Hybrid Journal   (Followers: 4)
International Journal of Computer & Electronics Research     Full-text available via subscription   (Followers: 1)
International Journal of Control     Hybrid Journal   (Followers: 14)
International Journal of Electronics     Hybrid Journal   (Followers: 2)
International Journal of Electronics & Data Communication     Open Access   (Followers: 4)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 3)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal   (Followers: 1)
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 1)
International Journal of Nano Devices, Sensors and Systems     Open Access   (Followers: 4)
International Journal of Nanoscience     Hybrid Journal  
International Journal of Numerical Modelling:Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 2)
International Journal of Power Electronics     Hybrid Journal   (Followers: 8)
International Journal of Review in Electronics & Communication Engineering     Open Access   (Followers: 2)
International Journal of Sensors, Wireless Communications and Control     Hybrid Journal   (Followers: 4)
International Journal of Superconductivity     Open Access  
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 2)
International Journal on Communication     Full-text available via subscription   (Followers: 11)
International Journal on Electrical and Power Engineering     Full-text available via subscription   (Followers: 10)
International Transaction of Electrical and Computer Engineers System     Open Access  
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 2)
Journal of Advanced Dielectrics     Open Access   (Followers: 1)
Journal of Artificial Intelligence     Open Access   (Followers: 5)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 1)
Journal of Computational Intelligence and Electronic Systems     Full-text available via subscription  
Journal of Electrical and Electronics Engineering Research     Open Access   (Followers: 4)
Journal of Electrical Bioimpedance     Full-text available via subscription   (Followers: 2)

        1 2 | Last

Journal Cover   IEEE Transactions on Power Electronics
  [SJR: 2.866]   [H-I: 128]   [21 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0885-8993
   Published by Institute of Electrical and Electronics Engineers (IEEE) Homepage  [177 journals]
  • IEEE Power Electronics Society Information
    • Abstract: Provides a listing of current committee members and society officers.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Table of contents
    • Abstract: Presents the table of contents for this issue of this publication.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • IEEE Transactions on Power Electronics publication information
    • Abstract: Provides a listing of current staff, committee members and society officers.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Research on Linear Output Voltage Transfer Ratio for Ultrasparse Matrix
    • Authors: Xia; C.;Li, S.;Yan, Y.;Shi, T.;
      Pages: 1811 - 1815
      Abstract: Many existing research works of ultrasparse matrix converter (USMC) show that the maximum linear output voltage transfer ratio (MLO-VTR) is less than 0.866, however, this paper proves that based on space vector modulation, MLO-VTR for USMC can break the ultimate value. First, based on the condition that input power factor is one, the maximum output voltage within one carrier period and the maximum linear output voltage are derived. Further, the mathematical equations among MLO-VTR, the output/input frequency ratios, and the output voltage initial phase are also derived. After that, by solving the operating limits of the mathematical relationship of the MLO-VTR, we can obtain the maximum value of MLO-VTR under different output/input frequency ratios which can be more than 0.866. Finally, all of theoretical derivations are verified by experiments.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Failure Analysis of 1200-V/150-A SiC MOSFET Under Repetitive
           Pulsed Overcurrent Conditions
    • Authors: Schrock; J.A.;Pushpakaran, B.N.;Bilbao, A.V.;Ray, W.B.;Hirsch, E.A.;Kelley, M.D.;Holt, S.L.;Bayne, S.B.;
      Pages: 1816 - 1821
      Abstract: SiC MOSFETs are a leading option for increasing the power density of power electronics; however, for these devices to supersede the Si insulated-gate bipolar transistor, their characteristics have to be further understood. Two SiC vertically oriented planar gate D-MOSFETs rated for 1200 V/150 A were repetitively subjected to pulsed overcurrent conditions to evaluate their failure mode due to this common source of electrical stress. This research supplements recent work that demonstrated the long term reliability of these same devices [1]. Using an RLC pulse-ring-down test bed, these devices hard-switched 600 A peak current pulses, corresponding to a current density of 1500 A/cm2. Throughout testing, static characteristics of the devices such as B_{{\rm VDSS}} , R_{{\rm DS}({\rm on})} , and V_{{\rm GS}({\rm th})} were measured with a high power device analyzer. The experimental results indicated that a conductive path was formed through the gate oxide; TCAD simulations revealed localized heating at the SiC/SiO2 interface as a result of the extreme high current density present in the device's JFET region. However, the high peak currents and repetition rates required to produce the conductive path through the gate oxide demonstrate the robustness of SiC MOSFETs under the pulsed overcurrent conditions common in power electronic applications.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • High-Performance Constant Power Generation in Grid-Connected PV Systems
    • Authors: Sangwongwanich; A.;Yang, Y.;Blaabjerg, F.;
      Pages: 1822 - 1825
      Abstract: An advanced power control strategy by limiting the maximum feed-in power of PV systems has been proposed, which can ensure a fast and smooth transition between maximum power point tracking and constant power generation (CPG). Regardless of the solar irradiance levels, high-performance and stable operation are always achieved by the proposed control strategy. It can regulate the PV output power according to any set point, and force the PV systems to operate at the left side of the maximum power point without stability problems. Experimental results have verified the effectiveness of the proposed CPG control in terms of high accuracy, fast dynamics, and stable transitions.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Stabilization of a Cascaded DC Converter System via Adding a Virtual
           Adaptive Parallel Impedance to the Input of the Load Converter
    • Authors: Zhang; X.;Zhong, Q.;Ming, W.;
      Pages: 1826 - 1832
      Abstract: Connecting converters in cascade is a basic configuration of dc distributed power systems (DPS). The impedance interaction between individually designed converters may make the cascaded system become unstable. The previous presented stabilization approaches not only need to know the information of the regulated converter, but also have to know the characteristics of the other converters in the system, which are contradictory to the modularization characteristic of dc DPS. This letter proposes an adaptive-input-impedance-regulation (AIIR) method, which connects an adaptive virtual impedance in parallel with the input impedance of the load converter, to stabilize the cascaded system. This virtual impedance can adaptively regulate its characteristic for different source converters. Therefore, with the AIIR method, all the load converters can be designed to a fixed standard module to stably adapt various source converters. In addition, at any cases, the AIIR approach only changes the load converter's input impedance in a very small frequency range to keep the load converter's original dynamic performance. The requirements on the AIIR method are derived and the control strategies to achieve the AIIR method are proposed. Finally, considering the worst stability problem that often occurs at the system whose source converter is an LC filter, a load converter cascaded with two different LC input filters is fabricated and tested to validate the effectiveness of the proposed AIIR control method.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Family of Bridgeless Quasi-Resonant LED Drivers
    • Authors: Shmilovitz; D.;Abramovitz, A.;Reichman, I.;
      Pages: 1833 - 1836
      Abstract: A family of offline bridgeless quasi-resonant LED drivers is introduced. The prominent features of the proposed drivers are the capacitive isolation feature, inherent low line-current distortion, and high power factor. The concept is validated by a 30-W prototype operated in the range of 150–200 kHz and 30-V dc output (LED string voltage).
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A DC-Link Modulation Scheme With Phase-Shifted Current Control for
           Harmonic Cancellations in Multidrive Applications
    • Authors: Yang; Y.;Davari, P.;Zare, F.;Blaabjerg, F.;
      Pages: 1837 - 1840
      Abstract: This letter proposes a harmonic mitigation strategy to cancel out current harmonics induced by the front-end rectifiers in multidrive systems, which consist of diode rectifiers, silicon-controlled rectifiers (SCR), and boost converters in the dc-link. The proposed strategy is a combination of a new dc-link modulation scheme with a phase-shifted current control enabled by the SCR. The dc-link current modulation scheme is implemented by adding and subtracting specific modulation levels, which makes the total currents drawn from the grid “multilevel,” resulting in an improved current quality. Simulations and experiments have validated the effectiveness of the proposed harmonic mitigation solution for multidrive systems.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Leakage Current Elimination of Four-Leg Inverter for Transformerless
           Three-Phase PV Systems
    • Authors: Guo; X.;He, R.;Jian, J.;Lu, Z.;Sun, X.;Guerrero, J.M.;
      Pages: 1841 - 1846
      Abstract: Eliminating the leakage current is one of the most important issues for transformerless three-phase photovoltaic (PV) systems. In this paper, the leakage current elimination of a three-phase four-leg PV inverter is investigated. With the common-mode loop model established, the generation mechanism of the leakage current is clearly identified. Different typical carrier-based modulation methods and their corresponding common-mode voltages are discussed. A new modulation strategy with Boolean logic function is proposed to achieve the constant common-mode voltage for the leakage current reduction. Finally, the different modulation methods are implemented and tested on the TMS320F28335 DSP +XC3S400 FPGA digital control platform. The experimental results verify the effectiveness of the proposed solution.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Fast Orthogonal Signal-Generation Algorithm Characterized by Noise
           Immunity and High Accuracy for Single-Phase Grid
    • Authors: Xiong; L.;Zhuo, F.;Wang, F.;Liu, X.;Zhu, M.;
      Pages: 1847 - 1851
      Abstract: Conventional orthogonal signal-generation methods for single-phase grid suffer from long response time, approximation errors, and/or noise amplification. To remedy this problem, a novel orthogonal signal-generation algorithm, which is characterized by remarkable response speed, high accuracy, noise immunity, and easy implementation, is developed in this paper. The developed algorithm can precisely calculate the orthogonal signal within about 2.5 ms when the amplitude/phase of the grid signal changes suddenly, under the premise of not significantly increasing the computational burden compared with the conventional methods. Far more important is that the high accuracy of the proposed method is independent of the system sampling frequency; hence, effectively avoiding the approximation errors in a wide range of sampling frequencies. In addition, it is shown how the noise amplification issue caused by the developed algorithm, which is nearly equal to that of the first-order differentiating method, can be effectively solved by proper time-span scaling and restricted into an acceptable range. Finally, the validity and advancement of the developed algorithm are verified by experimental results.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Measurement Method to Solve a Problem of Using DG Interfacing Converters
           for Selective Load Harmonic Filtering
    • Authors: He; J.;Li, Y.W.;Wang, R.;Wang, C.;
      Pages: 1852 - 1856
      Abstract: Flexible control of interfacing converter has been utilized to compensate the harmonics from nonlinear loads in a power distribution system. However, the site selection of a DG unit is mainly determined by the location of renewable energy resources that might be far away from the nonlinear load. This can degrade the performance of conventional nonlinear load current measurement methods using current transformers and shielded twisted-pair wires, and accordingly, make the harmonic compensation less effective. To solve this issue, the fundamental components of the PCC voltage and the DG installation point voltage are utilized to establish links between the DG unit controller and the power quality (PQ) meter for PCC nonlinear load monitoring. With this method, the harmonic current waveform can be accurately sent from the PQ meter to the DG unit controller with a very low bandwidth communication system, and it is not required to have any clock synchronization at the sending and the receiving ends of the communication system. Simulated and experimental results are provided to verify the correctness of the proposed measurement method.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Scalable Hybrid Regulator For Down Conversion of High Input Voltage
           Using Low-Voltage Devices
    • Authors: Kar; M.;Ahmed, K.Z.;Mukhopadhyay, S.;
      Pages: 1857 - 1862
      Abstract: This paper presents a voltage regulator topology, implemented using low-voltage devices, for converting high input voltage (>4.5 V) to low output voltages with fine-grain control (0.3 to 1 V). The topology merges a Dickson's switched-capacitor stage with a current-mode inductive buck stage, and optimizes the frequency of operations to reduce the overall passive size. The proposed two-stage hybrid regulator, designed in 130-nm standard digital process, operates from 4.8 to 6 V at input and regulates output voltage as low as 0.3 V with a maximum output power of 90 mW and a peak efficiency of 69%.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Steady-State Analysis of a ZVS Bidirectional Isolated Three-Phase
           DC–DC Converter Using Dual Phase-Shift Control With Variable Duty
    • Authors: de Oliveira Filho; H.M.;de Souza Oliveira, D.;Praca, P.P.;
      Pages: 1863 - 1872
      Abstract: This study presents the steady-state analysis and experimental results on a soft-switching bidirectional isolated three-phase dc–dc converter using DPS control with variable duty cycle. The topology uses three single H-bridges in the primary side and a three-phase inverter in the secondary side. High-frequency isolation is ensured by using three single-phase transformers connected in open delta-wye configuration. The variation of both phase-shift angles between the H-bridge legs and/or primary and secondary sides allows controlling the power flow, while reduced reactive power flow is possible. The variable duty cycle is used to ensure a constant voltage bus and/or zero voltage switching operation. A detailed analysis is presented considering a model based on the fundamental components for the voltages and currents in the transformer. A comparison between the fundamental and the actual models is carried out to validate the proposed model. Experimental results on a 96 V/350–400 V, 3.5 kW prototype are presented and discussed to validate the proposed approach.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Simplified Space Vector Modulation Scheme for Multilevel Converters
    • Authors: Deng; Y.;Wang, Y.;Teo, K.H.;Harley, R.G.;
      Pages: 1873 - 1886
      Abstract: This paper proposes a simplified space vector modulation (SVM) scheme for multilevel converters. Compared with earlier SVM methods, the proposed scheme simplifies the detection of the nearest three vectors and the generation of switching sequences, and therefore is computationally more efficient. Particularly, for the first time, the proposed scheme achieves the same easy implementation as phase-voltage modulation techniques. Another superior characteristic of the proposed scheme over earlier methods is its potential for multiphase multilevel applications. The proposed scheme also offers the following significant advantages: 1) independence of the level number of the converter; 2) more degrees of freedom, i.e., redundant switching sequences and adjustable duty cycles, to optimize the switching patterns; and 3) no need for lookup tables or coordinate transformations. These advantages make the proposed scheme well suited to large level-number applications, such as modular multilevel converters and high voltage direct current systems. Simulation and experimental results verify this new concept.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Bidirectional Three-Phase Push–Pull Converter With Dual
           Asymmetrical PWM Method
    • Authors: Kwon; M.;Park, J.;Choi, S.;
      Pages: 1887 - 1895
      Abstract: This paper proposes a new bidirectional three-phase push–pull converter that has a simple structure and achieves zero-voltage switching turn-on of switches. Also, due to use of a single inductor, an imbalance among phase currents on the low-voltage high-current side is trivial in the proposed converter although no current sharing control is employed. In this paper, a new dual asymmetrical pulse width modulation (PWM) switching method is proposed for bidirectional power flow control with seamless mode change. The proposed switching method offers reduced circulating current and makes the converter easier to implement compared to the PWM plus phase shift-based control method since it is a general PWM method having two independent duty cycle controls on each side. Experimental results from a 3-kW prototype are provided to validate the proposed concept.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Grouping-Sorting-Optimized Model Predictive Control for Modular Multilevel
           Converter With Reduced Computational Load
    • Authors: Liu; P.;Wang, Y.;Cong, W.;Lei, W.;
      Pages: 1896 - 1907
      Abstract: Featuring high efficiency, low harmonic distortion, high modularity and scalability, the modular multilevel converter (MMC) is particularly suitable for high voltage direct current transmission applications. As an advanced control strategy, model predictive control (MPC) has the advantage of direct modeling and fast dynamic response. It can simultaneously control multiple variables through an appropriate cost function. The conventional MPC can achieve an optimal control objective by evaluating all the candidate switching states for the MMC; however, with increasing number of submodules, there is an increasing number of candidate switching states that place an enormous burden on the control. In this paper, a grouping-sorting-optimized MPC (GSOMPC) strategy is proposed for the MMC with the number of submodules for each arm increases to hundreds. It divides all submodules of each arm into M groups, with each containing X submodules. By the implementation of the first level and second level optimized MPC between groups and submodules, respectively, the computational load of each phase decreases from C_{2N}^N to 2X + M + 3(N = M \times X) . In addition, to reduce the strict requirements of control hardware for sorting and calculation, the proposed strategy is able to simultaneously control the submodule voltage, ac current, circulating current, and switching frequency. Applied to a 2.7-kV/60-kW MMC back-to-back dynamic test system, experimental results verify the feasibility and effectiveness of the proposed GSOMPC strategy.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Flying-Capacitor-Based Hybrid LLC Converters With Input Voltage
           Autobalance Ability for High Voltage Applications
    • Authors: Li; W.;Luo, Q.;Mei, Y.;Zong, S.;He, X.;Xia, C.;
      Pages: 1908 - 1920
      Abstract: An advanced hybrid LLC series resonant converter with integrated flying-capacitor cell is proposed in this paper to enable the high step-down conversion in the high input voltage applications. The inherent flying-capacitor branch in the primary side can effectively halve the primary switch voltage stress compared with the half-bridge LLC converters. And the input voltage can be shared equally and automatically between the two series half-bridge modules without additional balance circuit or control strategies due to the built-in flying-capacitor cell. Moreover, the inherent soft switching performance during wide load range that exists in the LLC converters is still kept to reduce the switching losses, which ensures the high efficiency. Besides, the proposed converter can be extended to further decrease the switch voltage stress by employing stacked connection. Finally, a 500 ∼ 640 V-input 48 V-output 1 kW prototype is built and tested to verify the effectiveness of the proposed converter. The results prove that the proposed converter is an excellent candidate for the high input voltage and high step-down dc/dc conversion systems.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • An Active Voltage-Balancing Method Based on Phase-Shifted PWM for Stacked
           Multicell Converters
    • Authors: Ghias; A.M.Y.M.;Pou, J.;Agelidis, V.G.;
      Pages: 1921 - 1930
      Abstract: This paper proposes and evaluates an active voltage-balancing method for stacked multicell converters (SMCs) using phase-shifted pulse width modulation. The method is easy to implement and can be applied to SMCs with any number of levels. The proposed method balances the voltages of the capacitors by modifying the duty cycle of each switch of the SMC using a proportional controller. The direction of the output current and the crossed effect among the duty cycles of the switches is considered and used to improve capacitor voltage balance. The performance of the proposed voltage-balancing method is verified experimentally for different loads, such as linear and nonlinear loads, and under transient conditions.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Time-Offset Injection Method for Neutral-Point AC Ripple Voltage Reduction
           in a Three-Level Inverter
    • Authors: Lee; J.;Lee, K.;
      Pages: 1931 - 1941
      Abstract: The purpose of neutral-point voltage balancing algorithms in the three-level neutral-point clamped (3L-NPC) topology is to eliminate the voltage unbalance of top- and bottom-side dc-link voltages (neutral-point voltage). These algorithms are divided into dc unbalance and ac unbalance compensation methods. The dc unbalance causes distortion of output currents; therefore, this problem has to be solved. The ac unbalance implies that there is an ac ripple in the top- and bottom-side dc-link voltages. In applications using 3L-NPC topology, a large dc-link capacitor value is required to mitigate this ac unbalance problem. As a result, the size and the cost of applications become large and expensive. In this paper, a compensation method for mitigating the ac unbalance of the neutral-point voltage is proposed, which causes the dc-link capacitor value to be small, when a carrier-based pulse width modulation method is applied. The proposed method compensates the ac unbalance of the neutral-point voltage by adding an optimal compensation value to the reference duty signals. This compensation value is calculated simply by currents and reference duty signals. The calculation process of the optimal compensation value is discussed, and the effectiveness of the proposed method is verified with simulations and experiments.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Dynamics and Robust Control of a Grid-Connected VSC in Multiterminal DC
           Grids Considering the Instantaneous Power of DC- and AC-Side Filters and
           DC Grid Uncertainty
    • Authors: Davari; M.;Mohamed, Y.A.I.;
      Pages: 1942 - 1958
      Abstract: The electric energy sector is moving toward extensive integration of renewable and clean energy resources, energy storage units, and modern loads via highly efficient and flexible multiterminal dc grids integrated within the traditional ac grid infrastructure. A voltage-source converter (VSC) is the main technology enabling the interconnection of dc and ac grids. In such demanding applications, dc-link voltage control is crucial to maintain system stability. However, the dynamics and control of VSCs considering the instantaneous power of both ac- and dc-side filters and dc grid uncertainties are not addressed in the current literature. Furthermore, as shown in this paper, the uncertainty in the effective dc grid parameters, including filter capacitance and dc-side inductance owing to connecting/disconnecting electric devices to/from the dc grid remarkably affects the converter stability and performance. To overcome these difficulties, this paper presents 1) a detailed small-signal model of the dc-link dynamics in grid-connected VSCs considering the instantaneous power of both ac- and dc-side energy storage components, and 2) a robust optimal dc-link voltage controller. The proposed controller ensures excellent tracking performance, robust disturbance rejection, and robust performance against operating point and parameter variation with a simple fixed-parameter controller. A theoretical analysis, comparative simulation studies, and experimental results are presented to show the effectiveness of the proposed control structure.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Novel Five-Level Voltage Source Inverter With Sinusoidal Pulse Width
           Modulator for Medium-Voltage Applications
    • Authors: Narimani; M.;Wu, B.;Zargari, N.R.;
      Pages: 1959 - 1967
      Abstract: This paper proposes a new five-level voltage source inverter for medium-voltage high-power applications. The proposed inverter is based on the upgrade of a four-level nested neutral-point clamped converter. This inverter can operate over a wide range of voltages without the need for connecting power semiconductor in series, has high-quality output voltage and fewer components compared to other classic five-level topologies. The features and operation of the proposed converter are studied and a simple sinusoidal PWM scheme is developed to control and balance the flying capacitors to their desired values. The performance of the proposed converter is evaluated by simulation and experimental results.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Integrated Reconfigurable Converter Topology for High-Voltage Battery
    • Authors: Momayyezan; M.;Hredzak, B.;Agelidis, V.G.;
      Pages: 1968 - 1979
      Abstract: In series-connected battery systems, typically, separate converters for intramodule balancing bidirectional connection to a load and charging from an external power source are employed. In this paper, an integrated reconfigurable converter for high-voltage series-connected battery storage systems is proposed. The main advantage of the proposed converter is that it can be reconfigured to operate in different operating modes: feeding the load from the battery system, feeding the load from a backup power source, regenerative mode, intramodule balancing mode, and charging mode. Unlike conventional systems, the proposed topology shares the semiconductor devices and an inductor among the different operating modes which makes it compact. The proposed converter exhibits redundant modes which together with a backup mode increase its reliability. Additionally, the proposed topology minimizes stress on the batteries during the charging/discharging cycles. A scaled down experimental prototype of the proposed converter is implemented for a five-module battery system to verify its viability and demonstrate all operating modes.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Theoretical Comparison in Energy-Balancing Capability Between Star- and
           Delta-Configured Modular Multilevel Cascade Inverters for Utility-Scale
           Photovoltaic Systems
    • Authors: Sochor; P.;Akagi, H.;
      Pages: 1980 - 1992
      Abstract: This paper provides a theoretical discussion and comparison in energy balancing between a modular multilevel cascade inverter based on single-star bridge cells (SSBC) and that on single-delta bridge cells (SDBC). Attention is paid to applications involving asymmetric active-power generation in utility-scale grid-tied photovoltaic systems. Both qualitative and quantitative evaluation metrics to assess the energy-balancing capability are introduced and applied to both SSBC and SDBC inverters. As for the SSBC inverter, six zero-sequence voltage waveforms with different harmonic content enabling enhanced energy-balancing capability are analyzed and compared regarding their effectiveness. This paper also emphasizes on the SDBC as an alternative to the SSBC and highlights its superior operating characteristics under asymmetric active-power generation.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • LCL Grid Filter Design of a Multimegawatt Medium-Voltage
           Converter for Offshore Wind Turbine Using SHEPWM Modulation
    • Authors: Zabaleta; M.;Burguete, E.;Madariaga, D.;Zubimendi, I.;Zubiaga, M.;Larrazabal, I.;
      Pages: 1993 - 2001
      Abstract: The switching frequency of medium-voltage high-power converters is limited to about 1 kHz due to semiconductor junction temperature constraint. The frequency band between the fundamental and carrier frequency is limited to a little more than one decade and the LCL filter design is usually a challenge to meet grid codes for grid-connected applications. Traditional designs focus on the optimization of the filter parameters and different damping circuits. However, this design is very influenced by the modulation technique and produced low-order harmonics. Widely used pulse width modulations (PWM), such as phase disposition PWM (PDPWM), produce low-order harmonics that constraint the design of the filter. Selective harmonic elimination PWM (SHEPWM) can eliminate theses low-order harmonics, enabling a more efficient design of the LCL filter. In this paper, the LCL grid filter of a multimegawatt medium-voltage neutral-point-clamped converter for a wind turbine is redesigned using the SHEPWM modulation. Experimental results demonstrate that the efficiency of the converter, filter, and overall efficiency are increased compared to that obtained with PDPWM.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Control and Experiment of an H-Bridge-Based Three-Phase Three-Stage
           Modular Power Electronic Transformer
    • Authors: Wang; X.;Liu, J.;Ouyang, S.;Xu, T.;Meng, F.;Song, S.;
      Pages: 2002 - 2011
      Abstract: Compared with conventional power transformer, the power electronic transformer (PET) or solid-state transformer has many attractive additional features. This paper focuses on an H-bridge-based three-phase three-stage modular PET, which consists of an input stage with series-connected H-bridge converters, an isolation stage with several independent dual-active-bridge converters, and an output stage with parallel-connected H-bridge converters. This PET suffers dc-link capacitor voltage unbalancing issue, and the parallel-connected module current unbalancing sharing issue. In this paper, a system control structure is proposed for the PET to deal with these issues. Different input-stage individual module dc-link voltage balancing control methods are analyzed and compared. It is found that the one implemented by directly trimming module output voltage amplitude is most suitable for PET. Moreover, a downscaled laboratory prototype is designed, built, and tested to verify the control strategy.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Design of AC–DC PFC High-Order Converters With Regulated Output
           Current for Low-Power Applications
    • Authors: Bodetto; M.;El Aroudi, A.;Cid-Pastor, A.;Calvente, J.;Martinez-Salamero, L.;
      Pages: 2012 - 2025
      Abstract: AC–DC power factor corrector circuits used in low-power applications have to overcome important power quality problems related to crest and power factors as well as total harmonic distortion (THD), and in many cases, they have to exhibit a high degree of output regulation. The design of efficient drivers for low-power applications using high-order converters is considered in this paper. Power factor correction is achieved by imposing a loss-free resistor behavior to SEPIC and Ćuk converters by means of an internal loop based on sliding-mode control, which requires a hysteretic comparator for its implementation. However, with a constant hysteresis width, the system exhibits harmful harmonic distortion in the input line current waveform so that a variable hysteresis window is used instead to avoid this distortion near the zero crossings of the input current. The subsequent analysis of the ideal sliding dynamics around the equilibrium point allows the design of an outer control loop to regulate the output current. Mathematical analysis, numerical simulations, and experimental results are presented to demonstrate the functionality of the proposed technique obtaining a significant improvement in terms of decreasing the THD. A dimmable LEDs driver supplying an HBLEDs string with a wide range of output current regulation illustrates the design.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Line Current Distortion Compensation for DCM/CRM Boost PFC
    • Authors: Chen; Y.;Chen, Y.;
      Pages: 2026 - 2038
      Abstract: This paper proposes a line current distortion compensation method, which is a fusion of the conventional variable on-time (VOT) control and the average current mode (ACM) control, for DCM/CRM boost PFC converter with zero current switching (ZCS)/zero voltage switching (ZVS)/valley switching (VS)/switching frequency limitation (SFL) functions. In this paper, the mathematical analyses of the line current distortion for the DCM/CRM boost PFC converter with ZCS/ZVS/VS/SFL functions are also derived to explain the causes of the line current distortion. In order to increase efficiency, the ZVS/VS/SFL functions are needed but the line current will be further distorted. To compensate the distorted line current, the ACM-based VOT (ABVOT) control for the DCM/CRM boost PFC converter is proposed. In addition, the constant-on-time-based noise-immunity S/H method is proposed to replace the multiplier, which is always needed for the conventional ACM-based control. The performance of the proposed ABVOT control with S/H method will be demonstrated by simulation and experiment results.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Control of Single-Phase Power Converters Connected to Low-Voltage
           Distorted Power Systems With Variable Compensation Objectives
    • Authors: Bonaldo; J.P.;Morales Paredes, H.K.;Pomilio, J.A.;
      Pages: 2039 - 2052
      Abstract: This paper presents a flexible control technique for power electronics converters, which can function as an active power filter, as a local power supply interface, or perform both functions simultaneously. Thus, it can compensate for current disturbances while simultaneously injecting active power into the electrical grid, transforming the power converter into a multifunctional device. The main objective is to use all the capacity available in the electronic power converter to maximize the benefits when it is installed in the electricity grid. This objective is achieved by using the orthogonal current decomposition of the conservative power theory. Each current component is weighted by compensation coefficients ( k_i ), which are adjusted instantaneously and independently, in any percentage, by means of load conformity factors ( \lambda _i ), thus providing online flexibility with respect to the objectives of compensation and injection of active power. Finally, simulated and experimental results are presented to validate the effectiveness and performance of the proposed approach.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Power Semiconductor Filter: Use of Series-Pass Device in Switching
           Converters for Filtering Input Current Harmonics
    • Authors: Fan; W.;Yuen, K.K.;Chung, H.S.;
      Pages: 2053 - 2068
      Abstract: An investigation into the use of series-pass device (SPD) to filter out input current harmonics of switching converters is presented. The idea is based on connecting a SPD in series with the input of the switching converter so that the input current of the entire system can be profiled by adjusting the biasing condition of the SPD. To minimize the power dissipation of the SPD, the input impedance of the switching converter is controlled to make the SPD operate at the boundary between the linear and saturation modes. Modeling, design, and analysis of the system architecture will be given. Selection guide for the SPD will also be given. The concept has been applied to a 75-W 90–140-V/24-V classical dc–dc buck converter. Investigations reveal that the proposed architecture allows a substantial reduction in the size of the filter section and gives comparable efficiency as the conventional passive-type LC filter. More importantly, the idea makes the input filter amenable to monolithic integration. These investigations lay the foundation for applying the proposed concept for other power electronic converter systems.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • High-Efficiency DAB Converter Using Switching Sequences and Burst Mode
    • Authors: Oggier; G.G.;Ordonez, M.;
      Pages: 2069 - 2082
      Abstract: Dual active bridge converters enable bidirectional power flow in buck and boost operating modes. This paper presents an advanced switching sequence and burst-mode strategy to balance conduction, switching, and magnetic losses under light, medium, and heavy loading conditions, leading to improved operating efficiency. The implementation of the switching sequence employs the natural state-plane trajectories of the converter and contributes to higher efficiency and the ability to perform burst mode. The proposed switching sequences improve the overall efficiency of the converter by enabling soft switching and adjusting the frequency to match the minimum RMS transformer current in the full operating range. Furthermore, it incorporates a fully controlled burst-mode switching sequence for light loading conditions to further extend the efficiency gains. As a result, maximum efficiency is obtained by taking advantage of all the possible switching structures of the converter. The analysis provides insight into the natural trajectories of the converter, which produce soft-switching transitions and enable the converter structures to achieve the target operating point directly. Simulation and experimental results are presented to validate the benefits of the switching sequence and illustrate the burst-mode operation.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Optimal Design of High-Order Passive-Damped Filters for Grid-Connected
    • Authors: Beres; R.N.;Wang, X.;Blaabjerg, F.;Liserre, M.;Bak, C.L.;
      Pages: 2083 - 2098
      Abstract: Harmonic stability problems caused by the resonance of high-order filters in power electronic systems are ever increasing. The use of passive damping does provide a robust solution to address these issues, but at the price of reduced efficiency due to the presence of additional passive components. Hence, a new method is proposed in this paper to optimally design the passive damping circuit for the LCL filters and LCL with multituned LC traps. In short, the optimization problem reduces to the proper choice of the multisplit capacitors or inductors in the high-order filter. Compared to existing design procedures, the proposed method simplifies the iterative design of the overall filter while ensuring the minimum resonance peak with a lower damping capacitor and a lower rated resistor. It is shown that there is only one optimal value of the damping resistor or quality factor to achieve a minimum filter resonance. The passive filters are designed, built, and validated both analytically and experimentally for verification.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Individual Phase Current Control Based on Optimal Zero-Sequence Current
           Separation for a Star-Connected Cascade STATCOM Under Unbalanced
    • Authors: Shi; Y.;Liu, B.;Shi, Y.;Duan, S.;
      Pages: 2099 - 2110
      Abstract: This paper proposes an individual phase current control (IPCC) method based on optimal zero-sequence current separation for star-connected cascade STATCOMs under unbalanced grid voltage. The IPCC is adopted to get better adaptation to unbalanced conditions. Each cluster of the cascade STATCOM has its own phase current control loop and dc-voltage feedback loop, and it can generate the necessary negative-sequence current automatically to rebalance power. However, the zero-sequence current which is unnecessary and harmful in star configuration is introduced in the process. An optimal zero-sequence current separation is presented to remove the zero-sequence current by reconstructing the reactive current command. This improved IPCC enables star-connected STATCOMs adapt to unbalanced conditions without the need for any power balancing algorithms. Also, the operation range of the proposed control method is analyzed. Simulation research studies are performed to verify the operation range analysis, and the experimental operation is tested on a 25-level ±10 Mvar/10-kV STATCOM product installed at a wind farm.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Fundamental Study of Influence of Ripple Noise From DC–DC Converter
           on Spurious Noise of Wireless Portable Equipment
    • Authors: Sugahara; S.;Matsunaga, S.;
      Pages: 2111 - 2119
      Abstract: Power supply noise is a serious concern in noise-sensitive radio frequency or analog circuits. This paper presents an analysis of the influence of the synchronous rectification buck-type dc–dc converters for power amplifiers. An output ripple noise equation of the converter and a spurious noise equation of the carrier output voltage of the class-A amplifier powered by the converter are derived to analyze fundamental characteristics of these noise components theoretically. The amplifier's output spurious noise is calculated by these equations and measured by the evaluation circuit board. The spurious noise variation caused by the parameter variations of the amplifier or the converter is discussed based on these experimental and theoretical results. The spurious noise can be suppressed by decreasing the channel length modulation coefficient of the n-channel MOSFET constituting the amplifier and the natural frequency of the converter output LC filter. The spurious noise is reduced to low level below − 60 dB compared to the carrier signal by setting the channel length modulation coefficient below 0.1 V−1 and the natural frequency below 120 kHz. Furthermore, when the natural frequency is below 40 kHz, the spurious noise is − 80 dB below the carrier signal.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Function-Based Maximum Power Point Tracking Method for Photovoltaic
    • Authors: Reza Tousi; S.M.;Moradi, M.H.;Basir, N.S.;Nemati, M.;
      Pages: 2120 - 2128
      Abstract: In this paper, a novel maximum power point tracking (MPPT) algorithm based on introducing a complex function for photovoltaic (PV) systems is proposed. This function is used for determination of the duty cycle of the dc–dc converter in PV systems to track the MPP in any environment and load condition. It has been suggested based on analyzing the expected behavior of converter controller. The function is formed by a two-dimensional Gaussian function and an Arctangent function. It has been shown that contrary to many algorithms that produce wrong duty cycles in abrupt irradiance changes, the proposed algorithm is able to behave correctly in these situations. In order to evaluate the performance of method, various simulations and experimental tests have been carried out. The method has been compared with some major MPPT techniques with regard to start-up, steady-state, and dynamic performance. The results reveal that the proposed method can effectively improve the dynamic performance and steady-state performance simultaneously.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Magnetic Integration of Discrete-Coupled Inductors in Single-Phase Direct
           PWM AC–AC Converters
    • Authors: Khan; A.A.;Cha, H.;Kim, H.;
      Pages: 2129 - 2138
      Abstract: Recently, novel direct pulse width modulated (PWM) ac–ac converters using coupled inductors with switching cell structure have been introduced as an alternative to the conventional ac–ac converter topology. The converters can effectively solve the commutation problem associated with the conventional direct PWM ac–ac converters. However, the two coupled inductors used in the topology make the converters less attractive for use in practical applications. This paper proposes magnetic integration of the discrete-coupled inductors in single-phase ac–ac converters. The dc offset fluxes generated by the common-mode currents are cancelled out perfectly when the windings on the common core are appropriately arranged, resulting in ac flux only. The proposed inductor shows significant improvements over discrete-coupled inductors, in that the proposed inductor does not have an air gap, it exhibits symmetrical winding currents, and it has smaller volume with large current handling capability. The proposed inductor can handle an unlimited amount of current due to the absence of core saturation caused by the current and is well suitable for high power ac–ac conversion applications. The performance evaluation and comparison of the experimental results show that the net volume of the coupled magnetic components can be reduced by more than 50% with the proposed integration scheme.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Synchronization Method for Single-Phase Grid-Tied Inverters
    • Authors: Hadjidemetriou; L.;Kyriakides, E.;Yang, Y.;Blaabjerg, F.;
      Pages: 2139 - 2149
      Abstract: The controllers of single-phase grid-tied inverters require improvements to enable distribution generation systems to meet the grid codes/standards with respect to power quality and the fault ride through capability. In that case, the response of the selected synchronization technique is crucial for the performance of the entire grid-tied inverter. In this paper, a new synchronization method with good dynamics and high accuracy under a highly distorted voltage is proposed. This method uses a Multiharmonic Decoupling Cell (MHDC), which thus can cancel out the oscillations on the synchronization signals due to the harmonic voltage distortion while maintaining the dynamic response of the synchronization. Therefore, the accurate and dynamic response of the proposed MHDC-PLL can be beneficial for the performance of the whole single-phase grid-tied inverter.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Scaled Current Tracking Control for Doubly Fed Induction Generator to
           Ride-Through Serious Grid Faults
    • Authors: Huang; Q.;Zou, X.;Zhu, D.;Kang, Y.;
      Pages: 2150 - 2165
      Abstract: For doubly fed induction generator (DFIG)-based wind turbine, the main constraint to ride-through serious grid faults is the limited converter rating. In order to realize controllable low voltage ride through (LVRT) under the typical converter rating, transient control reference usually need to be modified to adapt to the constraint of converter's maximum output voltage. Generally, the generation of such reference relies on observation of stator flux and even sequence separation. This is susceptible to observation errors during the fault transient; moreover, it increases the complexity of control system. For this issue, this paper proposes a scaled current tracking control for rotor-side converter (RSC) to enhance its LVRT capacity without flux observation. In this method, rotor current is controlled to track stator current in a certain scale. Under proper tracking coefficient, both the required rotor current and rotor voltage can be constrained within the permissible ranges of RSC, thus it can maintain DFIG under control to suppress overcurrent and overvoltage. Moreover, during fault transient, electromagnetic torque oscillations can be greatly suppressed. Based on it, certain additional positive-sequence item is injected into rotor current reference to supply dynamic reactive support. Simulation and experimental results demonstrate the feasibility of the proposed method.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Single-Phase PV Quasi-Z-Source Inverter With Reduced Capacitance Using
           Modified Modulation and Double-Frequency Ripple Suppression Control
    • Authors: Zhou; Y.;Li, H.;Li, H.;
      Pages: 2166 - 2173
      Abstract: In single-phase photovoltaic (PV) system, there is double-frequency power mismatch existed between the dc input and ac output. The double-frequency ripple (DFR) energy needs to be buffered by passive network. Otherwise, the ripple energy will flow into the input side and adversely affect the PV energy harvest. In a conventional PV system, electrolytic capacitors are usually used for this purpose due to their high capacitance. However, electrolytic capacitors are considered to be one of the most failure prone components in a PV inverter. In this paper, a capacitance reduction control strategy is proposed to buffer the DFR energy in single-phase Z-source/quasi-Z-source inverter applications. Without using any extra hardware components, the proposed control strategy can significantly reduce the capacitance requirement and achieve low input voltage DFR. Consequently, highly reliable film capacitors can be used. The increased switching device voltage stress and power loss due to the proposed control strategy will also be discussed. A 1-kW quasi-Z-source PV inverter using gallium nitride (GaN) devices is built in the lab. Experimental results are provided to verify the effectiveness of the proposed method.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Three-Port DC/DC Converter With All Ports Current Ripple Cancellation
           Using Integrated Magnetic Technique
    • Authors: Zhu; H.;Zhang, D.;Liu, Q.;Zhou, Z.;
      Pages: 2174 - 2186
      Abstract: This paper presents a novel integrated magnetic three-port converter (IMTPC) with high power density and all three ports’ current ripple cancellation. The proposed IMTPC can interface one PV port, one bidirectional battery port, and one load port of the PV-battery dc power system. Only two high power magnetic devices are needed in an IMTPC for realizing power conversion, ripple cancellation, and switch driver simultaneously. Three extra capacitors were added to achieve three ports’ current ripple cancellation. Therefore, the port of the IMTPC will always in continuous-conduction mode with “zero current ripple,” thus, size of passive filter can be reduced and accuracy of maximum power point tracking can be improved. Meanwhile, simple driving of the high-side switch can be realized by integrated magnetic winding, which is responsible for MOSFET driver's voltage level shift. The using of the integrated magnetic technique not only performs aforementioned advantages but also shows great potential for reducing the weight and volume of the dc–dc converter. Finally, experimental verifications are given to illustrate the feasibility and effectiveness of the proposed topology and control method.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Output-Impedance Shaping of Bidirectional DAB DC–DC Converter Using
           Double-Proportional-Integral Feedback for Near-Ripple-Free DC Bus Voltage
           Regulation in Renewable Energy Systems
    • Authors: Cao; L.;Loo, K.H.;Lai, Y.M.;
      Pages: 2187 - 2199
      Abstract: This paper investigates the design and implementation of virtual-output-impedance shaping on an inverter-loaded, fuel-cell-battery-powered dc–dc converter system for achieving near-ripple-free dc bus voltage regulation. The method is based on the insertion of a second output-voltage feedback loop as can be inferred from the Mason's gain formula. Three basic modes of virtual-output-impedance shaping (proportional, derivative, integral) are discussed and the closed-loop output-impedance characteristics due to each of them are analyzed in detail and with their Thévenin equivalent circuits derived. Despite the suitability of integral feedback for minimizing converter's output impedance, it can give rise to an unwanted resonance peak near the converter's crossover frequency, thus potentially destabilizing the system. The solution to the problem using combination of basic virtual-output-impedance shaping modes and its practical implementation are discussed. When implemented on a fuel-cell-battery-powered dual-active-bridge dc–dc converter, the second-harmonic distortion of dc bus voltage is shown to have been reduced by 85.5% compared to a conventionally PI-compensated system.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Soft-Switched Asymmetric Flying-Capacitor Boost Converter With
           Synchronous Rectification
    • Authors: Lefevre; G.;Mollov, S.V.;
      Pages: 2200 - 2212
      Abstract: The multilevel flying-capacitor boost converter was analyzed for asymmetric voltage operation—this permits loss optimization that takes advantage of different voltage class MOSFETs. A cost-motivated design of a suitable zero-voltage zero-current switching snubber is then developed that permits a great reduction of the inductor size. With the proposed snubber, synchronous rectification operation is compared to that of diode boost, with a particular attention to the contribution of nonlinear MOSFET parasitics. Experimental results from a 2-kW/30-kHz prototype justify the effectiveness of this solution with a conversion efficiency around 99% \pm 0.1% for a wide load range.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Bidirectional Three-Level LLC Resonant Converter With
           PWAM Control
    • Authors: Jiang; T.;Zhang, J.;Wu, X.;Sheng, K.;Wang, Y.;
      Pages: 2213 - 2225
      Abstract: This paper proposes a bidirectional three-level LLC resonant converter with a new pulse width and amplitude modulation control method. With different control signals, it has three different operation modes with different voltage gains. Therefore, it can achieve wide voltage gain range by switching among these three modes, which is attractive for energy storage system applications needing wide voltage variation. The proposed topology operates with constant switching frequency, which is easy to implement with digital control, and it can achieve soft switching for all the switches and diodes in the circuit as a conventional LLC resonant converter. The performance of the proposed converter is validated by the experimental results from a 1-kW prototype with 20 A maximum output current.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Lithium Polymer Battery State-of-Charge Estimation Based on Adaptive
           Unscented Kalman Filter and Support Vector Machine
    • Authors: Meng; J.;Luo, G.;Gao, F.;
      Pages: 2226 - 2238
      Abstract: An accurate algorithm for lithium polymer battery state-of-charge (SOC) estimation is proposed based on adaptive unscented Kalman filters (AUKF) and least-square support vector machines (LSSVM). A novel approach using the moving window method is applied, with AUKF and LSSVM to accurately establish the battery model with limited initial training samples. The effectiveness of the moving window modeling method is validated by both simulations and lithium polymer battery experimental results. The measurement equation of the proposed AUKF method is established by the LSSVM battery model and AUKF has the advantage of adaptively adjusting noise covariance during the estimation process. In addition, the developed LSSVM model is continuously updated online with new samples during the battery operation, in order to minimize the influence of the changes in battery internal characteristics on modeling accuracy and estimation results after a period of operation. Finally, a comparison of accuracy and performance between the AUKF and UKF is made. Simulation and experiment results indicate that the proposed algorithm is capable of predicting lithium battery SOC with a limited number of initial training samples.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Dual-Loop Control Strategy for DFIG-Based Wind Turbines Under Grid Voltage
    • Authors: Zhu; R.;Chen, Z.;Tang, Y.;Deng, F.;Wu, X.;
      Pages: 2239 - 2253
      Abstract: For a multimegawatts doubly-fed induction generator (DFIG), the grid voltage disturbances may affect the stator flux and induce the transient stator flux, due to the direct connection of the stator and the grid. The accumulation of the transient stator flux caused by the variations of the stator voltage may introduce harmful power and torque oscillations to the DFIG, and even lead to rotor overcurrent. For the conventional field-oriented vector control strategy, the design of the controller is based on the steady-state model of the DFIG, which neglects the dynamic of the stator flux, and, therefore, it cannot work well during the transient state to decay the transient flux and to suppress the flux accumulation. In this paper, a dual-loop control strategy, which includes the conventional current loop and an additional flux loop, is proposed to not only control the active and reactive power, but also decay the stator transient flux, and avoid the accumulation of the stator transient flux. Moreover, the proposed strategy can obtain nearly constant stator active power and electromagnetic torque, which may prolong the lifetime of the drive train. A case study on a typical 2-MW DFIG-based wind turbine demonstrating the effectiveness of the proposed control methods is verified with simulations in MATLAB/Simulink. The proposed control methods are also experimentally validated using a scaled-down 7.5-kW DFIG. The simulation and experimental results clearly validate the effectiveness and feasibility of the proposed strategy, and show the improved dynamic performances of the DFIG.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Multiinput Bridgeless Resonant AC–DC Converter for
           Electromagnetic Energy Harvesting
    • Authors: Tang; Y.;Khaligh, A.;
      Pages: 2254 - 2263
      Abstract: Flapping electromagnetic-reed generators are investigated to harvest wind energy, even at low cutoff wind speeds. Power electronic interfaces are intended to address ac–dc conversion and power conditioning for single- or multiple-channel systems. However, the generated voltage of each generator reed at low wind speed is usually below the threshold voltage of power electronic semiconductor devices, increasing the difficulty and inefficiency of rectification, particularly at relatively low output powers. This paper proposes a multiinput bridgeless resonant ac–dc converter to achieve ac–dc conversion, step-up voltage and match optimal impedance for a multichannel electromagnetic energy harvesting system. Alternating voltage of each generator is stepped up through the switching LC network and then rectified by a freewheeling diode. Its resonant operation enhances efficiency and enables miniaturization through high frequency switching. The optimal electrical impedance can be adjusted through resonance impedance matching and pulse-frequency-modulation control. A 5 cm × 3 cm, six-input standalone prototype is fabricated to address power conditioning for a six-channel wind panel.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • An Interleaved PFM LLC Resonant Converter With
           Phase-Shift Compensation
    • Authors: Murata; K.;Kurokawa, F.;
      Pages: 2264 - 2272
      Abstract: The interleaved structure of LLC resonant converter with the phase-shift modulation (PSM) is presented and then its optimum operating region is discussed. The LLC resonant converters can achieve zero-voltage switching (ZVS) of the primary switches and zero-current switching (ZCS) of the secondary switches. However, the secondary peak current is large due to the discontinuous conduction mode (DCM). The interleaved PFM LLC resonant converter has difficulty in synchronizing switching instants among phases owing to the parameter mismatch of resonant circuits. In the proposed method, the current unbalance caused by the parameter mismatch is compensated by PSM. It is confirmed that the proposed method achieves lower peak current even when there is parameter mismatch and that the operation of below resonant frequency is suitable, both of which are simulated and experimentally verified.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A 300-mV Low-Power Management System for Energy Harvesting Applications
    • Authors: Dallago; E.;Lazzarini Barnabei, A.;Liberale, A.;Torelli, G.;Venchi, G.;
      Pages: 2273 - 2281
      Abstract: In this paper, a power management system (PMS) for low-voltage and low-power harvesters is presented. The PMS consists of an energy storage module and a supply regulation (SR) unit. The energy provided by the harvester is first stored in a capacitor C_{{\rm IN}} . When enough energy is accumulated in C_{{\rm IN}} , the SR block is enabled and transfers the charge from C_{{\rm IN}} to an output capacitor C_{{\rm OUT}} at a higher voltage. The storage process is controlled by a 300-mV voltage supervisor. The voltage step-up process is realized through a two-stage self-starting switching converter, which is able to automatically reconfigure itself after the cold start to improve conversion efficiency during the steady state. Correct system operation is ensured with harvesters that deliver at least 8 μA at 300 mV. The PMS exhibits an average steady-state charge transfer efficiency of 55% in the 2.5 μW–1 mW input power range. The circuit is built with no need for programmable devices and is battery free, low cost, and small sized. A prototype was realized and tested with two different low-voltage harvesters, namely a microbial fuel cell and a photovoltaic cell.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Analysis and Design of Modified Half-Bridge Series-Resonant Inverter With
           DC-Link Neutral-Point-Clamped Cell
    • Authors: Ryu; S.;Woo, D.;Kim, M.;Lee, B.;
      Pages: 2282 - 2295
      Abstract: In this paper, a modified half-bridge (HB) resonant inverter topology with a dc-link neutral-point-clamped cell is proposed. A pseudo asymmetrical voltage-cancellation PWM method and a control strategy are introduced. The proposed topology can maximize the inverter output power factor, and minimize variations in the switching frequency. In addition, most switches are clamped to half of the dc input voltage at turn-off, increasing the overall efficiency of the system for a wide load range. The efficiency of the proposed inverter is improved up to 7% at light-load conditions compared with that of the conventional HB inverter. Informative expressions for performance comparison between the proposed inverter and its counterpart are provided. In addition, the losses in the inverter primary components are analytically analyzed in detail. For validation, a 120-W prototype is implemented, and experimental results are presented.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Single-Inductor Multiple-Output Auto-Buck-Boost DC–DC Converter
           With Autophase Allocation
    • Authors: Zheng; Y.;Ho, M.;Guo, J.;Mak, K.;Leung, K.N.;
      Pages: 2296 - 2313
      Abstract: A single-inductor multiple-output (SIMO) converter with auto-buck-boost feature is presented in this paper. A seamless auto-buck-boost scheme for SIMO dc–dc converter using time-multiplexing control is proposed. Additionally, with the proposed first-order phase-locked loop (FOPLL) and autophase allocation, this circuit solves the problem of unbalanced loadings of different channels, and it also keeps the locking time of the inductor current sufficiently short to minimize average inductor current for attaining higher efficiency. By combining with all channel controllers, FOPLL not only allows fast load-transient response without degrading the power efficiency, but it also reduces controller order of the frequency control loop, attenuates the noise injected from charge pump, and achieves robust stability. The scheme enables the dc–dc converter to operate from wide input and output ranges. Implemented in a 0.35-μm CMOS technology, the chip area is 5000 μm × 1850 μm, including ESD test pads. The switching frequency is fixed at 0.25 MHz. The load-transient response time is less than 100 μs. The proposed converter achieves a peak efficiency of 89% and maximum output power up to 1.46 W with efficiency of 70%.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Analysis and Design of a Single-Switch Forward-Flyback Two-Channel LED
           Driver With Resonant-Blocking Capacitor
    • Authors: Kim; J.;Moon, J.;Moon, G.;
      Pages: 2314 - 2323
      Abstract: In order to balance the light-emitting-diode (LED) current in each channel, many active and passive methods have been investigated. Among the various methods, the passive method using the LLC converter with a blocking capacitor or flyback converter with a current-sharing transformer (CST) in the secondary side is one of the simplest methods because it does not use any active component. However, the LLC driver requires two main switches and external resonant inductor to obtain a wide output voltage range. Also, flyback with a CST requires an additional magnetic component for CST and high-voltage rated diodes, resulting in the limitation of the cost and system volume. In this paper, a single-switch forward-flyback driver for a two-channel LED is proposed. The most powerful advantage of the proposed driver is the cost effectiveness, since it eliminates additional magnetic component. Furthermore, due to the reduced-voltage stress on rectifier diodes compared to the flyback driver, the proposed driver achieves a higher efficiency. The prototype of the 150–100-V/0.3-A two-channel LED verifies the effectiveness of this paper.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Design and Analysis of an Adaptively Biased Low-Dropout Regulator Using
           Enhanced Current Mirror Buffer
    • Authors: Maity; A.;Patra, A.;
      Pages: 2324 - 2336
      Abstract: This paper presents an adaptively biased low-dropout regulator using an enhanced current mirror (ECM) buffer for effectively driving the gate of the PMOS power transistor. The proposed ECM buffer offers very low output impedance, which pushes out the pole at the gate of the PMOS power transistor to improve the stability. At the same time, it offers a symmetric pull-up/down slew rate to enhance the speed of the buffer, whenever the regulator is under large signal operation during the load transient. Moreover, the ECM buffer is modified to develop the regulator topology without introducing an error amplifier as a separate independent stage. It helps to minimize the overall quiescent current consumption at low-load condition and makes frequency compensation easier. Finally, the speed of the adaptive bias loop is increased by avoiding the highly capacitive gate node of the PMOS power transistor. A comprehensive small-signal analysis of the proposed regulator is also carried out for a clear understanding of the stability of each loop considering the interaction of the other loop. The regulator is implemented in a 0.18- \mu m CMOS technology with a quiescent current of 900 nA. A maximum transient output voltage variation of 2.1% is observed with C_{o} = 470 nF.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Active Damping of LLCL-Filter Resonance Based on
           LC-Trap Voltage or Current Feedback
    • Authors: Huang; M.;Wang, X.;Loh, P.C.;Blaabjerg, F.;
      Pages: 2337 - 2346
      Abstract: LLCL-filter is an emerging fourth-order filter proposed after the third-order LCL -filter. It uses smaller passive components than the LCL-filter, but is still burdened by resonance complications when used with a grid converter. An LLCL-filtered converter must, hence, be passively or actively damped. Active damping is presently more efficient, and can easily be realized by feeding back a state variable. For the LCL-filter, the variable is usually its middle capacitor current. However, with computational delays considered, a simple proportional damper cannot be used with the capacitor current. Instead, a high-pass damper must be used, which as commonly known, may cause undesired noise complications depending on operating conditions. In this paper, the same capacitor current damper has been investigated for the LLCL -filter with its limitations clarified. Both cases of with and without delays have been considered. The investigation has also been extended to consider the LC-trap voltage feedback, which based on the formulated transfer functions and experimental results, permits a simple proportional damper to be used. Lesser noise complications and faster dynamic can then be achieved. Circuit equivalences for the presented dampers have also been derived, from which quick damping insights can be easily drawn. These equivalences are, therefore, helpful tools to the practicing engineers.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • High-Order Resonant Converter Topology With Extremely Low-Coupling
           Contactless Transformers
    • Authors: Thenathayalan; D.;Lee, C.;Park, J.;
      Pages: 2347 - 2361
      Abstract: Although a large number of typical resonant converter topologies have been developed for use in contactless power transfer applications, these topologies need to be precisely optimized to obtain maximum efficiency and maximum power transferring capacity. High-order resonant power converters with flexible designs are invariably required to develop energy-efficient and cost-effective converter systems. An ideal converter topology can contribute toward realizing efficient converter systems if it is capable of providing an optimized output that is insensitive to load variations, coupling coefficient, type of the wireless transformer used, and other operating conditions. This paper presents a new contactless power converter topology for a low-coupling (0.14) ferrite-core transformer that has low cost, small size, high efficiency, and a wide gap (20 mm). In addition, the merits and demerits of conventional converter topologies are studied herein, and results for these topologies are compared with those for the proposed converter topology.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • An Integrated High-Power-Factor Converter With ZVS Transition
    • Authors: Chang; C.;Cheng, C.;Chang, E.;Cheng, H.;Yang, B.;
      Pages: 2362 - 2371
      Abstract: This paper proposes a single-phase high-power-factor ac/dc converter with soft-switching characteristic. The circuit topology is derived by integrating a boost converter and a buck converter. The boost converter performs the function of power-factor correction to obtain high power factor and low current harmonics at the input line. The buck converter further regulates the dc-link voltage to provide a stable dc output voltage. Without using any active-clamp circuit or snubber circuit, the active switches of the proposed converter can achieve zero-voltage switching-on transition together with high power factor that satisfies the IEC 61000-3-2 standards over a wide load range from 30% to 100% rated power. The steady-state analysis is developed and a design example is provided. A prototype circuit of 60 W was built and tested. Experimental results verify the feasibility of the proposed circuit with satisfactory performance.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Phase-Shift-Controlled Isolated Buck-Boost Converter With Active-Clamped
           Three-Level Rectifier (AC-TLR) Featuring Soft-Switching Within Wide
           Operation Range
    • Authors: Wu; H.;Lu, Y.;Sun, K.;Xing, Y.;
      Pages: 2372 - 2386
      Abstract: An active-clamped three-level rectifier (AC-TLR) is derived from the diode-clamped three-level inverter, by replacing the active switches and the diodes in the three-level inverter with the diodes and active switches, respectively. Novel isolated buck-boost converters, featuring single-stage conversion and soft-switching within wide operation range, are developed based on the proposed AC-TLR. By utilizing the AC-TLR, the voltage stress on the power devices and passive components, including the rectifying diodes, the active-clamping switches, the flying capacitor, and output filter capacitors, is reduced to the half of the output voltage. Low-voltage rating switching devices with better switching and conduction performances and a transformer with reduced turns ratio and parasitic parameters are used to enhance the efficiency. The full-bridge isolated buck-boost converter with the proposed AC-TLR is analyzed in detail as an example. An optimized phase-shift control strategy is employed to realize isolated buck and boost conversion. Soft switching of all of the switching devices in both the primary- and secondary-side circuits is achieved within the whole operation range by using the proposed AC-TLR and the phase-shift control strategy. Experimental results on a prototype with 380-V output verify the effectiveness of the proposed AC-TLR and its derived isolated buck-boost converters.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • DBC Switch Module for Management of Temperature and Noise in
           220-W/in3 Power Assembly
    • Authors: Shin; J.;Kim, W.;Ngo, K.D.T.;
      Pages: 2387 - 2394
      Abstract: A switch module integrates semiconductor dies on a direct-bond-copper (DBC) substrate to achieve both noise robustness and low thermal resistance. Negative couplings between conductors as well as compact layout with 2.89-nH common-source inductance in the module eliminate self-turn-on from 420-A/μs di/dt . The low thermal resistance of the DBC substrate provides 2.35-°C/W thermal resistance from junction to heat sink and limits the temperature rise of semiconductors switches to 50 °C. The maximum rated power and system density of the DBC and PCB modules are provided for 400-V application. A 2-kW dc–dc boost converter switched between 400 kHz and 1 MHz achieved a power density of 220 W/in3 and an efficiency of 98.4% by employing the switch module.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Reliability Assessment of the Switched Reluctance Motor Drive Under Single
           Switch Chopping Strategy
    • Authors: Chen; H.;Yang, H.;Chen, Y.;Iu, H.H.;
      Pages: 2395 - 2408
      Abstract: In this paper, a detailed set of reliability prediction methodology for switched reluctance motor drive (SRD) considering system specific control strategy and component fault classification is elaborated from component level to system level. At component level, introduction to SRD and its single switch chopping strategy is presented to capture characteristics of SRD reliability under a certain control strategy. The unique fault modes classification and summary methods which are tailored to SRD are applied for identification of system dominant fault modes. Then at system level, binary models (reliability block diagram and part-count model) and multivariate model (Markov model) are adopted to build systematic SRD reliability model, respectively. Especially in the Markov model, state transition diagram and state probability matrix P(t) are built in detailed description to constitute the graphical and numerical Markov reliability model. Conclusions can be drawn that compared with RBD, Markov model can capture the effect of specific control strategy on system reliability, and further demonstrates the stronger consistency with SRD practical operation. Fault simulation and experiments are conducted to illustrate the influence on system operation state caused by a control strategy. Also, the results verify the state assessment of system performance after component-level fault occurs.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Novel Quasi-Z-Source Inverter Topology With Special Coupled Inductors
           for Input Current Ripples Cancellation
    • Authors: Battiston; A.;Miliani, E.;Pierfederici, S.;Meibody-Tabar, F.;
      Pages: 2409 - 2416
      Abstract: This paper proposes an inductors coupling technique to cancel input current ripples of a quasi-Z-source inverter (ZSI) without adding any additional components. The source input filter thus might be suppressed. This remains valid whatever the boost factor value. This cancellation property is made possible by a suitable coupling of the two existing quasi-Z-source inductors according to mathematical condition. The considered system in this paper is an electric drive system composed of a motor fed by the proposed coupled quasi-ZSI. An experimental prototype to validate both the theoretical and simulation analyses has been developed. The results have validated the proposed coupling strategy and show that it does not degrade the global efficiency of the system.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Field-Oriented Control and Direct Torque Control for Paralleled VSIs Fed
           PMSM Drives With Variable Switching Frequencies
    • Authors: Wang; Z.;Chen, J.;Cheng, M.;Chau, K.T.;
      Pages: 2417 - 2428
      Abstract: In this paper, three control schemes with variable switching frequencies are proposed and analyzed for the paralleled voltage source inverters (VSIs) fed permanent magnet synchronous motor (PMSM) drive. The proposed schemes could be applied in the low-speed operation region of high-power drive system, where the frequency modulation index is high. First, the field-oriented control (FOC) with phase-shifted chaotic space vector modulation (SVM) under synchronous frame and the FOC with phase-shifted chaotic sinusoidal pulse width modulation under stationary frame is proposed for the paralleled VSIs fed PMSM drive. The proposed phase-shifted chaotic PWM schemes not only eliminate specific switching harmonics completely but also suppress all remaining switching harmonic peaks in the spectrum. The avoidance of inherent circulating current is also considered in designing these two schemes. Second, the direct torque control (DTC) for the paralleled VSIs fed PMSM drive is proposed with circulating current suppression. Besides inheriting the advantages of DTC, the output currents of paralleled VSIs are kept balanced. The working principles of these three methods are presented in detail. Experimental results on a laboratory prototype are given to verify the validity of the three proposed control schemes for the paralleled VSIs fed PMSM with variable switching frequencies.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Simplified Three-Level Five-Phase SVPWM
    • Authors: Sakthisudhursun; B.;Pandit, J.K.;Aware, M.V.;
      Pages: 2429 - 2436
      Abstract: A simplified space vector pulse width modulation (SVPWM) is proposed for a three-level five-phase inverter. The proposed method generates the duty cycle of the three-level inverter switches based on dwell times of the two-level inverter and carrier index. The proposed method automatically determines the eligible vectors, region, and switching sequence of optimized five vectors based on the modulation index. Out of 243 available vectors, 113 most eligible vectors are used for generation of desired voltage reference in main subspace, while zeroing the average voltage in the auxiliary subspace by using the proper switching sequence. This method also uses the redundant vectors in each subcycle thus balances the dc-link capacitor voltages and no additional algorithm or techniques are needed to balance the dc-link capacitor voltage. The identification of the reference location with the carrier index using the signum function simplifies the algorithm implementation. Thus, the proposed method eases the implementation of optimum five vectors to a greater extent. Based on only changing the carrier index, the proposed method can be easily extended for any multiphase multilevel (5, 7,…, n) inverter. The simulation and hardware results of the three-level five-phase inverter validate the proposed simplified method.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Transformation and Load Parameters of the Disk Piezoelectric Transformer
    • Authors: Erhart; J.;
      Pages: 2437 - 2442
      Abstract: The main aim of this paper is the theoretical analysis and experimental verification of the transformation parameters for the nonhomogeneously poled disk transformer with an excellent transformation ratio and efficiency. The input part is poled in thickness direction and output part in radial direction. Parameters like transformation ratio and efficiency are calculated analytically and measured as a function of resistive load, electrode dimensions, and electromechanical coefficients. The optimum electrode size aspect ratio d/D \approx 0.4 has been found experimentally. The fundamental as well as higher overtone resonances were studied for the transformation ratio, the optimum resistive load, efficiency, and no-load transformation ratio. All studied disk transformers exhibit very high transformation ratios ( U_{2}/U_{1} \approx 50 ) under no-load conditions and high efficiency ( \eta \approx 90% ) at the optimum load. The presented disk transformer is studied analytically and realized experimentally for the first time. The excellently high transformation ratio allows for the plasma generation at the output electrode.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Design Tools for Rapid Multidomain Virtual Prototyping of Power Electronic
    • Authors: Evans; P.L.;Castellazzi, A.;Johnson, C.M.;
      Pages: 2443 - 2455
      Abstract: The need for multidisciplinary virtual prototyping in power electronics has been well established, however, design tools capable of facilitating a rapid iterative virtual design process do not exist. A key challenge in developing such tools is identifying and developing modeling techniques which can account for 3-D geometrical design choices without unduly affecting simulation speed. This challenge has been addressed in this paper using model order reduction techniques and a prototype power electronic design tool incorporating these techniques is presented. A relevant electrothermal power module design example is then used to demonstrate the performance of the software and model order reduction techniques. Five design iterations can be evaluated, using 3-D inductive and thermal models, under typical operating and start-up conditions on a desktop PC in less than 15 min. The results are validated experimentally for both thermal and electrical domains.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Novel Method to Predict the Real Operation of Ferrite Inductors With
           Moderate Saturation in Switching Power Supply Applications
    • Authors: Di Capua; G.;Femia, N.;
      Pages: 2456 - 2464
      Abstract: This paper presents a method to predict the real operation current wave-shape of Ferrite Core (FC) inductors in switching power supply applications involving a moderate inductor saturation. The method is based on a behavioral analytical model of inductance versus current saturation curve, obtained starting from the data provided by inductors manufacturers. The algorithm developed to solve the nonlinear model of the inductor can be applied to predict the range of the operating conditions involving a sustainable partial saturation for FC inductors, and the resulting method is best suited for the selection of minimum size inductors for high-power-density power supply design solutions.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • An Alternative Approach to LED Driver Design Based on High-Voltage Driving
    • Authors: Wong; C.S.;Loo, K.H.;Lai, Y.M.;Chow, M.H.L.;Tse, C.K.;
      Pages: 2465 - 2475
      Abstract: This paper discusses an alternative approach to designing LED drivers based on high-voltage operation. Compared with the conventional approach of driving LEDs with low voltage and high current, the alternative approach aims to deliver the same power to LED load with high voltage and low current so that small and nonelectrolytic capacitor can be used. High-voltage operation also facilitates the use of simple PFC preregulators such as boost or SEPIC converters as single-stage LED drivers. This paper begins with the derivation of the relationship between the nominal output voltage and output capacitor's size of a PFC preregulator for achieving a given output voltage ripple's size, followed by a review of the recently emerged high-voltage LED packages suitable for the proposed application. This paper also discusses the flicker and colorimetric performances of LED light sources under the influence of large current ripple when nonelectrolytic capacitor is used. The method of third-harmonic current injection to the input current of LED drivers is also incorporated as an option for further reducing the output capacitor's size while meeting a specified flicker limit. Finally, a design example of high-voltage LED driver based on a boost PFC preregulator with third-harmonic current injection is presented and verified experimentally.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Double-Loop Primary-Side Control Structure for HB-LED Power Regulation
    • Authors: Shagerdmootaab; A.;Moallem, M.;
      Pages: 2476 - 2484
      Abstract: This paper presents a study of high-brightness LED (HB-LED) strings under power drive control, in which the LED's input power is controlled rather than its current. In the conventional constant current drive technique, any changes in the LED string's forward voltage results in output light variations due to a strong dependence between the LED output light to its input power. Under constant power drive control, the LED string's forward voltage variations due to ambient temperature changes and aging are compensated. To evaluate the power drive control method, an inner–outer-loop control structure is developed by utilizing an ac–dc flyback converter. To this end, a primary-side LED power estimator and controller are proposed to achieve simultaneous output power regulation and input power factor correction. An expression is obtained for the LED power in terms of its input current and ambient temperature that can provide qualitative and quantitative behavior in constant-current and constant-power drive regimes. Experimental results using a Cree CR22-32L LED string are presented and compared with the constant current drive technique for temperature variations in the range 25–80  ^\circ C. For the aforementioned temperature range and using similar hardware, the proposed controller results in an 8% reduction of the LED output light when compared to a 13% reduction using the constant current drive technique.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Analytical Switching Loss Model for Superjunction MOSFET With Capacitive
           Nonlinearities and Displacement Currents for DC–DC Power Converters
    • Authors: Castro; I.;Roig, J.;Gelagaev, R.;Vlachakis, B.;Bauwens, F.;Lamar, D.G.;Driesen, J.;
      Pages: 2485 - 2495
      Abstract: A new analytical model is presented in this study to predict power losses and waveforms of high-voltage silicon superjunction MOSFET during hard-switching operation. This model depends on datasheet parameters of the semiconductors, as well as the parasitics obtained from the printed circuit board characterization. It is important to note that it also includes original features accounting for strong capacitive nonlinearities and displacement currents. Moreover, these features demand unusual extraction of electrical characteristics from regular datasheets. A detailed analysis on how to obtain this electrical characteristic is included in this study. Finally, the high accuracy of the model is validated with experimental measurements in a double-pulse buck converter setup by using commercial SJ MOSFET, as well as advanced device prototypes under development.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Modeling and Analysis of Interturn Short Fault in Permanent Magnet
           Synchronous Motors With Multistrands Windings
    • Authors: Qian; H.;Guo, H.;Ding, X.;
      Pages: 2496 - 2509
      Abstract: This paper develops an analytical model for describing the behaviors of the interturn short fault in the permanent magnet synchronous motors (PMSMs) with multistrands windings. An analysis of the fault modes resulted from the deterioration of insulation in multistrands windings are first carried out. According to the possible fault influences, a consistent expressions of interturn short-circuit current, phase voltages, and electromagnetic torque for modeling the different modes of interturn short faults are then derived. The proposed model allows studying the postfault performances of these motors under transient and steady state, including fault resistance, quadrature- and direct-axis current, or speed variations. Both finite-element analysis and experimental results demonstrate the effectiveness of the developed model for predicting the interturn short-circuit behaviors in the PMSMs with multistrands windings.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Front-End Monitoring of Multiple Loads in Wireless Power Transfer Systems
           Without Wireless Communication Systems
    • Authors: Yin; J.;Lin, D.;Lee, C.K.;Parisini, T.;Hui, S.Y.R.;
      Pages: 2510 - 2517
      Abstract: This paper describes a method for monitoring multiple loads from the front end of a wireless power transfer system without using any wireless communication systems. A mathematical approach based on scanning the frequency around the resonant frequency has been developed for deriving the load conditions. The proposal requires only information of the input voltage and current, thereby eliminating the requirements of using wireless communication systems for feedback control. The proposal has been practically confirmed in hardware prototype with good results.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Distributed Auxiliary Inverter of Urban Rail Train—Load Sharing
           Control Strategy Under Complicated Operation Condition
    • Authors: Chen; J.;Wang, L.;Diao, L.;Du, H.;Liu, Z.;
      Pages: 2518 - 2529
      Abstract: Paralleling is the development tendency of the auxiliary inverter. This paper analyzes the problems of the parallel process in detail. First, for inherent contraction between voltage regulation performance and current sharing performance, the paper adopts the resistive droop method. Second, the paper improves dynamic performance and reliability of the droop method by improving power calculation and introducing the whole cycle adaptive droop method. Third, in order to solve the unshared current problem caused by inconsistent parameters, the paper increases active power proportion droop coefficient, and introduces voltage compensation strategy to compensate voltage drop caused by increased proportion droop coefficient. Fourth, the auxiliary parallel system has complicated load characteristics; the paper proposes voltage compensation strategy to compensate voltage drop caused by the pump load. This paper utilizes three-phase total reactive power to droop frequency and active power of each phase to droop amplitude, unbalanced current can be shared. This paper introduces special virtual impedance technology to solve the harmonic current sharing problem caused by the nonlinear load. Finally, the effectiveness of above theory is fully verified by simulation and experiment.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Adaptive-Linear-Neuron-Based Dead-Time Effects Compensation Scheme for
           PMSM Drives
    • Authors: Qiu; T.;Wen, X.;Zhao, F.;
      Pages: 2530 - 2538
      Abstract: This paper presents an adaptive-linear-neuron (ADALINE)-based dead-time compensation method for vector-controlled permanent-magnet synchronous motor drives. The proposed strategy is achieved by suppressing the sixth-order current harmonics in the dq-axes synchronous reference frame. Four ADALINEs are employed in the proposed algorithm. Two ADALINEs are used for estimating the sixth-order harmonic components of dq-axes currents and the other two are used for generating the dq-axes compensation voltages. The voltage compensators are self-tuned by minimizing the estimated current distortion by means of the least mean square algorithm. The proposed compensation algorithm does not require any additional hardware or complicated signal processing algorithms. Experimental results validating the proposed compensation method are also presented.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Second-Order Sliding-Mode Controlled Synchronous Buck DC–DC
    • Authors: Ling; R.;Maksimovic, D.;Leyva, R.;
      Pages: 2539 - 2549
      Abstract: In this paper, second-order sliding-mode (SOSM) control approach is applied to synchronous buck dc–dc converters. The proposed SOSM controller can stabilize synchronous buck dc–dc converters using a simple digital state-machine structure, without requiring current sensing or an integral term in the control loop. The SOSM controller results in fast step-load and start-up transient responses, and is robust against parameter uncertainties. Fast transients and current limitation during start up can be accomplished by adjusting one controller parameter. Furthermore, a hysteresis method is introduced to control the switching frequency. The proposed approach is verified by experimental results on a 1.25-V 10-A prototype.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Novel Type-1 Frequency-Locked Loop for Fast Detection of Frequency and
           Phase With Improved Stability Margins
    • Authors: Kanjiya; P.;Khadkikar, V.;Moursi, M.S.E.;
      Pages: 2550 - 2561
      Abstract: The synchronous reference frame phase-locked loop (SRF-PLL) is a widely used synchronization technique in power electronics and power systems applications due to its ease of implementation and robust performance. The conventional SRF-PLL is a type-2 control system due to the use of proportional-integral controller as loop filter. With higher bandwidth design, it can achieve fast detection of frequency and phase under ideal grid conditions. However, its bandwidth should be sufficiently lowered to obtain proper disturbance rejection under unbalanced and distorted grid conditions. This results in a slower detection speed. Recently, several advanced PLLs with pre/in-loop filtering stage have been proposed to improve the detection speed. A major challenge with the PLLs is how to further improve their dynamic performance without compromising the disturbance rejection capability and stability. To resolve this issue, in this paper, a novel type-1 frequency-locked loop (FLL) is proposed. The disturbance rejection capability of the proposed FLL is improved using a modified structure low-pass filter with selective harmonics filtering ability. As the proposed FLL is type-1 control system, it achieves better dynamic performance with higher stability margins. The effectiveness of the proposed FLL is confirmed through experimental results and comparison with advanced type-2 PLLs.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • High Dynamic Performance Nonlinear Source Emulator
    • Authors: Nguyen-Duy; K.;Knott, A.;Andersen, M.A.E.;
      Pages: 2562 - 2574
      Abstract: As research and development of renewable and clean energy based systems is advancing rapidly, the nonlinear source emulator (NSE) is becoming very essential for testing of maximum power point trackers or downstream converters. Renewable and clean energy sources play important roles in both terrestrial and nonterrestrial applications. However, most existing NSEs have only been concerned with simulating energy sources in terrestrial applications, which may not be fast enough for testing of nonterrestrial applications. In this paper, a high-bandwidth NSE is developed that is able to simulate the behaviors of a typical nonlinear source under different critical conditions that can happen during their operations. The proposed 200-W NSE, which consists of a fourth-order output filter buck converter and a novel nonlinear small-signal reference generator, can quickly react not only to an instantaneous change in the input source but also to a load step between nominal and open circuit. Moreover, all of these operation modes have a very fast settling time of only 10 \mu s, which is hundreds of times faster than that of existing works. This attribute allows for higher speed and a more efficient maximum power point tracking algorithm. The proposed NSE, therefore, offers a superior dynamic performance among devices of the same kind.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A Capacitor Voltage-Balancing Method for Nested Neutral Point Clamped
           (NNPC) Inverter
    • Authors: Tian; K.;Wu, B.;Narimani, M.;Xu, D.D.;Cheng, Z.;Reza Zargari, N.;
      Pages: 2575 - 2583
      Abstract: A capacitor voltage-balancing method for a nested neutral point clamped (NNPC) inverter is proposed in this paper. The NNPC inverter is a newly developed four-level voltage-source inverter for medium-voltage applications with properties such as operating over a wide range of voltages (2.4–7.2 kV) without the need for connecting power semiconductor in series and high-quality output voltage. The NNPC topology has two flying capacitors in each leg. In order to ensure that the inverter can operate normally and all switching devices share identical voltage stress, the voltage across each capacitor should be controlled and maintained at one-third of dc bus voltage. The proposed capacitor voltage-balancing method takes advantage of redundancy in phase switching states to control and balance flying capacitor voltages. Simple and effective logic tables are developed for the balancing control. The proposed method is easy to implement and needs very few computations. Moreover, the method is suitable for and easy to integrate with different pulse width modulation schemes. The effectiveness and feasibility of the proposed method is verified by simulation and experiment.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Robust Stability Analysis of Active Voltage Control for High-power IGBT
           Switching by Kharitonov's Theorem
    • Authors: Yang; X.;Yuan, Y.;Long, Z.;Goncalves, J.;Palmer, P.R.;
      Pages: 2584 - 2595
      Abstract: The main idea of active voltage control (AVC) is to employ classic feedback-control methods forcing the IGBT collector voltage transient to follow a predefined trajectory. This feedback control of IGBTs has great advantages in guaranteeing that IGBTs remain in safe operating area (SOA), restricting EMI, mitigating the voltage/current stress, minimizing/predicting their power losses, and balancing voltages of IGBTs in series. Inevitably, however, AVC introduces stability issues. Based on the assumption that accurate IGBT small-signal model parameters are available, an analogue proportional-derivative and multiloop feedback control was proposed to achieve stable performance in previous work. Due to nonlinearities and uncertainties in IGBT parameters, previous stability analysis methods have important limitations. This work uses Kharitonov's theorem during the IGBT controlled turn-off to assess the system's stability and guide the AVC design to account for model uncertainties and varying parameters. We conducted experiments to investigate the system's robust stability due to these uncertainties in the IGBT parameters, which confirm the validity of the proposed theoretical analysis. With the use of wide bandwidth op-amps, it is shown that the feedback design may be simplified.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • On-the-Fly Topology-Morphing Control—Efficiency Optimization Method
           for LLC Resonant Converters Operating in Wide Input-
           and/or Output-Voltage Range
    • Authors: Jovanovic; M.M.;Irving, B.T.;
      Pages: 2596 - 2608
      Abstract: This paper presents a control method for efficiency improvement of the LLC resonant converter operating with a wide input-voltage and/or output-voltage range by means of topology morphing, i.e., changing of power converter's topology to that which is the most optimal for given input-voltage and/or output-voltage conditions. The proposed on-the-fly topology-morphing control maintains a tight regulation of the output during the topology transitions so that topology transitions are made without noticeable output-voltage transients. The performance of the proposed topology morphing method is verified experimentally on an 800-W LLC dc/dc converter prototype designed for a 100-V to 400-V input-voltage range.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Design Method of Adaptive Full Order Observer With or Without Estimated
           Flux Error in Speed Estimation Algorithm
    • Authors: Sun; W.;Yu, Y.;Wang, G.;Li, B.;Xu, D.;
      Pages: 2609 - 2626
      Abstract: The performance of adaptive full order observer for sensorless induction motor drives can be improved further though it has been researched for many years. In this paper, two different design methods for improving the speed estimation stability and robustness are proposed: 1) In classical speed estimation algorithm used in adaptive full order observer, the estimated rotor flux error is neglected. A robust design method of feedback gains with classical speed estimation algorithm is proposed. Compared with existed three main design methods of feedback gains, the stability of speed estimation and estimated speed error are improved. 2) A robust speed estimation algorithm with estimated rotor flux error and the corresponding feedback gains are proposed in this paper. Through Lyapunov's theorem, the stability of proposed speed estimation algorithm is proved. The stability of flux estimation and estimated speed error can be improved much more. Finally, the feasibility of two proposed methods is verified by experiments.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • A New SVPWM for the Phase Current Reconstruction of Three-Phase
           Three-level T-type Converters
    • Authors: Li; X.;Dusmez, S.;Akin, B.;Rajashekara, K.;
      Pages: 2627 - 2637
      Abstract: This paper presents a new space vector pulsewidth modulation scheme to reconstruct phase currents using neutral-point current sensing in three-level T-type converters (TLTTCs). For this purpose, zero vector and offset vectors are replaced with complementary active vectors. These active vectors do not affect the resultant output voltage and the voltage balance at the neutral point of TLTTCs. Hence, the pulsewidths of corresponding active vectors can be adjusted even at low speeds without much additional switching losses and low-frequency noise in the inverter. The modified switching patterns can easily be generated without significant computational complexity. The proposed method is experimentally verified using Texas Instruments TMS320F28335 and Spartan 6 controllers, on a custom designed T-type converter based on Fuji IGBT modules.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Use of Boundary Control With Second-Order Switching Surface to Reduce the
           System Order for Deadbeat Controller in Grid-Connected Inverter
    • Authors: He; Y.;Chung, H.S.;Ho, C.N.;Wu, W.;
      Pages: 2638 - 2653
      Abstract: Deadbeat control is commonly used in grid-connected inverter with L filter, but it faces the challenge of having filter resonance in inverter with LCL filter. Although many active damping techniques have been proposed to tackle such phenomenon, their digital implementation would introduce nonminimum phase characteristics. Furthermore, the plant viewed by the deadbeat controller is of high order, making the system performance be susceptible to the drift of the filter parameters. This paper introduces a new perspective of using boundary control with second-order switching surface to reduce the order of the plant viewed by the deadbeat controller. The structure hybridizes the merits of the deadbeat control in its simplicity and the boundary control in achieving wide control bandwidth. Small-signal dynamic modeling of the boundary control is formulated. The performance sensitivities of the overall system to filter parameters and grid inductance variations are studied with the derived models. An online grid inductance estimation algorithm is proposed to assure sufficient phase margin under an extremely weak-grid condition. A 2-kW, 220-V, 50-Hz prototype with the switching frequency of 8 kHz has been built and evaluated. Its steady-state and transient behavior, and harmonic rejection capability under stiff- and weak-grid conditions are discussed.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Modulation Scheme for Three-Phase Differential-Mode Ćuk Inverter
    • Authors: Mehrnami; S.;Mazumder, S.K.;Soni, H.;
      Pages: 2654 - 2668
      Abstract: Three-phase differential-mode inverters are single-stage inverters, which have the potential to reduce the number of devices and cost with higher power density. Among such inverter topologies, differential-mode three-phase Ćuk inverter (DTCI) has some advantage over other topologies, including modularity, lower number of switches, bidirectional power flow capability, and galvanic isolation. DTCI is a promising configuration for renewable-/alternative-energy applications with isolated and nonisolated structures. The continuous modulation scheme (CMS), which was introduced originally for the DTCI, activates all of three modules of the inverter. CMS increases the circulating power in modules and hence increases inverter power loss. This paper describes a discontinuous modulation scheme (DMS) for the DTCI which deactivates one module at a time resulting in a discontinuous operation of the inverter modules. The experimental open- and closed-loop results of DMS- and CMS-based DTCI are provided and compared. DMS reduces the circulating power, device voltage ratings, and mitigates the DTCI losses. The DTCI exhibits a nonlinear voltage gain with both DMS and CMS. It has been demonstrated that by feed-forwarding the input voltage and incorporating a static linearization method, the harmonic distortion of the output voltage is considerably reduced.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • High-Performance Grid Simulator Using Parallel Structure Fractional
           Repetitive Control
    • Authors: Liu; T.;Wang, D.;Zhou, K.;
      Pages: 2669 - 2679
      Abstract: In this paper, a high-performance grid simulator based on a parallel structure fractional repetitive control scheme is employed to emulate various operation scenarios of power grids for testing power products. In this paper, a simple fractional repetitive control scheme is proposed for grid simulators to achieve high-accuracy tracking performance. Using parallel branches, the proposed repetitive controller can flexibly select the interested harmonics for compensation, and independently, tune the convergency rate at selective harmonic frequencies. Compared with the conventional repetitive control, the proposed control scheme achieves faster transient response. Moreover, the number of delay units required in the proposed repetitive controller is reduced to at least half of that in a conventional repetitive controller. Design process and stability criteria are presented in details. A set of experimental results is provided to verify the effectiveness of the proposed approach.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
  • Configurable Multimode Digital Control for Light Load DC–DC
           Converters With Improved Spectrum and Smooth Transition
    • Authors: Kapat; S.;
      Pages: 2680 - 2688
      Abstract: Efficiency in a light load dc–dc converter is improved by reducing the switching frequency with the load current. Further, a bifrequency operation (BFO) using pulse train (PT) control can achieve spread spectrum. Using discrete-time models, this paper shows that a stable periodic BFO is generally not achievable in existing PT control methods. Thereafter, a unified multimode digital control technique is proposed, in which a voltage-mode digital pulse-width-modulator (DPWM) is used to control a predefined periodic BFO. Beside the fixed-frequency DPWM, an extra multiplexer is considered for real-time configuration to: 1) bifrequency pulse frequency modulation; 2) PT control; or 3) pulse regulation control; or 4) pulse skipping control with smooth transition. Analysis and design methods are discussed to ensure periodic BFO and to customize the power spectrum with predictable ripple parameters. A buck converter prototype is made, and the proposed control is implemented using an FPGA device.
      PubDate: March 2016
      Issue No: Vol. 31, No. 3 (2016)
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