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  Subjects -> ELECTRONICS (Total: 158 journals)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 2)
Advances in Electronics     Open Access   (Followers: 6)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 6)
Advances in Microelectronic Engineering     Open Access   (Followers: 7)
Advances in Power Electronics     Open Access   (Followers: 11)
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 110)
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: 8)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 4)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 16)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 14)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 23)
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 5)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 6)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 1)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access  
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 14)
China Communications     Full-text available via subscription   (Followers: 5)
Circuits and Systems     Open Access   (Followers: 9)
Consumer Electronics Times     Open Access   (Followers: 5)
Control Systems     Hybrid Journal   (Followers: 42)
Edu Elektrika Journal     Open Access  
Electronic Design     Partially Free   (Followers: 30)
Electronic Markets     Hybrid Journal   (Followers: 5)
Electronic Materials Letters     Hybrid Journal   (Followers: 1)
Electronics     Open Access   (Followers: 12)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 5)
Electronics Letters     Hybrid Journal   (Followers: 18)
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 28)
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: 1)
Frontiers of Optoelectronics     Hybrid Journal  
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 19)
Giroskopiya i Navigatsiya     Open Access  
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 2)
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 28)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 22)
IEEE Consumer Electronics Magazine     Full-text available via subscription   (Followers: 22)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 18)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 4)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 21)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 21)
IEEE Transactions on Audio, Speech, and Language Processing     Hybrid Journal   (Followers: 12)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 38)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 19)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 7)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 14)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 36)
IEEE Transactions on Signal and Information Processing over Networks     Full-text available via subscription   (Followers: 3)
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 7)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 6)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 5)
IET Power Electronics     Hybrid Journal   (Followers: 17)
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 11)
IETE Journal of Education     Open Access   (Followers: 1)
IETE Journal of Research     Open Access   (Followers: 7)
IETE Technical Review     Open Access   (Followers: 4)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 15)
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 3)
Informatik-Spektrum     Hybrid Journal   (Followers: 2)
Instabilities in Silicon Devices     Full-text available via subscription  
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 5)
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: 14)
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: 12)
International Journal of Antennas and Propagation     Open Access   (Followers: 5)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 1)
International Journal of Biomedical Nanoscience and Nanotechnology     Hybrid Journal   (Followers: 5)
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: 13)
International Journal of Electronics     Hybrid Journal   (Followers: 1)
International Journal of Electronics & Data Communication     Open Access   (Followers: 3)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 4)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal  
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Image, Graphics and Signal Processing     Open Access   (Followers: 4)
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 1)
International Journal of Nano Devices, Sensors and Systems     Open Access   (Followers: 5)
International Journal of Nanoscience     Hybrid Journal   (Followers: 1)
International Journal of Numerical Modelling:Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 2)
International Journal of Power Electronics     Hybrid Journal   (Followers: 11)
International Journal of Review in Electronics & Communication Engineering     Open Access   (Followers: 3)
International Journal of Sensors, Wireless Communications and Control     Hybrid Journal   (Followers: 4)
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 2)
International Journal of Wireless and Microwave Technologies     Open Access   (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: 5)
International Transaction of Electrical and Computer Engineers System     Open Access  
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 3)
Journal of Advanced Dielectrics     Open Access  
Journal of Artificial Intelligence     Open Access   (Followers: 6)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 1)

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Journal Cover IEEE Transactions on Power Electronics
  [SJR: 2.866]   [H-I: 128]   [36 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 board members, committee members and society officers.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Table of Contents
    • Abstract: Provides a listing of the editors, board members, and current staff for this issue of the publication.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • IEEE Transactions on Power Electronics publication information
    • Abstract: Provides a listing of the editors, board members, and current staff for this issue of the publication.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Stabilization of Cascaded DC/DC Converters via Adaptive
           Series-Virtual-Impedance Control of the Load Converter
    • Authors: Zhang; X.;Zhong, Qing-Chang;Ming, Wen-Long;
      Pages: 6057 - 6063
      Abstract: It has been shown recently that a cascaded dc/dc converter system can be stabilized via amplitude compensation (SAC) or phase compensation (SPC) for the input impedance of the load converter. In this letter, it is shown that the cascaded system when adopting the SAC is unconditionally stable but conditionally stable when adopting the SPC, that is, SAC is more stable than SPC. Then, the comparison is carried out for the parallel-virtual-impedance (PVI) and series-virtual-impedance (SVI) control strategies that are adopted to implement the SAC, and it is found that only the SVI control strategy can achieve the SAC for the whole load and input voltage range of the load converter without limitation. Therefore, SVI is in general better than PVI when realizing SAC. Following on this, an adaptive mechanism is introduced to improve the traditional SVI control strategy so that the load converter can be stably connected to different source converters such as LC input filters and traditional dc/dc converters. Finally, a load converter cascaded with three different source converters is fabricated to validate the effectiveness of the proposed adaptive SVI control strategy.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Derivation of Dual-Switch Step-Down DC/DC Converters With Fault-Tolerant
    • Authors: Lu; D.D.-C.;Soon, J.L.;Verstraete, D.;
      Pages: 6064 - 6068
      Abstract: This letter presents a graph-theoretic approach to deriving a family of dual-switch step-down dc/dc converters with fault-tolerant capability. The constraint sets in the derivation process ensure that minimum additional component is used to achieve fault-tolerant operation. The operation of converters derived is flexible. Under normal operating conditions, one of the two switches can serve as a main switch to control the power flow (i.e., single-switch converter operation) and the other switch is in stand-by mode. When a fault occurs on the main switch, the other switch will be activated to provide an alternate current path to continue converter operation and maintain output regulation. The fault-tolerant converters are derived by integrating a buck converter with a buck-boost converter. They share all the components except for the power switches. Due to different duty cycles required between the two operating conditions, a feedback controller is necessary to adjust the duty cycle for tight output regulation. The derivation procedure and experimental results on fault occurrence are reported. The converter derivation approach is able to identify reported topologies and can be extended to synthesize other topologies with fault-tolerant capability.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Design of Fuse–MOSFET Pair for Fault-Tolerant DC/DC Converters
    • Pages: 6069 - 6074
      Abstract: This letter presents a method for selecting an appropriate rating of fuse and MOSFET in a fault-tolerant dc/dc converter to protect the circuit in a short-circuit operating condition. The proposed method is based on the Joule-integral principle to calculate the amount of energy associated with the fuse. Different fuse melting characteristics are used to select the appropriate melting time by comparing them with the thermal characteristics of the circuit. The tests performed demonstrate consistent behavior with simulation results and they show that the fuse current rating must be lower than the current rating of the switch in order to provide a safe and reliable operation of the converter.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Efficient Implicit Model-Predictive Control of a Three-Phase Inverter With
           an Output LC Filter
    • Pages: 6075 - 6078
      Abstract: Three-phase inverters with an output LC filter are commonly used to provide sinusoidal voltages with low-harmonic distortion. Constraint on peak filter current is often desirable to protect the components from potential damage. In case of constraints, implicit and explicit model-predictive control (MPC) are some of the feasible controller options. The conventional implicit MPC requires a large number of computations, whereas explicit MPC cannot directly incorporate real-time changes in model parameters, while still being computationally expensive than some of the other control schemes, e.g., hysteresis, dead beat control, etc. In this paper, we propose a new approach to solve the optimization problem in implicit MPC that has a computational complexity approximately five times less than that of explicit MPC. We have been able to achieve lower computational requirements by exploiting the inverter model and the structure of constraints.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Use of Transmitter-Side Electrical Information to Estimate Mutual
           Inductance and Regulate Receiver-Side Power in Wireless Inductive Link
    • Authors: Chow; J.;Chung, H.;Cheng, C.;
      Pages: 6079 - 6091
      Abstract: It is well-known that the power transfer efficiency and the power transmitted over a wireless inductive link are significantly affected by the strength of the magnetic coupling and the spatial displacement between the transmitting and receiving coils. Misalignment between the transmitting and receiving coils is practically unavoidable. In order to control and regulate the receiver-side power, on-the-spot measurement of electrical quantities and establishment of communication link between the transmitter and receiver are typically required. This paper will present an investigation into the use of the transmitter-side electrical information to estimate the mutual inductance and regulate the power consumption of the receiver side. The nonlinear input voltage-current characteristics of the diode-bridge rectifier, which causes current distortions in the system, are taken into account in the mathematical formulations. The proposed technique is successfully implemented on a 4-W wireless-powered LED driver prototype. Experimental results reveal that the LED power can be regulated within ±25% spatial misalignment over the operating zone. The estimated mutual inductance is also found to be in close agreement with the theoretical predictions.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Application of Transformer-Less UPFC for Interconnecting Two Synchronous
           AC Grids With Large Phase Difference
    • Authors: Liu; Y.;Yang, S.;Wang, X.;Gunasekaran, D.;Karki, U.;Peng, F.;
      Pages: 6092 - 6103
      Abstract: In this paper, the application of an innovative transformer-less unified power flow controller (UPFC) for interconnecting two synchronous ac grids with large phase difference is presented. The proposed transformer-less UPFC is based on two cascaded multilevel inverters. As is well known, the real power flow between two generators is mainly determined by their phase difference. If two grids with large phase difference are initially separate from each other, once connected, there will be huge current flowing through the transmission line and will, thus, damage the generators or other supplementary equipments. Therefore, to connect two synchronous ac grids with each other without using an extra device is impossible. For decades, researchers have been investigating different approaches to this problem but still difficult to conquer, especially for real hardware implementation. An effective solution using the transformer-less UPFC is demonstrated in this paper. The transformer-less UPFC can realize grid interconnection, independent active and reactive power control, dc-link voltage balance control, etc. Furthermore, a 1-pu equipment can compensate system with phase difference as large as 30°. Experimental results based on the 13.8-kV/ 2-MVA transformer-less UPFC prototype are shown to validate the theoretical analysis.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Switched-Mode Active Decoupling Capacitor Allowing Volume Reduction of the
           High-Voltage DC Filters
    • Authors: Michal; V.;
      Pages: 6104 - 6111
      Abstract: This paper describes active shunt LC decoupling circuit with ceramic capacitors, allowing volume reduction and lifetime improvement of the high-voltage dc filters. Active filtering is based on the energy exchange between high-voltage coupling and low-voltage auxiliary capacitors. The coupling capacitor enables use of the low-voltage switched-mode power stage and low-voltage auxiliary decoupling capacitor. Advantageously, this allows to reduce power dissipation, switching frequency ripple current, and to reduce volume of the circuit. Additionally, power efficiency and capacitor lifetime are improved by using recent high-voltage coupling multilayer ceramic capacitors, reaching very low ESR. This paper provides description of the active decoupling capacitor, and shows an example of the feedback control. Obtained performances are demonstrated on the prototype of 1300-μF/450-V capacitor, allowing to reduce volume by three, when compared to ordinary 450-V electrolytic capacitor.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Application of an Advanced Repetitive Controller to Mitigate Harmonics in
           MMC With APOD Scheme
    • Authors: mMadichetty; S.;Dasgupta, A.;Mishra, S.;Panigrahi, C.K.;Basha, G.;
      Pages: 6112 - 6121
      Abstract: In a modular multilevel converter (MMC), the second and other even-order harmonics in the circulating currents are mainly due to the fluctuations in the capacitor voltages in the sub modules of the MMC. The increased circulating currents affect the system performance and threatens the safety operation of power devices. To mitigate the circulating currents, this article puts forward the application of an advanced repetitive controller with alternate phase opposition and disposition pulse-width modulation technique. The proposed controller was operated in tandem with a proportional integral controller for better results of circulating current harmonic suppression and then the stability analysis was analyzed by the Popov criteria. This method is very simple to implement and suitable for multiple harmonic mitigation. Computer simulations and experimental results on a prototype shows that the proposed controller is effective and easy to implement for MMCs.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Analysis and Design of a Multicell Topology Based on
           Three-Phase/Single-Phase Current-Source Cells
    • Authors: Melin; P.E.;Rohten, J.A.;Espinoza, J.R.;Baier, C.R.;Espinosa, E.E.;Munoz, J.A.;Riedemann, J.A.;
      Pages: 6122 - 6133
      Abstract: This work proposes a multicell topology based on current-source cells in order to inherit the advantages of current-source topologies such as reduced load dv/dt voltage and natural bidirectional power flow and to adopt a similar behavior of the multicell topology based on a voltage source converter such as voltage controlled behavior where nC cells are connected in series to feed one load phase. In order to check the technical feasibility and performance of the proposed topology, a mathematical model is introduced and studied and key design guidelines of passive components are defined. The analysis shows the possibility of using components with a lower voltage rating than that of the classic multilevel current source topologies and allows the use of low switching frequencies in both rectifier and inverter stages while at the same time obtaining a high-quality waveform in both load voltage and converter input currents. A case of example is used to corroborate the theoretical analysis and the component design methodology, as well as the performance of the topology using a low-power prototype.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Wireless Power Transmission Based on Sandwiched Composite Piezoelectric
           Transducers in Length Extensional Vibration
    • Authors: Lin; S.;Cao, H.;qiao, x.;
      Pages: 6134 - 6143
      Abstract: A new type of wireless power transmission system is proposed. It is composed of two sandwiched composite piezoelectric transducers in length extensional vibration, which are connected together by an intermediate metal transmission cylinder. When the dielectric and mechanical losses are considered, the resonance/antiresonance frequency equations are obtained. The effect of the mechanical and the dielectric loss, the geometrical dimension and the load electric impedance on the effective electromechanical coupling coefficient, the voltage gain, and the power ratio is analyzed. It is shown that the mechanical and the dielectric losses almost have no effect on the resonance/antiresonance frequency. The geometrical dimension has obvious effect on the resonance/antiresonance frequency, the voltage gain, the effective electromechanical coupling coefficient and the power ratio. Corresponding to definite geometrical dimensions, the effective electromechanical coupling coefficient and the voltage gain have maximum values. There is optimum load electric impedance at which the power ratio reaches the maximum value. Two wireless power transmission systems are designed and manufactured; the resonance/antiresonance frequencies, the voltage gain, and the power ratio are measured. It is shown the measured frequencies are in good agreement with the theoretical results.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • A Natural-Sampling-Based SVM Scheme for Current Source Converter With
           Superior Low-Order Harmonics Performance
    • Authors: Wei; Q.;Wu, B.;Xu, D.;Zargari, N.R.;
      Pages: 6144 - 6154
      Abstract: The device switching frequency of current source converters (CSCs) in high-power medium-voltage (MV) drive applications is normally around 500 Hz. Conventional space vector modulation (SVM) features fast dynamic response but its output contains low-order harmonics with high magnitudes. In this paper, a natural-sampling-based SVM (NS-SVM) scheme is proposed to substantially suppress the low-order harmonics in practical CSC-based drives. This study proposes an equivalent discretization of NS-SVM wherein natural sampling pulse width modulation performance can be achieved with regular sampling frequency (same as a conventional SVM) instead of a high or even infinite sampling frequency. Equations for natural-sampling-based dwell time calculations for each selected vector are developed. The corresponding simplified but precise enough equations are derived on the basis of the Newton-Raphson algorithm to achieve fast online digital implementation. The proposed NS-SVM features superior low-order harmonic performance and inherits the high dynamic response and low sampling frequency of conventional SVM. Simulations and experiments are provided to verify the proposed NS-SVM scheme.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Real-Time Device-Level Transient Electrothermal Model for Modular
           Multilevel Converter on FPGA
    • Authors: Shen; Z.;Dinavahi, V.;
      Pages: 6155 - 6168
      Abstract: Real-time simulation of modular multilevel converters (MMCs) is challenging due to their complex structure consisting of a large number of submodules (SMs). In the literature, the computational speed is emphasized for MMC modeling in real-time simulation, while accurate and detailed information of insulated-gate bipolar transistor (IGBT) modules in SMs is sacrificed. A novel datasheet-based device-level electrothermal model for an MMC on the field programmable gate array (FPGA) is presented in this paper for real-time hardware emulation. Conduction and switching power losses, junction temperatures, temperature-dependent electrical parameters, and linearized switching transient waveforms of IGBT modules are adequately captured in the proposed model. Simultaneously the system-level behavior of the MMC is accurately modeled. Five-level and nine-level MMC systems are emulated in the hardware with the time step of 10 μs and 10 ns for system-level and device-level computations, respectively. The paralleled and pipelined hardware design using IEEE 32-bit floating point number precision runs on Xilinx Virtex-7 XC7VX485T device. The emulated real-time results by an oscilloscope have been validated by offline simulation on SaberRD software.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Bipolar Steep Pulse Current Source for Highly Inductive Load
    • Authors: Zhu; X.;Su, X.;Tai, H.;Fu, Z.;Yu, C.;
      Pages: 6169 - 6175
      Abstract: A bipolar pulse current source is proposed for a highly inductive load. The current source exploits a noninductive capacitor to store or release the energy back to and from inductive load during switching on or off of power inverter. A boost module is designed at the dc side of inverter to supplement the required energy gap so that edge steepness of the load current can be improved. The capacitor and boost elements are configured based on the analysis of capacitor impact on the load current and boost inductor current. The stability of load current can be guaranteed by the multiple driving pulses generated from closed-loop control of boost switch, regardless of load changes or initial pulse width offset. An experiment prototype is built to generate a flat-top 20 A current with the 200 μs rise/fall time for an inductive load of 2 mH or higher. Due to the steep rising and falling edges, the inductive load can realize high-frequency pulse currents. Moreover, the steep pulse current source can excite strong magnetic field, which make it especially useful for the inductive coils of high-power geophysical transient electromagnetic method (TEM) transmitter.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • A Three-Level Buck Converter With a Wide Voltage Operation Range for
           Hardware-in-the-Loop Test Systems
    • Authors: Carstensen; C.;Biela, J.;
      Pages: 6176 - 6191
      Abstract: Hardware-in-the-Loop tests of components for high-voltage dc transmission grids, for example circuit breakers, require converter systems capable of generating a high output current with fast transients of the output signal at different output voltages. In this paper, a three-level buck converter (N3L) employing three different supply voltages to enable a wide voltage operation range is presented. The modulation of the converter is investigated in detail with special focus on ripple cancellation, the startup of the interleaved converter and the level shifting between different converter output voltages. A prototype system is designed and constructed, optimized for pulsed power operation and compared to a two level and to a neutral point clamped converter design. The system has been simulated numerically and the design boundaries are validated by measurements on the prototype system.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Challenges Facing PFC of a Single-Phase On-Board Charger for Electric
           Vehicles Based on a Current Source Active Rectifier Input Stage
    • Authors: Saber; C.;Labrousse, D.;Revol, B.;Gascher, A.;
      Pages: 6192 - 6202
      Abstract: This paper aims to study the power factor (PF) correction scheme for a single-phase on-board charger of electric vehicles. The topology is based on a unidirectional current source active rectifier (CSAR) consisting of four insulated-gate bipolar transistors in series with four diodes followed by a boost converter. Buck-type rectifiers inject low-order input current harmonics into the ac mains. Thus, an inductor-capacitor (LC) input filter is employed. The capacitor's reactive energy results in a leading grid current. In order to achieve a unity displacement power factor, a phase shift control is implemented. However, the LC filter is prone to series and parallel resonances coming from the grid disturbances and the converter harmonics, respectively. Therefore, the phase shift control strategy combined with the topology of the CSAR results in a periodical resonance of the input filter. This phenomenon is studied in detail. In order to reduce the grid current's distortion level, an active damping control with resonance frequency tracking that achieves a good PF while meeting the IEC's international standards on harmonic current emissions is presented. An experimental test bench is developed to validate the simulations' theoretical findings. Compliance with the standards is achieved and system limitations are discussed.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • A Double-Resistive Active Power Filter System to Attenuate Harmonic
           Voltages of a Radial Power Distribution Feeder
    • Authors: Sun; X.;Han, R.;Shen, H.;Wang, B.;Lu, Z.;Chen, Z.;
      Pages: 6203 - 6216
      Abstract: Harmonic propagation between power-factor correction capacitors and system inductors seriously deteriorates power quality in a radial power distribution feeder. Installation of a resistive active power filter (RAPF) at the end bus only suppresses harmonic propagation, not attenuates harmonic voltages. This paper proposes a double-resistive active power filter (D-RAPF) system consisting of a terminal-RAPF and an attenuation-RAPF for each individual harmonic. The terminal-RAPF operating as the characteristic impedance of the feeder is installed at the end bus to suppress harmonic propagation at all harmonic frequencies. The attenuation-RAPF, whose control gain can be set according to the requirements of the harmonic voltage distortion limit, is installed at a specific position for each individual harmonic to attenuate the corresponding harmonic voltages. The D-RAPF system not only suppresses harmonic propagation and attenuates harmonic voltages more effectively, but also has the same rated power capacity as the RAPF. However, both the harmonic damping performance and the rated power capacity must be considered to choose the D-RAPF system or the RAPF when a harmonic current source exists at a position between the attenuation-RAPF and the terminal-RAPF. Simulation and experiment results verify the theoretical analysis and demonstrate the effectiveness of the D-RAPF system.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Wide Correction Range Three-Level Dynamic Voltage Corrector
    • Authors: cao; j.;Liu, H.;Ding, P.;Yang, B.;Xie, S.;
      Pages: 6217 - 6225
      Abstract: The dynamic sag correctors are used at the sensitive load terminals of the centralized power supply in order to avoid the grid voltage sag. This paper focuses on the correction of grid voltage swell/sag in large range and the quality of compensated voltage. A wide correction range dynamic voltage corrector is proposed for solving above problems with low cost. The operation principle, the voltage corrector range, and the design consideration of key parameters are analyzed. The increase of dc-link voltage broadens the voltage sag correction range, while the realization of the voltage swell correction benefits from the bidirectional energy flow. The simulation and experimental results verify the validity of the theoretical analysis. A prototype which applies to the centralized power supply-based ground power unit for aircrafts has been developed. It is characterized as small size, light weight, high compensation efficiency, good dynamic performance, and high quality of output waveform.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Modulation With Sinusoidal Third-Harmonic Injection for Active Split
           DC-Bus Four-Leg Inverters
    • Authors: Bifaretti; S.;Lidozzi, A.;Solero, L.;Crescimbini, F.;
      Pages: 6226 - 6236
      Abstract: Three-phase four-leg inverters are commonly employed to supply unbalanced loads avoiding the use of a transformer. A suitable output filter is necessary to improve the harmonic content of the output voltage and current waveforms. To this aim, different kind of filters, presenting both symmetrical and asymmetrical phase-to-phase and phase-to-neutral behavior, can be used. The paper discusses and analyzes the effects of different carrier-based modulation techniques, based on the independent control of the fourth leg from that of the other phases, with reference to the different filter topologies. The comparison, performed through extensive simulations and experimental tests, have demonstrated that in case of the asymmetrical filter utilization, such as the active split dc-bus (also known as split-link), the conventional continuous and discontinuous space-vector modulations produce a significant harmonic content in the output voltages even at no-load condition. Moreover, the analysis is extended considering the interaction between the modulation strategy and load characteristics as linear, nonlinear, balanced and unbalanced loads. The problem is discussed in detail and a specific design procedure for the active split dc-bus is presented.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Global Synchronous Pulse Width Modulation of Distributed Inverters
    • Authors: Xu; T.;Gao, F.;
      Pages: 6237 - 6253
      Abstract: Traditionally, the parallel-connected multileg inverter could assume the interleaved pulse width modulation (PWM) to attenuate the high-frequency harmonics by using a single controller to generate the corresponding interleaved switching sequences. However, the interleaved PWM cannot be employed in multiple distributed independent inverters installed at different locations with their own controllers because the multiple independent controllers cannot work synchronously and the operational conditions are different among the distributed inverters. The summed current harmonics of multiple distributed inverters could vary at the point of common coupling (PCC) and worsen the power quality of consumers. This paper, therefore, proposes a global synchronous PWM method for the distributed inverters to attenuate the high-frequency current harmonics at PCC. The optimal interleaved switching angles among the distributed inverters are calculated by fully considering line impedances, modulation indexes, switching frequencies, the number of distributed inverters, etc. Particle swarm optimization method is assumed to find the optimal solution. Then, the low-frequency synchronization operation will synchronize the multiple PWM switching sequences in the wanted variation range. Experimental results are presented to prove the validity of this method.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Modeling and Stability Analysis of Active/Hybrid Common-Mode EMI Filters
           for DC/DC Power Converters
    • Authors: Chu; Y.;Wang, S.;Wang, Q.;
      Pages: 6254 - 6263
      Abstract: Hybrid electromagnetic interference (EMI) filters (HEFs), which are composed of an active filter and a passive filter, have been proposed to reduce the size and weight of conventional passive EMI filters in literatures. However, accurate models that can be used to predict the stability and performance of HEFs have not been developed. To cope with this, this paper presents a modeling technique for a hybrid common-mode (CM) filter. The technique can be applied to the modeling of other HEFs. Critical component models were first developed for the HEF. HEF's overall model was further developed based on these individual component models. Experimental results validated that the developed model can successfully predict the stability and performance of active/hybrid CM filters.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Static Synchronous Generator Model: A New Perspective to Investigate
           Dynamic Characteristics and Stability Issues of Grid-Tied PWM Inverter
    • Authors: Xiong; L.;Zhuo, F.;Wang, F.;Liu, X.;Chen, Y.;Zhu, M.;Yi, H.;
      Pages: 6264 - 6280
      Abstract: With increasing penetration of the renewable energy, the grid-tied PWM inverters need to take corresponding responsibilities for the security and stability of future grid, behaving like conventional rotational synchronous generator (RSG). Therefore, recognizing the inherent relationship and intrinsic differences between inverters and RSGs is essential for such target. By modeling the typical electromechanical transient of grid-tied PWM inverters, this paper first proves that PWM inverters and RSGs are similar in physical mechanism and equivalent in mathematical model, and the concept of static synchronous generator (SSG) is thereby developed. Furthermore, the comprehensive comparison between RSG and SSG is carried out in detail, and their inherent relation is built. Based on these findings, the rationality and feasibility of migrating the concepts, tools, and methods of RSG stability analysis to investigate the dynamic behaviors and stability issues of SSG is therefore confirmed. Taking stability issues as an example, the criteria of small signal and transient stability of a typical grid-tied PWM inverter is put forward to demonstrate the significance of the developed SSG model (including synchronizing coefficient, damping coefficient, inertia constant, and power-angle curve), providing clear physical interpretation on the dynamic characteristics and stability issues. The developed SSG model promotes grid-friendly integration of renewable energy to future grid and stimulates interdisciplinary research between power electronics and power system.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Partial Shading Detection and Smooth Maximum Power Point Tracking of PV
           Arrays Under PSC
    • Authors: Ghasemi; M.A.;Foroushani, H.M.;Parniani, M.;
      Pages: 6281 - 6292
      Abstract: One of the most important issues in the operation of a photovoltaic (PV) system is extracting maximum power from the PV array, especially in partial shading condition (PSC). Under PSC, P-V characteristic of PV arrays will have multiple peak points, only one of which is global maximum. Conventional maximum power point tracking (MPPT) methods are not able to extract maximum power in this condition. In this paper, a novel two-stage MPPT method is presented to overcome this drawback. In the first stage, a method is proposed to determine the occurrence of PSC, and in the second stage, using a new algorithm that is based on ramp change of the duty cycle and continuous sampling from the P-V characteristic of the array, global maximum power point (MPP) of array is reached. Perturb and observe algorithm is then re-activated to trace small changes of the new MPP. Open-loop operation of the proposed method makes its implementation cheap and simple. The method is robust in the face of changing environmental conditions and array characteristics, and has minimum negative impact on the connected power system. Simulations in Matlab/Simulink and experimental results validate the performance of the proposed methods.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Decoding and Synthesizing Transformerless PWM Converters
    • Authors: Wu; T.;
      Pages: 6293 - 6304
      Abstract: Pulse-width-modulated (PWM) converters have been widely applied for power processing, and they are typically the stems of other types of converters, such as quasi-resonant, Z-source, and switched-inductor hybrid converters. Development of PWM converters has been spanning over a century, starting from the buck converter. The well-known PWM converters include buck, boost, buck-boost, Ćuk, single ended primary inductive converter (SEPIC), zeta, Z-source, quasi-Z source, etc. Many attempts have been proposed to develop these converters based mostly on canonical cell concepts and by introducing extra LC filters to the cells. This paper presents an enhancement to the layer and graft schemes by introducing the ideas of dc voltage/current offsetting, capacitor/inductor component splitting, diode grafting, and inverse operation of PWM converters. The PWM converters, which can be operated in continuous conduction mode (CCM) or discontinuous conduction mode (DCM), therefore can be synthesized systematically according to decoded transfer gains. Decoding and synthesizing PWM converters uniquely bridge transfer gains to converter topologies and provide readers a comprehensive understanding of PWM-converter evolution from the original converter, the buck converter. Additionally, in this paper, the Ćuk, SEPIC, and zeta converters all with the same transfer gain of D/(1 - D) are proved to be equivalent to the buck-boost converter with an extra LC filter. For further illustrating the proposed approaches, various types of Z-source converters, switched-capacitor/switched-inductor hybrid converters, and a single-stage interleaved converter are reviewed, and new PWM converters are developed.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Efficient Transformerless MOSFET Inverter for a Grid-Tied Photovoltaic
    • Authors: Islam; M.;Mekhilef, S.;
      Pages: 6305 - 6316
      Abstract: The unipolar sinusoidal pulse width modulation full-bridge transformerless photovoltaic (PV) inverter can achieve high efficiency by using latest superjunction metal-oxide-semiconductor field-effect transistor (MOSFET) together with silicon carbide (SiC) diodes. However, the MOSFETs aSiCre limited to use in transformerless PV inverter due to the low reverse-recovery characteristics of the body diode. In this paper, a family of new transformerless PV inverter topology for a single-phase grid-tied operation is proposed using superjunction MOSFETs and SiC diodes as no reverse-recovery issues are required for the main power switches for unity power operation. The added clamping branch clamps the freewheeling voltage at the half of dc input voltage during the freewheeling period. As a result, the common-mode voltage kept constant during the whole grid period that reduces the leakage current significantly. In addition, dead time is not necessary for main power switches at both the high-frequency commutation and the grid zero crossing instant, results low-current distortion at output. Finally, a 1-kW prototype is built and tested to verify the theoretical analysis. The experimental results show 98.5% maximum efficiency and 98.32% European efficiency. Furthermore, to show the effectiveness, the proposed topology is compared with the other transformerless topologies.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Elimination of Filter Inductor in Switching Cell AC–AC Converters
           Using Magnetic Integration
    • Authors: Khan; A.A.;Cha, H.;Ahmed, H.F.;Kim, H.;
      Pages: 6317 - 6326
      Abstract: The switching cell (SC) direct pulse width modulation ac-ac converters have several advantages; in particular, they do not experience commutation issues, are not susceptible to reverse-recovery losses of body diode of switching devices, produce output waveforms of good quality, are more immune to EMI noise, and have smaller input/output current ripples. The magnetic components of the SC ac-ac converters consist of coupled inductors and a filter inductor. This paper proposes an integrated inductor which integrates all magnetic components of the SC ac-ac converters into one magnetic assembly. The leakage inductance of the proposed integrated inductor is utilized to eliminate the filter inductor in buck, boost, and buck-boost-type SC ac-ac converters. The proposed integrated inductor improves the power density and reduces cost and losses because it requires fewer magnetic cores, coils, and soldering connections. The proposed integrated inductor is especially suitable for high-current applications because it can avoid the magnetic core saturation caused by current, and can eliminate the air gap in the core. The proposed integrated inductor can realize high leakage inductance; therefore, the input and output current ripples can be reduced significantly. To verify the proposed integrated inductor, a 2.3-kW prototype inductor was built and tested.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • A Family of Isolated Buck-Boost Converters Based on Semiactive Rectifiers
           for High-Output Voltage Applications
    • Authors: Lu; Y.;Wu, H.;Sun, K.;Xing, Y.;
      Pages: 6327 - 6340
      Abstract: A systematic method for developing isolated buck-boost (IBB) converters is proposed in this paper, and single-stage power conversion, soft-switching operation, and high-efficiency performance can be achieved with the proposed family of converters. On the basis of a nonisolated two-switch buck-boost converter, the proposed IBB converters are generated by replacing the dc buck-cell and boost-cell in the non-IBB converter with the ac buck-cell and boost-cell, respectively. Furthermore, a family of semiactive rectifiers (SARs) is proposed to serve as the secondary rectification circuit for the IBB converters, which helps to extend the converter voltage gain and reduce the voltage stresses on the devices in the rectification circuit. Hence, the efficiency is improved by employing a transformer with a smaller turns ratio and reduced parasitic parameters, by using low-voltage rating MOSFETs and diodes with better switching and conduction performances. A full-bridge IBB converter is proposed and analyzed in detail as an example. The phase-shift modulation strategy is applied to the full-bridge IBB converter to achieve IBB conversion. Moreover, soft-switching performance of all active switches and diodes can be achieved over a wide load and voltage range by the proposed converter and control strategy. A 380-V-output prototype is fabricated to verify the effectiveness of the proposed family of IBB converters, the SARs, and the control strategies.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • A 0.45-to-1.2-V Fully Digital Low-Dropout Voltage Regulator With
           Fast-Transient Controller for Near/Subthreshold Circuits
    • Authors: Li; Y.;Zhang, X.;Zhang, Z.;Lian, Y.;
      Pages: 6341 - 6350
      Abstract: A low quiescent current digital low-dropout (DLDO) voltage regulator with fast-transient response time is proposed for self-powered wireless sensor applications operating at near/subthreshold supply voltage. The D-LDO regulator incorporates both hill-climbing and binary search algorithms (HCBS) in the control logic, thus leveraging on each other's strengths to minimize the output voltage's ripple and the quiescent current during the steady-state period as well as output voltage's spike and response time during the transition period. Additional features such as hysteresis mode control and freeze mode control are incorporated into the system to improve the performance of the D-LDO regulator. A dynamic comparator is proposed for the near/subthreshold supply voltage operation, which minimizes the voltage error and improves the maximum operating frequency. Fabricated in 130-nm CMOS technology, the D-LDO regulator regulates the output voltage VOUT from 350 to 1150 mV, while the input supply voltage VIN ranges from 450 to 1200 mV. At a VOUT of 450 mV, VIN of 500 mV and an operating frequency of 10 MHz, the regulator delivers 1500-μA load current with IQUIESCENT of 8.9 μA and a transient response time of 1.6 μs. The maximum current and power efficiencies reach 99.9% and 89.9%, respectively. The measured line regulation and load regulation are 1.6 and 0.6 mV/mA, respectively.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Computationally Efficient Simulation of High-Frequency Transients in Power
           Electronic Circuits
    • Authors: Subbiah; A.;Wasynczuk, O.;
      Pages: 6351 - 6361
      Abstract: A computationally efficient simulation framework is set forth in which the semiconductor devices are represented by the physical phenomena relevant to the accurate prediction of high-frequency circuit-level transients and energy losses. Key elements of this framework include an encapsulated diode model and a method of coupling device models with those of external circuit elements given a user-specified SPICE-like netlist. The framework is applied to a single-phase full-bridge diode rectifier circuit with a discussion on time-step requirements and overall computational performance. Comparisons between simulated and measured waveforms are also provided revealing excellent agreement.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • A CMOS Low-Dropout Regulator With Dominant-Pole Substitution
    • Authors: Ho; M.;Guo, J.;Mak, K.;Goh, W.L.;Bu, S.;Zheng, Y.;Tang, X.;Leung, K.;
      Pages: 6362 - 6371
      Abstract: A dominant-pole substitution (DPS) technique for low-dropout regulator (LDO) is proposed in this paper. The DPS technique involves signal-current feedforward and amplification such that an ultralow-frequency zero is generated to cancel the dominant pole of LDO, while a higher frequency pole substitutes in and becomes the new dominant pole. With DPS, the loop bandwidth of the proposed LDO can be significantly extended, while a standard value and large output capacitor for transient purpose can still be used. The resultant LDO benefits from both the fast response time due to the wide loop bandwidth and the large charge reservoir from the output capacitor to achieve the significant enhancement in the dynamic performances. Implemented with a commercial 0.18-μm CMOS technology, the proposed LDO with DPS is validated to be capable of delivering 100 mA at 1.0-V output from a 1.2-V supply, with current efficiency of 99.86%. Experimental results also show that the error voltage at the output undergoing 100 mA of load transient in 10-ns edge time is about 25 mV. Line transient responses reveal that no more than 20-mV instantaneous changes at the output when the supply voltage swings between 1.2 and 1.8 V in 100 ns. The power-supply rejection ratio at 3 MHz is -47 dB.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • A High-Precision CV/CC AC–DC Converter Based on Cable and
           Inductance Compensation Schemes
    • Authors: Chang; C.;Xu, Y.;Bian, B.;Zhao, X.;
      Pages: 6372 - 6382
      Abstract: This paper proposes a high-precision primary-side regulation constant voltage (CV) and constant current (CC) ac-dc converter. CV output is achieved by adjusting the switching frequency and primary peak voltage simultaneously, for better dynamic adjustment ability. In order to improve CV precision, a cable compensation module is adopted to inject current to pull-down resistor of auxiliary winding divider, compensating the cable voltage loss caused by the output cable resistance. On the other hand, CC output is acquired by maintaining the ratio of switching frequency and output voltage constant. The inductance compensation module regulates further to keep the product of demagnetization time and switching frequency fixed, equalizing the inconsistent output current result from the big tolerance of the transformer primary-side inductance in the same batch. Moreover, an improved demagnetization time detector is proposed, which is beneficial to raise CC precision. The control chip is implemented based on TSMC 0.35-μm 5-V/40-V BCD process, and a 12 V/1 A prototype has been built to prove the proposed control method. In CV mode, the deviation of the output voltage is within ±1.5%, while that of output current is within ±3% in CC mode.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • An Input-Series Flyback Auxiliary Power Supply Scheme Based on
           Transformer-Integration for High-Input Voltage Applications
    • Authors: Meng; T.;Li, C.;Ben, H.;Zhao, J.;
      Pages: 6383 - 6393
      Abstract: An input-series flyback auxiliary power supply scheme is proposed and investigated, which is suitable for the high-input-voltage multiple-output low-power applications. In this power supply, a common integrated-transformer is adopted, all of the series-modules are operating synchronously, and the active input voltage sharing (IVS) can be achieved efficiently without any special controller. The active IVS mechanism of the proposed scheme is analyzed in detail. Furthermore, design considerations of the common integrated-transformer and the input filter capacitor of each series-module are discussed, as well as the influence analysis when the series-modules are operating asynchronously. Finally, a 60-W laboratory-made prototype of the auxiliary power supply composed of three flyback series-modules is built, and the feasibility of the proposed scheme and the validity of the theoretical analysis are verified by the experimental results.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Improved ZVS Three-Level DC–DC Converter With Reduced Circulating
    • Authors: Guo; Z.;Sun, K.;Sha, D.;
      Pages: 6394 - 6404
      Abstract: An improved three-level (TL) dc-dc converter is proposed in this paper. The converter contains two transformers. Like the conventional TL dc-dc converter, there are no additional switches on the primary side of the transformer. The rectifier stage is composed of four diodes in the center-tapped rectification. On the primary side of the transformer, the two transformers are connected in series. The middle node of the two transformers is connected to the neutral point of the split flying capacitors. Because it cooperates with the four-diode rectifier stage, the circulating current on the primary side of the transformer decays to zero during the freewheeling period. The zero-voltage switching (ZVS) of the leading switches is determined by energy stored in the output filter inductor, which is similar to the conventional TL converter. The ZVS of the lagging switches is determined by the energy stored in the magnetizing inductor of a transformer, rather than the energy stored in the leakage inductor. The proposed converter can reduce the output filter inductance. Because of the advantages given above, the efficiency of the proposed converter is far better than that of traditional methods. Finally, a 1-kW prototype was built to verify the performance of the proposed converter.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • High Gain DC–DC Converter Based on the Cockcroft–Walton
    • Authors: Muller; L.;Kimball, J.W.;
      Pages: 6405 - 6415
      Abstract: Recent advancements in renewable energy have created a need for both high step-up and high-efficiency dc-dc converters. These needs have typically been addressed with converters using high-frequency transformers to achieve the desired gain. The transformer design, however, is challenging. This paper presents a high step-up current fed converter based on the classical Cockcroft-Walton (CW) multiplier. The capacitor ladder allows for high voltage gains without a transformer. The cascaded structure limits the voltage stresses in the converter stages, even for high gains. Being current-fed, the converter (unlike traditional CW multipliers) allows the output voltage to be efficiently controlled. In addition, the converter supports multiple input operation without modifying the topology. This makes the converter especially suitable for photovoltaic applications where high gain, high efficiency, small converter size, and maximum power point tracking are required. Design equations, a dynamic model, and possible control algorithms are presented. The converter operation was verified using digital simulation and a 450-W prototype converter.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • A 200-V 98.16%-Efficiency Buck LED Driver Using Integrated Current
           Control to Improve Current Accuracy for Large-Scale Single-String LED
           Backlighting Applications
    • Authors: Lim; B.;Ko, Y.;Jang, Y.;Okhwan, K.;Han, S.;Lee, S.;
      Pages: 6416 - 6427
      Abstract: This paper presents an average current mode buck dimmable light-emitting diode (LED) driver for large-scale single-string LED backlighting applications. The proposed integrated current control technique can provide exact current control signals by using an autozeroed integrator to enhance the accuracy of the average current of LEDs while driving a large number of LEDs. Adoption of discontinuous low-side current sensing leads to power loss reduction. Adoption of a fast-settling technique allows the LED driver to enter into the steady state within three switching cycles after the dimming signal is triggered. Implemented in a 0.35-μm HV CMOS process, the proposed LED driver achieves 1.7% LED current error and 98.16% peak efficiency over an input voltage range of 110 to 200 V while driving 30 to 50 LEDs.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Synchronized Space-Vector PWM for Three-Level VSI With Lower Harmonic
           Distortion and Switching Frequency
    • Authors: Chen; W.;Sun, H.;Gu, X.;Xia, C.;
      Pages: 6428 - 6441
      Abstract: A novel synchronized space-vector pulsewidth modulation (SSVPWM) strategy is proposed for three-level inverters, which focuses on improving the output waveforms while reducing the device switching frequency. The modulation index m is segmented in linear modulation region reasonably, and the switching sequences are designed at each segmentation independently. The sequences for two reference vector distribution modes are designed, respectively, which ensure the synchronization and symmetry in output waveforms and the minimization of switching frequency. Then, the optimal sequence at each segmentation is selected from the two sequences (corresponding to the two modes) in terms of the weighted total harmonic distortion (THD) of line voltage. The proposed strategy is verified through simulation and experiment on a constant v/f open-loop induction motor drive, and the results show that both line voltage weighted THD and no-load stator current THD can be significantly reduced compared to conventional SSVPWM (CSSVPWM) and space-vector-based synchronized discontinuous PWM (SDPWM) in linear modulation region. Moreover, at a certain reference vector number, the switching frequency can be reduced by 33.3% compared to CSSVPWM and 13.3% to SDPWM. The proposed strategy can also be implemented in the overmodulation region.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Calculation of Power Losses in Litz Wire Systems by Coupling FEM and PEEC
    • Authors: Rosskopf; A.;Joffe, C.;Baer, E.;Bonse, C.;
      Pages: 6442 - 6449
      Abstract: The frequency-dependent resistance of inductive components with high-frequency litz wires is essential for the design of power electronic systems. A novel simulation approach is demonstrated, which combines the specific benefits of two numerical methods: The magnetic field distribution is calculated by standard finite-element method tools for complex 3-D geometries based on a solid conductor. The resulting magnetic field on cut sections of the conductor is used as boundary condition for the partial element equivalent circuit method. Based on the coupling of these methods, power losses on litz wire level have been calculated taking different bundle structures and pitch lengths into account. The work flow has been automatized and enables simulations of litz wire systems with hundreds of strands. For different simulation setups, the simulations have been verified by comparison to measurements up to 500 kHz. The average deviation is less than 5% in the relevant frequency range.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Modeling and Analysis of the Bendable Transformer
    • Authors: Ho; K.;Zhang, C.;Pong, B.;Hui, S.;
      Pages: 6450 - 6460
      Abstract: This paper presents a study of a bendable transformer for wearable electronics. Printed on a thin and bendable film, this transformer is bendable to wrap around body limbs such as the forearm. A model using a partial equivalent circuit theory has been developed to analyze the characteristic of an inductor and a bendable transformer. The mutual inductance and self-inductance for the bendable transformer over a range of bent curvatures have been calculated based on the model and compared favorably with measurements. Simulation and experimental results of applying the bendable inductor and transformer in dc-dc converters as a 5-V 500-mA power supply are included to confirm the usefulness of the transformer and the validity of the model.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Novel PWM Schemes With Multi SVPWM of Sensorless IPMSM Drives for Reducing
           Current Ripple
    • Authors: Gu; M.;Ogasawara, S.;Takemoto, M.;
      Pages: 6461 - 6475
      Abstract: This paper proposes novel pulsewidth modulation (PWM) schemes for multi-space-vector pulsewidth modulation (MSVPWM), which is used in position sensorless control of interior permanent-magnet synchronous motor drives. The estimation of the rotor position is based on magnetic saliency and employs high-frequency components of voltage and current, which are excited by MSVPWM. The difference between the instantaneously applied voltage vector and the reference voltage vector causes current ripple. Since six or four voltage vectors are generated during a PWM period, the sequences of the error voltage vectors lead to different types of current ripples. In this paper, the proposed MSVPWM schemes employ six sequences for zero-/low-speed operation and 24 sequences for high-speed operation to reduce line current ripple. Experimental results confirm that the proposed MSVPWM schemes lead to significant reduction in harmonic current while maintaining high performance of sensorless estimation.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Dual Flying Capacitor Active-Neutral-Point-Clamped Multilevel Converter
    • Authors: Naderi; R.;Khoshkbar-Sadigh, A.;Smedley, K.;
      Pages: 6476 - 6484
      Abstract: Hybrid multilevel converters combine features of conventional multilevel topologies to provide an acceptable tradeoff between the advantages and disadvantages of these converters. For many industrial applications, common dc link is a requirement that limits the choice of topologies to neutral point clamped (NPC) and flying capacitor multicell (FCM) hybrid types. This paper investigates the operation of a hybrid five-level topology and proposes a modulation method that takes the advantage of the combined features of NPC and FCM. The dual flying capacitor (FC) active-neutral-point-clamped (DFC-ANPC) converter provides certain advantages such as natural soft switching of line frequency switches, elimination of the transient voltage balancing snubbers, and a more even loss distribution. Simulation results and experimental verification of the five-level DFC-ANPC converter are presented to validate the performance of the converter as well as the applied modulation technique.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Constant Switching Frequency Based Direct Torque Control of Interior
           Permanent Magnet Synchronous Motors With Reduced Ripples and Fast Torque
    • Authors: Foo; G.;Zhang, X.;
      Pages: 6485 - 6493
      Abstract: The conventional direct torque control (DTC) features control structure simplicity, fast dynamic response, and parameter robustness. Nevertheless, it suffers from the problems of variable switching frequency and large torque ripples. This paper presents a modified DTC algorithm for interior permanent magnet synchronous motor drives with fast torque dynamics and constant switching frequency. The aforementioned problems are alleviated by adding a PI torque regulator to autonomously alter the effective duty cycle of the applied voltage vector. As a result, a constant switching frequency and also reduced torque ripples are obtained while retaining the benefits of the classical DTC. In addition, the torque dynamic response is further improved by introducing a modified switching table during transient conditions. By incorporating the modified switching table, the torque dynamic response is superior to that of the classical DTC. Simulation and experiment results included confirm the effectiveness of the proposed method.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • A Parallel Speed and Rotor Time Constant Identification Scheme for
           Indirect Field Oriented Induction Motor Drives
    • Authors: Zhao; L.;Huang, J.;Chen, J.;Ye, M.;
      Pages: 6494 - 6503
      Abstract: Rotor time constant identification is necessary for high-performance indirect field oriented control of induction motor drives. Meanwhile, speed sensorless technique has many advantages such as low cost and reduced hardware complexity. In recent years, the estimation methods for motor speed have respectively grown to maturity, but the research in the identification of rotor time constant remains to be extended. In this paper, an online scheme for parallel motor speed and rotor time constant identification is proposed according to parameter features, with the operating frequencies of all modules carefully considered. First, the speed is estimated via rotor slot harmonic extraction technique. On the premise of estimated speed, a derivative form of induction motor model is proposed for rotor time constant identification, which overcomes the problems of pure integration in rotor flux calculation. Correspondingly, instead of rotor flux, derivative rotor flux is used in the proposed model. Finally, an adjusted particle swarm optimization method is utilized on the proposed model to track the rotor time constant. The robustness and effectiveness of the proposed scheme have been validated experimentally.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Speed Control of the Surface-Mounted Permanent-Magnet Synchronous Motor
           Based on Takagi–Sugeno Fuzzy Models
    • Authors: Chang; Y.;Chen, C.;Zhu, Z.;Huang, Y.;
      Pages: 6504 - 6510
      Abstract: The speed control of the surface-mounted permanent-magnet synchronous motor (SPMSM) based on Takagi-Sugeno (T-S) fuzzy models is designed and implemented in this paper. In motor drive speed control, proportional-integral controller is generally applied. However, the tracking performance and load regulation capability should be compromised in the designing process of the controller. This study develops a speed controller based on the T-S fuzzy model with good tracking ability and load variation regulation. First, the dynamic model of an SPMSM is demonstrated and the load torque variation is treated as disturbances. Accordingly, the speed control strategy is developed based on the T-S fuzzy model. The defuzzification process and parallel distributed compensation are introduced. The ability of disturbance suppression and the Lyapunov stability of this system are established and analyzed. The controller gains are obtained via the linear matrix inequality toolbox. The speed control and all essential procedures are realized by the microcontroller Renesas RX62T. The tracking performance and load regulation capability are verified by the experimental results.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Single-Phase On-Board Integrated Battery Chargers for EVs Based on
           Multiphase Machines
    • Authors: Subotic; I.;Bodo, N.;Levi, E.;
      Pages: 6511 - 6523
      Abstract: The paper considers integration of multiphase (more than three phases) machines and converters into a single-phase charging process of electric vehicles (EVs) and, thus, complements recently introduced fast charging solutions for the studied phase numbers. One entirely novel topology, employing a five-phase machine, is introduced and assessed jointly with three other topologies that use an asymmetrical nine-phase machine, an asymmetrical six-phase machine, and a symmetrical six-phase machine. In all topologies, both charging and vehicle-to-grid (V2G) mode are viable. Moreover, all are capable of unity power factor operation. A torque is not produced in machines during charging/V2G process so that mechanical locking is not required. Hardware reconfiguration between propulsion and charging/V2G mode is either not required or minimized by using a single switch. Theoretical analysis of operating principles is given, and a control scheme, applicable to all topologies and which includes current balancing and interleaving strategy, is developed. Finally, operation of all topologies is compared by means of experiments in both charging and V2G mode, with a discussion of influence of current balancing and interleaving strategy on the overall performance.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Improving Wireless Power Transfer Efficiency Using Hollow Windings With
    • Authors: Cove; S.R.;Ordonez, M.;Shafiei, N.;Zhu, J.;
      Pages: 6524 - 6533
      Abstract: With the widespread growth of slim portable electronics, research into planar spiral windings for wireless power transfer (WPT) battery charging systems has gained a lot of attention due to their low profile, reproducibility, and manufacturability. The major design goal for windings in WPT systems is high-quality factor (Q) for a given inductance. This study presents a new method to improve Q by using a nonunity track-width-ratio (TWR) geometrical arrangement in conjunction with increasing the inner radius of winding to make an improved hollow planar spiral winding. The inductance regulation of this technique combined with its exceptional improvements in Q make it a superior choice for resonant WPT systems. Inductance and resistance models are provided in order to assess the Q improvement. A 5-W, 110-200-kHz WPT system was built and tested based on the wireless power consortium Qi standard to confirm the advantages of the improved windings on the transmission efficiency of the system. An increase from 70% to 90% are observed from employing the proposed winding technique designed using the provided models.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Implementation of a Nonlinear Planar Magnetics Model
    • Authors: Tria; L.A.R.;Zhang, D.;Fletcher, J.E.;
      Pages: 6534 - 6542
      Abstract: A nonlinear lumped element model for planar magnetics is presented. This technique develops an equivalent circuit model for multilayer planar magnetic components using 1-D analysis of Maxwell's equations. Conducting layers are represented as impedance networks, while the insulating regions are modeled as air-cored inductors. The equivalent circuit model is extended by representing the nonlinear magnetic core material as a nonlinear impedance whose magnetization characteristic is based on the Jiles-Atherton hysteresis model as well as modeling skin and proximity effects in the conductors and current distribution across windings, the improved model also integrates hysteresis loss of the magnetic core and saturation effects. The technique can be implemented in circuit simulation software. A prototype planar transformer, using printed circuit boards to mount windings, was characterized to validate the performance of the model. It is demonstrated that the developed nonlinear model more accurately represents the characteristics of the experimental transformer compared to the existing linear lumped element model. This includes the effect of core saturation on the input current and output-voltage waveforms. The technique is generalized and can be applied to many topologies and geometries.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Static Regulated Multistage Semiactive LED Drivers for High-Efficiency
    • Authors: Lee; E.S.;Choi, B.H.;Tan, D.T.;Choi, B.G.;Rim, C.T.;
      Pages: 6543 - 6552
      Abstract: Semiactive light-emitting diode (LED) drivers with high efficiency that regulate LED power statically against source voltage variation are proposed. By adopting multistage switching circuits in the proposed LED driver, the number of operating LED strings in series is appropriately selected according to the source voltage variation, which results in slow regulation of the LED power. A detailed procedure for selecting hysteresis control of the proposed LED driver with an LC3 input filter is fully established. A prototype five-stage LED driver of 100-W class was implemented and verified by experiments, which shows LED power variation of 90-110 W with a very high efficiency of 95.1-97.3% for source voltage variation of 200-253 V, meeting power factor and total harmonic distortion regulations.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Flicker-Free Electrolytic Capacitor-Less Universal Input Offline LED
           Driver With PFC
    • Authors: Valipour; H.;Rezazadeh, G.;Zolghadri, M.;
      Pages: 6553 - 6561
      Abstract: Recent developments in improving lighting efficiency and cost reduction of LEDs have made them suitable alternatives to the current lighting systems. In this paper, a novel offline structure is proposed to drive LEDs. The proposed circuit has a high-input power factor, high efficiency, a long lifetime, and it produces no flicker. To increase the lifetime of the converter, the proposed circuit does not include any electrolytic capacitors in the power stage. The proposed circuit consists of a transition mode flyback converter in order to improve power factor. Additionally, a buck converter is added to the third winding of the flyback transformer in order to create two parallel paths for the electrical power to feed the output load. DC power reaches the load through one stage (flyback) and ac power reaches the load through two stages of conversion (flyback + buck). Therefore, in the proposed one-and-a-half stage circuit, the efficiency is improved compared to a regular two-stage circuit. Although the proposed structure has some output current ripple, it is low enough (less than 8%) that the structure can be rendered flicker free, as shall be discussed. Principles of operation and design equations are presented as well as experimental results for a 700 mA/20 W universal input prototype.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • An Overview of Photonic Power Electronic Devices
    • Authors: Mazumder; S.;
      Pages: 6562 - 6574
      Abstract: This paper provides an outline on optically switched power electronic devices-an area of increasing promise. Starting with an outline of the need and benefits of optically activated power electronics, a brief chronological overview of the past optical-technology work is provided, followed by some of the recent novel work conducted by the author's group. The latter focuses on optical power semiconductor device technologies at different voltage levels and relatively recent device controls technologies. Finally, looking forward, some of the potential application areas of photonic power electronics are captured.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • ++Stress+Cycle+Effect+in+IGBT+Power+Module+Die-Attach+Lifetime+Modeling&rft.title=IEEE+Transactions+on+Power+Electronics&rft.issn=0885-8993&;Chen,++M.;Ran,++L.;Alatise,++O.;Xu,++Y.;Mawby,++P.;">Low \Delta T_{j}
    Stress Cycle Effect in IGBT Power Module Die-Attach
           Lifetime Modeling
    • Authors: Lai; W.;Chen, M.;Ran, L.;Alatise, O.;Xu, Y.;Mawby, P.;
      Pages: 6575 - 6585
      Abstract: Operational management for reliability of power electronic converters requires sensitive condition monitoring and accurate lifetime modeling. This study adds to the second aspect by examining the effect of cyclic junction temperature variations ΔTj of low amplitude in different stages of the power module ageing process. It is found that such relatively minor stress cycles, which happen frequently during normal operation, may not be able to directly initiate a crack but can contribute to the development of damage due to stress concentration. This agrees with the observation that the ageing process tends to accelerate toward the end of life. This study investigates the dependence of the ageing effect on the amplitude of ΔTj, the mean junction temperature T,,,, and the present health condition of the module, and proposes a lifetime model focusing on die-attach solder fatigue. It is assumed that the future-ageing process is independent of the operational history that has led to the current state of health. The model is intended for operational management of converter systems that are subjected to frequent low ΔTj stress cycles and are supposed to be in service reliably for a long time with a slow ageing process. Experimental results validate the model.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Simulation, Analysis, and Verification of Substrate Currents for Layout
           Optimization of Smart Power ICs
    • Authors: Buccella; P.;Stefanucci, C.;Sallese, J.;Kayal, M.;
      Pages: 6586 - 6595
      Abstract: Today circuit failures in Smart Power ICs due to substrate couplings are partially addressed during the circuit design phase. The state-of-the-art guidelines for the optimization of parasitic couplings provide mainly qualitative rules, which are difficult to implement and to verify during the design of a complex Smart Power circuit. These rules are often based on the physical device simulations or on the empirical results extracted from predefined benchmark structures. In this paper, a novel approach is proposed for designing robust circuits integrating accurate and specific analysis of substrate couplings already into the design flow. First, substrate currents injected by power transistors are discussed to show the spatial distribution of voltage and currents into the substrate. A set of guidelines to optimize substrate currents is presented as a summary of the studied test cases. Then, an H-Bridge output driver was implemented in a 0.35- μm HVCMOS technology to investigate substrate currents by both measurements and simulations. Reverse currents were deliberately injected into the chip to activate substrate lateral and vertical parasitic bipolar junction transistors and measured data closely match circuit simulation results in both cases.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • A Digital Phase Leading Filter Current Compensation (PLFCC) Technique for
           CCM Boost PFC Converter to Improve PF in High Line Voltage and Light Load
    • Authors: Youn; Han-Shin;Lee, Jae-Bum;Baek, Jae-Il;Moon, Gun-Woo;
      Pages: 6596 - 6606
      Abstract: This paper proposes a digital phase leading filter current compensation (PLFCC) technique for a continuous conduction mode boost power factor correction to improve PF in high line voltage and light load conditions. The proposed technique provides a corrected average inductor current reference and utilizes an enhanced duty ratio feed-forward technique which can cancel the adverse effect of the phase leading currents caused by filter capacitors. Moreover, the proposed PLFCC technique also provides the switching dead-zone in nature so the switching loss can be reduced. Therefore, the proposed PLFCC can significantly improve power quality and can achieve a high efficiency in high line voltage and light load conditions. The principle and analysis of the proposed PLFCC are presented, and performance and feasibility are verified by experimental results from the universal input (90-260 VAC) and 750 W-400 V output laboratory prototype.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Control Design of a PFC With Harmonic Mitigation Function for Small Hybrid
           AC/DC Buildings
    • Authors: Pena-Alzola; R.;Bianchi, M.;Ordonez, M.;
      Pages: 6607 - 6620
      Abstract: Unprecedented expansion of native dc powered equipment (LEDs, computers, and consumer electronics) has increased commercial and residential dc electricity usage over the past decade. Thus, it is foreseeable that hybrid ac/dc buildings featuring both ac and dc infrastructures will coexist. A hybrid ac/dc building will involve an efficient centralized rectifier that supplies all the dc loads, while legacy ac loads will remain connected to the existing ac infrastructure. This paper explores the opportunity of harmonic mitigation at distribution level in small hybrid ac/dc building by using a centralized power factor corrector (PFC) with large bandwidth. The current reference generator for the harmonic mitigation function (HMF) is explained along with power considerations. The PFC uses a proportional resonant controller, instead of a PI controller, without requiring additional sensors in the rectifier. A computationally inexpensive implementation of the phase-locked loop is also proposed along with considerations on parameter selection. The proposals provide all the steps for the straightforward control design of the PFC+HMF with fast calculations. The HMF requires only software modifications in the PFC and one sensor to measure the nonlinear load. Simulation and experiments validate the proposed procedures.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Comparison of Two SVPWM Control Strategies of Five-Phase Fault-Tolerant
           Permanent-Magnet Motor
    • Authors: Liu; G.;Qu, L.;Zhao, W.;Chen, Q.;Xie, Y.;
      Pages: 6621 - 6630
      Abstract: Five-phase fault-tolerant permanent-magnet motors incorporate the merits of high-efficiency and high fault-tolerant capability. By adopting the fault-tolerant control technique, these motors can continue operating even fault occurs. This paper proposes two space vector pulse-width modulation (SVPWM) control strategies, namely the symmetric one and the asymmetric one. The novelty of the proposed SVPWM control strategies includes two parts. One is that voltage vector locations in both SVPWM strategies are reconfigured based on a new vector space diagram. Another is that the process of switching vector calculation under fault is similar to that under healthy condition. A five-phase fault-tolerant permanent-magnet motor drive is developed and the proposed fault-tolerant control strategies are evaluated in terms of the torque, voltage, current waveforms, and total harmonic distortion. Simulated and experimental results are provided to verify the effectiveness of the theoretical analysis.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Reduction of Common-Mode Voltage in Multiphase Two-Level Inverters Using
           SPWM With Phase-Shifted Carriers
    • Authors: Liu; Z.;Zheng, Z.;Sudhoff, S.D.;Gu, C.;Li, Y.;
      Pages: 6631 - 6645
      Abstract: The increasing interest in multiphase drive systems has led to the extension of inverter topologies and pulse width modulation (PWM) methods from three-phase to multiphase occasions. Carrier-based PWM (CPWM) dominates space vector PWM when the phase number increases, because of its simple computation and modular implementation. Although intensive work has been done on modifying PWM methods to reduce the common-mode voltage (CMV), not enough work has been done on CPWM methods with CMV reduction for multiphase drives. This paper extends the phase-shifted sinusoidal PWM (PS-SPWM) method for five-phase and six-phase two-level voltage-source inverters (VSI) and employs the intersection-plotting method and Fourier analysis to reveal the nature of the CMV. Both experiment and simulation results comply with theoretical analysis that compared with the conventional SPWM, the PS-SPWM can effectively reduce the CMV in peak-to-peak value and RMS value, though it leads to a higher phase current distortion. In addition, the hardware realization of PS-SPWM for multiphase inverters by a distributed control system is presented in this paper.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • High-Bandwidth and Strong Robust Current Regulation for PMLSM Drives
           Considering Thrust Ripple
    • Authors: Wang; M.;Li, L.;Pan, D.;Tang, Y.;Guo, Q.;
      Pages: 6646 - 6657
      Abstract: This paper presents a high-performance current controller for the permanent-magnet linear synchronous motor considering the bandwidth and disturbances caused by the parameter variation and thrust ripple. First, an improved predictive current control (PCC) scheme based on the discretized model is proposed to increase the current control bandwidth. Besides the time-delay issue, it is noteworthy that the parameter variation in the PCC method can degrade the steady-state response. Through utilizing the information of first two sampling periods, the proposed PCC strategy can overcome such two issues at the same time. Second, a new discrete-time linearization observer is designed to estimate the thrust ripple. Then, the ripple can be suppressed by injecting the estimated value into the control system. Meanwhile, the stability analysis is given by the Lyapunov stability theory. A precise test platform based on the aerostatic guideway is established, and experimental results are shown to demonstrate the effectiveness and correctness of the proposed scheme.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • An Improved Distributed Secondary Control Method for DC Microgrids With
           Enhanced Dynamic Current Sharing Performance
    • Authors: Wang; P.;Lu, X.;Yang, X.;Wang, W.;Xu, D.;
      Pages: 6658 - 6673
      Abstract: This paper proposes an improved distributed secondary control scheme for dc microgrids (MGs), aiming at overcoming the drawbacks of conventional droop control method. The proposed secondary control scheme can remove the dc voltage deviation and improve the current sharing accuracy by using voltage-shifting and slope-adjusting approaches simultaneously. Meanwhile, the average value of droop coefficients is calculated, and then it is controlled by an additional controller included in the distributed secondary control layer to ensure that each droop coefficient converges at a reasonable value. Hence, by adjusting the droop coefficient, each participating converter has equal output impedance, and the accurate proportional load current sharing can be achieved with different line resistances. Furthermore, the current sharing performance in steady and transient states can be enhanced by using the proposed method. The effectiveness of the proposed method is verified by detailed experimental tests based on a 3 × 1 kW prototype with three interface converters.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • A Control Algorithm for Electric Vehicle Fast Charging Stations Equipped
           With Flywheel Energy Storage Systems
    • Authors: Sun; B.;Dragicevic, T.;Freijedo, F.;Vasquez, J.;Guerrero, J.;
      Pages: 6674 - 6685
      Abstract: This paper proposes a control strategy for plug-in electric vehicle (PEV) fast charging station (FCS) equipped with a flywheel energy storage system (FESS). The main role of the FESS is not to compromise the predefined charging profile of the PEV battery during the provision of a hysteresis-type active power ancillary service to the overhead power system. In that sense, when the active power is not being extracted from the grid, an FESS provides the power required to sustain the continuous charging process of the PEV battery. A key characteristic of the whole control system is that it is able to work without any digital communication between the grid-tied and FESS converters. Detailed system modeling and dynamics analysis of the controller are carried out for the different operating modes of the FCS system. A lab-scale prototype was built to validate the proposal. The presented experimental results proved the high accuracy of the theoretical analysis.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Asynchronous-Switching Map-Based Stability Effects of Circuit Parameters
           in Fixed Off-Time Controlled Buck Converter
    • Pages: 6686 - 6697
      Abstract: Both constant on-time (COT) and fixed off-time (FOT) control techniques are suitable for various applications requiring fast transient response. However, the discrete-time model of COT controlled buck converter only has two switched borderlines, whereas that of FOT controlled buck converter has four switched borderlines. Based on the derivations of these borderlines, an asynchronous-switching map of FOT controlled buck converter is established. With the decrease of equivalent series resistance (ESR) of output capacitor, instability and mode shifting from continuous conduction mode (CCM) to discontinuous conduction mode (DCM) are discussed. Furthermore, with small ESR of output capacitor, stability effects of load resistance and inductance on dynamical behaviors are investigated, and the approximate stability criteria and the corresponding normalized critical conditions are obtained. The theoretical analyses and experimental results show that the converter operates in DCM chaos via period-doubling and border-collision bifurcation routes, and its instability caused by small ESR can be removed by choosing appropriate load resistance, inductance, and voltage transfer ratio, which are very suitable for the circuit design of FOT controlled buck converter.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • A Generalized Algorithm to Eliminate Spikes of Common-Mode Voltages for
    • Authors: Tan; G.;Wu, X.;Wang, Z.;Ye, Z.;
      Pages: 6698 - 6709
      Abstract: This paper presents a generalized algorithm to eliminate spikes of common-mode voltages (CMV) caused by dead-time effect for common-mode voltage reduction pulse width modulation (CMVRPWM). The characteristics of the CMV spikes for the popular CMVRPWM strategies (AZSPWM1, NSPWM, CRLO-CMVRPWM, and SLO-CMVRPWM) are studied and compared by analyzing the extreme switch pulse patterns. The proposed CMV spikes elimination method directly adjusts the injected zero-sequence voltages instead of the durations of the adopted voltage space vectors to avoid the overlaps of the adjacent dead time periods. The CMV spikes can be eliminated regardless of the output voltages in the dead time periods; thus, the signs of phase currents are not needed to detect and overcome the problem caused by the resolution of the current sensors when the phase currents approach to zero. In addition, an effective method by online selecting low or high active pulses for the three legs is proposed to ensure that at most one leg switches between adjacent carrier periods. The proposed method is generalized and effective for all the CMVRPWM with symmetrical switch pulse patterns and no simultaneous switching problem. The simulation and experimental results validate the effectiveness.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Dynamic Control and Analysis of DC-Capacitor Voltage Fluctuations in
           Three-Phase Active Power Filters
    • Authors: Mannen; T.;Fujita, H.;
      Pages: 6710 - 6718
      Abstract: This paper proposes a new control method of three-phase active power filters for reducing the dc capacitor voltage fluctuations in transient load change. The proposed control method introduces a new k-step compensator, which maintains the mean active power flowing into the dc capacitor at zero every 1/(k-1) ac line period. Therefore, the compensator can suppress the transient voltage fluctuations across the dc capacitor even when a quick load change occurs. This paper theoretically reveals the relationship between the step number k and the reduction effect of the dc voltage fluctuations. The experimental setup introducing the proposed seven-step compensator exhibits a good suppression effect of the dc voltage fluctuations and makes it possible to reduce the required capacitance value of the dc capacitor by a factor of seven.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Control of Three-Phase Bidirectional Current-Source Converter to Inject
           Balanced Three-Phase Currents Under Unbalanced Grid Voltage Condition
    • Authors: Vekhande; V.;Kanakesh, V.K.;Fernandes, B.G.;
      Pages: 6719 - 6737
      Abstract: A single-stage, bidirectional, current-source converter (CSC) topology to interface a dc microgrid with an ac grid is reported in the literature. In this topology, under a balanced grid voltage condition, the dc-link inductor current can be regulated over a wide range-from zero to rated value-while the ac-side current has low harmonic distortion. However, unbalanced grid voltages result in second-harmonic pulsation in the current and power on the dc side of the converter. In addition, the ac-side currents will be unbalanced due to the presence of a negative-sequence component. This would result in undesired tripping of the converter if one of the phase currents exceeded its rated value. Various control loop structures for the operation of voltage-source converter under unbalanced grid voltage conditions are reported in the literature. However, use of similar control loop structures for CSC may lead to unstable operation. Therefore, a control scheme to inject balanced three-phase currents into the ac grid under an unbalanced grid voltage condition is proposed in this paper. The stability of the proposed control scheme is studied using a small-signal model of the converter. Performance of the proposed control scheme is studied using MATLAB/Simulink and is experimentally validated.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Fast Transient Response of Series Resonant Converters Using Average
           Geometric Control
    • Authors: Mohammadi; M.;Ordonez, M.;
      Pages: 6738 - 6755
      Abstract: Linear controllers and small-signal modeling techniques have been used for over 40 years to control power electronic converters around the equilibrium operating point. Outside the quiescent area, the shortcomings of linear controllers are well known and include uncertain large-signal transient behavior and sluggish dynamic/recovery response. In particular, resonant converters have inherent large-signal behavior, making the transient performance of small-signal linear controllers poor. This paper develops a geometric controller based on large-signal modeling to achieve enhanced dynamic response of the series resonant converter (SRC). The proposed modeling strategy provides detailed insight into the behavior of the SRC and creates an analytical framework to successfully perform geometric control. A new geometric control law is mathematically derived using average circular trajectories producing accurate and fast dynamics during startup, sudden load or reference changes. In order to validate the theoretical analysis, experimental and simulation results of an SRC are presented and compared to those of a linear and a nonlinear controller. The dynamic response is, on average, over 100 times faster than that of the designed linear controller, while overshoot is virtually eliminated.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
  • Constant Resonant Current Limiting Strategy for LLC
           Converter Without Current Sensing
    • Authors: Li; Q.;Liu, B.;Zheng, R.;Duan, S.;
      Pages: 6756 - 6764
      Abstract: There are great current shocks in LLC resonant converter during startup and over load condition. Conventional open loop current limiting method suffers from limited effect and complicated design process, while closed loop current limiting method requires extra current sensing. This paper investigates the relationship between resonant current, output voltage, and switching frequency based on state plane analysis, then a constant resonant current limiting strategy without current sensing is proposed, which adjusts switching frequency corresponding to the output voltage. The proposed strategy can realize constant peak value of resonant current during startup, shock load stepping, and over load condition, achieving optimal control of the primary current stress. Together with conventional output voltage regulating strategy, regulation of output voltage under normal load condition is also guaranteed. The maximum available output voltage under current limiting condition is estimated, and simple parameter design method of current limiting strategy is provided.
      PubDate: Sept. 2016
      Issue No: Vol. 31, No. 9 (2016)
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