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  Subjects -> ELECTRONICS (Total: 159 journals)
Advances in Biosensors and Bioelectronics     Open Access   (Followers: 2)
Advances in Electronics     Open Access   (Followers: 4)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 6)
Advances in Microelectronic Engineering     Open Access   (Followers: 6)
Advances in Power Electronics     Open Access   (Followers: 10)
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 106)
American Journal of Electrical and Electronic Engineering     Open Access   (Followers: 15)
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: 11)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 5)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 12)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 18)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 16)
Biomedical Instrumentation & Technology     Hybrid Journal   (Followers: 6)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 5)
BULLETIN of National Technical University of Ukraine. Series RADIOTECHNIQUE. RADIOAPPARATUS BUILDING     Open Access   (Followers: 2)
Bulletin of the Polish Academy of Sciences : Technical Sciences     Open Access  
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 15)
China Communications     Full-text available via subscription   (Followers: 4)
Circuits and Systems     Open Access   (Followers: 11)
Consumer Electronics Times     Open Access   (Followers: 5)
Control Systems     Hybrid Journal   (Followers: 36)
Edu Elektrika Journal     Open Access  
Electronic Design     Partially Free   (Followers: 23)
Electronic Markets     Hybrid Journal   (Followers: 5)
Electronic Materials Letters     Hybrid Journal   (Followers: 3)
Electronics     Open Access   (Followers: 10)
Electronics and Communications in Japan     Hybrid Journal   (Followers: 5)
Electronics Letters     Hybrid Journal   (Followers: 20)
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 25)
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: 10)
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Frequenz     Hybrid Journal   (Followers: 3)
Frontiers of Optoelectronics     Hybrid Journal   (Followers: 2)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 20)
Giroskopiya i Navigatsiya     Open Access  
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 3)
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 24)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 18)
IEEE Consumer Electronics Magazine     Full-text available via subscription   (Followers: 21)
IEEE Journal of Emerging and Selected Topics in Power Electronics     Hybrid Journal   (Followers: 17)
IEEE Journal of the Electron Devices Society     Open Access   (Followers: 5)
IEEE Power Electronics Magazine     Full-text available via subscription   (Followers: 16)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 19)
IEEE Transactions on Audio, Speech, and Language Processing     Hybrid Journal   (Followers: 15)
IEEE Transactions on Automatic Control     Hybrid Journal   (Followers: 35)
IEEE Transactions on Consumer Electronics     Hybrid Journal   (Followers: 19)
IEEE Transactions on Electron Devices     Hybrid Journal   (Followers: 10)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 14)
IEEE Transactions on Power Electronics     Hybrid Journal   (Followers: 30)
IEEE Transactions on Signal and Information Processing over Networks     Full-text available via subscription   (Followers: 1)
IEICE - Transactions on Electronics     Full-text available via subscription   (Followers: 8)
IEICE - Transactions on Information and Systems     Full-text available via subscription   (Followers: 8)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 6)
IET Power Electronics     Hybrid Journal   (Followers: 16)
IET Wireless Sensor Systems     Hybrid Journal   (Followers: 10)
IETE Journal of Education     Open Access   (Followers: 2)
IETE Journal of Research     Open Access   (Followers: 11)
IETE Technical Review     Open Access   (Followers: 4)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 17)
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 4)
Informatik-Spektrum     Hybrid Journal  
Instabilities in Silicon Devices     Full-text available via subscription  
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 4)
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: 22)
International Journal of Advances in Telecommunications, Electrotechnics, Signals and Systems     Open Access   (Followers: 3)
International Journal of Aerospace Innovations     Full-text available via subscription   (Followers: 13)
International Journal of Antennas and Propagation     Open Access   (Followers: 7)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 1)
International Journal of Biomedical Nanoscience and Nanotechnology     Hybrid Journal   (Followers: 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: 14)
International Journal of Electronics     Hybrid Journal   (Followers: 2)
International Journal of Electronics & Data Communication     Open Access   (Followers: 4)
International Journal of Electronics and Telecommunications     Open Access   (Followers: 3)
International Journal of Granular Computing, Rough Sets and Intelligent Systems     Hybrid Journal   (Followers: 1)
International Journal of High Speed Electronics and Systems     Hybrid Journal  
International Journal of Image, Graphics and Signal Processing     Open Access   (Followers: 2)
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  
International Journal of Numerical Modelling:Electronic Networks, Devices and Fields     Hybrid Journal   (Followers: 2)
International Journal of Power Electronics     Hybrid Journal   (Followers: 9)
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: 1)
International Journal on Communication     Full-text available via subscription   (Followers: 13)
International Journal on Electrical and Power Engineering     Full-text available via subscription   (Followers: 10)
International Transaction of Electrical and Computer Engineers System     Open Access  
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 2)
Journal of Advanced Dielectrics     Open Access   (Followers: 1)
Journal of Artificial Intelligence     Open Access   (Followers: 5)
Journal of Circuits, Systems, and Computers     Hybrid Journal   (Followers: 2)

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Journal Cover IEEE Transactions on Power Electronics
  [SJR: 2.866]   [H-I: 128]   [30 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]
  • Table of contents
    • Abstract: Presents the cover/table of contents for this issue of the periodical.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • IEEE Transactions on Power Electronics publication information
    • Abstract: Provides a listing of current staff, committee members and society officers.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • IEEE Power Electronics Society Information
    • Abstract: Provides a listing of current committee members and society officers.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Sensorless Control for High-Speed Brushless DC Motor Based on the
           Line-to-Line Back EMF
    • Authors: Liu; G.;Cui, C.;Wang, K.;Han, B.;Zheng, S.;
      Pages: 4669 - 4683
      Abstract: A sensorless control method for a high-speed brushless DC motor based on the line-to-line back electromotive force (back EMF) is proposed in this paper. In order to obtain the commutation signals, the line-to-line voltages are obtained by the low-pass filters. However, due to the low-pass filters, wide speed range, and other factors, the actual commutation signals are significantly delayed by more than 90 electrical degrees which limits the acceleration of the motor. A novel sensorless commutation algorithm based on the hysteresis transition between “90-α” and “150-α” is introduced to handle the severe commutation retarding and guarantee the motor works in a large speed range. In order to compensate the remaining existing commutation errors, a novel closed-loop compensation algorithm based on the integration of the virtual neutral voltage is proposed. The integration difference between the adjacent 60 electrical degrees interval before and after the commutation point is utilized as the feedback of the PI regulator to compensate the errors automatically. Several experiment results confirm the feasibility and effectiveness of the proposed method.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Stationary Frame Fault-Tolerant Current Control of Polyphase
           Permanent-Magnet Machines Under Open-Circuit and Short-Circuit Faults
    • Authors: Sen; B.;Wang, J.;
      Pages: 4684 - 4696
      Abstract: The paper presents a stationary frame control strategy to achieve optimal current control for star-connected polyphase permanent-magnet machine under asymmetric phase faults, namely, phase open circuit (OC) and phase short-circuit (SC) condition. Current regulation under these faults is particularly challenging because optimal torque control strategy generates nonsinusoidal current references with unbalance in both fundamental and higher order working harmonics, to achieve minimal copper losses and torque ripple under fault condition. Under field-weakening operation, voltage limit introduces additional control problems. The paper describes a solution for these control issues by employing a novel controller in stationary frame. This control strategy allows minimal reconfiguration of the control structure from healthy to postfault operation. Extensive simulation and experimental results are presented as validation for the proposed strategy.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Detection and Discrimination of Open-Phase Fault in Permanent Magnet
           Synchronous Motor Drive System
    • Authors: Hang; J.;Zhang, J.;Cheng, M.;Ding, S.;
      Pages: 4697 - 4709
      Abstract: Open-phase fault in permanent magnet synchronous motor (PMSM) drive system occurs as the phase winding is disconnected or one leg of the inverter bridge fails. It may generate large electromagnetic torque ripple and serious mechanical vibration. Therefore, a rapid fault detection method is greatly required to identify this fault at early stage and prevent damage to the system. This paper develops a method of the open-phase fault detection and discrimination for the PMSM drive system based on the zero-sequence voltage components, in which the discrimination of the fault types, namely internal stator winding failure and switches failure of the inverter is realized. Then, appropriate fault-tolerant measures may be taken according to the different fault types. The experimental platform is established, and the experimental results verify the effectiveness of the proposed method, showing that not only the open-phase fault can be rapidly detected, but also the fault type can be effectively discriminated.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • High-Resistance Connection Detection in Permanent Magnet Synchronous
           Machine Using Zero-Sequence Current Component
    • Authors: Hang; J.;Zhang, J.;Cheng, M.;Zhang, B.;Ding, S.;
      Pages: 4710 - 4719
      Abstract: This paper focuses on the development of an online method for diagnosing high-resistance connection (HRC) in delta-connected permanent magnet synchronous machine (PMSM) using zero-sequence current component (ZSCC). The development of this method begins with the establishment of the mathematic model of the PMSM with the HRC. Based on the model, a ZSCC-based method is proposed to diagnose the HRC. The fault indicator and angle differences are defined for fault diagnosis. To implement online diagnosis, an effective frequency tracking algorithm is applied. Finally, the fault diagnosis steps are presented. This method is capable of detecting the fault, evaluating the fault severity, and identifying the faulty phases. The simulation and experiment are carried out to verify the proposed method. Both the results show the validity of the proposed method, leading to the effective diagnosis of the HRC in the delta-connected PMSM.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • High-Precision Rotor Position Detection for High-Speed Surface PMSM Drive
           Based on Linear Hall-Effect Sensors
    • Authors: Song; X.;Fang, J.;Han, B.;
      Pages: 4720 - 4731
      Abstract: Accurate rotor position detection is essential for the surface permanent magnet synchronous motor (SPMSM) drive system to realize the stable and reliable operation. In this paper, two linear hall-effect sensors are utilized to detect the rotor position. However, the estimated errors in the measured signals, especially the harmonic components, impact on the accuracy of the rotor angle estimation significantly. For this reason, a high-precision rotor position detection method, which is based on the synchronous frequency extractors (SFEs) is presented. Two SFEs are used to filter out the high-order harmonics contained in the hall-effect signals. Further, the estimation of the rotor speed is used for the field-oriented control scheme of the PMSM. The proposed method is advantageous since it is simple, low cost, and high estimation accuracy. Finally, an experimental driveline system used for testing the electrical performance of developed high-speed magnetically suspended motor is built. The experimental results validate the feasibility and effectiveness of the proposed method in whole speed range.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Turn-On Optimization for Class D Series–Parallel
           LCC-Type Constant Current High-Power LED Driver Design
           Based on Traditional Fluorescent Control IC
    • Authors: Chen; K.;Xiao, P.;Johnsen, A.;Saenz, R.E.;
      Pages: 4732 - 4741
      Abstract: This research investigated a method to optimize the start-up performance of a dimmable light-emitting diode (LED) driver based on half-bridge Class D series–parallel LCC topology. This LED driver is designed for outdoor or high bay applications with 347–480 V_{{\rm ac}} input voltage. The total maximum output power is 100 W with a wide tunable output current range (from 50 to 800 mA). The wide load range makes it difficult to achieve a start-up time of less than 1 s under each load condition as well as limit the output overshoot level to below 150% by implementing only one set of KI values in the feedback loop. Moreover, in this design, a fluorescent control IC is used due to the cost efficiency of repurposing existing fluorescent ballast manufacturing systems. The start-up sequence of the fluorescent control IC introduces an additional challenge to the start-up design. In order to comply with Energy Star, which requires the output current to reach 75% of its nominal value and also limit the overshoot level, a self-adjusted-duty-cycle control algorithm is designed. This duty-cycle signal generated by measuring the load condition through a secondary side microcontroller is used to determine the switching frequency of the LCC tank. With this method, the start-up performance is greatly improved and meets all requirements.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • High Switching Performance of 1700-V, 50-A SiC Power MOSFET Over Si
           IGBT/BiMOSFET for Advanced Power Conversion Applications
    • Authors: Hazra; S.;De, A.;Cheng, L.;Palmour, J.;Schupbach, M.;Hull, B.A.;Allen, S.;Bhattacharya, S.;
      Pages: 4742 - 4754
      Abstract: Due to wider band gap of silicon carbide (SiC) compared to silicon (Si), MOSFET made in SiC has considerably lower drift region resistance, which is a significant resistive component in high-voltage power devices. With low on-state resistance and its inherently low switching loss, SiC MOSFETs can offer much improved efficiency and compact size for the converter compared to those using Si devices. In this paper, we report switching performance of a new 1700-V, 50-A SiC MOSFET designed and developed by Cree, Inc. Hard-switching losses of the SiC MOSFETs with different circuit parameters and operating conditions are measured and compared with the 1700-V Si BiMOSFET and 1700-V Si IGBT, using same test set-up. Based on switching and conduction losses, the operating boundary of output power and switching frequency of these devices are found out in a dc–dc boost converter and compared. The switching dv/dts and di/dts of SiC MOSFET are captured and discussed in the perspective of converter design. To validate the continuous operation, three dc–dc boost converters using these devices, are designed and tested at 10 kW of power with 1 kV of output voltage and 10 kHz of switching frequency. 1700-V SiC Schottky diode is used as the blocking diode in each case. Corresponding converter efficiencies are evaluated and the junction temperature of each device is estimated. To demonstrate high switching frequency operation, the SiC MOSFET is switched upto 150 kHz within permissible junction temperature rise. A switch combination of the 1700-V SiC MOSFET and 1700-V SiC Schottky diode connected in series is also evaluated for zero voltage switching turn-ON behavior and compared with those of bipolar Si devices. Results show substantial power loss saving with the use of SiC MOSFET.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Analysis and Suppressing Method for the Output Voltage Harmonics of
           Modular Multilevel Converter
    • Authors: Wu; D.;Peng, L.;
      Pages: 4755 - 4765
      Abstract: Although many high-power voltage source converters are of three-phase three-wire type, there may also be other types of configuration with which tripplen harmonics in the ac voltage and/or current are of great concern. This paper analyzes the harmonic characteristic of the output voltage of modular multilevel converter (MMC) in cases where the third-order harmonic voltage and current are inevitable, such as in three-phase four-wire configurations. The interaction among the capacitor voltage, arm current, and the modulating signal will generate multiple harmonics in the output voltage, in which the third-order harmonic is the most dominant. The third-order harmonic in the MMC output voltage will cause excessive amount of third-order harmonic in the output current in grid-connected applications with three-phase four-wire configuration. Analytical expression for the output voltage is derived for open-loop case, considering both the fundamental-frequency reference signal and the circulating current-control signal in the modulating signals. A feedforward compensation (FFC) method is proposed for suppressing the influence of the third-order harmonic in the output voltage for grid-connected applications. Simulation and experimental results verified the correctness of the analysis and effectiveness of the proposed FFC method.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • High-Frequency-Link DC Transformer Based on Switched Capacitor for
           Medium-Voltage DC Power Distribution Application
    • Authors: Zhao; B.;Song, Q.;Li, J.;Liu, W.;Liu, G.;Zhao, Y.;
      Pages: 4766 - 4777
      Abstract: This paper proposes a practical solution of high-frequency-link dc transformer based on switched capacitor (SCDCT) for medium-voltage dc (MVDC) power distribution application. Compared to the traditional dc transformer scheme, the proposed SCDCT can disconnect from MVDC distribution grid effectively as a dc breaker when a short fault occurs in the distribution, can enhance power transfer capacity, and always ensures high-frequency-link voltage match to improve current impact and efficiency performances, and the redundancy design can be achieved when some submodules fail to improve the reliability. In the paper, the topology, voltage and power characterization, control strategy, startup, and fault solution of SCDCT are presented and analyzed comprehensively. At last, an SCDCT prototype is built and the experimental results verify the correctness and effectively of the proposed solution.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Review of Active Power Decoupling Topologies in Single-Phase Systems
    • Authors: Sun; Y.;Liu, Y.;Su, M.;Xiong, W.;Yang, J.;
      Pages: 4778 - 4794
      Abstract: Active power decoupling methods are developed to deal with the inherent ripple power at twice the grid frequency in single-phase systems generally by adding active switches and energy storage units. They have obtained a wide range of applications, such as photovoltaic (PV) systems, light-emitting diodes (LEDs) drivers, fuel cell (FC) power systems, and electric vehicle (EV) battery chargers, etc. This paper provides a comprehensive review of active power decoupling circuit topologies. They are categorized into two groups in terms of the structure characteristics: independent and dependent decoupling circuit topologies. The former operates independently with the original converter, and the latter, however, shares the power semiconductor devices with the original converter partially and even completely. The development laws for the active power decoupling topologies are revealed from the view of “duality principle,” “switches sharing,” and “differential connection.” In addition, the exceptions and special cases are also briefly introduced. This paper is targeted to help researchers, engineers, and designers to construct some new decoupling circuit topologies and properly select existing ones according to the specific application.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Isolated Swiss-Forward Three-Phase Rectifier With Resonant Reset
    • Authors: Silva; M.;Hensgens, N.;Oliver, J.A.;Alou, P.;Garcia, O.;Cobos, J.A.;
      Pages: 4795 - 4808
      Abstract: This paper presents a new isolated single-stage pulse-width modulation rectifier system based on the recently presented Swiss rectifier topology providing the isolation by replacing a buck with a forward converter. The principle of operation and a new modulation technique which compensates the reactive power generated by the input filter at light load and maximizes the power factor are discussed. Furthermore, the analytical equations for the stress in the semiconductor devices useful for the system optimization are derived. The proposed topology and modulation technique are experimentally validated on a 3.3-kW 115 Vac to 270 Vdc prototype demonstrator.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Energy Efficiency Analysis of U-Coil Wireless Power Transfer System
    • Authors: Ye; Z.;Sun, Y.;Dai, X.;Tang, C.;Wang, Z.;Su, Y.;
      Pages: 4809 - 4817
      Abstract: In order to improve the power transfer efficiency and ensure the space cleanliness of power transfer direction in inductive coupled wireless power transfer (WPT) system, a new U-coil WPT system is proposed. Based on the mutual inductance coupling theory, a new methodology for ensuring that a U-coil system is more energy efficient than a two-coil counterpart is presented in this paper. The theoretical proof and the conditions for meeting the objective are derived and practically verified in a practical prototype. The experimental results show: 1) comparing with two-coil system, power transfer efficiency can be improved more than ten times by using U-coil system; and 2) with the same power transfer efficiency principle, the dimension of primary and load coils in U-coil system shrinks at least 66% comparing with that of two-coil system. The U-coil system not only improves power transfer efficiency but also ensures the cleanliness of the space along the energy transfer direction.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Virtual Flux Sensorless Control for Shunt Active Power Filters With
           Quasi-Resonant Compensators
    • Authors: Ketzer; M.B.;Jacobina, C.B.;
      Pages: 4818 - 4830
      Abstract: This paper presents a sensorless control strategy for pulsewidth modulated active filters. The complete solution uses only two current sensors, which are located in the grid interface. The compensation is performed by the imposition of sinusoidal current references in the grid, and does not require algorithms for disturbance estimation. The virtual flux concept for grid synchronization and multiple quasi-resonant compensators in the current scheme are employed for selective harmonic mitigation. A discretization analysis is presented in order to obtain a precise digital realization of the current controllers. It is proposed as a regulator for the direct-current bus voltage in the active filter, which employs only information of the modulated voltage and is compatible with the previous sensorless synchronization solution. Experimental results from a 1-kVA prototype converter are presented, covering the solution with and without the voltage sensor in the direct current bus. Analyses of stationary and transient responses are performed by using a six-pulse diode rectifier as nonlinear load.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Control of Doubly-Fed Induction Generator to Ride-Through Recurring Grid
           Faults
    • Authors: Chen; W.;Xu, D.;Zhu, N.;Chen, M.;Blaabjerg, F.;
      Pages: 4831 - 4846
      Abstract: The wind turbine system (WTS) is required to ride-through recurring grid faults by the new grid codes. Under single grid faults, the fault ride-through (FRT) strategy with rotor-side crowbar is normally used for the doubly-fed induction generator (DFIG) WTS. However, under recurring faults, larger transient current and voltage may be produced, and the DFIG may fail to ride-through the second fault even with the rotor-side crowbar. The crowbar can be active again during the voltage recovery, but large electromagnetic torque (EM-torque) fluctuations will be introduced. The reliability of the mechanical system will be influenced. In this paper, an FRT strategy for the DFIG WTS to ride-through recurring symmetrical grid faults is investigated. An improved control strategy is introduced and it is applied during the voltage recovery of the grid faults. The decay of the stator natural flux can be accelerated so the transient current and voltage under recurring fault will be no larger than that under single fault. At the same time, the EM-torque fluctuations can be suppressed, the mechanical stress can be reduced, and higher reliability can be expected to the WTS. It is verified by simulations on a 1.5-MW DFIG model and by experiments on a 30-kW DFIG test system.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Secondary-Side-Regulated Soft-Switching Full-Bridge Three-Port Converter
           Based on Bridgeless Boost Rectifier and Bidirectional Converter for
           Multiple Energy Interface
    • Authors: Wu; H.;Zhang, J.;Qin, X.;Mu, T.;Xing, Y.;
      Pages: 4847 - 4860
      Abstract: A systematic method for deriving soft-switching three-port converters (TPCs), which can interface multiple energy, is proposed in this paper. Novel full-bridge (FB) TPCs featuring single-stage power conversion, reduced conduction loss, and low-voltage stress are derived. Two nonisolated bidirectional power ports and one isolated unidirectional load port are provided by integrating an interleaved bidirectional Buck/Boost converter and a bridgeless Boost rectifier via a high-frequency transformer. The switching bridges on the primary side are shared; hence, the number of active switches is reduced. Primary-side pulse width modulation and secondary-side phase shift control strategy are employed to provide two control freedoms. Voltage and power regulations over two of the three power ports are achieved. Furthermore, the current/voltage ripples on the primary-side power ports are reduced due to the interleaving operation. Zero-voltage switching and zero-current switching are realized for the active switches and diodes, respectively. A typical FB-TPC with voltage-doubler rectifier developed by the proposed method is analyzed in detail. Operation principles, control strategy, and characteristics of the FB-TPC are presented. Experiments have been carried out to demonstrate the feasibility and effectiveness of the proposed topology derivation method.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • An Energy Management Scheme With Power Limit Capability and an Adaptive
           Maximum Power Point Tracking for Small Standalone PMSG Wind Energy Systems
           
    • Authors: Hui; J.C.Y.;Bakhshai, A.;Jain, P.K.;
      Pages: 4861 - 4875
      Abstract: Due to its high energy generation capability and minimal environmental impact, wind energy is an elegant solution to the growing global energy demand. However, frequent atmospheric changes make it difficult to effectively harness the energy in the wind because maximum power extraction occurs at a different operating point for each wind condition. This paper proposes a parameter-independent intelligent power management controller that consists of a slope-assisted maximum power point tracking (MPPT) algorithm and a power limit search (PLS) algorithm for small standalone wind energy systems with permanent synchronous generators. Unlike the parameter-independent perturb & observe algorithms, the proposed slope-assisted MPPT algorithm preempts logical errors attributed to wind fluctuations by detecting and identifying atmospheric changes. The controller's PLS is able to minimize the production of surplus energy to minimize the heat dissipation requirements of the energy release mechanism by cooperating with the state observer and using the slope parameter to seek the operating points that result in the desired power rather than the maximum power. The functionality of the proposed energy management control scheme for wind energy systems is verified through simulation results and experimental results.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • DC Microgrids—Part I: A Review of Control Strategies and
           Stabilization Techniques
    • Authors: Dragicevic; T.;Lu, X.;Vasquez, J.C.;Guerrero, J.M.;
      Pages: 4876 - 4891
      Abstract: This paper presents a review of control strategies, stability analysis, and stabilization techniques for dc microgrids (MGs). Overall control is systematically classified into local and coordinated control levels according to respective functionalities in each level. As opposed to local control, which relies only on local measurements, some line of communication between units needs to be made available in order to achieve the coordinated control. Depending on the communication method, three basic coordinated control strategies can be distinguished, i.e., decentralized, centralized, and distributed control. Decentralized control can be regarded as an extension of the local control since it is also based exclusively on local measurements. In contrast, centralized and distributed control strategies rely on digital communication technologies. A number of approaches using these three coordinated control strategies to achieve various control objectives are reviewed in this paper. Moreover, properties of dc MG dynamics and stability are discussed. This paper illustrates that tightly regulated point-of-load converters tend to reduce the stability margins of the system since they introduce negative impedances, which can potentially oscillate with lightly damped power supply input filters. It is also demonstrated that how the stability of the whole system is defined by the relationship of the source and load impedances, referred to as the minor loop gain. Several prominent specifications for the minor loop gain are reviewed. Finally, a number of active stabilization techniques are presented.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Modeling, Modulation, and Control of the Three-Phase Four-Switch PWM
           Rectifier Under Balanced Voltage
    • Authors: Zeng; Z.;Zheng, W.;Zhao, R.;Zhu, C.;Yuan, Q.;
      Pages: 4892 - 4905
      Abstract: The modeling, modulation, and control of the three-phase four-switch (TPFS) PWM rectifier are investigated in this paper. Three space vector pulse width modulation methods using different equivalent zero vectors are developed, where sector identification and the trigonometric function are not required. Then, the high-frequency model for the current ripple analysis is proposed, and the effects of three SVM approaches on the ac current ripple are investigated. According to the analytical results, the method introducing the smallest current ripple is selected. With the optimized SVM approach, a control-oriented model, considering the capacitor voltage oscillation and deviation, is built in the dq synchronous frame to facilitate the controller design. Furthermore, a control strategy implementing the proportional controller is developed to eliminate the capacitor voltage deviation. Meanwhile, the dual-loop control of the TPFS is not affected by the proposed strategy as the capacitor voltage deviation is eliminated. Finally, a novel linear modulation index function is defined to reject the low-frequency harmonic current introduced by the overmodulation. Experimental results demonstrate that excellent current performance is achieved with comprehensive considerations of the modeling, modulation, and control strategy.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • A Simple Hysteretic Energy Harvesting Method for Nonneutral AC Switches in
           Load Automation
    • Authors: A; K.;Umanand, L.;
      Pages: 4906 - 4915
      Abstract: This paper presents a simple hysteretic method to obtain the energy required to operate the gate-drive, sensors, and other circuits within nonneutral ac switches intended for use in load automated buildings. The proposed method features a switch-mode low part-count self-powered mosfet ac switch that achieves efficiency and load current THD figures comparable to those of an externally gate-driven switch built using similar mosfets. The fundamental operation of the method is explained in detail, followed by the modifications required for practical implementation. Certain design rules that allow the method to accommodate a wide range of single-phase loads from 10 VA to 1 kVA are discussed, along with an efficiency enhancement feature based on inherent mosfet characteristics. The limitations and side effects of the method are also mentioned according to their levels of severity. Finally, experimental results obtained using a prototype sensor switch are presented, along with a performance comparison of the prototype with an externally gate-driven mosfet switch.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • A MultiWinding Transformer Cell-to-Cell Active Equalization Method for
           Lithium-Ion Batteries With Reduced Number of Driving Circuits
    • Authors: Chen; Y.;Liu, X.;Cui, Y.;Zou, J.;Yang, S.;
      Pages: 4916 - 4929
      Abstract: The bidirectional cell-to-cell equalization methods perform well to prevent the series-connected batteries from overcharging and undercharging. However, it remains a challenge to achieve fast equalization and high equalization efficiency with low complexity. To address the issue, we propose a new bidirectional cell-to-cell active equalization method using a multiwinding transformer. The new method allows the energy to transfer directly from the highest voltage cell to the lowest one by fly-back operation or forward operation which gives a short balancing path and guarantees a fast equalization speed. We adopt the bidirectional switches of low conduction loss for high equalization efficiency. Since the bidirectional switches are turned on or off simultaneously, a common driving circuit for the bidirectional switch has been designed to reduce the number of the driving circuits by half. The experiments with a six 50-Ah Lithium-ion battery strings are conducted and the results have demonstrated that our new approach has achieved a good overall performance of equalization in terms of speed, efficiency, and complexity of the circuit.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Ultrahigh Step-up DC–DC Converter for Distributed Generation by
           Three Degrees of Freedom (3DoF) Approach
    • Authors: Hu; Y.;Wu, J.;Cao, W.;Xiao, W.;Li, P.;Finney, S.J.;Li, Y.;
      Pages: 4930 - 4941
      Abstract: This paper proposes a novel dc–dc converter topology to achieve an ultrahigh step-up ratio while maintaining a high conversion efficiency. It adopts a three degree of freedom approach in the circuit design. It also demonstrates the flexibility of the proposed converter to combine with the features of modularity, electrical isolation, soft-switching, low voltage stress on switching devices, and is thus considered to be an improved topology over traditional dc–dc converters. New control strategies including the two-section output voltage control and cell idle control are also developed to improve the converter performance. With the cell idle control, the secondary winding inductance of the idle module is bypassed to decrease its power loss. A 400-W dc–dc converter is prototyped and tested to verify the proposed techniques, in addition to a simulation study. The step-up conversion ratio can reach 1:14 with a peak efficiency of 94% and the proposed techniques can be applied to a wide range of high voltage and high power distributed generation and dc power transmission.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Analysis on Load-Adaptive Phase-Shift Control for High Efficiency
           Full-Bridge LLC Resonant Converter Under Light-Load
           Conditions
    • Authors: Kim; J.;Kim, C.;Kim, J.;Lee, J.;Moon, G.;
      Pages: 4942 - 4955
      Abstract: Recently, the full-bridge (FB) LLC resonant converter is getting more attention due to its zero-voltage switching of the primary switches, zero-current switching of rectifier diodes, and high power capability. However, the conversion efficiency is degraded under light-load conditions due to the core loss in magnetic components and the switching loss in semiconductor devices. In this paper, a new control method is proposed for the FB LLC resonant converter. In the proposed method, the frequency control is basically used to regulate the output voltage over entire load conditions. Moreover, the proposed method utilizes phase-shifted gate signals between switch legs, based on predetermined optimal duty ratio under light-load conditions. At this point, the optimal duty ratio is determined to get minimum power loss under each light-load condition through the loss analysis of all components. Therefore, the proposed method makes high efficiency under light-load conditions. To confirm the validity of this paper, the prototype of the network power supply with 320–385 V dc input and 48 V/720 W dc output is tested.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • On Automatic Resonant Frequency Tracking in LLC Series
           
    • Authors: Li; H.;Jiang, Z.;
      Pages: 4956 - 4962
      Abstract: In order to achieve higher efficiency for the unregulated LLC series resonant converter, the switching frequency must be equal to the resonant frequency. However, since the converter works in open-loop condition, the switching frequency usually deviates from the resonant frequency in real converter. This paper proposed a new control method to track the resonant frequency of the unregulated LLC series resonant converter. Theoretically, the time of zero diode current in secondary is zero when the working frequency is equal or greater than the resonance frequency, and it is changed as the frequency varies when the working frequency is less than the resonance frequency. The proposed control algorithm is based on the time measurement of zero diode current to realize the resonance frequency tracking. A closed-loop digital controller is designed to realize the proposed tracking approach. The simulation and experiments are conducted to verify the proposed tracking approach. The simulation and experimental results show that (1) the switching frequency can be well controlled to track the resonant frequency, and (2) the tracking accuracy can be at least 96%.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Asymmetrical Duty Cycle-Controlled LLC Resonant Converter
           With Equivalent Switching Frequency Doubler
    • Authors: Zong; S.;Luo, H.;Li, W.;Deng, Y.;He, X.;
      Pages: 4963 - 4973
      Abstract: In the conventional full-bridge LLC converter, the duty cycle is kept as 0.5 and the phase-shift angle of the half-bridge modules is 0° to be a symmetrical operation, which makes the resonant tank operating frequency only equal to the switching frequency of the power devices. By regulating the duty cycles of the upper and lower switches in each half-bridge module to be 0.75 and 0.25 and the phase-shift angle of the half-bridge modules to be 180°, the asymmetrical duty cycle controlled full-bridge LLC resonant converter is derived. The proposed asymmetrical duty cycle controlled scheme halves the switching frequency of the primary switches. As a result, the driving losses are effectively reduced. Compared with the conventional full-bridge LLC converter, the soft-switching condition of the derived asymmetrical controlled LLC converter becomes easier to reduce the resonant current. Consequently, the conduction losses are decreased and the conversion efficiency is improved. The asymmetrical control scheme can be also extended to the stacked structure for high input voltage applications. Finally, two LLC converter prototypes both with 200-kHz resonant frequency for asymmetrical and symmetrical control schemes are built and compared to validate the effectiveness of the proposed control strategy.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • A Novel High Step-Up Dual Switches Converter With Coupled Inductor and
           Voltage Multiplier Cell for a Renewable Energy System
    • Authors: Liu; H.;Li, F.;Ai, J.;
      Pages: 4974 - 4983
      Abstract: A novel high step-up converter, which is suitable for a renewable energy system, is proposed in this paper. The proposed converter is composed of the dual switches structure, three-winding coupled inductor, and two voltage multiplier cells in order to achieve the high step-up voltage gain. The dual switches structure is beneficial to reduce the voltage stress and current stress of the switch. In addition, two multiplier capacitors are, respectively, charged during the switch-on period and switch-off period, which increases the voltage conversion gain. Meanwhile, the energy stored in the leakage inductor is recycled with the use of clamped capacitors. Thus, two main power switches with low on-resistance and low current stress are available. As the leakage inductor, diode reverse-recovery problem is also alleviated. Therefore, the efficiency is improved. This paper illustrates the operation principle of the proposed converter; discusses the effect of the leakage inductor; analyzes the influence of parasitic parameters on the voltage gain and efficiency, the voltage stresses and current stresses of power devices are shown; and a comparison between the performance of the proposed converter and the previous high step-up converters is performed. Finally, the prototype circuit with input voltage 20 V, output voltage 200 V, and rated power 200 W is operated to verify its performance.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • A Fully Integrated Switched-Capacitor Regulator With Frequency Modulation
           Control in 28-nm FDSOI
    • Authors: Souvignet; T.;Allard, B.;Trochut, S.;
      Pages: 4984 - 4994
      Abstract: The fully integrated switched capacitor voltage regulator comprises power cells distributed as a ring around the digital area to supply while the MIM capacitors are stacked above. Multiratio cells provide a wide output voltage range from 0.2 to 1.1;{\rm V} with an input voltage of 1.8;{\rm V} . A frequency modulation control loop is designed with proportional-integral control. Sampled-data modeling is used to derive the necessary transfer functions to build the control loop. A primarily test chip is fabricated in 28-nm FDSOI technology to evaluate the design. A power density of 310;{text{mW/}}{text{mm}^2} is achieved at 72.5% peak efficiency with a silicon area overhead of 11.5% .
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • A Passive Flyback Auxiliary Circuit With Integrated Transformer Suitable
           for Three-Phase Isolated Full-Bridge Boost PFC Converter
    • Authors: Meng; T.;Ben, H.;Wang, X.;
      Pages: 4995 - 5003
      Abstract: A passive flyback auxiliary circuit with integrated transformer is proposed and investigated in a three-phase isolated full-bridge boost power factor correction (PFC) converter, by which the voltage across primary side of the power transformer can be clamped to a fixed value and the absorbed energy can be transferred to the load by itself automatically. The auxiliary circuit is composed of two capacitors, four diodes, and one flyback integrated transformer. With the help of the flyback integrated transformer, synchronous resonances in the auxiliary circuit can be achieved, which will avoid the unbalance of the voltage and current in the auxiliary circuit. Compared with the passive snubbers, voltage spike of the three-phase PFC converter is suppressed more effectively with the adoption of the auxiliary circuit, and current stress of the switches is much lower. The operational principle of the auxiliary circuit is discussed in the three-phase isolated full-bridge boost PFC converter. Furthermore, the design considerations of the auxiliary circuit are analyzed. Finally, experimental study of the auxiliary circuit has been done on a laboratory-made three-phase PFC prototype, and the feasibility of the proposed method and the validity of the theoretical analysis are verified by the experimental results.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Analysis and Verification of Inductor Coupling Effect in Interleaved
           Multiphase dc–dc Converters
    • Authors: Huang; W.;Lehman, B.;
      Pages: 5004 - 5017
      Abstract: Interleaved multiphase synchronous buck converters are often used to power computer CPU, GPU, and memory to meet the demands for increasing load current and fast current slew rate of the processors. This paper reports and explains undesired coupling between discrete inductors in typical commercial multiphase applications where space is limited. In this paper, equations of coupling coefficient are derived for single-turn and multiturn Ferrite core inductors commonly used in multiphase converters and are verified by Maxwell static simulation. The influence of the coupling effect on inductor current waveforms is demonstrated by Maxwell transient simulation and confirmed by experiments. The analysis provides a useful tool for mitigating the coupling effect in multiphase converters to avoid early inductor saturation and interference between phases. Design guidelines and recommendations are provided to minimize the unwanted coupling effect in multiphase converters.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Wireless Power Transfer With Concurrent 200-kHz and 6.78-MHz Operation in
           a Single-Transmitter Device
    • Authors: Ahn; D.;Mercier, P.P.;
      Pages: 5018 - 5029
      Abstract: This paper proposes a wireless power transfer (WPT) transmitter that can concurrently operate at 200 kHz and 6.78 MHz in order to simultaneously power two receivers operating with different frequency standards. Unlike a dual-resonant single-coil design, the use of two separate coils decouples the design for one frequency from the other, enabling independent selection of inductance and Q-factor to simultaneously maximize efficiency at both frequencies. The two coils then support separate coil drivers, enabling concurrent multistandard operation. Dual-band operation is achieved in the same area as an equivalent single-band design by placing a low-frequency coil within the geometry of a high-frequency coil, where the outer diameter of inner coil is sacrificed only by 1.2 cm in a 12.5 × 8.9-cm2 design. Circuit analysis is presented to identify the eddy current between the two Tx coils and its associated loss, after which an eddy-current filter design is proposed. To validate the proposed design, a dual-mode transmitter, along with two receivers designed at 6.78 MHz and 200 kHz, respectively, have been fabricated. At 25-mm separation, the system is able to simultaneously deliver 9 and 7.4 W with efficiencies of 78% and 70.6% at 6.78 MHz and 200 kHz, respectively.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • A Novel High Step-up Converter With a Quasi-active Switched-Inductor
           Structure for Renewable Energy Systems
    • Authors: Liu; H.;Li, F.;
      Pages: 5030 - 5039
      Abstract: A novel high step-up dc–dc converter with a quasi-active switched-inductor structure for a renewable energy system is presented in this paper. The proposed converter is composed of two coupled inductors which can be integrated into one magnetic core, two capacitors, two active switches, and three diodes. The primary sides of coupled inductors are charged in parallel by the input source, and the secondary sides of coupled inductors are discharged in series with the input source and two capacitors to achieve high step-up voltage gain with an appropriate duty ratio. The two sets of diode–capacitor circuits not only help to lift the voltage conversion gain but also alleviate voltage spike affected by the leakage inductance to limit the voltage stress across the power switch effectively. Therefore, the two low on-state resistance switches can be adopted to reduce conduction loss. Furthermore, the two diodes have no reverse-recovery problem due to turn off naturally, the reverse-recovery problem of the output diode is also alleviated by the leakage inductor and lower part count is needed; therefore, the power conversion efficiency can be further improved. The operating principles and steady-state analyses are discussed in detail; then, the performance of the proposed converter is compared with existing converters. Finally, a prototype is established in the laboratory, and the experimental results are given to verify the correctness of the analysis.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Impedance Control Network Resonant DC–DC Converter for Wide-Range
           High-Efficiency Operation
    • Authors: Lu; J.;Perreault, D.J.;Otten, D.M.;Afridi, K.K.;
      Pages: 5040 - 5056
      Abstract: This paper introduces a new resonant converter architecture that utilizes multiple inverters and a lossless impedance control network (ICN) to maintain zero-voltage switching and near zero-current switching across wide operating ranges. Hence, the ICN converter is able to operate at fixed frequency and maintain high efficiency across wide ranges in input and output voltages and output power. The ICN converter architecture enables increase in switching frequency (hence reducing size and mass), while achieving very high efficiency. Three prototype 200-W 500-kHz ICN resonant converters, one with low-Q, one with medium-Q, and one with high-Q resonant tanks, designed to operate over an input voltage range of 25 to 40 V and an output voltage range of 250 to 400 V are built and tested. The low-Q prototype ICN converter achieves a peak efficiency of 97.1%, maintains greater than 96.4% full power efficiency at 250 V output voltage across the nearly 2:1 input voltage range, and maintains full power efficiency above 95% across its full input and output voltage range. It also maintains efficiency above 94.6% over a 10:1 output power range across its full input and output voltage range owing to the use of burst-mode control.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Critical Design Criterion for Achieving Zero Voltage Switching in
           Inductorless Half-Bridge-Driven Piezoelectric-Transformer-Based Power
           Supplies
    • Authors: Foster; M.P.;Davidson, J.N.;Horsley, E.L.;Stone, D.A.;
      Pages: 5057 - 5066
      Abstract: A methodology for predicting the ability of inductorless-driven piezoelectric transformer (PT)-based power supplies to achieve zero voltage switching (ZVS) is presented. A describing function approach is used to derive an equivalent circuit model of the PT operating in the vicinity of ZVS and the subsequent application of the model provides a quantitative measure of a PT's ability to achieve ZVS when driven by an inductorless half-bridge inverter. Through detailed analysis of the analytical model, the limitations of the inductorless half-bridge-driven PT are exposed from which guidelines for designing both the PT and inverter are derived.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • A Novel Soft-Switching Battery Charge/Discharge Converter With the Zero
           Voltage Discharge Function
    • Authors: Yu; S.;Nguyen, M.Q.;Choi, W.;
      Pages: 5067 - 5078
      Abstract: One important test for the formation and grading of a lithium-ion battery is to confirm the performance of the battery while discharging it down to zero volts. In this paper, a novel soft-switching charge/discharge converter with the zero voltage discharge function is proposed. The proposed converter is able to discharge a battery until its voltage reaches zero volts. The phase-shift full-bridge method is used to charge the battery and the current-fed push–pull method with bidirectional switches is used for the discharge. Zero voltage switching (ZVS) of the switches is achieved at turn-on during the charge operation. ZVS turn-on and zero current switching turn-off of the switches are achieved during the discharge operation. The charge/discharge controllers are designed taking into account the internal impedance of the battery. The performance of the system is verified by the experiments using lithium-ion batteries.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Analysis on the Ring-Type Piezoelectric Ceramic Transformer in Radial
           Vibration
    • Authors: Lin; S.;Xu, J.;Cao, H.;
      Pages: 5079 - 5088
      Abstract: A new type of ring-type piezoelectric ceramic transformer in radial vibration is studied. It is composed of two concentric piezoelectric ceramic thin rings polarized axially and radially. Based on the electromechanical equivalent circuit, when the dielectric loss of the piezoelectric ceramic materials and the mechanical contacting loss between the input and the output piezoelectric rings are taken into account, the electromechanical characteristics of the piezoelectric transformer are studied. The dependence of the voltage gain, the power gain, or the efficiency (the ratio of the output power over the input power) and the effective electromechanical coupling coefficient on the geometrical dimensions are analyzed. Meanwhile, the load dependence of the electromechanical parameters of the transformer is also investigated. Some prototypes of the piezoelectric transformers are designed and made. The resonance/antiresonance frequency and the voltage gain are measured. It is shown that the measured electromechanical parameters are in good agreement with the theoretical results. The conclusions can be used for the optimization design of the ring-type piezoelectric ceramic transformers in the engineering applications.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Analysis and Optimization of the Efficiency of Induction Heating
           Applications With Litz-Wire Planar and Solenoidal Coils
    • Authors: Lope; I.;Acero, J.;Carretero, C.;
      Pages: 5089 - 5101
      Abstract: Optimization of the efficiency of an induction heating application is essential in order to improve both reliability and performance. For this purpose, multistranded cables with litz structure are often used in induction heating applications. This paper presents an analysis and optimization of the efficiency of induction heating systems focusing on the optimal copper volume of the winding with respect to different constraints. The analysis is based on the concept of a one-strand one-turn coil, which captures the dissipative effects of an induction heating system and reduces the number of variables of the analysis. An expression for the efficiency of the induction heating system is derived. It is found that, with the geometry and the other parameters of the system fixed, efficiency depends on the copper volume of the windings. In order to use this result to optimize the efficiency of an application, volume restrictions, the packing factor and the window utilization factor are also considered. The optimum frequency for an induction heating system is also studied in this study. An experimental verification for both planar and solenoidal cases is also presented.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Design of Electronic Ballast for Short-Arc Xenon Lamp With Interleaved
           Half-Wave Rectifier
    • Authors: Chan; S.;Yang, T.;Chang, Y.;
      Pages: 5102 - 5112
      Abstract: This paper presents an interleaved half-wave rectifier circuit, which constitutes an electronic ballast with high open-voltage gain and current doubler. It is suitable for applications in short-arc xenon lamp needing high open-circuit voltage and low operating voltage. By integrating interleaved half-wave rectifier with LCC resonant circuit, the electronic ballast can provide a low arc-sustaining current dc power source with low ripple and dimmable capability along with starting current suppression feature. Finally, a 25-A 500-W short-arc xenon lamp electronic ballast is developed to possess full load efficiency as high as 91.32% along with dimming range falling between 7.6% and 100% and peak starting current being as low as 16 A.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Design and Layout Strategy in the 60-V Power pLDMOS With Drain-End
           Modulated Engineering of Reliability Considerations
    • Authors: Chen; S.;Huang, Y.;
      Pages: 5113 - 5121
      Abstract: This study reports the impacts of various drain end layouts on the reliability and electrical performance of 60-V p-channel laterally diffused metal–oxide-semiconductor (pLDMOS) FETs. For effectively improving the reliability, drain-end “N-P-N” and “P-N-P” permutated pLDMOSs embedded with silicon-controlled rectifiers (pLDMOS–SCRs) with discrete regulated structures in the drain strap were manufactured using a 0.25-μm BCD process. According to transmission-line pulse data, the I_{t2} value is very low (only 0.644 A) for a pure pLDMOS transistor. However, embedding an SCR in the drain end results in a decrease in V_{t1} , V_{h} , and V_{\rm BK} and increase in I_{t2} values (>7 A), even for N-P-N and P-N-P drain-end arranged types. In addition, the I_{t2} capability of the nonbutted-contact pLDMOS–SCR devices is satisfactory. By contrast, N-P-N and P-N-P stripe-type devices with the highest N+/P+ area ratio have less favorable electrical properties and lower anti-latchup (LU) immunity compared with a pure pLDMOS. In addition, the V_{h} (and V_{\rm BK} ) improvement of the P-N-P stripe type is more than 278% (and 23.7%) compared with the N-P-N stripe type. Therefore, pLDMOS–SCRs with a P-N-P stripe-type structure are a potential candidate for enhancing electrostatic discharge, LU immunities and electrical performance.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Junction Temperature Extraction Approach With Turn-Off Delay Time for
           High-Voltage High-Power IGBT Modules
    • Authors: Luo; H.;Chen, Y.;Sun, P.;Li, W.;He, X.;
      Pages: 5122 - 5132
      Abstract: Thermo-sensitive electrical parameter (TSEP) approaches are widely employed in the junction temperature extraction and prediction of power semiconductor devices. In this paper, the turn-off delay time is explored as an indicator of a TSEP to extract the junction temperature from high-power insulated gate bipolar transistor (IGBT) modules. The parasitic inductor L_{\rm eE} between the Kelvin and power emitter terminals of an IGBT module is utilized to extract the turn-off delay time. Furthermore, the monotonic dependence between the junction temperature and turn-off delay time is investigated. The beginning and end point of the turn-off delay time can be determined by monitoring the induced voltage v_{\rm eE} across the inductor L_{\rm eE} . A dynamic switching characteristic test platform for high-power IGBT modules is used to experimentally verify the theoretical analysis. The experimental results show that the dependency between IGBT junction temperature and turn-off delay time is near linear. It is established that the turn-off delay time is a viable TSEP with good linearity, fixed sensitivity, and offers nondestruction on-line IGBT junction temperature extraction.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Design of a Double-Gate Power LDMOS With Improved SOA by Complementary
           Majority Carrier Conduction Paths
    • Authors: Du; W.;Chen, X.;
      Pages: 5133 - 5140
      Abstract: An bm{n} -type power LDMOS with an integrated bm{p} -MOS is proposed to improve the safe operation area. The proposed structure has three external terminals and majority carriers of both types are used for conduction under high-voltage and high-current condition. The bm{p} -MOS is implemented outside of the voltage-sustaining region of the bm{n} -MOS. Under high-voltage and high-current condition, the gate of the bm{p} -MOS is turned ON by a self-generated negative gate-to-source voltage. Majority hole current from bm{p} -MOS is introduced into the bm{p} -top region. It alters the electric field profile in the voltage-sustaining region and reduces impact ionization. As a result, the output I–V curves become flatter and the saturation current is more than twice of that of a conventional bm{n} -MOS with the same breakdown voltage at V_{{\rm GS}} \geq 8 {\rm V} .
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Estimation Method of Stator Winding Temperature for Dual Three-Phase
           Machines Based on DC-Signal Injection
    • Authors: Baneira; F.;Yepes, A.G.;Lopez, O.;Doval-Gandoy, J.;
      Pages: 5141 - 5148
      Abstract: Dual three-phase machines are becoming increasingly popular due to advantages such as inherent fault tolerant capability and lower current per phase for a given power. As in three-phase machines, it is important to provide thermal protection, in order to prevent reduction of the lifetime. Proposals specifically targeted to dual three-phase machines for estimating the stator winding temperature, and thus, avoiding the installation of thermal sensors, have not been reported so far. Concerning three-phase machines, previous publications have proposed techniques based on injecting a dc signal for estimating the stator winding temperature. However, a certain torque ripple is caused during the injection period, giving rise to a tradeoff between the magnitude of such ripple and the accuracy of the temperature estimation. This paper presents a method based on dc-signal injection for stator winding temperature estimation in dual three-phase machines with sinusoidally distributed windings and driven by field-oriented control. By applying the signal to the x - y plane, which is available in this type of machines and does not produce air-gap flux, no torque ripple is generated. Experimental results validate the proposed technique.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • An Active Life Extension Strategy for Thermally Aged Power Switches Based
           on the Pulse-Width Adjustment Method in Interleaved Converters
    • Authors: Dusmez; S.;Akin, B.;
      Pages: 5149 - 5160
      Abstract: The research on noninvasive incipient fault diagnosis of power converters is very critical to avoid strenuous periodic checkups and costly interruptions. In many of the research studies, on-state resistance of power MOSFETs is identified as the fault precursor, and suggested to be monitored online for prognosis. In this paper, a condition monitoring algorithm is proposed for power MOSFETs of interleaved converters and integrated with the conventional current loops. The proposed technique utilizes on-state resistance information of the switches to adjust the current reference of each interleaving leg. In addition, a pulse-width adjustment method is proposed to avoid one current sensor and current-control loop. With the proposed scheme, the thermal stress on the aged device can be reduced, and the overall lifetime of the converter can be extended. The proposed approach is verified on two-leg interleaved converters both in simulation and experimentally.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Suppression of Real Power Back Flow of Nonregenerative Cascaded H-Bridge
           Inverters Operating Under Faulty Conditions
    • Authors: Sun; L.;Wu, Z.;Xiao, F.;Cai, X.;Wang, S.;
      Pages: 5161 - 5175
      Abstract: When the faulty cells of a nonregenerative cascaded H-bridge inverter are bypassed, it is necessary to inject a zero-sequence voltage into the inverter phase voltages so as to achieve the maximum balanced line-to-line voltage. However, the injected zero-sequence voltage may lead to a back flow of real power (BFRP) in at least one phase so that the dc voltage will rise to an intolerable level. To solve the problem, this paper proposes a new method of generating zero-sequence voltages. This method can not only maximize the available output voltage but also suppress the BFRP effectively. The zero-sequence voltage is always limited to an appropriate range to achieve the maximum output voltage through linear modulation. Closed-loop control is used to minimize the fundamental component of the zero-sequence voltage so that the power is less likely to flow back. Compared with the conventional methods, the proposed method allows the inverter to drive a load with a lower power factor not inducing BFRP or degrading the output voltage capability. As a result, the probability of overvoltage on the dc side is reduced. The experimental results show that the proposed method is effective and feasible.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Control Architecture for Parallel-Connected Inverters in Uninterruptible
           Power Systems
    • Authors: Zhang; C.;Guerrero, J.M.;Vasquez, J.C.;Coelho, E.A.A.;
      Pages: 5176 - 5188
      Abstract: In this paper, a control strategy for the parallel operation of three-phase inverters forming an online uninterruptible power system (UPS) is presented. The UPS system consists of a cluster of paralleled inverters with LC filters directly connected to an ac critical bus and an ac/dc forming a dc bus. The proposed control scheme comprises two layers: 1) a local layer that contains a “reactive power-to-phase droop” in order to synchronize the phase angle of each inverter and a virtual resistance loop that guarantees equal power sharing among inverters; and 2) a central controller that guarantees synchronization with an external real/fictitious utility, and critical bus voltage amplitude restoration. Improved transient and steady-state frequency, active, reactive, and harmonic power sharing, and global phase-locked loop resynchronization capability are achieved. Detailed system topology and control architecture are presented in this paper. Furthermore, a mathematical model was derived in order to analyze critical parameters effects on system stability. The proposed control approach has been validated by means of experimental results obtained for several case-study scenarios.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Finite Control Set Model Predictive Current Control for Grid-Connected
           Voltage-Source Converters With LCL Filters: A Study Based
           on Different State Feedbacks
    • Authors: Panten; N.;Hoffmann, N.;Fuchs, F.W.;
      Pages: 5189 - 5200
      Abstract: This paper presents different state feedback approaches of finite control set model predictive control (FCS-MPC) applied to a grid-connected voltage-source converter (VSC) with an LCL filter. Besides converter-side current feedback, two multivariable control approaches and line-side current control are introduced and compared based on theoretical and experimental evaluation. As the LCL filter introduces an additional resonance frequency to the system, the use of different active damping (AD) methods in combination with FCS-MPC is discussed. Furthermore, practical control implementation issues are discussed. The presented methods reveal the great potential, high dynamic performance, and flexibility of FCS-MPC, enabling multivariable control as well as both reduced switching losses and low harmonic current distortion at the same time. Eventually, the feasibility of the theoretical control concepts is shown in a laboratory environment.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • An Improved Control Technique of Switching-Frequency-Modulated Power
           Factor Correctors for Low THD and High Power Factor
    • Authors: Stepins; D.;
      Pages: 5201 - 5214
      Abstract: This paper deals with switching-frequency modulation (SFM) for conducted electromagnetic interference (EMI) suppression in active power factor correctors (PFCs) operating in discontinuous conduction mode (DCM). The effect of SFM on different performance characteristics of DCM PFC is studied in details. It is shown that the use of SFM in PFC with conventional control approach leads to significant increase in total harmonic distortion (THD) and harmonic content of input current. Moreover, SFM leads to noticeable increase in peak power components currents. In order to use SFM for EMI reduction more effectively without significantly worsening THD, power factor, and harmonic content of DCM PFC, an improved control technique and a control circuit are proposed and verified by simulations and experimentally. The technique is based on the use of specific time delay injection to power MOSFET control signal. As show simulations and experiments, SFM PFC with the proposed delay technique in comparison to PFC without SFM has noticeably lower conducted EMI and THD of input current, at the cost of slightly decreased efficiency and moderately increased peak currents.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Basic Control Principles of Omnidirectional Wireless Power Transfer
    • Authors: Zhang; C.;Lin, D.;Hui, S.Y.;
      Pages: 5215 - 5227
      Abstract: This paper presents the basic control principles of omnidirectional wireless power transfer (WPT) based on the current amplitude control. The principles involve 1) an “omnidirectional” scanning process for detecting the power requirements in a 3-D space and 2) a “directional” power flow control for focusing the wireless power toward the targeted areas. Such principles apply to any WPT system comprising three orthogonal transmitter coils and multiple receivers with coil resonators. A current amplitude control method capable of generating a magnetic vector at a set of points evenly distributed on a spherical surface is explained. Based on the voltage and the current information in the transmitter circuit, the power involved in each vector over the spherical surface can be obtained. By scanning the vector over the spherical surface, the collective power flow requirements for the targeted loads can be determined. Based on the power requirements for the vectors over the spherical surface, a weighted time-sharing scheme is adopted to focus the wireless power toward the targeted areas. This method has been successfully applied to a hardware prototype. Both theoretical and experimental results are included to confirm these principles.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Control Strategies of Three-Phase Distributed Generation Inverters for
           Grid Unbalanced Voltage Compensation
    • Authors: Nejabatkhah; F.;Li, Y.W.;Wu, B.;
      Pages: 5228 - 5241
      Abstract: The high penetration level of power electronics interfaced distributed generation (DG) systems creates great ancillary services potential through the DG interfacing converters, such as the grid unbalanced voltage compensation. However, the unbalanced voltage compensation may cause adverse effects on the DGs' operation, such as output active power oscillation and dc-link voltage variations. Moreover, since the compensation is realized through the available rating of DGs' interfacing converters, it is equally important to consider the effectiveness of control strategy for unbalanced voltage compensation. Considering these challenging issues, two grid unbalanced voltage compensation strategies for three-phase power electronics interfaced DG systems are proposed in this paper. Especially, the first control strategy aims at minimizing the DG's active power oscillation and reducing the adverse effects of unbalanced voltage compensation on DG's operation. The second control strategy focuses on the effectiveness of unbalanced voltage compensation by controlling DG's negative sequence current to be inphase with the grid negative sequence current. Performances of the two proposed control strategies under different grid conditions and DG operating conditions are studied, and recommendations for appropriate control strategy utilization under various conditions are provided. Finally, validity of the proposed strategies is verified by both simulations and experimental results.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Squirrel-Cage Induction Generator System Using Wavelet Petri Fuzzy Neural
           Network Control for Wind Power Applications
    • Authors: Tan; K.;
      Pages: 5242 - 5254
      Abstract: A wavelet Petri fuzzy neural network (WPFNN) controller is proposed to control squirrel-cage induction generator (SCIG) system with an ac/dc power converter and a dc/ac power inverter for grid-connected wind power applications. First, the ac/dc power converter and the dc/ac power inverter are developed to deliver the electric power generated by a three-phase SCIG to power grid. Moreover, the ac/dc power converter and the dc/ac power inverter are mainly designed to control the mechanical rotor speed, dc-link voltage, and reactive power output of the SCIG system, respectively. Furthermore, since the varying active power outputs of the dc/ac power inverter seriously affect the tracking control of the dc-link voltage, a novel intelligent WPFNN controller is proposed to replace the traditional proportional-integral controller for the tracking control of the dc-link voltage in this study. In addition, the network structure and the online learning algorithm of the proposed WPFNN are described in detail. Finally, some experimental results are provided to show the effectiveness of the intelligent controlled-SCIG system using the proposed WPFNN controller for grid-connected wind power applications.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Stability Analysis of Vector-Controlled Modular Multilevel Converters in
           Linear Time-Periodic Framework
    • Authors: Chaudhuri; N.R.;Oliveira, R.;Yazdani, A.;
      Pages: 5255 - 5269
      Abstract: Stability analysis of average value models (AVMs) of vector-controlled modular multilevel converters (MMCs) is the subject matter of this paper. Stability analysis of fundamental frequency phasor-based AVMs of MMCs can be conducted in a traditional linear time-invariant framework through eigenvalue computation. This class of models does not consider circulating current control loop and hence fails to capture system instability that occurs in a certain range of gains of the circulating current controller. We propose stability analysis in a linear time-periodic (LTP) framework to solve this issue. To that end, a nonlinear AVM is presented that considers the submodule capacitor insertion dynamics and takes into account the output and the circulating current control schemes in the vector control approach. Upon linearization, an LTP model is derived from this averaged model. It is shown that the Poincar \acute {e} multipliers are indicative of system instability corresponding to a certain range of gains of the circulating current controller.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Development of Wireless In-Wheel Motor Using Magnetic Resonance Coupling
    • Authors: Sato; M.;Yamamoto, G.;Gunji, D.;Imura, T.;Fujimoto, H.;
      Pages: 5270 - 5278
      Abstract: In-wheel motors (IWMs) in electric vehicles are particularly important for motion control. A conventional IWM is powered from a battery aboard the vehicle via cables. Since power cables and signal cables of an IWM are exposed to harsh environments, they can possibly become disconnected by high acceleration or vibration. In order to overcome this problem, the wireless-in wheel motor (W-IWM) has been proposed. The risk of disconnection would disappear if the cables of the IWM are removed. One way to implement wireless power transfer is by utilizing the magnetic resonance coupling method. However, motion of the W-IWM, and thus, a misalignment between the wheel and the vehicle, leads to variations in the secondary-side voltage provided. To account for this, this paper discusses two new control methods. One proposed method maintains the secondary voltage using a hysteresis comparator. The other proposed method estimates the secondary inverter output power, applying it to a feedforward controller in order to keep the secondary dc-link voltage constant. Experimental results show that these methods can drive a W-IWM effectively with high efficiency.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • A Simple Model Predictive Power Control Strategy for Single-Phase PWM
           Converters With Modulation Function Optimization
    • Authors: Song; W.;Deng, Z.;Wang, S.;Feng, X.;
      Pages: 5279 - 5289
      Abstract: This paper proposes a simple model predictive direct power control (MP-DPC) of single-phase pulsewidth-modulated rectifiers with constant switching frequency using modulation function optimization. The instantaneous active and reactive power theory for single-phase converters is discussed, on the basis of a second-order generalized integrator. The modulation function is resolved from the cost function of the MP-DPC scheme. The relationship between the instantaneous powers and ac-side inductance mismatch is discussed. The inductance mismatch has an effect on the reactive power, but not effect on active power. The quantitative expression of reactive power caused by inductance mismatch is shown and verified in the experimental test. An inductance parameter online estimation scheme is proposed to eliminate its effect on reactive power. Compared with the conventional proportional-integral-based instantaneous current control scheme and finite-control-set MP-DPC scheme, the proposed MP-DPC can provide these advantageous features: lower current harmonics and total harmonic distortion components, faster dynamic response, fewer adjusted parameters, and zero steady-state error. In addition, the proposed MP-DPC is free of the weighting factor selection in cost function. The effectiveness of the proposed MP-DPC scheme is verified by experimental results.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Digital Current Control in a Rotating Reference Frame–-Part I:
           System Modeling and the Discrete Time-Domain Current Controller With
           Improved Decoupling Capabilities
    • Authors: Hoffmann; N.;Fuchs, F.W.;Kazmierkowski, M.P.;Schroder, D.;
      Pages: 5290 - 5305
      Abstract: Digital current control of three-phase voltage-source power electronic converters is analyzed. Special attention is paid to the exact discrete time-domain modeling of inductive-resistive current dynamics in the rotating reference frame whereas three different regular sampling strategies are incorporated to the analysis. The exact system model motivates the development of a new current control structure in the rotating reference frame that is based on discrete time-domain analysis. Ideally, the new discrete time-domain current controller leads to a full compensation of all cross-coupling effects that appear in the controlled system. The experimental results (performed on a 22 kW test-bench) reveal that even under test conditions an excellent decoupling capability of the presented controllers is achieved.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Output Impedance Modeling and Stability Prediction of Three-Phase
           Paralleled Inverters With Master–Slave Sharing Scheme Based on
           Terminal Characteristics of Individual Inverters
    • Authors: Liu; Z.;Liu, J.;Hou, X.;Dou, Q.;Xue, D.;Liu, T.;
      Pages: 5306 - 5320
      Abstract: Paralleled inverters are widely employed as the power source in the AC distributed power system, whose output impedance and stability status are required in the impedance-based stability analysis of the whole system. This paper presents an output impedance model as well as a stability prediction method for three-phase paralleled inverters with master–slave sharing scheme. While the output impedance of three-phase paralleled inverters is generally modeled under synchronous reference frame (SRF), the terminal characteristics of individual inverters operating standalone are innovatively adopted in the proposed output impedance model, with no need for knowledge about inner parameters of the inverters. Furthermore, the stability criterion is derived with this model according to the generalized Nyquist criterion, where the stability of paralleled inverters can be predicted by investigating characteristic loci of two return ratios. Meanwhile, the terminal characteristics of individual inverters controlled under SRF is comprehensively modeled. Finally, the proposed output impedance model and stability criterion were experimentally verified.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • A Simple and Cost-effective Precharge Method for Modular Multilevel
           Converters by Using a Low-Voltage DC Source
    • Authors: Tian; K.;Wu, B.;Du, S.;Xu, D.D.;Cheng, Z.;Zargari, N.R.;
      Pages: 5321 - 5329
      Abstract: A simple and cost-effective precharge method for modular multilevel converter (MMC) by using a low-voltage direct current (dc) source is proposed in this paper. The submodule (SM) capacitors in MMC are required to be precharged to their nominal voltage values at start-up to ensure MMC work normally. Conventional methods perform the precharging either through grid side or dc side by using costly high-voltage bypass breakers, charging resistors or a high-voltage dc source. Voltage of the high-voltage dc source must be equal to SM capacitor voltage and could be as high as thousands of volts. By contrast, the proposed method employs a very low voltage dc source on dc bus through a series-connected blocking diode, and requires no charging resistor and bypass breakers. It takes advantages of the existing power devices, arm inductors, and SM capacitors in MMC, and configures them into boost circuit for the precharging. The proposed method is simple and cost-effective. Moreover, the characteristics of the boost circuit render the proposed method flexible. For instance, the voltage selection of the dc source is flexible and not restricted to a fixed value. The SM capacitors can be charged in different groups. In addition, the method is applicable to different MMC SMs, including SM with different capacitor voltages. The effectiveness of the proposed method is verified through simulation and experiment.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Adaptive Ramp Technique for Controlling Chaos and Subharmonic Oscillations
           in DC–DC Power Converters
    • Authors: Morcillo; J.D.;Burbano, D.;Angulo, F.;
      Pages: 5330 - 5343
      Abstract: We propose an adaptive ramp control strategy with self-tuning offset and amplitude, as a simple yet effective solution for controlling dc–dc power converters despite load and input voltage variations. It is shown that our control technique is able to suppress chaos and subharmonic oscillations for a wide range of input voltage and loads. Furthermore, a systematic methodology based on bifurcation diagrams for tuning the controller is proposed. Stability and performance analysis have been done together with a proper comparison of our technique, and the classical control strategies often used in the literature. Particularly, V_{text{\rm \in}} feed-forward and adaptive slope compensation controllers have been considered for the buck and boost converters, respectively. Finally, the effectiveness of the control technique is validated for the buck converter via experimental setup.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Small Signal Analysis of V2 Control Using Equivalent Circuit
           Model of Current Mode Controls
    • Authors: Yan; Y.;Lee, F.C.;Mattavelli, P.;Tian, S.;
      Pages: 5344 - 5353
      Abstract: In V^{2} control, the direct feedback contains the information of the inductor current, the capacitor voltage, and the load current. In this paper, by separating the current feedbacks and the capacitor voltage feedback, an equivalent circuit of V^{2} control with ESR dominant output capacitor is proposed. The proposed equivalent circuit is based on the unified equivalent circuit of current mode controls. It is a completed frequency domain model for V^{2} control with a clear physical insight. V^{2} control can be interpreted as an advanced implementation of current mode control with a proportional voltage feedback and an additional load current feedback. The load current feedback dramatically reduces the output impedance of a current mode controlled converter. The model is extended to the enhanced V^{2} control. The proposed model is applicable to both variable frequency modulations and constant frequency modulations. The modeling results are verified by the Simplis simulation and the experimental results.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
  • Control of Single-Phase Grid-Connected Converters With
           LCL Filters Using Recurrent Neural Network and
           Conventional Control Methods
    • Authors: Fu; X.;Li, S.;
      Pages: 5354 - 5364
      Abstract: Single-phase grid-connected inverters are widely used to connect small-scale distributed renewable resources to the grid. However, unlike a three-phase system, control for a single-phase inverter is more challenging, especially when the inverter is used with an LCL filter. This paper proposes a novel recurrent neural network-based vector control method for a single-phase inverter with an LCL filter. The neural network is trained based on adaptive dynamic programming principle, and the objective of the training is to approximate optimal control. The Levenberg–Marquardt plus forward accumulation through time algorithm is developed for training the proposed recurrent neural network controller. The neural network vector control approach is compared with the conventional control methods, including the conventional PI-based vector control method and the PR-based control technique for single-phase inverters. Both the simulations and hardware experiments demonstrate the great advantages of the proposed neural network vector control over the conventional control methods. Compared with conventional control methods, the neural network control allows for low sampling rate and low switching frequency, while maintaining high performance in controlling a single-phase inverter. In addition, no specific damping policy is required to implement the proposed neural network vector control for an LCL-filter based single-phase inverter. The study shows that the neural network vector control is a robust control method, and can provide better control performance even when facing system parameter changes, while under this case, both the conventional PI-based vector control and the PR-based control failed to yield the acceptable results.
      PubDate: July 2016
      Issue No: Vol. 31, No. 7 (2016)
       
 
 
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