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This paper presents the newly proposed hybrid resonant commutation bridge-leg link (HRCB) snubber circuit which can achieve zero voltage and zero current soft-switching commutation for single-phase and three-phase voltage source-type inverter, along with its unique features and operation principle. The circuit parameter design approach for the HRCB snubber circuit and the determination estimating scheme of the gate pulse timing processing which is more suitable and acceptable for single-phase and space voltage vector modulated three-phase voltage source inverter using the HRCB snubber circuit are described in this paper. In particular, the three-phase voltage source soft-switching inverter associated with the proposed HRCB circuits are evaluated and discussed from simulation and experimental viewpoints. The practical effectiveness of the HRCB snubber-assisted three-phase voltage source soft-switching inverter using IGBT power modules which is based on the instantaneous space voltage vector modulation is clarified on the output voltage waveform, actual efficiency of electromagnetic noise in comparison with three-phase voltage source-type conventional hard-switching inverter. [ABSTRACT FROM AUTHOR]

This paper proposes a new current balancer in single-phase three-wire secondary distribution systems using the correlation coefficients. The components of the load currents correlative to the primary side voltage waveform, which correspond to the active currents, are detected in each feeder, then the nonactive and unbalanced-active components are compensated on the source side. The balanced currents with unity power factor are obtained in each feeder. The basic principle of the proposed method is discussed in detail, and then confirmed by digital computer simulation. A prototype experimental system is constructed and tested. Experimental results demonstrate that the balanced source currents with unity power factor are obtained in spite of unbalanced load currents. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(1): 50–58, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20843 [ABSTRACT FROM AUTHOR]

This paper proposes a new topology for a current balancer with half-bridge inverters in single-phase three-wire distribution systems. Two half-bridge inverters are connected to the sources. The midpoint of the two capacitors on the DC-side is connected to a neutral line. The two half-bridge inverters function as a current balancer for single-phase three-wire distribution systems by exchanging the active and reactive power on each feeder through the two DC capacitors. The third leg functions as a DC-capacitor-voltage balancer for two DC capacitors connected to the half-bridge inverters. Thus, balanced source voltages and currents are obtained on the secondary side on the pole- mounted distribution transformer with balanced DC-capacitor voltages. The basic principle of the proposed current balancer is discussed in detail, and then confirmed by digital computer simulation using PSIM software. A prototype experimental model is constructed and tested. Experimental results show that balanced source voltages and currents are obtained on the secondary side on the pole-mounted distribution transformer with balanced DC-capacitor voltages. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(4): 38-46, 2012; Published online in Wiley Online Library (). DOI 10.1002/eej.22277 [ABSTRACT FROM AUTHOR]

This paper presents a single lossless inductive snubber-assisted ZCS-PFM series resonant DC-DC power converter with a high-frequency high-voltage transformer link for industrial-use high-power magnetron drive. The current flowing through the active power switches rises gradually at a turned-on transient state with the aid of a single lossless snubber inductor, and ZCS turn-on commutation based on overlapping current can be achieved via the wide range pulse frequency modulation control scheme. The high-frequency high-voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high-frequency high-voltage transformer and the magnetizing inductance of the high-frequency high-voltage transformer. As a result, this high-voltage power converter circuit for the magnetron can achieve a complete zero current soft switching under the condition of broad width gate voltage signals. Furthermore, this high-voltage DC-DC power converter circuit can regulate the output power from zero to full over audible frequency range via the two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 79–87, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20126 [ABSTRACT FROM AUTHOR]

A variety of switched-mode high-voltage DC power supplies using voltage-fed-type or current-fed-type high-frequency transformer resonant inverters with MOS gate bipolar power transistors (IGBTs) have been recently developed for medical-use X-ray high power generators. In general, the high-voltage high-power X-ray generator using voltage-fed high-frequency inverter with a high-voltage transformer link has to meet some performances such as (i) short rising period in start transient of X-ray tube voltage, (ii) no overshoot transient response in tube voltage, (iii) minimized voltage ripple in periodic steady-state under extremely wide load variations and filament heater current fluctuation conditions of the X-ray tube. This paper presents two lossless inductor snubber-assisted series resonant zero current soft switching high-frequency inverters using a diode-capacitor ladder-type voltage multiplier called Cockcroft-Walton circuit, which is effectively implemented for a high DC voltage X-ray power generator. This DC high-voltage generator which incorporates a pulse frequency modulated series resonant inverter using IGBT power module packages is based on the operation principle of zero current soft switching commutation scheme under discontinuous resonant current and continuous resonant current transition modes. This series capacitor compensated for transformer resonant power converter with a high-frequency transformer-linked voltage boost multiplier can efficiently work a novel selectively changed dual mode PFM control scheme in order to improve the start transient and steady-state response characteristics and can completely achieve stable zero current soft switching commutation tube filament current dependent on wide load parameter setting values with the aid of two lossless inductor snubbers. It is proved on the basis of simulation and experimental results in which a simple and low cost control implementation based on selectively changed dual-mode PFM for high-voltage X-ray DC-DC power converter with a voltage multiplier strategy has some specified voltage pattern tracking voltage response performances under rapid rising time and no overshoot in start transient tube voltage as well as the minimized steady-state voltage ripple in tube voltage. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(4): 60–72, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10345 [ABSTRACT FROM AUTHOR]