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SUMMARYThis paper proposes a new circuit topology of the three-phase soft-switching PWM inverter and PFC converter using IGBT power modules, which has the improved active auxiliary switch and edge resonant bridge leg-commutation-link soft-switching snubber circuit with pulse current regenerative feedback loop as compared with the typical auxiliary resonant pole snubber discussed previously. This three-phase soft-switching PWM double converter is more suitable and acceptable for a large-capacity uninterruptible power supply, PFC converter, utility-interactive bidirectional converter, and so forth. In this paper, the soft-switching operation and optimum circuit design of the novel type active auxiliary edge resonant bridge leg commutation link snubber treated here are described for highpower applications. Both the main active power switches and the auxiliary active power switches achieve soft switching under the principles of ZVS or ZCS in this three-phase inverter switching. This three-phase soft-switching commutation scheme can effectively minimize the switching surge-related electromagnetic noise and the switching power losses of the power semiconductor devices; IGBTs and modules used here. This three-phase inverter and rectifier coupled double converter system does not need any sensing circuit and its peripheral logic control circuits to detect the voltage or the current and does not require any unwanted chemical electrolytic capacitor to make the neutral point of the DC power supply voltage source. The performances of this power conditioner are proved on the basis of the experimental and simulation results. Because the power semiconductor switches (IGBT module packages) have a trade-off relation in the switching fall time and tail current interval characteristics as well as the conductive saturation voltage characteristics, this three-phase softswitching PWM double converter can improve actual efficiency in the output power ranges with a trench gate controlled MOS power semiconductor device which is Key words: new active auxiliary edge resonant bridge leg link snubber; improved ARCP snubber; threephase voltage-source inverter; sine-wave PWM control; double converter; zero-voltage soft switching; power conditioner.

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Axial structures of the Alfvén ion cyclotron (AIC) mode have been investigated in the GAMMA10 tandem mirror. The AIC mode is a microinstability driven by an anisotropy in the velocity space, and is excited as an axial eigenmode in the GAMMA10. There are several discrete peaks in the frequency range of ω/Ω ci∼0.8–0.9, where Ω ci is the ion cyclotron frequency at the midplane of the central cell. A driving term of the AIC mode is theoretically given by β⊥(T ⊥/T //)2. Here, β⊥ is a perpendicular beta value and T ⊥/T // is a temperature anisotropy (an ion temperature ratio between perpendicular and parallel to the magnetic field line). In GAMMA10, the AIC mode is observed in the range of β⊥(T ⊥/T //)2≥0.3 (which is much smaller than the theoretical prediction of β⊥(T ⊥/T //)2≥3.52). This is thought to be related to the wave structure in the axial direction. The frequency ω and axial wave number k // of each mode changed with β⊥ and T ⊥/T //. As β⊥ and T ⊥/T // increased, the AIC frequency range became wide and the AIC wave changed from a propagating wave to a standing wave.

Abstract-This paper presents an efficient high-frequency soft switching PWM boost chopper controlled DC-DC power converter with a single auxiliary passive resonant snubber, which is more suitable and acceptable for high power applications. The proposed boost chopper type power converter capable of operating under soft commutation principles of series inductor-assisted Zero Current Soft Switching (ZCS) at turn-on transition and parallel capacitor-assisted Zero Voltage Soft Switching (ZVS) at tum-off transition is more effective to reduce switching power losses of an active power switch and EMI noises relating to switching surges on the basis of the DC load side power recovery feedback power processing. The operating principle of soft switching boost chopper type DC-DC power converter treated here is described and its performance evaluations are discussed and evaluated through simulation and experimental set-up for 5 kW power rating specification. The validity and effectiveness of this soft switching PWM boost type power converter using IGBTs are proved as compared with some performances of a hard switching boost chopper type power converter from an experimental point of view. The modified soft switching converter topologies using a single passive resonant snubber are demonstrated in here.