A novel lossless passive snubber is proposed for soft switching boost-type converters. The proposed snubber does not use any auxiliary switches, but uses two identical snubber capacitors which are charged in parallel at turn off of the main switch and discharged in series at turn on automatically, and the discharged energy is recovered effectively (more than 95% recovery) into the output capacitor. Thus, the snubber provides zero-voltage switching for the converter main switch, reducing both the turn-off losses and the electromagnetic interference (EMI) noise, which improves the converter performance. The experimental results of a 20 kHz 600 W DC-DC boost converter and a single-phase AC-DC boost rectifier with the new snubber are presented.

A novel lossless passive snubber for soft-switching boost-type converters

High switching frequency operation of static power converters is often required to reduce size, weight, and electromagnetic interference levels, at the cost of increased switching losses and reduced efficiency. Switching losses include the current and voltage overlap loss during the switching interval and the capacitance loss during turn-on. Recently, the use of passive soft switching methods has been emphasized as a better alternative to active methods, mainly because they do not require extra switches or additional control circuitry. This paper proposes a passive lossless snubber applied to the interleaved boost converter. The use of a soft commutation cell causes the main switches to be turned on and off under null current and null voltage conditions, respectively, as high efficiency results over the entire load range. The theoretical analysis including the description of the operating stages and the design procedure are included. Experimental results on a 2 kW prototype are presented and discussed to validate the proposal.

A Passive Lossless Snubber Applied to the AC–DC Interleaved Boost Converter

The efficiency of a contactless power transformer is determined by the output load. We propose a high-efficiency contactless power transfer system for a low-voltage and large-current load. The proposed system is composed of a contactless power transfer system with series and series resonant capacitors and a current-doubler rectifier circuit. This paper presents the characteristic of the proposed system that charged electric double layer capacitors as a low-voltage and large-current load, as well as the experimental results.

Contactless power transfer system suitable for low voltage and large current charging for EDLCs

This paper is concerned with a family of soft switching Pulse Width Modulation(PWM) DC–DC converter employing a novel Zero Voltage and Zero Current Switching(ZVZCS) Active auxiliary Edge-Resonant Cell(AERC). The non-isolated DC–DC converters introduced here can achieve a high frequency ZVS and ZCS operations in a main and an auxiliary switch with minimizing the voltage and current stresses as well as circulating currents. For demonstrating the effectiveness of the new soft switching cell, the boost DC-DC converter is evaluated by simulations and experiments using its 100 kHz laboratory prototype. In addition to that, the one-switch dual boost DC– DC converter is newly demonstrated as the new AERC-applied high voltage step-up power converter.

A new family of soft switching PWM non-isolated DC-DC converters with Active auxiliary Edge-Resonant Cell

This paper proposes a soft-switched three-phase-single-switch-boost-rectifier circuit. The proposed circuit can perform zero-voltage-switching (ZVS) without any current and voltage sensors. For this circuit, both simulation and experiments have been performed. The results not only confirmed the zero-voltage-switching (ZVS) but also indicated that, compared to the conventional hard-switched rectifier, the proposed circuit improves the efficiency as much as 2.7% while keeping the same high power factor and small harmonic distortion in their AC input.

Soft switched three-phase single switch boost-type rectifier

A soft-switching circuit for three-phase converter with unity power factor is proposed in this paper. A discontinuous conduction mode converter eliminates the complicated circuit control requirement, reduces a number of components, and reduces the filter reactive components size. In the discontinuous mode converter, the device must be switched off at a maximum inductor current. To achieve the zero voltage switching, the proposed converter is constructed by using a new resonant network in parallel with the switch of the conventional PWM converter. Soft-switched operation of the proposed PWM converter is verified by digital simulation and experimental results. A new PWM converter achieves the soft-switching for all switching devices without increasing their voltage and current stresses.

Katsuya Hirachi

Papers

Soft-Switching Circuit for Three-Phase Converter with Unity Power Factor

Current Doubler Rectifier