An improved ZCS-PWM commutation cell for IGBT's applications

An improved zero current switching pulse width modulation (ZCS-PWM) commutation cell is proposed, which is suitable for high power applications using IGBTs as the power switches. It provides ZCS operation for active switches with low current stress, without overvoltage and PWM operating at constant frequency. The main advantage of this cell is a substantial reduction of the resonant current peak through the main switch during the commutation process. Therefore, the RMS current through it is very close to that observed in hard-switching PWM power converters. Also, small ratings auxiliary components can be used. To demonstrate the feasibility of the proposed ZCS-PWM commutation cell, it was applied to a boost power converter. Operating principles, theoretical analysis, design guidelines and a design example are described and verified by experimental results obtained from a prototype operating at 40 kHz, with an input voltage rated at 155 V and 1 kW output power. The measured efficiency at full load was 97.5%.