In recent years, the soft-switching techniques have attracted attention for their peculiar advantages such as low switching loss, high power density, EMI/RFI noise reduction, and so on. The authors have previously reported on a quasi-resonant de-de converter using new phase-shift PWM control scheme. By using the proposed control scheme, circulating current is eliminated and ZVS (Zero Voltage Switching) is achieved with small commutating current. As a result, the conduction losses caused by their currents are substantially reduced. In this paper, the authors apply a proposed control scheme to a quasi-resonant high-frequency transformer link dc-ac converter. As a result, all switching devises in this dc-ac converter can achieve soft switching with small commutating current irrespective of inverter mode and rectifier mode. Its operating principle and unique features are described as compared with the symmetrical control scheme of dc-ac converter. Operating performance of this dc-ac converter in the steady state is illustrated by means of simulation results. (C) 1999 Scripta Technica.
