The Analysis of a Novel Zero-Voltage-Transition PWM Soft-Switching Power Converter

In order to solve the problems of large current ripple of resonant snubber inverter in high-precision application, a novel zero-voltage-transition (ZVT) PWM soft-switching power converter was proposed. A LC branch is added to reduce the current ripple. In light load condition, the filter inductor current changing polarity is used to achieve zero-voltage switching of the main switches; while in heavy load condition, the properly conducted resonant branch can contribute zero-voltage switching of the main switches. Meanwhile, the auxiliary switches can work in zero-current switching. This topology has the advantages of high efficiency, low switching current ripple and fixed switching frequency. In this paper, detailed circuit operation is described and the main parameters in each period are calculated. The soft-switching condition is analyzed. A hardware prototype has been designed and tested to verify the validity of this proposed topology with relatively high switching frequency 200 kHz. Compared with hard-switching power converter in the same condition, the efficiency is improved a lot. However, the efficiency is a little lower than that of RSI, but the output current noise is far lower than that of RSI.