Research on the ZVZCS full bridge converter with current-double rectifier

Soft-switching phase-shifted full-bridge converter is widely used in high-power applications currently. However, due to the reverse recovery characteristic and the parallel parasitic capacitance of the output rectifier diodes, the voltage spikes and parasitic oscillation exist on the output rectifier diodes in the conventional phase-shift full-bridge ZVZCS PWM converter. As a result, the diode will suffer from high voltage and current stress and the efficiency will be compromised. To tackle this challenge, this paper adopts the current double rectifier circuit to replace the traditional rectifier topology which can guarantee the soft-switching of both the leading-leg and the lagging-leg of the full bridge converter simultaneously. Meanwhile, the output rectifier diodes will turn off in the zero-current condition, avoiding the parasitic oscillation and voltage spikes. The proposed method will also help to eliminate the electromagnetic interference and increase the efficiency of the converter. In this paper, the working process of the output diodes as well as the output current ripple are analyzed in detail. Besides, the effect of load variation on zero- current switching for the output diodes and the lagging-leg switches is discussed. Finally, a 1.25kW prototype using IGBT is built, which works at 20 kHz and the theoretical analyses are verified.