A forward converter employing a simple ZCS-PWM auxiliary circuit to achieve soft-switching and power transformer resetting

This paper proposed a zero-current-switching pulsewidth-modulation (ZCS-PWM) forward dc/dc converter using a simple ZCS-PWM auxiliary circuit. The main switch and auxiliary switch operate at zero-current-switching turn on and turn off, and the all passive semiconductor devices in the proposed converter operate at zero-voltage-switching (ZVS) turn on and turn off. Besides operating at constant frequency and reducing commutation losses, the proposed converter has no additional current stress and conduction loss in the main switch in comparison to the conventional hard switching forward converter counterpart. The power transformer can self-reset without the conventional reset winding. The averaging approach is used to estimate and examine the steady-state of the proposed converter. The principle of operation, theoretical analysis, and experimental results of the proposed ZCS-PWM forward converter, rated 500 W and operating at 40 kHz, are provided in this paper to verify the performance of the proposed converter.