Novel Zero-Voltage and Zero-Current Switching (ZVZCS) PWM Three-Level DC/DC Converter Using Output Coupled Inductor

In this paper, a novel zero-voltage and zero-current switching (ZVZCS) pulsewidth modulation (PWM) half-bridge (HB) three-level (TL) dc/dc converter is proposed. Compared with traditional ZVZCS PWM TL dc/dc converters, this converter does not include auxiliary resonant circuits. It can achieve zero-voltage switching (ZVS) for the leading switches and approximate ZCS for the lagging switches with the aid of the transformer parasitic inductance, snubber capacitors, and tapped-inductor-type smoothing filter. This converter can reduce the voltage and current spikes of the power switches as well as the primary circulating current loss effectively. The operation principle of the novel converter and the soft-switching implementation condition are analyzed according to equivalent circuits under different stages. Besides, the effects of the tapped-inductor turns ratio on the current stress of the power switches and the output voltage characteristic under open-loop control scheme are discussed. The validity and features of the proposed converter are demonstrated by simulation results and experimental results via a 6-40 kHz prototype using the fast switching insulated gate bipolar transistor (IGBT).