A Low-Stress Zero-Current Switching Technique for Power Converters

Huge voltage spikes on auxiliary switches is a common issue for most of the existing zero-current switching (ZCS) pulsewidth-modulated (PWM) converters. The reason for the spike lies in the parasitic resonance between the resonant inductance and the stray output capacitance Coss of the auxiliary switch, which does not have the negative impact in zero-voltage switching (ZVS) converters. This paper proposes a low-stress ZCS technique to eliminate the negative consequence of the Coss in ZCS PWM converters. All the power devices, including the auxiliary switch, show low voltage stresses and ZCS. The auxiliary cell of the low-stress ZCS technique introduced a clamping diode to realize the low-voltage stress for the power devices. The low-stress ZCS buck converter is taken as an example to explain both the low-stress and ZCS characteristics. A 2-kW hardware prototype is developed. The simulation and experiment results both validate the effectiveness of the proposed low-stress ZCS technique.