Study on a novel low-stress zero current switching technique in power converters

Huge voltage spikes on auxiliary switches is a common issue for most of the existing zero current switching (ZCS) techniques. The spikes are caused by the energy oscillations between the resonant inductor and the stray capacitor of the auxiliary switch, since the stray capacitor of the auxiliary switch can´t be employed as the resonant capacitor. In this paper, a novel low-stress ZCS technique is proposed, which makes all switches in power converter, including the auxiliary switch, have lower voltage stresses than that with the traditional ZCS by introducing an auxiliary cell. In this paper, a Buck converter is taken as an example. To realize the proposed low-stress ZCS technique, the auxiliary cell is added in the basic Buck converter, and then all power switches in the Buck converter can achieve ZCS under full range of power load. Finally, a 2kW Buck converter prototype is established, the experimental results validate the effectiveness of the proposed low-stress ZCS technique.