Design procedure for minmimizing conduction loss for ZCT PWM boost converter

In this paper, the design procedure to minimize the conduction loss of the auxiliary switch resonant-path is proposed for a Zero-Currents-Transition PFC boost converter circuit. The soft-switching technique decreases switching loss at main switch, but increases conduction loss at the auxiliary switch resonant-path due to the occurrence of the resonant current. The proposed design procedure helps to reduce this problem. The detail operation and circuit waveform in each mode are presented. In addition, the theoretical expressions at the each mode are also derived. Based on the theoretical analysis, the Lr and the Cr in the resonant path are selected in order to minimizing the conduction loss, while securing the ZCT operation in the entire operation. Several simulation results are provided to verify the effectiveness of the proposed design procedure and theoretical analysis.