새로운 소프트 스위칭형 PFC 스텝 업-다운 초퍼에 관한 연구

In this paper, authors propose a novel power factor correction (PFC) step up-down chopper by soft switching. The proposed chopper for a discontinuous conduction mode (DCM) eliminates the complicated circuit control requirement and reduces the size of components. The input current wavform in the proposed chopper is got to be a sinusoidal form of discontinuous pulse in proportion to magnitude of ac input voltage under the constant duty cycle switching. Therefore, the input power factor is nearly unity and the control method is simple. To achieve a soft switching (ZCS and ZVS) of the proposed chopper is constructed by using a new loss-less snubber which is operated with a partial resonant circuit. The result is that the switching loss is very low and the efficiency of converter is high. Some simulative results on computer and experimental results are included to confirm the validity of the analytical results.