부스트 PFC 컨버터에서의 ZVT 소프트 스위칭을 위한 최적 스위칭 듀티 추정

To achieve soft switching in wide range operation point, ZVT (Zero Voltage Transition) soft switching technique can be used in boost PFC (Power Factor Correction) converter. But because it uses additional switch to make the soft switching condition, the efficiency of converter changes according to the operation of a operation time of additional switch. This paper presents the optimization of duty in MOSFET to maximize the efficiency when using zero voltage transition soft switching technique in conventional boost PFC converter. It describes the optimum point with the relationship of switching loss of main converter and conduction loss of auxiliary circuit. To get the fitted graphs of switching loss of boost switch and conduction loss of resonant switch, it uses curve fitting tool of MATLAB. Boost PFC converter is evaluated based on PSIM and converter operation sequence, switching loss and converter efficiency is also presented.