A fully soft-switched extended-period quasi-resonant power-factor-correction circuit

This paper presents the design criteria, procedure, and implementation of a soft-switched power-factor-correction (PFC) circuit based on the extended-period quasi-resonant (EP-QR) principles, All power electronic devices including switches and diodes in the circuit are fully soft switched, The design method is demonstrated in a prototype circuit, The operating principles are confirmed with computer simulation and experimental results, A comparison of the EP-QR operation and zero-voltage-transition (ZVT) pulse-width modulation (PWM) method, supported with simulation and measurements, is included.