A novel zero-voltage-transition PWM Cuk power factor corrector

A novel zero-voltage-transition (ZVT) PWM Cuk power factor corrector (PFC) is proposed to achieve unity power factor under zero-voltage-switching (ZVS) operations. In the proposed ZVT PWM Cuk PFC, not only the power switch but also the power diode commutate under ZVS. The proposed ZVT topology has the shortest ZVT time and thus the shortest minimum duty cycle compared with other ZVT topologies. The resonant inductor can be discharged regardless of the state of the main switch. Extremely short ZVT time and robust discharge of a resonant inductor make the proposed ZVT topology well qualified for variable duty and high switching frequency applications. Analytical studies on the proposed ZVT PWM Cuk PFC are presented in detail. A 400 W, 50 kHz prototype has been built in the laboratory to experimentally verify the analysis.