A novel ZVT PWM Cuk power-factor corrector

A novel zero-voltage-transition (ZVT) pulsewidth modulated (PWM) Cúk power-factor corrector (PFC) is proposed to achieve unity power factor under zero-voltage-switching (ZVS) operations. In the proposed ZVT PWM Cúk PFC, not only the power switch, but also the power diode, commutate under ZVS. The proposed topology has the shortest ZVT time and, thus, the shortest minimum duty cycle compared with other ZVT PWM topologies. The resonant inductor can be discharged regardless of the state of the main switch. Extremely short ZVT time and robust discharge of the resonant inductor make the proposed topology well qualified for variable-duty and highswitching-frequency applications. Analytical studies, design rules, and experimental waveforms of the ZVT PWM Cúk PFC are presented in detail.