Abstract: The zero voltage switching quasi-resonant PFC buck-boost converter is directed to a circuit and method of operating the circuit that provides improved efficiency, decreased switching losses and operation at higher frequencies as compared to conventional bridgeless PFC buck-boost converter. The zero voltage switching quasi-resonant PFC buck-boost converter includes a buck transistor switch coupled to an input AC voltage source, a PFC transistor switch and a PFC diode coupled to an output voltage bulk capacitor, and a zero crossing detect inductor magnetically coupled to a buck-boost inductor for determining minimum voltage levels at which to turn ON the buck transistor switch and the PFC transistor switch. The zero voltage switching quasi-resonant PFC buck-boost converter with voltage shifter control addresses the problems of conventional bridgeless PFC buck-boost converters by using different voltage modes and zero crossing detection control.

Abstract: A Fai 2 converter includes an isolated Fai 2 inverter coupled to a resonant rectifier with either clamped diodes or clamped self-driven synchronous rectifiers. The Fai 2 inverter converts an input DC signal to a high-frequency AC signal. The resonant rectifier with either clamped diodes or clamped self-driven synchronous rectifiers rectifies the high-frequency AC signal to a DC signal while clamping the voltage across the clamped diodes or clamped self-driven synchronous rectifiers to the output voltage. Clamping the voltage in this manner minimizes the voltage stress and enables the use of low voltage stress components (diodes or synchronous rectifiers) with low conduction voltage drop.