Soft-switching single stage isolated AC-DC converter for single-phase high power PFC applications

In this paper, a novel single-stage isolated AC-DC converter is proposed for single-phase high power PFC applications. The circuit is derived by combining the boost converter and the matrix-based isolated AC-DC converter. Compare to traditional PFC plus DC/DC configuration, this topology has no diode front end and the number of semiconductors in the current path is minimized. Thus the conduction loss is decreased. By adding a small clamping capacitor and two small size commutation inductors, softswitching for all switches can be realized. Thus the system efficiency can be significantly improved. Furthermore, traditional PWM technology can be applied. Problems of resonant based soft-switching converters including large EMI filter size, high devices voltage and current stress, and low light load efficiency can be avoided. In this paper, the topology derivation and circuit operational analysis are given. The control strategy is introduced and a simulation is carried out to verify the circuit.