A new high-efficiency zero-voltage-switching AC-DC boost converter using energy recovery circuits

This paper presents a novel single-phase high power factor soft switching PWM rectifier, featuring soft commutation of the main and auxiliary switches using a simplified combined inductor energy recovery circuit. In conventional soft switching PFC circuits, both a boost inductor and an additional transformer are required separately to achieve soft switching and energy recovery. In this paper, the two devices are combined as one unit. The combined inductor with simple additional winding can work as a boost inductor and an auxiliary inductor at the same time. The input current shaping is achieved with average current mode, and continuous inductor current mode control. Principle of operation, theoretical analysis, a design example, and experimental results from a laboratory prototype rated 2 kW with 400 VDC output voltage are presented. The measured efficiency and power factor were 97.63% and 0.998 respectively with an input current THD less than 2.5%. Thus the proposed topology can reduce the number of devices in the circuits while achieving high efficiency.