A new generation of buck-boost resonant AC-link DC-DC converters

This paper introduces soft-switched high-frequency ac-link dc-dc converters. An ac inductor and a small ac capacitor form the parallel high-frequency ac link. The link inductor is the main element for transferring power, and the link capacitor creates partial resonances to obtain zero-voltage turn-on and turn-off for the converter's switches. Both link inductor and capacitor handle ac voltages and currents with low reactive ratings, so they are considerably small and efficient. Moreover, the converters have the ability to make the step-up and step-down operations by using two reverse-blocking switches for unidirectional power flow and two bidirectional switches for bidirectional operation. The converters' link frequency varies slightly by changing the input voltage and load current. The basic operation of the resonant converters includes four modes, which are described in detail. The comprehensive analysis of the proposed topologies is carried out as well. Various simulation and experimental results are provided to verify the performance of the proposed power converters.