A family of high efficiency bidirectional DC-DC converters using switching cell structure

The traditional hard switching bidirectional dc-dc converters cannot simply avoid the reverse recovery problem of MOSFET body diode, and they also require dead time between the switches to avoid current shoot-through. Therefore, the traditional bidirectional dc-dc converters are usually designed with IGBTs. The IGBTs have long tail current, low switching speed and fixed voltage drop when compared with MOSFETs. This paper proposes bidirectional buck, boost, inverting buck-boost and non-inverting buck-boost dc-dc converters. The proposed single-phase converters can be extended into N-phase. In the proposed converters, the body diodes of switching devices do not conduct, therefore the MOSFET can be used as switching device, and the reverse recovery problem and loss of body diodes can be eliminated. The current freewheeling diodes can be selected externally with extremely good reverse recovery features and low forward voltage drop, therefore the conduction and switching losses can be reduced, and high efficiency can be obtained. In the proposed converters, the switches have no current shoot-through problem, therefore the dead-time between the switches can be eliminated. Experimental results obtained with 1 kW non-inverting buck-boost dc-dc converter are provided to verify the correctness of the proposed converters.