Single pulse width modulation for dual-active-bridge converters considering parasitic capacitance of MOSFETs

Abstract

Dual-active-bridge (DAB) converters are suitable for delivering insulated bidirectional large-capacity power with a high power density. To increase efficiency, zero voltage switching (ZVS) operation is required. However, if the DC terminal voltages on both sides are different, the range in which the ZVS conditions may not be satisfied becomes large. To minimize the hard switching operation, single pulse width modulation (SPWM) has been studied. This paper analyzes the characteristics of SPWM for various DC voltage conditions of a DAB converter. In particular, a method for determining a zero voltage ratio to maximize the ZVS operating range is proposed in consideration of the parasitic capacitor of MOSFET switches. In addition, the power characteristics of SPWM are proposed as an equations for the phase shift and zero voltage ratio of SPWM. The validity of both the proposed SPWM and the proposed power control method are confirmed through simulation and actual 1 kW DAB converter experiments.