Novel Phase Shift Angle Compensation Method of DAB Converter Considering Parasitic Capacitance of SiC MOSFET

Abstract

This study proposes a novel method to compensate phase shift angle of dual active bridge (DAB) converters by considering the parasitic capacitance of SiC metal-oxide-semiconductor field-effect transistors (MOSFETs). In general, the DAB converter bidirectionally transfers power between the primary and secondary sides using a phase shift angle. The conventional methods calculate the phase shift angle with an assumption of the instantaneous changes in the voltage and current. However, SiC MOSFETs used in a DAB converter have parasitic capacitances such as the input, output, and reverse transfer capacitance which affect the voltage and current leading to inaccurate phase shift angle calculation. For instance, the input parasitic capacitance delays the voltage slew rate between the drain and the source of the SiC MOSFET. Moreover, during the dead time, the output parasitic capacitance of the SiC MOSFET and leakage inductance in the DAB converter resonate, delaying the slew rates of both current and voltage. Therefore, this study analytically quantifies the effect of parasitic capacitances on the performance of the SiC DAB converter and proposes a novel phase shift angle compensation method. The proposed method was validated through simulations and experiments with a 4-kW SiC DAB converter prototype.

Keywords

• DAB converter
• single phase shift
• SiC MOSFET
• parasitic capacitance