Dual Active Bridge DC-DC Converter with Tunable Dual Pulse-Width Modulation for Complete Zero Voltage Switching Operation

Abstract

A dual active bridge (DAB) dc-dc converter with the conventional combined pulse-width modulation (CPWM) performs hard-switching operation in the low power range when the input or output voltage varies. In this paper, a novel modulation strategy named tunable dual pulse-width modulation (TDPWM) is proposed to modify Interval 1 of CPWM, which enables the DAB converter to perform complete zero voltage switching (ZVS) operation, only in the low power range, by adding two tunable parameters. In order to tune the two parameters accurately, the dead time effect and the parasitic components are considered in the complete ZVS analysis. In addition, the TDPWM strategy combines the three independent parameters into two tunable parameters and the fundamental phase which, enables bidirectional power transfer. The efficiencies of the DPWM and TDPWM operations are compared under various voltage variations using a prototype. The experimental results demonstrated that the complete ZVS operation with TDPWM achieved higher efficiency than that with DPWM when the input/output voltage was varied.