Bidirectional Isolated DC/DC Dual Active Bridge Converters: Optimum Soft Switching Control Method for Electric Vehicle Applications

Abstract

This paper presents an optimum soft-switching control strategy for a bidirectional isolated DC/DC Dual Active Bridge (DAB) converter designed for Electric Vehicle (EV) on-board battery charging and Vehicle-to-Grid (V2G) energy exchange applications. The proposed Extended Phase-Shift with Dead-Band Optimization (EPS-DBO) control method simultaneously minimizes reactive power circulation, achieves Zero Voltage Switching (ZVS) across the full load range, and reduces switching losses by up to 47% compared to conventional Single Phase Shift (SPS) modulation. A comprehensive analytical model based on fundamental harmonic approximation and time-domain analysis is developed. The ZVS boundary conditions are derived explicitly for both primary and secondary bridges under variable battery voltage (200–400 V) and DC bus voltage (48–100 V). Simulation results for a 3.3 kW DAB prototype confirm EPS-DBO maintains soft-switching even at 10% load with peak efficiency of 96.8%. Experimental validation on a hardware prototype at 100 kHz verifies superior performance over SPS and Dual Phase Shift (DPS) methods.