Switch Loss Balancing Strategy for Dual-Active-Bridge DC/DC Converter Employing Extended Phase-Shift Switching Modulation

Dual-active-bridge (DAB) converter utilizing conventional extended phase-shift modulation suffers from the unbalanced switch loss among the primary-side switches in buck operation and among the secondary-side switches in boost operation. To overcome this problem, we propose the switch loss balancing strategy for DAB dc/dc converter operating with extended phase-shift modulation. The split complementary duty signals over two switching cycles enable balancing of turn-off switching loss and conduction loss over the switches in both forward and backward power flow directions. Corresponding different dead-times allow all the switches to be turned on with zero-voltage-switching (ZVS) at both heavy and light loads. The duty and phase-shift values are selected separately, thereby simplifying the control logic. Experimental validation on a 3.3 kW prototype designed for a 800-V input and an output range of 500 to 800-V demonstrates the uniform heat distribution across switches while preserving the inherent advantages of extended phase-shift modulation for DAB converter.