Minimize Current Stress of Dual-Active-Bridge DC-DC Converters for Electric Vehicles Based on Lagrange Multipliers Method

Abstract Optimal modulation scheme is proposed for the dual-active-bridge DC-DC converter to minimize current stress of the switching devices. The converter is an ideal alternative for bidirectional power transfer, as an Electric Vehicle charger or a power interface in a micro-grid. A PWM plus phase-shift control strategy is presented, and the working principle is analyzed. The mathematical models of the power and peak current are established, and the method of Lagrange Multipliers is applied to the optimization. Experimental results confirm a considerable decrement of the current stress achieved with the proposed optimal schemes, as compared with traditional single phase shift modulation under light load. The efficiencies are enhanced correspondingly.