Sliding Mode Control with Improved Reaching Law for Dual Active Bridge Adopted for Off-Board Charger

In this paper, an augmented sliding mode control (SMC) strategy for dual active bridge serving off-board electric vehicle (EV) chargers is proposed to ensure smooth control performance over variable load conditions, with robustness towards voltage/current perturbations. The chattering issue is a common problem in SMC methods which needs careful tuning of several parameters. Unlike the traditional SMC, an effective reaching law is integrate with the sliding surface control to achieve better stability and disturbance rejection. The proposed control strategy can efficiently eliminate the chattering problem, while still obtaining a certain reliable control performance with some severe load conditions both in forward and backward power flow. Finally, the proposed method is validated by PSIM simulation tool, and the simulation results prove that the proposed method has less charging current ripples, fast convergence of the state error performance than classical SMC. This proves that the proposed control strategy outperforms the tradition SMC which suffers from chattering problems.