Transient DC Offset Mitigation for Dual Active Bridge Converters Based on Model Predictive Control With Optimized Dynamic Performance

Abstract

Transient dc offset and the relevant high current impact are crucial for dual active bridge (DAB) converters. Many previous works require additional resources or complicated implementations. Furthermore, the tradeoff between dynamic performance and the mitigation of dc offset is challenging. A fast dynamic response and a mild dc offset are usually contradictory. To address the current state of research, this article proposes a mitigation method based on model predictive control. Herein, the adjusting subshift angles are calculated based on predictive value and current value. The implementation is easy, and fast dynamics are achieved. Moreover, to address the unexpected current impact caused by the sharp changed shift angles of MPC, an optimization for transient state is proposed. The maximum output power matching references is released as much as possible, provided that the resulting current impact remains below the specified safety threshold. These methods give DABs a fast response speed with no dc offset and release the maximum power while limiting the current impact. Finally, the experimental comparisons with other schemes verify the effectiveness and superiority of the proposed method.