Model Predictive Control of DAB Converters for RMS Inductor Current Minimization Under ZVS Constraints

This paper introduces a model predictive control (MPC) method for dual active bridge (DAB) converters, which minimizes the root mean square (RMS) inductor current while ensuring zero-voltage switching (ZVS). First, the power losses that reduce DAB efficiency are analyzed. It is revealed that achieving optimal efficiency requires both minimizing the RMS inductor current and maintaining ZVS, thereby reducing switching, conduction, and magnetic component losses. Subsequently, an expression for the RMS inductor current is derived, which involves two decision variables: the inter-phase and outer-phase shifts. By formulating and solving an optimization problem that minimizes the RMS inductor current under ZVS constraint, the steady-state solutions for the inner and outer phase shifts are determined. To achieve fast-tracking performance and eliminate steady-state error, the MPC approach is designed based on the output filter. Additionally, Lyapunov stability theory is employed to guarantee system stability. The steady-state inner phase shift solution is used to satisfy the ZVS constraints, while the final outer-phase shift is determined based on the MPC approach and inter-phase steady-state solution, ensuring power transmission. To validate and highlight the effectiveness of the proposed method, extensive hardware experiments are conducted and compared with recent studies.