Circulating current mitigation in Dual Active Bridge converter

This work brings forward a new methodology to maximize the efficiency of Dual Active Bridge (DAB) converter for its several patterns of operation. This goal is reached by the mitigation of its processed circulating energy. It is proposed a figure of merit which relates the average input current and the RMS current of the power transfer inductor, and an algorithm to select the trio of control variables (D1, D2, φ) ensuring that this objective is achieved. It has been performed a detailed steady-state analysis of every pattern for all the possible modulations, as well as the identification of all commutations under zero voltage of the Full-Bridges that compose the DAB. Due to the twelve different modulation patterns presented by the DAB that affect directly the operation mode, the design, the volume, the weight, and different performances can be achieved. In this way, it is verified the impact of the control variables on converter efficiency, as well its relationships with the average input current and the RMS inductor current. Results show that the converter efficiency obtained for different operation points making the use of the developed algorithm are very close to those obtained making the computation by the optimal converter efficiency.