Loss Minimization of Dual Active Bridge Converter Through Design Optimization in CC-CV Mode for Electric Vehicle Battery Charging Applications

The dual active bridge (DAB) converter is the most widely adopted topology for the dc-dc power conversion stage in electric vehicle battery charging owing to its inherent capabilities such as soft switching and galvanic isolation. However, the performance of DAB is compromised when it's operating under a constant-current constant-voltage (CC-CV) charging process. Therefore, the optimal design and operation of the DAB converter become of paramount importance to achieve its efficient operation during CC-CV charging. The existing design methods optimize the converter, particularly in CC mode, and take no notice of the CV mode in the design optimization process. Furthermore, the DAB converter's zero voltage switching (ZVS) operation range is limited during the light-load conditions in CV mode. This article overcomes the aforementioned concerns by proposing a loss minimization approach for the DAB converter through design optimization throughout CC-CV mode. Also, a smooth mode transition from CC to CV is achieved for the DAB converter through the control mechanism. The proposed method is formulated analytically and validated with simulation results.