Different Purpose Design Strategies and Techniques to Improve the Performance of a Dual Active Bridge With Phase-Shift Control

This paper addresses the performance of the bidirectional dual active bridge (DAB) converter. One of the advantages of the DAB is the possibility to achieve the zero-voltage switching (ZVS) operation in all the switches of this converter. However, the ZVS operation range can be lost for light loads, especially if high voltage is required in at least one of the DAB ports and the phase-shift control is used to regulate the power processed by the converter. Theoretically simple averaged and small-signal models are presented for the DAB converter. Using the study presented in this paper, the boundaries of the ZVS operation can be easily evaluated. The proposed models and analysis of the ZVS boundaries allow the proposal and evaluation of two different design strategies with different purposes: on the one hand, increasing the ZVS operation range and, on the other, improving efficiency at full load. Moreover, some techniques are presented for increasing the ZVS operation range and improving the efficiency of the DAB at full load (both using phase-shift control) employing the aforementioned analysis to obtain certain design criteria and conclusions. Finally, the proposed models, design strategies, and techniques to improve the performance of the DAB are experimentally tested using a 1-kW prototype with input and output voltages of 48 and 400 V, respectively.