Modified Phase Shift Control for Dual Active Bridge to achieve switching loss reduction in the High Voltage side active converter

The Dual Active Bridge (DAB) is getting greater attention in the research area after the introduction of Wide Band Gap devices for high frequency power converters. The DAB is one of the bidirectional converters in the High Voltage (HV) DC to Low Voltage (LV) DC conversion with galvanic isolation, is widely preferred for industry applications. The Power flow between the active converters is established by popular phase shift control. The reduction of switching losses by Zero Voltage Switching (ZVS) and Zero Current Switching (ZCS) techniques is not simultaneously possible in the phase shift control by keeping the LV side DC voltage constant. Hence, higher losses and reduction in efficiency. In this paper a modified phase shift control is proposed with ZVS control loop to judiciously maintain the ZVS/ZCS for the HV side converter active switches. The proposed control dynamically controls the LV side DC voltage for varying load to supplement the required reactive power from the LV side of the converter. This paper mainly emphasizes on the estimation of ZVS control for varying load and the controller implementation in the real time control hardware. The control implementation methodology is discussed with the support of necessary experimental results presented in the paper