Optimized Switching Strategy for ANPC-DAB Converter Through Multiple Zero States

Multi-level circuits can achieve high voltage level, power density, and performance. This paper considers a dual active bridge (DAB) based on the active neutral-point-clamped (ANPC) three-level circuit (ANPC-DAB). The soft-switching characteristics of the ANPC circuit during the switching process between switching states are analyzed, and the conditions for enabling all 12 switching devices to achieve zero-voltage switching (ZVS) on all the turn-on switching transitions are obtained. Based on this, the distribution of hard-switching turn-off and conduction losses of power devices is further analyzed, and an optimized switching strategy that can balance the loss distribution of power devices is proposed by the evaluation of all zero states and analysis of a switching-state sequence. Moreover, this paper examines the effect of the proposed switching strategy by analyzing the loss distribution of power devices and efficiency of the ANPC-DAB. Finally, experiments are conducted using a 1-kW prototype. The simulation and experimental results show that the proposed switching strategy can effectively improve the loss distribution of power devices while all the power devices realize ZVS.