A New Voltage Distribution Strategy in Input-Series Connected Dual Active Bridge Converters

This paper proposes a new voltage distribution strategy in input-series connected dual active bridge (DAB) converters. Previous studies focus on maintaining an equal voltage distribution across all inputs to ensure a balanced power distribution. However, the strategy of uniform distribution has its limitations, especially when using single phase shift (SPS) modulation. ZVS range of SPS modulation is limited when voltage gain deviates from unity. Therefore, this paper suggests a new voltage distribution strategy. By allowing a non-uniform distribution of input voltage, additional switches can achieve ZVS. This not only broadens the ZVS range but also the remaining switches undergo hardswitching at reduced voltages. Furthermore, conduction loss does not increase in the secondary-side bridge. As a result, switching loss can be significantly reduced.