Soft Switching Method of TPS Modulated DAB Converters with Wide Band Gap Devices

The dual active bridge (DAB) converter is a promising topology in the bidirectional power conversion system. With the development of wide band-gap semiconductor device, power density is increasing significantly. However, switching loss becomes a non-negligible part. Based on the RMS current optimization method, a novel control strategy that enables the converter to realize zero voltage switching (ZVS) of all the switching devices (ALL-ZVS) with low power range for both cases of voltage transfer ratios of M>1 and M<1, is proposed in this paper. Based on the proposed controller, the quasi RMS current optimization control with ALL-ZVS can be achieved. The proposed control strategy can improve the conversion efficiency significantly at low power range. Finally, an experiment platform based on GaN is built, and the experimental results verify the correctness and effectiveness of the proposed control strategy.