A Bidirectional Three-Level DC-DC Converter with Reduced Circulating Loss and Fully ZVS Achievement for Battery Charging/Discharging

In this paper, a high-frequency isolated bidirectional three-level dc-dc converter is proposed for battery charging/discharging applications. To reduce the circulating loss, a double pulse-width modulation (PWM) plus double-phase-shifted control with voltage matching control is proposed. Zero voltage switching (ZVS) for all switches can be obtained throughout full-load range even at no-load condition by using the transformer magnetizing current. The mode analysis is given to illustrate its working principle. The system parameters' design criterion is given in view of the efficiency improvement and ZVS achievement for all switches. A detailed comparison of root-mean-square value and peak value of the leakage inductor current is made with the voltage matching control and mismatching control, respectively. The conversion efficiency curves using the proposed control and PWM plus phase shift control have been compared. The effectiveness of the proposed control for the dc-dc converter is verified by experimental results of a 1-kW three-level prototype.