A bidirectional non-isolated hybrid modular DC-DC converter with zero-voltage switching

Abstract

In this paper, a bidirectional non-isolated hybrid modular DC-DC converter for high-voltage (HV) applications is investigated. In this configuration, conventional Half-Bridge Sub-Modules (HB-SMs) are employed. The proposed DC-DC converter is based on connecting the SMs capacitors in series across the high DC voltage level while connecting them sequentially across the low DC voltage level. On another frontier, an HV valve, based on series-connected Insulated-Gate Bipolar Transistors (IGBTs), is required at the HV side. The main confronted challenge of the series-connected IGBTs is the voltage sharing during turn-on and turn-off periods, which necessitates the engagement of an intricate voltage sharing technique. In this work, a switching pattern is proposed to ensure zero-voltage switching (ZVS) of the involved HV valve. In order to reduce the switching losses and avoid complex active gate control recruited for dynamic voltage sharing, the zero-voltage state is extended beyond the switching time. A detailed illustration of the hybrid modular DC-DC converter is presented, elucidating the proposed switching pattern. Simulation results, using Matlab/Simulink platform, are presented to validate the contribution of the paper. Finally, a scaled-down prototype is employed for experimental verification.