PWM plus secondary-side phase-shift controlled full-bridge three-port bidirectional converter for application in MVDC distribution networks

This paper presents the characteristics and control structure of a high power three-port bidirectional DC-DC converter (TPBC) based on full bridge and interleaved-boost converters (IBC) with pulse-width-modulation and phase-shift control for photovoltaic-storage hybrid systems to integrate to MVDC distribution system. The FB-TPBC, featuring one input port, one bidirectional port and one isolated bidirectional output port. The operation principles of the proposed converter are analyzed. Moreover, the phase shift between the primary side and the corresponding secondary side switches and the duty cycle of the input bridge switches are two control freedoms in order to reach the power management between three ports while regulating the output voltage. This control scheme is called PWM+SSPS. Moreover, zero-voltage-switching (ZVS) can be obtained for the switches of both input and output bridges due to the proposed PWM+SSPS which improves power density and efficiency. Unified control scheme is helped to prepare higher reliability and better dynamic performance with the complex communication systems cancellation. In order to verify the theoretical analyses, the proposed FB-TPBC has been simulated in MATLAB/Simulink software environment and tested under various scenarios.