Performance evaluation of a non-isolated bidirectional three-port power converter for energy storage applications

A pulse width modulation (PWM) plus phase-shift controlled (PPS) non-isolated bidirectional three-port converter (TPC) is analyzed for energy storage power system to interface multiple energy sources, storage devices and regulated voltage bus. A staked dual half-bridge converter (DHB) is integrated into a non-isolated bidirectional buck/boost converter to achieve the bidirectional power transmission between any two of the three ports. With the shared switching bridge in the low voltage side, the number of active switches is reduced. Thanks to the integration structure, low voltage stress on the active switches and high voltage conversion ratio will be achieved. PPS control strategy is employed to provide two control freedoms and single-stage power conversion between any two of the three ports is achieved. What's more, with PPS control scheme, wide range voltage/power regulation and soft-switching of all the low-voltage and high-voltage side active switches can be realized. Operational principles, control strategy and characteristics of the analyzed converter are presented. Experiments of a 1-kW prototype have been carried out to verify the feasibility and effectiveness of the converter.