Symmetric Bipolar Output Full-Bridge Four-Port Converter with Phase-Shift Modulated Buck-Boost Voltage Balancer

A multi-port converter with bipolar outputs to integrate renewable energy and energy storage into the bipolar dc bus is the desirable solution due to its high reliability and efficiency. A novel symmetric bipolar outputs full-bridge four-port converter based on phase-shift modulated buck-boost voltage balancer is proposed in this paper. The interleaved bidirectional buck/boost circuit with pulse width modulation is used as the primary side to achieve the integration of renewable energy and energy storage, while the phase-shift modulated buck-boost voltage balancer is derived as a secondary side circuit to generate a symmetrical and common ground bipolar output voltage. Single-stage power conversion, symmetrical bipolar output voltage, approximately decoupled control loop, and soft switching can be realized in the proposed four-port converter. Detailed analysis of the proposed converter is presented, including operation principle, steady-state performance, soft switching performance, and control method. Finally, experimental verifications are carried out to illustrate the feasibility and effectiveness of the proposed topology.