A Common-mode Voltage Fluctuation Reduction Method and Topology for Triple Active Bridge DC-DC Converter

Compared with single-phase-shift (SPS) control, the introduction of duty cycle control in a triple active bridge (TAB) circuit reduces the energy loss of the whole system and extends the soft-switching operation. However, the port for duty cycle regulation produces a variable common-mode voltage, resulting in leakage current flowing through the interwinding parasitic capacitance of the high-frequency transformer, which will damage the insulation of the transformer. In this paper, the port in TAB circuits that are highly affected by common-mode voltage fluctuations is added to the Highly Efficient and Reliable Inverter Concept (HERIC) structure. This addition has no bearing on the advantage of using duty cycle regulation strategy while keeping the common mode voltage constant, to protect the transformer and improve the safety of the circuit. The simulation results indicate that the structure successfully mitigates common-mode voltage fluctuations and reduces common-mode currents.