Bipolar Current-Fed DC–DC Converter With Automatic Voltage Balance and Full Range ZVS for Bipolar DC System

The bipolar dc microgrid is attracting attention for its high efficiency and reliability, but the bipolar dc bus is susceptible to unbalanced power. This article proposes a bipolar current-fed dc–dc converter with automatic voltage balance under phase-shift plus pulsewidth control. Combined with the current-fed dual active bridge converter and voltage balancer, the circuit structure is streamlined and fewer devices are required. The proper magnetizing inductance allows the converter to achieve automatic bipolar voltage balancing even under extreme load imbalance, and achieve full-range zero-voltage switching (ZVS) over a wide voltage range. In addition, the coupled inductor is utilized to further reduce the number of magnetic components. Finally, based on the accurate ZVS analysis considering parasitic capacitance, the parameters of the converter are designed, and an experimental prototype is constructed to verify the feasibility of the proposed scheme.