Automatic Voltage-Balancing DC–DC Converter With Wide Voltage Gain and Full Range ZVS for Bipolar DC Microgrids

In order to balance the bipolar dc voltage and avoid dc bias for high-frequency transformer under unbalanced load conditions, a bipolar dc–dc converter is proposed. With the balanced inductor, it can be guaranteed to achieve automatic voltage-balancing under any load conditions, without additional voltage-balancing control. While with the inserted blocking capacitor on the secondary side, the dc bias is eliminated. The employed interleaved parallel boost structure increases and widens the voltage gain and reduces the input current ripple. In addition, the proposed converter can realize zero-voltage-switching (ZVS) and reduce backflow power over a wide input voltage range and full load range. The operating principle, steady state performance, ZVS range, and voltage gain of the proposed converter are analyzed in detail. Finally, a 930-W experimental prototype is designed and fabricated to demonstrate the effectiveness of the proposed converter.