A Three-Winding Coupled-Inductor High-Voltage-Gain Soft-Switching DC–DC Converter With Bipolar Outputs

The bipolar dc microgrid system has the advantages of high reliability, high flexibility, and high efficiency. By introducing coupled-inductor and switched-capacitor step-up units on Boost bipolar output converter, a three-winding coupled-inductor high-voltage-gain soft-switching dc–dc converter with bipolar outputs is proposed in this article. The proposed converter has the advantages of low input current ripple, high-voltage-gain, and low voltage stress of switches, and can flexibly adjust bipolar output voltage by duty ratio of the main switch and turns ratio of the coupled-inductor. Meanwhile, all switches achieve zero voltage switching (ZVS) turn-<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and all diodes achieve zero current switching (ZCS) turn-<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small>, which creates conditions for the converter to operate at high frequencies and efficiency. Finally, a 100 kHz 200 W 32 to 190 V and −190 V experimental prototype is built to validate the feasibility of the proposed converter. The efficiency of the proposed bipolar output converter is 96.27% at the rated power.