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A novel three-phase single-stage PFC converter with limited double-polarity control

In more electric aircraft (MEA) system, multi-voltage grade are needed for various aircraft loads. In the paper, a novel three-phase single-stage power factor correction (PFC) converter is introduced, which can supply 28V dc output to the aircraft electrical equipment. The converter bases on full-bridge structure and operates in constant-frequency discontinuous condition mode (DCM). To restrict excessive single-stage dc-bus voltage, the full-bridge uses limited double-polarity control strategy. An auxiliary circuit, which comprises two freewheeling diodes and a small-capacity clamp capacitor, is added in the tansformer secondary. The main function of the auxiliary circuit is to reset the primary current quikly, which can provides zero-voltage zero-current switching (ZVZCS) conditions to the four power switches of full-bridge. In the meantime, the duty-cycle loss is also reduced thanks to the clamp capacitor. The new converter's operation is explicated and analyzed. Simulation results are given to verify the theory.