Three-Phase Buck Rectifier Based on SiC MOSFETs Used in Power Factor Correction

Abstract

This paper presents a power factor correction (PFC) module based on SiC MOSFETs and SiC Schottky diodes for aircraft power system. The structure of the PFC module is a three-phase buck rectifier cascade with a DC/DC boost converter. The first stage of the structure can attenuate the harmonic current in grid side current and realize the unity power factor. The second stage is a boost converter to convert the first stage output 200V DC voltage to output 270V DC voltage. This two stages cascade structure can also fully use the characteristics of three-phase buck rectifier’s ability to limit the current when an output short circuit happened and extend output voltage range. A three-loop direct current control strategy based on the dq rotating coordinate system is proposed. This control strategy can successfully maintain the output voltage of the three-phase buck rectifier. In addition, applying seven-segment SVPWM modulation scheme can improve the utilization rate of the dc current, so that the system can realize higher power level. A 115V acrms /400Hz input voltage PFC module model is built in Simulink/MATLAB, and the simulation results proof the feasibility of this cascade structure and three-loop direct current control strategy. A 115V acrms /50Hz input voltage, 1.5kW 200V output, 0.97 power factor, THD of the grid side current below 0.05 three-phase buck rectifier prototype based on SiC MOSFET and SiC Schottky diode (SBD) has been built up in lab. A low power whole PFC module prototype verify the effectiveness of this proposed cascade structure.