MOdified One-Cycle-Controlled Three-Phase Power-Factor-Correction

The one-cycle-controlled (OCC) three-phase power-factor-correction (PFC) is a promising rectification method that eliminates harmonics and improves the power factor. It features great simplicity, high performance, and excellent stability. In the conventional OCC control strategy, the PWM signals are generated by the sampling input inductor currents and carrier waveform whose amplitude is generated by voltage regulator. So, the generation of PWM signals can be regarded by SPWM (Sinusoidal Pulse Width Modulation) modulation. Under this control strategy, the output voltage of three-phase PFC rectifier is quite high, which is not benefit for reducing the switches voltage level and improving the efficiency of rectifier. Based on the analyses of OCC three-phase four-leg rectifier that used in 3P4W (three-phase four-wire) system, the SAPWM (Saddle Pulse Width Modulation) modulation that can be obtained by injecting three times harmonic into SPWM modulation is proposed to introduce in the conventional OCC control strategy. The rectifier´s output voltage could be reduced by the modified OCC control strategy and the efficiency of converter could be also improved. The modified OCC control strategy can be also applied in the three-phase three-leg rectifier and three-phase three switches Vienna rectifier that used in the 3P3W(three-phase three-wire)system. The validity of the theoretical analysis and feasibility of the modified OCC control strategy are verified by system simulation and experimental results based on a 4.5-kW three-phase four-leg rectifier prototype.