Performance Comparison of Three-Step and Six-Step PWM in Average-Current-Controlled Three-Phase Six-Switch Boost PFC Rectifier

In this paper, a three-step PWM method for the average-current-controlled three-phase six-switch boost PFC rectifier is proposed. It is shown that the three-step PWM compared to the conventional six-step PWM exhibits a lower total harmonic distortion of the input currents and higher power factor. However, the three-step PWM, unlike the six-step PWM, is adversely affected by the duty-cycle limitations and has unbalanced conduction losses of the upper and lower switches of the three-phase rectifier bridge. The average-current control of the three-step and six-step PWM is illustrated with MATLAB/Simulink simulation waveforms and experimentally verified on a 3 kW prototype.