Modified Carrier-based Pulse Width Modulation Strategy for Three-phase Vienna Rectifier

Considering the influence factors such as filter inductance, parasitic parameters of switching devices and control delay, so the rectifier may work in the state of non-unity power factor. At this time, if the rectifier adopts the traditional carrier-based pulse width modulation (CB-PWM) strategy, an area with inconsistent voltage and current polarity will be generated, which may cause the switching tubes to malfunction and the performance of the rectifier to decrease. For this reason, a modified carrier-based pulse width modulation strategy (MCB-PWM) is proposed based on the traditional CB-PWM strategy to improve the zero-crossing distortion of the rectifier. First, based on the working principle of the three-phase Vienna rectifier, a mathematical model is established in a two-phase rotating (d-q) coordinate system; secondly, the causes of waveform distortion at the grid-side current zero-crossing point caused by the traditional CB-PWM strategy is analyzed in detail, the compensation measure is designed, and the specific principle of the MCB-PWM strategy is given; in addition, the overall control block diagram of the system is formed by combining the traditional double closed-loop control; finally, the traditional CB-PWM strategy is compared with the MCB-PWM strategy by the simulation in Matlab/Simulink. The results show that the input current zero-crossing distortion phenomenon can be significantly improved by using the MCB-PWM strategy, and the correctness and effectiveness of the theoretical analysis are verified.