A Hybrid PWM Method for Three-Phase Voltage Source Converter Based on Equivalent Model

When a three-phase voltage source converter works as an active power filter, it is difficult to ensure the steady-state accuracy and the dynamic response performance of current tracking at the same time by traditional hysteresis modulation or space vector pulse-width modulation independently. To address this issue, a hybrid PWM method based on equivalent model is proposed for the three-phase voltage source converter. The relation between switching frequency, loop width and total harmonics distortion of current is deduced by analyzing working principles of hysteresis modulation and SVPWM modulation. Furthermore, the segment switching hybrid control method and the switching standard of two modulation modes could be proposed. This hybrid modulation method simplifies the design of switched ripple filter, ensures dynamic response speed, high steady-state accuracy and the ability of eliminating high frequency harmonics. Experimental results are carried out to verify the effectiveness and superiority of the proposed hybrid PWM method.