Effect of Pulse-Width Modulation Schemes on the Performance of Three-Phase Voltage Source Converter

This paper investigates the direct effect of different pulse-width modulation schemes on the performance of three phase voltage source PWM converter. Two different modulation schemes, namely, the sinusoidal PWM (SPWM) scheme and the space vector PWM (SVPWM) scheme have been evaluated and the analytical expressions for the average PWM duty cycles for the different modulation schemes have been derived. With the proposed converter model, the transfer functions between the control inputs and the output dc voltage have also been obtained. It has been shown analytically that the SVPWM scheme provides a 33.3% higher gain as compared to the SPWM scheme. Thus, the PWM converter with the SVPWM scheme shows better dynamic performances. For the same ac input voltage, the converter using the SVPWM scheme can provide 13.4% lower output voltage than that using the SPWM scheme. It shows that the SVPWM scheme provides a wider operating range for the PWM converter. In steady state, THD of the input ac current with the SVPWM scheme is smaller than that with the SPWM scheme. The experimental test results obtained confirm that improved transient and steady state performances can be achieved using the SVPWM scheme.