Comparative Evaluation of Space Vector Based PWM Techniques in terms of Switching Losses

Space vector based bus-clamping pulse width modulation (BCPWM) and advanced BCPWM (ABCPWM) schemes are well known for reducing total harmonic distortion (THD) in line current and switching losses in a two-level inverter. In case of the three-level neutral-point-clamped (3LNPC) inverter, these PWM methods are extensively studied in terms of line current distortions. This paper analyses the space vector based BCPWM and ABCPWM schemes employed in the 3LNPC inverter in terms of inverter switching loss, and compares it with the centered space vector PWM technique. Unlike the two-level inverter, the inverter switching loss due to the PWM schemes varies with change in modulation indices. The effect of the load power factor and modulation index over its full range on switching loss is analytically evaluated and the detailed results are presented.