Performance analysis of reduced common-mode voltage space vector modulation techniques for three-phase four-leg voltage-source inverter

In order to generate the switching signals of the power converters for obtaining high quality output voltages, pulse-width modulation is a common method. But, PWM methods produce common-mode voltage (CMV) as a serious problem. In this paper, reduced common-mode voltage methods (RCMV) of 3-D MSVPWM, 3-D NSVPWM and 3-D RSPWM for three-phase four-leg voltage-source inverter (VSI) are introduced, and their pulse pattern and CMV pattern are illustrated. Their performance characteristics are thoroughly investigated to find out whether they are able to maintain the merit of three-dimensional conventional space vector PWM (3-D CSVPWM) in addition to CMV reduction, or not. The switching and conduction loss, linear modulation region and output voltage harmonic distortion factor of each modulation technique is evaluated by analytical methods and simulations. The appropriate PWM method can be selected for needed application by analysis presented in this paper.