Research on reduced common-mode voltage nonzero vector pulse width modulation technique for three-phase inverters

This paper investigates the nonzero vector pulse width modulation (NZPWM) technique for three-phase inverters, and provides a theoretical instruction for the selection and application of pulse width modulation (PWM) methods. Firstly, the efficiency of DC voltage for different NZPWM technique are investigated theoretically, and the inferior modulation strategy is excluded. Secondly, the efficiency of DC voltage and harmonic content of traditional space vector modulation (SVM) and different NZPWM are compared by using the simulation method. Finally, the efficiency of DC voltage and harmonic content at different modulation index are studied. The research makes conclusion that active zero state PWM1 (AZSPWM1), active zero state PWM3 (AZSPWM3) and near state PWM (NSPWM) modulation technique can reduce the common-mode voltage (CMV), and also maintain high efficiency of DC voltage, but they will increase the harmonic content, and influence the quality of output current and voltage.