Carrier based implementation of reduced common mode voltage PWM strategies

This paper investigates the reduced common mode voltage pulse width modulation (RCMV-PWM) strategies for three-phase two-level converters in ac motor drive systems. A brief comparison of the RCMV-PWM methods is given and a conclusion is achieved that only three kinds of PWM methods are suitable for practical applications, including near state PWM (NSPWM), active zero state PWM1 (AZSPWM1) and 3-dimensional active zero state PWM (3D-AZSPWM). After that, the carrier based implementation of these three RCMV-PWM methods is studied and their modulation and carrier waves are deduced. Then a generalized active zero state PWM (GAZSPWM) is proposed. NSPWM and AZSPWM1 are found to be special cases of GAZSPWM. Actually, the proposed carrier based implementation of the three RCMV-PWM methods is found just as easy as that of the conventional PWM methods. Finally, the effects and carrier based implementation of the RCMV-PWM methods are validated through simulation and experiments.