Comparison of major PWM methods from the aspect of the system efficiency of machine drive system

System efficiency is one of the key performance for machine drive system. Taking the application of electric vehicle for example, improving the system efficiency of the drive system is able to increase the mileage range, and is of important practical use. PWM methods are directly related to the loss of the inverter and THD of the currents and have a significant impact on the system efficiency. Major PWM methods including SVPWM, DPWM1, DPWM2 are analyzed comparatively in this paper from the aspect of system efficiency. Firstly, theory and realization of the three PWM methods are introduced. Then, we adopt the loss of the inverter and THD of the currents as the evaluation standards to investigate the PWM methods comparatively. The system efficiency of DPWM methods are higher than SVPWM when the modulation ration become greater than or equal to the maximum value of the linear modulation region. Between the two DPWM methods, DPWM2 is more suitable in the application with inductance load similar to the machine drive. Lastly, the theoretical analysis is validated through simulation and experimental results. The results manifest DPWM is advantageous only if the modulation ration is greater enough. For the DPWM methods, both the efficiency of the inverter and that of the system of the DPWM2 are higher in machine drive.