Iron loss evaluation and comparison in application of reduced common mode voltage PWM methods

The application of reduced common mode voltage pulse width modulation methods bring much high order harmonics to the variable speed drive system, which causes considerable iron loss inside the electric motor. In this paper, an improved iron loss model considering those high order harmonics is proposed. Iron loss coefficients are obtained based on experimental data by utilizing multiple linear regression and harmonics analysis method. Comparisons of the iron losses between various PWM methods are made for both experimental results and calculated results. It is found that by utilizing RCMV PWM methods, the iron loss of the induction motor becomes larger. The differential values of iron losses between RCMV PWM and CPWM decrease with the increase of the modulation ratio as a result of the reduction of zero space vectors´ action time.