Investigation of the Influence of Harmonics on Iron Loss of Soft Magnetic Composites

Increase of power density and efficiency improvement in electric motors are required due to expanding electrification of automotive applications. We have developed soft magnetic composites (SMCs) with high magnetic flux density and low iron loss. To improve efficiency of electric motors, it is necessary to suppress increase of iron loss due to harmonics associated with inverters. It is expected that SMCs with low iron loss at high frequency can reduce the increase of iron loss by harmonics. In this study, the iron losses of SMC and laminated steel sheet (LSS) were measured under PWM and excitations and compared. SMC shows less increase. Moreover, hysteresis loop of SMC under DC superimposition is less distorted compared to LSS. From these results, it is presumed that the SMC’s feature of small iron loss increase under DC superimposition also contributes to suppress the increase of iron loss by harmonics.