Loss Evaluation in a Ductile Cast Iron Frame of a Permanent Magnet Synchronous Motor

In this study, the loss of a PMSM with a ductile iron frame is evaluated. First, the magnetic and electrical properties of the ductile iron FCD400 used for the frame were measured. Then, the measured properties were applied to the loss analysis of the PMSM with the ductile iron frame. The results of the analysis clarify that significantly large losses are generated in the fame when the stator core is highly saturated. In addition, the effect of carrier harmonics on the loss generated in the frame was examined. As a result, the frame loss is mainly generated by the fundamental component included in the pulse-width modulation (PWM) voltage waveform, and the contribution of the carrier harmonics is negligibly small. Furthermore, the presence of the frame reduces the magnetic resistance of the stator core, which leads to the improvement of the torque at the low-speed and high-torque condition.