A Dynamic Hysteresis-Based Iron Loss Calculation Method and Its Application in a PWM-Fed IPMSM

For PWM-fed motors, many harmonics are induced in the magnetic field by excitations, which makes accurate iron loss calculation more difficult. This paper presents a general iron loss calculation method based on a dynamic hysteresis model and finite element analysis. The dynamic hysteresis model is developed by introducing the derivative of the magnetic field induction, which can precisely describe the dynamic hysteresis effects of frequency and harmonics. The measured fundamental magnetization curve is introduced to improve the accuracy. To examine the suitability of the hysteresis model, an Epstein frame and a ring core are both utilized to build the hysteresis model and calculate the iron loss. The results based on the ring core show better performance in this paper. An iron loss calculation package based on the built hysteresis model is developed and can be directly applied in the post-processing of finite element analysis. The proposed iron loss calculation method is applied to a PWM-fed IPMSM. The hysteresis distortion and iron loss distribution inside the PWM-fed motor can be analyzed in detail. The comparison of measured and calculated iron loss over a wide range of operating frequencies proves the feasibility and accuracy of the proposed method.