Studies of high-frequency iron core loss for synchronous electric machines used in electric vehicles

Application of Permanent Magnet Synchronous Motor (PMSM) has been increasingly popular in Electric Vehicle (EV) area since cost-effective magnetic materials were recently discovered. This paper mainly presents numerical calculation and experimental measurement of core loss of PMSM at various frequencies among 50Hz, 100Hz, 200Hz and 400Hz. A novel design strategy of PMSM will be described. The motor designed by authors is mounted on the vehicle and has 12 poles and 48 slots. It gives a numerical algorithm for iron core loss. At first, the hysteric and eddy current loss of single electrical steel will be calculated, followed by measurement at different frequency among 20Hz up to 2500Hz. Then, the dynamic hysteresis loop and high-frequency harmonic losses will be accurately calculated with power loss and dimension of single sheet, which plays a key role in the total loss calculation, especially at high flux densities and high frequencies. The final section shows the experimental results of (1) power losses of single sheet of non-grain oriented electrical steel, and (2) high-frequency iron core losses at 50Hz, 100Hz, 200Hz and 400Hz, which verify numerical algorithm. It is clarified that the numerical model and experimental iron core losses in each experiment are showed to be in good agreement. The numerical model for iron core losses and experimental results for single electrical steel sheet are especially useful to estimate power losses of electric machines running at higher frequency of 1000Hz∼2000Hz.