An improved iron loss estimation for permanent magnet brushless machines

This paper presents an improved approach for predicting iron losses in perm anent magnet brushless machines. The new approach is based on the fundament al concept that eddy current losses are proportional to the square of the t ime rate of change of flux density. Expressions are derived for predicting hysteresis and eddy current losses in the stator teeth and yoke. The so-cal led anomalous or excess losses, caused by the induced eddy current concentr ation around moving magnetic domain walls and neglected in the conventional core loss calculation, are also Included in the proposed approach. In addi tion, the model is also capable of accounting for the stator skewing, if pr esent. The core losses obtained from the proposed approach are compared wit h those measured on an existing PM motor at several operating speeds, showi ng very good agreement.