Numerical method for calculating cogging torque by simulation of actual measurement

For accurate calculation and effective reduction of cogging torques,a new method of the numerical simulation is proposed based on the standard measurement principle of the cogging torque.The model considers the influences of slot opening,core saturation,moving and time-varying electromagnetic filed.The agreement of the calculation results with the measured data shows that this method is correct and effective.The cogging torques of 9 permanent magnet DC motors(PMDCMs) with different matching numbers of poles and slots are calculated by the finite element method.The results explain and verify that the cogging torque could be reduced obviously when the least common multiple of the numbers of poles and slots reaches the maximum value.