Research on fast and accurate calculation method of cogging torque

Abstract

The cogging torque in the interior permanent magnet synchronous machine(PMSM) leads to mechanical resonance, vibration, and noise, which would reduce the control accuracy of the machine. It is important to calculate the cogging torque of the interior PMSM. Up to now, there is no accurate calculation method of the cogging torque for the interior PMSM, and the accurate calculation relies on the Finite Element Method (FEM) which consumes long time. In view of this situation, a fast and accurate calculation method of cogging torque in interior PMSM is proposed in this paper. The distributions of air gap flux density with different armature structures have been obtained by FEM, then from which the air gap magnetomotive force and effective air gap length are deduced. Applied the Fourier expansion, the effective harmonics can be solved and the cogging torque would be calculated with analytical formula. Compared with the FEM result, the accuracy of the calculation method has been verified.