Number of Poles Pairs Effects on Electromagnetic Torque Permanent Magnet Synchronous Motor

In this paper, study of correlation between electromagnetic torque and pole pairs numbers using one-dimensional nonlinear model PMSM have been implemented. It's shown that for the overall range of motor's flange diameters from 63 to 165 mm there is a number of pole pairs, providing the maximum electromagnetic torque and the maximum value of magnetic flux density in the airgap. At the same time, the optimal number of poles for maximum magnetic flux density does not correspond to the optimal number of poles obtaining for the maximum electromagnetic torque. This fact excludes the possibility of optimizing the dimensions of the motor according to the criterion of the maximum magnetic flux density in the airgap with save the maximum value of electromagnetic torque. Thus, the number of pole pairs for the different dimensions of the motors must be chosen from the conditions for finding the maximum electromagnetic torque.