Analytical Prediction of Cogging Torque for Spoke Type Permanent Magnet Machines

A generalized analytical field solution by conformal transformation is presented for calculation of no-load magnetic field distribution in the slot-less and slotted air gap of spoke-type permanent magnet (PM) machines. These analytical field solutions are used to predict the cogging torque of spoke-type PM motors. The computed cogging torque using the proposed method is compared with the results from 2D finite element analysis (FEA) in three application examples.