Effect of pole and slot number changes on the performance of a surface PM machine

The effect of changing the number of slots and poles on the performance of a particular surface permanent magnet (SPM) machine design is studied in detail using finite-element analysis. This includes examining the back-EMF, the open-circuit/full-load power losses, the cogging/ripple torque, and the field-weakening performance. The simulation results are compared with the expected relationships to provide electric machine designers useful insights on the effect of the number of slots and poles on the performance of surface PM machines.