Cogging Torque Minimization of Surface-Mounted Permanent Magnet Synchronous Machines Using Hybrid Magnet Shapes

This paper deals with the magnet pole shape design for the minimization of cogging torque in permanent magnet synchronous machines (PMSM). New shapes of permanent magnet are proposed. The magnet shape is modeled analytically by a set of stacked and well dimensioned layers relatively to the height and opening angle. The final shape of magnet is configured by using three models in view of obtaining lower magnitude of cogging torque. A 2-D exact analytical solution of magnetic field distribution taking into account the shape of magnet, the irregular mechanical thickness of air-gap and semi-closed stator slots is established. The influence of motor’s parameters such as the number of stator slots per pole and per phase and PM’s magnetization on cogging torque is discussed. Analytical results are validated by the static finite-element method (FEM).