Magnetic Field Prediction for Line-Start Permanent Magnet Synchronous Motor via Incorporating Geometry Approximation and Finite Difference Method Into Subdomain Model

A hybrid computing method for predicting the magnetic field of line-start permanent magnet synchronous motor is presented in this article. The vector magnetic potential (VMP) is selected to be the primary objective of the calculation. For the convenience of expressing the VMP in the polar coordinate system, the topology of each motor component is replaced by the assembly of radial sectors. Along with the topology approximation, the VMPs of the stator and air gap are determined analytically, whereas the finite difference method is used to calculate the VMP of the rotor with the eddy current. Combining the numerical technique with the analytical method not only enables solution efficiency higher than using the former one merely but also keeps away from the inefficacy of using the latter one solely to predict magnetic fields with complex geometry. The presented approach is validated by the finite-element analysis and prototyping tests.