A method for non-linear analysis and calculation of torque and radial forces in permanent magnet multiphase bearingless motors

In this paper an algorithm for non-linear magnetic analysis of surface-mounted permanent-magnet machines is presented. It is based on the equivalent magnetic circuit method and can be used as a useful design and computing tool. The duplication of an elementary cell of the machine allows building whatever typology of windings and ampere-turns distribution in a pole pair. The direct modification of electrical and dimensional parameters and the analysis of rotor movement in sinusoidal multiphase drives are the most important features of this algorithm. The proposed analysis determines the flux density distribution in the machine, the magnetic energy and co-energy, the torque and radial forces in presence of non-linear magnetic materials. The accuracy of calculations is verified by comparing the obtained results with FE analysis, in respect of which the algorithm allows a simplified machine description, reduced computation time but with very similar results.