Complete Subdomain Model for Surface-Mounted Permanent Magnet Machines

This paper presents a complete and improved analytical subdomain model for predicting the magnetic field distributions in surface-mounted permanent magnet (PM) machines accounting for tooth-tips and slotting effect, during open-circuit, armature reaction and on-load conditions. The model analytical derivations and field solutions are extended to overcome the shortcoming in previous subdomain model, and can be applied on PM machines having any combination of slots and pole numbers and any magnetization pattern in the magnets. This model is initially derived based on Laplace's and Poisson's equations in polar coordinates by the separation of variables technique in four subdomains, i.e., magnet region, airgap, winding slots, and slot-openings. The field solutions in each subdomain are obtained by applying the appropriate boundary conditions and interface conditions. Finite element analysis (FEA) is later deployed to validate the analytical results in surface-mounted PM machine having a non-overlapping winding arrangement. The results show that the proposed analytical model can accurately predict the magnetic field distributions in each subdomain in PM machines.