Hybrid Model Combining Analytical And Finite-element Model For The Calculation Of The Fields Of Permanent-magnet Machines

Permanent-magnet machines are widely used in daily life and industrial applications due to their high efficiency,energy saving,and reliability.With the broadening of applications,the requirements for motor design and optimization are also more diverse.In order to reduce the time spent on machine design and optimization,it is necessary to search electromagnetic field modeling methods that are fast and accurate.This thesis takes the electromagnetic field distribution of permanent magnet machines as the research object.An analytical subdomain model is established.And a new two-dimensional hybrid model is proposed combining subdomain and finite element method(FEM)taking magnetic saturation into account.Based on Maxwell’s equations,the theory and calculation process of the subdomain are derived.The analytical subdomain model of the surface-mounted permanent-magnet synchronous motor is established and the results are compared with the results of finite element method.The comparison shows that the analytical subdomain model gives accurate results and uses a short computation time.For the hybrid model,the theory and calculation steps of finite element method are derived.The subdomain method and the finite element method are directly coupled by processing the boundary conditions at the junction of the two regions.The hybrid model combines the advantages of the subdomain method and of finite element method.It can calculate the magnetic field distribution in the stator core region.It considers the saturation effect of the electromagnetic field and the influence of the stator’s parallel teeth.In the structure modelled in this thesis,the number of equations generated by the hybrid model is reduced by more than 50% compared with finite element method.Compared with subdomain,the error of the air gap flux density is reduced from16% to 5.6% in the no load case,and from 24.7% to 7.4% in the on load case.Finally,the content of this article is summarized and the direction for future improvement is proposed.