Analytical Modeling And Calculation Of Magnetic Fields In Permanent-Magnet Machines

With the characteristics of high efficiency and reliability,the application range of permanentmagnet machine is becoming wider.Meanwhile,the requirements for its design,optimization and research methods are also increasing.Accurate calculation of the magnetic field distribution of the permanent-magnet machine is the key to the follow-up research.The calculation methods of machine magnetic field are divided into numerical methods and analytical methods.In recent years,the analytical method of permanent-magnet machine magnetic field calculation has attracted much attention.It's advantages are fast modeling and clear physical meaning.This thesis focuses on the modeling of the magnetic fields of permanent-magnet machines using a subdomain method.A hybrid analytical method is also proposed.For the subdomain analytical method,the subdomain analytical models of an inner-rotor surface-mounted permanent-magnet machine and an outer-rotor spoke-array Vernier permanentmagnet machine are established respectively.Based on magnetic vector potential,the general solution of complex Fourier series in each domain is derived.The air-gap magnetic flux density and electromagnetic properties are calculated in the validated machines and verified by finite element method and prototype experiment.The symmetry of machine structure and harmonic prediction are used to simplify the computation and improve the computational efficiency of subdomain method.To overcome the limits of subdomain method,a hybrid analytical method coupling of subdomain method and magnetic reluctance network method is proposed to model and calculate the surface-mounted permanent-magnet machine.According to the existence of ferromagnetic medium,the solving area of the machine is divided into two parts.The subdomain method and the magnetic network method are respectively used for modeling,and the two models are coupled by using the boundary conditions.Two machines are modeled and calculated by using this method,and the air-gap magnetic flux density of no-load and loaded conditions are calculated respectively.The models are verified by finite element method,and the accuracy of the method is confirmed.Finally,the main contents of this thesis are summarized and the future research direction is looked forward.