Thermal Analysis Of New Permanent Magnet Motors And Development Of The Integrated Simulation Flatform

Permanent magnet electrical machine otters the merits of high power density, high efficiency and robust structure, attracting extensive research and applications in electric vehicles, wind power generation and other industrial aspects. But with the needs of the development of society, the motor capacity is increasing with the temperature all the time, which poses challenges to its reliability. The temperature rising of permanent magnet electrical machine is mainly manifested in the following aspects:increasing the winding resistance and additional copper losses, increasing heating of the motor, causing electrical machine insulations aging rapidly which will reduce the service life of the motor and increase the risk of short circuit, increasing the motor thermal deformation, vibration and noise, etc. For permanent magnets, the excessive temperature rising will seriously affect the magnetism performance and the motor running performance, even cause irreversible demagnetization and permanent magnet motor damage.The finite element (FE) control equation considering the anisotropic heat conduction of the three-dimensional temperature field is established based on the finite element program generation (FEPG) system, allowing a variety of materials with different main axes of heat transfer from the selected coordinate system. Copying the contact thermal resistance boundary coordinates and increasing corresponding nodes, the influence of the contact thermal resistance on the motor temperature distribution is taken into consideration, which can avoid the difficulties of tiny geometry entity modeling, grid subdivision and calculation accuracy problems. Only adding one node, the convective heat transfer between the air gap and the stator as well as the rotor can be calculated in the finite element analysis by modifying the stiffness matrix of boundary element. According to the principle of conservation of energy, the minimum stator and rotor symmetry unit is modelled. The FE method thermal model of a three-phase flux switching permanent magnet (FSPM) motor is established as an exemplification. The temperature field simulation results and parameter sensitivity analysis have proved the accuracy of the model.Based on the C++ Builder and FEPG system, three-dimensional steady state thermal field simulation platform is developed combined with the professional preprocessing and post-processing software GID. It can minimize the geometry model and consider the influence of anisotropic thermal conduction and thermal contact resistance in the aforementioned FSPM motor thermal field, which has certain reference significance for the design and optimization of motor with extensive applicability.Finally, using the hollow cylinder thermal resistance unit and the cube T thermal resistance unit, the temperature field of the three-phase FSPM motor is modelled and analyzed with equivalent thermal circuit method. The thermal conduction resistances of each unit and the boundary heat transfer thermal resistances are calculated and described in detail. According to the principle of thermal equilibrium, temperature field linear equilibrium equations of each node are listed and solved by the column principal component gauss elimination method in the paper. The accuracy of the model is certificated by average temperature distribution of the main parts in the researched motor compared with finite element method and experimental results.