Calculation And Analysis Of3-D Temperature Filed For The Solid Rotor In Line-Start High-Voltage Permanent Magnet Synchronous Motor

High-voltage permanent magnet synchronous motor (PMSM) has moreadvantage than the induction motor, such as higher efficiency, higher powerfactor, lower operation current, lower cable amount, lower cable loss, higherreliability, more remarkable power-saving efficiency and so on. It is of greatstrategic significance for the national policy of energy conservation andenvironmental protection and the sustainable development of national economy.But when the high-voltage PMSM works, it could cause the problem of heatexchange between stator and rotor more complex, and the heat dissipation abilityof the rotor gets worse, which will lead to the higher rotor temperature and thedemagnetization of permanent magnet material. Specially, the loss of solid rotoris so big that built-in permanent magnet material loses magnetism. That willimpact the performance of motor, operating efficiency and service life. So it isvery important to calculate the rotor temperature field. In this paper, the mainresearch is about the problems that the3-D temperature field of solid rotor ishard to calculate accuracy and how to lower the temperature rise of the solidrotor.Firstly, a315kW Line-Start High-voltage PMSM is taken as example, the2D transient electromagnetic field model of the machine is established. Eddycurrent losses of the solid rotor are calculated using the finite element methodwith some reasonable assumptions. Distribution of air-gap magnetic density andits harmonics is given. After that, the influence of air-gap change onelectromagnetic parameters is researched. That could provide theoretical basis fortemperature field calculation of PMSM. Secondly, to solve the problem, that the solid rotor has higher loss, heat andthe demagnetization of permanent magnet material, the method for reducingtemperature of permanent magnet in the solid rotor is studied by changing motorstructure. The influence of insulating material on the permanent magnet side onthe temperature is analyzed, the temperature differences between the rotor barsand two end-faces in different schemes, and those can provide solution to lowerthe temperature of permanent magnet.Finally, based on the study above, this paper chooses an optimizationscheme to analyze the influence of insulating material on heat insulation ofpermanent magnet, and research the relation between dielectric medium ofinsulation and temperature rise of permanent magnet emphatically. Meanwhilethe influence of dielectric material on temperature in the solid rotor is studied.The results could provide reference for the optimization design of Line-StartHigh-voltage PMSM.