Research On The Key Magnetothermal Problems Of Interior Permanent Magnet Synchronous Motor

Compared with induction motors,permanent magnet synchronous motors have many advantages such as high efficiency and low loss.However,due to their own structural factors,permanent magnet synchronous motors are affected by cogging torque.The cogging torque of the motor will cause the unstable output of the motor torque,which causes vibration and noise inside the motor,which affects the stability of the motor.During the high-speed operation of the motor,the temperature rise of the motor will cause damage to the insulation of the motor winding.If the internal temperature of the motor is too high,it will easily cause the fixed glue to fall off and cause the magnetic steel to sway,resulting in magnetic leakage,and the oscillation will damage the permanent magnet itself.Affect its magnetic problems.In addition,if the eddy current loss of the permanent magnet is too large,the temperature of the permanent magnet will be too high,causing the permanent magnet to seriously demagnetize,affecting the normal operation of the motor.This paper takes a 5k W interior permanent magnet synchronous motor as the research object,and studies the cogging torque and temperature field of the motor.Aiming at the problem of permanent magnet motor torque ripple caused by cogging torque,the forming principle of cogging torque is analyzed,the analytical formula of cogging torque is derived according to the energy method,and the influencing factors affecting the cogging torque of interior permanent magnet synchronous motor are studied.The two-dimensional transient field finite element model of the 48-slot 8-pole interior permanent magnet synchronous motor was established,and the structure improvement of the 48-slot 8-pole motor was carried out with pole-slot coordination,V-shaped magnetic steel angle and rotor surface eccentric.The two-dimensional transient field simulation results of the 9-slot 8-pole interior permanent magnet synchronous motor combined with the three are compared with the theoretical analysis results to demonstrate the weakening effect of the improved scheme on the cogging torque.The installation method of the permanent magnet of the interior permanent magnet synchronous motor has been improved.A series of structural components such as shrapnel and buffer groove are installed on the inner wall of the rotor permanent magnet slot to achieve the reliability and firmness of the permanent magnet.The influence of the improved scheme on the performance of the motor was studied,and the induced electromotive force,torque fluctuation,magnetic field distribution and various losses of the motor before and after the improvement were calculated and compared.The three-dimensional temperature field simulation model of the interior permanent magnet synchronous motor before and after optimization is established,and the heat source is set according to various losses obtained by the two-dimensional transient field.The temperature distribution of the motor model before and after optimization is obtained by finite volume method.The influence of the optimization scheme on the temperature rise of the interior permanent magnet synchronous motor is analyzed,and the influence on the temperature of the permanent magnet is mainly studied.