Study On Poles Optimization And Magneto-thermal Of Surface-mounted Permanent Magnet Synchronous Motor

Since the advent of the Surface-mounted permanent magnet synchronous motor,it has been widely applied in production and life due to its superior performance and many advantages.Therefore,the design and optimization of the permanent magnet motor are particularly important and have more practical significance.This dissertation studies a surface-mounted permanent magnet synchronous motor with an inner rotor of 10 poles and 4.5 k W rated power,then discusses the basic principles and various structural designs of permanent magnet synchronous motors and analyzes their advantages and disadvantages.In order to solve the problem of material waste in the manufacture of the traditional rotor arc magnetic pole structure,the dissertation adopts the method of making the tile-shaped permanent magnet into a rectangle and installing the metal pole shoes on the permanent magnet.The cogging torque of Surface-mounted permanent magnet synchronous motors will cause speed fluctuations,resonance and noise,which limit the better development and application of permanent magnet motors.In order to weaken the cogging torque,the magnetic pole structure is optimized.By means of formula analysis and theoretical derivation,the metal pole shoe of the magnetic pole is cut.The eccentric treatment method is adopted to establish the cutting size models of pole shoes with eccentricity of 0mm,6mm and 10 mm,then the optimal cutting size is obtained by comparing the simulation results.The electromagnetic performance of the motor under different pole shoe eccentricity is studied to prove the feasibility of the magnetic pole optimization method.The various loss of the motor is also an important factor to be considered in the design optimization,so the cause and mechanism of stator core loss,winding copper loss and eddy current loss are mainly analyzed,and a calculation model is established.The finite element method is used to calculate the loss of each part,and the time-domain loss curve is obtained to reveal the change rule of the loss under each motor model.In order to reduce the eddy current loss of the metal pole shoes,the method of circumferential cutting into segments is proposed,and the validity of the method is verified by finite element method.In order to clarify the influence of the change of motor pole structure on the temperature rise of each part,according to the basic theoretical knowledge of heat transfer,the finite element simulation method is used to establish the equivalent thermal model of the motor,calculate the temperature field of each main part of the motor,and study the distribution of the temperature field of the motor.When the temperature of the permanent magnet rises beyond its Curie temperature,it is easy to cause the magnetic weakening or demagnetization of the permanent magnet.Therefore,this dissertation focuses on the study of the change rule of the temperature field of the permanent magnet.