Research On Design Of Permanent Magnet Servo Motor For Joint Robot

The independent research of permanent magnet(PM)servomotor for joint robots,with high performance and high economic effect,is of great benefit to improve the technical and innovation ability of robot industry,which accelerates the nationalization of robots and enhances the core competitiveness of the domestic brands.This thesis is aimed at the design and analysis of permanent magnet servomotor for joint robots.The work are carried out as following.Firstly,an overview of current research of PM servomotor is presented by comparing products from domestic and overseas companies,which summarizes the disadvantages of domestic servomotors and several methods to reduce the torque ripple.The structure and dimensions of PM servomotor are investigated in terms of materials,pole-slot combination and the rotor structure.Two required design options are quickly proposed with magnetic circuit method.Then,comparing the electromagnetic performance of two options by finite element method(FEM),it has come to a solution that the 8-pole 12-slot designed servomotor is determined.The effect of machining error on motor performance is studied.By defining the parameter sensitivity and setting up a finite element parametric modeling platform,the independent sensitivity of ten motor size parameters is calculated against back-EMF,average torque and torque ripple.Meanwhile,it gives the comprehensive sensitivity analysis of slot width and pole arc coefficients of magnets,which verifies that the designed motor is in an insensitive region.In addition,the influence on static and dynamic eccentricity is also performed by FEM.It is found that back-EMF is hardly affected by eccentricity,while it causes more torque ripple and eddy current losses in PM.The temperature rise of the designed motor is analyzed.By calculating the heat dissipation coefficient and the contact thermal resistance between the various parts of the motor,both 3D FEM and LTPN method is utilized to analyze the temperature rise in designed motor.According to the design scheme,a prototype machine is manufactured.The drag method is used to test the back-EMF,cogging torque,the torque and temperature under rated condition.Compared with the simulation results,the error in back-EMF is not more than 4%,and the average torque and torque ripple caused by self-structure design is less than 9%.After 80 minutes,the motor case temperature is stable with a rise of 72.7 ?,which has an error of 2.84% against the simulations.Owing to the eccentricity between the stator and rotor,the torque ripple of prototype machine becomes larger,along with the eddy current in PM,which causes an increase in temperature rise.