Design And Research On Low-speed And High-torque Permanent Magnet Synchronous Motor

The low-speed and high-torque permanent magnet synchronous motor connects with the load directly,eliminates the intermediate deceleration device,reduces energy consumption and equipment manufacturing costs and maintenance costs.Low-speed and high-torque permanent magnet synchronous motors have been widely used in various industrial fields,and have become one of the research hotspots in the field of motor,which has high scientific significance and practical value.Combined with the transmission characteristics and the operating environment of low-speed and high-torque transmission system,the structure and design characteristics of the stator and rotor of low-speed and high-torque permanent magnet synchronous motors are introduced in detail from the aspects of electromagnetic load,stator punching,armature winding,elimination of tooth harmonics,rotor structure and pole permanent magnets in this paper.On this basis,combining with the electromagnetic design method of the conventional permanent magnet synchronous motor,a low-speed and high-torque permanent magnet synchronous motor with rated power 30 kW,rated torque 1500N·m,rated speed187.5r/min and 32 poles was designed by means of iteration calculation according to the performance requirements of the motor.Using the electromagnetic design parameters of this motor,the finite element analysis model is established.The magnetic field distribution of the motor at different time with no-load and load were simulated respectively,and the output electromagnetic performance parameters such as electromagnetic torque and loss value of each part of the motor were calculated,and then the working efficiency of the motor was calculated.The eddy current loss of the surface-mounted magnetic pole permanent magnets of the low-speed and high-torque permanent magnet synchronous motor's rotor wasstudied.Through the analysis and finite element calculation of eddy current loss of permanent magnets,the factors affecting the numerical value of eddy current loss are defined.By changing the sizes of the magnetic pole permanent magnets,the calculation models of the permanent magnets with different widths and thicknesses were established respectively,and the eddy current loss values of permanent magnets with different sizes were calculated and the rule of eddy current loss variation with the size of permanent magnets were obtained,which provided an important basis to reduce the eddy current loss of the magnetic pole and avoid the demagnetization caused by temperature rise effectively.Finally,for the static eccentricity problem of the rotor with great influence on the overall performance of the motor,the influence of the rotor static eccentricity on the magnetic field distribution and electromagnetic performance are analyzed by simulating the transient field of the rotor of the low-speed and high-torque permanent magnet synchronous motor under different eccentricity rates.With the increase of the eccentricity rate,the variation law of the performance parameters of each motor is obtained,and the change of the radial electromagnetic force when the rotor is eccentric is calculated.Accurate calculation of the magnetic field distribution,analysis of electromagnetic performance and changes of electromagnetic force after rotor eccentricity can provide important reference for calculating the temperature rise of motor under eccentricity fault,and provide guarantee for avoiding major safety accidents during motor operation.