Design And Demagnetization Research Of 55kW Low-speed And High-torque Permanent Magnet Synchronous Motor

For high energy-consuming industries such as port loading and unloading,coal production and raw material processing,the traditional "asynchronous motor + gearhead" structure of power transmission equipment is usually adopted,which has the disadvantages of complex structure,low transmission efficiency and high maintenance cost.In the context of advancing energy conservation,emission reduction,and transformation and upgrading,technical improvements and transformation and upgrading of equipment are urgently needed.Aiming at the problems of the "asynchronous motor + gearhead" transmission mechanism,this thesis studies the key technical issues in the direct drive or semi-direct drive system of a low-speed high-torque permanent magnet synchronous motor,and designs and optimizes a 55 k W low-speed high-torque permanent magnet synchronous motor Electric motor.The main work is as follows:First,introduce the background and significance of the research of this subject,and analyze the development status of low-speed and high-torque permanent magnet synchronous motors by domestic and foreign scholars and experts and the current status of demagnetization of permanent magnet motors.Furthermore,according to the design calculation method and technical requirements of traditional motors,the low-speed high-torque permanent magnet synchronous motor studied in this topic is calculated for various parameters and material selection,including stator size and structure design,the design of the stator slot and the permanent magnet,And the selection of pole-slot coordination,and establish a motor model in the ANSYS/RMxprt software environment to verify the rationality of the design data,and finally determine the preliminary parameters of the motor.Secondly,because the efficiency of the initially designed motor does not meet the design requirements and the cogging torque is large,the genetic algorithm is used in the finite element software to perform multi-objective optimization,and then the optimized motor model is under no-load and loaded conditions.Perform performance simulation analysis,including motor flux leakage,vector flux density distribution,magnetic field line distribution,stator core magnetic density,air gap magnetic density,cogging torque,motor magnetic density cloud map,rated torque,efficiency,etc.Comprehensive analysis of the motor design is more reasonable.Then,based on the demagnetization problem of permanent magnets,a finite element demagnetization simulation idea was proposed to verify the demagnetization of the motor under severe working conditions.Firstly,finite element is used to simulate severe working conditions,and the minimum magnetic density value position is obtained by simulating the magnetic density cloud map of the permanent magnet of the motor.After that,the minimum magnetic density processing permanent magnet work point measurement,and the permanent magnet degaussing recovery line.The simulation result found that the working point of the permanent magnet is lower than the inflection point,and it fails to return along the BH curve,but rises along the new recovery curve.Therefore,the motor in this paper will undergo irreversible demagnetization under severe working conditions.Finally,in order to improve the anti-demagnetization ability of the motor and improve the performance of the motor,this paper optimizes the motor in terms of permanent magnet size and air gap length,so that the cogging torque,anti-demagnetization ability and efficiency of the optimized motor model are significantly improved.