Research On Key Technology Of Mine Explosion-proof Permanent Magnet Direct Drive Motor

Compared with the traditional drive system of asynchronous motor acceleration and decelerator,the permanent magnet direct drive system has the advantages of short transmission chain,high transmission efficiency and high operation stability,so it is more accordant with the safe and efficient development requirements of the coal mine industry.The direct drive permanent magnet motor is relatively larger.At the same time,due to the special working conditions in the coal mine,explosion-proof performance is required,so the design work is relatively complicated.Therefore,some key technical problems of some mine direct drive permanent magnet motors,such as slot/pole combinations,cogging torque optimization,temperature,and explosion-proof performance,have been studied and analyzed in this thesis.In terms of electromagnetic design,first of all,the slot/pole combinations of the motor are studied.The distortion rate of the back-EMF waveform of the motor and torque fluctuation under different slot/pole combinations are compared and analyzed.After determining the slot/pole combination,the Taguchi optimization algorithm is used to optimize the cogging torque,no-load back-EMF waveform distortion rate,average value of the magnetic isolation bridge width,magnetic isolation bridge thickness,stator slot width and uneven air gap.The result is optimized and verified by finite element simulation.Finally,the application of forming windings to improve the full slot rate,which can reduce the size of the motor and increase the torque density has been quantitatively calculated,and then its disadvantages were analyzed.In terms of temperature field and cooling structure,the cooling structure of the motor is first designed according to Newton's heat dissipation law and the relationship between Reynolds number and fluid state.Then,the heat source of the motor is analyzed,and the relationship between the cooling coefficient of cooling water and the flow rate is deduced.The analysis method solves the temperature distribution of the motor.From the simulation result,it is shown that the axial water-cooling structure of the casing is reasonably designed,and the temperature distribution of each part is normal under the rated steady-state operation and shortterm overload operation.The motor can run stably and efficiently for a long time.In terms of motor flameproof performance analysis,first of all,the gaps of the flameproof joint surfaces of the motor casing are calculated according to the actual design,the threedimensional model of the shell is created,and the explosion process of the motor is simulated by the static finite element simulation.The mechanical deformation of the surface is analyzed,and the mechanical structure which does not meet the requirements is modified.The modified static simulation results show that the surface of the flameproof enclosure of the motor is elastically deformed after being subjected to force,and the flameproof performance of the motor will not be affected.The maximum value of the elastic deformation of each flameproof joint surface can still meet the flameproof requirements after superimposing the processing tolerance of the workpiece.Based on the design and analysis,a prototype is developed,and a experiment platform is set up to carry out no-load experiment,reverse drag experiment,load and temperature rise experiment on the prototype.The experimental results also further verify the correctness of the research content,and have certain reference value for the future design work of mining explosion-proof direct drive permanent magnet motors.