Design Of External Rotor Permanent Magnet Synchronous Motor For Belt Conveyor And Its Cooling System

As the most important conveying equipment of coal in coal mine,the belt conveyor’s smooth and efficient operation has a crucial influence on coal production.The traditional structure of belt conveyor generally adopts the structure form of three-phase asynchronous motor with reducer,its overall efficiency is low,consume a lot of electric energy;The external rotor permanent magnet synchronous motor is used to directly drive the belt conveyor,subtract the intermediate transmission structure,reduce the volume of the whole system,but also reduce the failure rate of the whole system and improve the work efficiency.However,the use of external rotor permanent magnet synchronous motor to directly drive the belt conveyor faces many technical difficulties.On the one hand,it is necessary to reduce the cogging torque of the motor,on the other hand,it is necessary to improve the belt directly covering the surface of the motor resulting in heat dissipation difficulties.In view of the above technical difficulties,this thesis designs an external rotor permanent magnet synchronous motor with 75 k W,60r/min and groove rotation <0.5%,and designs a reasonable cooling system to ensure stable operation for a long time.The specific research content of this thesis is as follows:Firstly,the principle of groove torque is analyzed.Taking an external rotor permanent magnet synchronous motor as the research object,the influence of the main pole Angle of the combined magnetic pole on the tooth groove torque is studied.Based on the combined magnetic pole,the combined eccentric magnetic pole with auxiliary magnetic pole is proposed,and the influence degree of the combined magnetic pole and the combined eccentric magnetic pole on the tooth groove torque is compared.The influence of the thickness of the edge magnetic pole and the cutting Angle on the groove torque is studied.The influence of the number of auxiliary slots on the motor slot torque is studied.By comparing the torque weakening effect of the tooth groove under different methods,it is found that the cutting magnetic pole has the most obvious effect on the torque weakening of the tooth groove.Secondly,an external rotor permanent magnet synchronous motor with 75 k W,60r/min and slot torque <0.5% is designed based on the angular pole scheme.The main dimensions of the motor are preliminarily calculated.Comparing the advantages and disadvantages of different magnetic circuit structures,the surface mounted rotor magnetic circuit structure with smaller torque ripple is selected.The tooth groove torque of the motor with three different pole grooves is compared.Key motor parameters such as motor winding,air gap length,magnetization direction length of permanent magnet were selected to form a motor design scheme,and the performance of the motor is simulated and analyzed.All the indicators of the motor met the design requirements of the motor.Finally,in view of the difficulty of heat dissipation of the motor in this thesis,a threedimensional model of the motor is established and the loss of each part of the motor is calculated.The cooling system is designed for the motor.The cooling effect of the motor under the circumferential spiral channel and annular multi-parallel channel is simulated and analyzed,and the conclusion that the circumferential spiral channel has better cooling effect on the motor is obtained.And the cooling channel section of different length-width ratio and inlet water velocity simulation analysis,determine the appropriate parameters of the cooling system,complete the final design of the motor cooling system.