| Belt conveyor is often used for coal mining tools,the traditional conveyor structure is usually the use of asynchronous motor coupled with coupling and reducer,such a way of low efficiency,high failure rate,transmission links,rotor permanent magnet direct drive system is characterized by high efficiency,low failure rate,small space.Belt conveyor monitoring system is directly related to mine safety and production efficiency,the traditional monitoring system has many faults,can not judge the motor internal faults.In this paper,the belt conveyor with external rotor permanent magnet direct drive motor electromagnetic design,by comparing the electromagnetic scheme with different pole groove to weaken the groove torque,by selecting different slot width and air gap length to weaken the permanent magnet eddy current loss,at the same time external rotor permanent magnet direct drive system remote monitoring design.Mainly for the motor inter-turn short circuit,permanent magnet demagnetization,rotor eccentricity,deviation,coal pile,skid,tear belt fault research,analysis caused by the fault of permanent magnet motor current,voltage changes to judge the fault type,to achieve real-time monitoring of the external rotor belt machine.According to the design requirements,the first external rotor permanent magnet direct drive motor electromagnetic design.The most suitable electrode groove fit was determined by comparing the tooth groove torque of the electromagnetic scheme under three kinds of electrode groove fit,and the electromagnetic performance of the optimized motor was analyzed by finite element simulation.The results of no-load back potential,magnetic density waveform and torque fluctuation with different loads of the prototype were obtained,which showed the rationality of electromagnetic design.In terms of temperature field,the first analysis of the heat source,compared to the same scheme under different air gap length and the influence on permanent magnet eddy current loss,slit width is derived to solve the coefficient of heat transfer,the parts using magnetic heat coupling analysis method to solve each part temperature of the motor in the rated load condition,the simulation results can be seen that the motor under rated the steady state temperature distribution is normal.Aiming at the problem of monitoring the inter-turn short circuit fault,the mathematical model of the motor when the inter-turn short circuit occurs in the stator is established first,and its unique fault characteristics are deduced.The amplitude of the second harmonic of the cross-axis voltage is selected as the fault signal.Aiming at the monitoring problem of permanent magnet demagnetization fault,the changes of air gap density,flux and current in local demagnetization and uniform demagnetization are studied respectively.The permanent magnet flux is selected as the fault signal in uniform demagnetization,and the harmonic amplitude of specific current frequency is selected as the fault signal in local demagnetization.Aiming at the eccentric fault,the change of air gap flux density and current when the fault occurs is studied,and the amplitude of harmonic of current specific frequency is selected as the fault signal of rotor eccentricity.The fault diagnosis module based on FFT algorithm is used for data processing of the above three types of motor internal faults.In view of coal heap fault,the relationship between load and current is analyzed,and then the method of current transformer setting threshold is used to judge.Establish the overall remote monitoring system control block diagram,select S7-1200 model PLC as the control core,analyze different data transmission modes,select the most suitable for Ethernet system Modbus protocol.Automatic monitoring,manual start and stop,overtemperature treatment,belt tensioning treatment,A/D conversion,indicator light,fault diagnosis program programming,the establishment of MCGS configuration,simulation of mine conditions,simulation results prove the correctness of the program. |
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