| Scraper conveyor is one of the key equipment of fully mechanized mining,and its safe and stable operation is the key to the normal operation of coal mining.The drive system is the core part of the scraper conveyor.It adopts the transmission mode of low-speed and high-torque permanent magnet motor to directly drive the scraper conveyor,which has the advantages of high transmission efficiency,fast dynamic response and high reliability.However,due to the complex underground environment of coal mine,bad working conditions such as coal wall caving and scraper chain jamming often occur,which has a great impact on the scraper conveyor and seriously affects the dynamic characteristics of permanent magnet direct drive system.Therefore,it is necessary to study the dynamic characteristics of permanent magnet direct drive scraper conveyor under impact load,and control the chain tension to reduce the tension fluctuation and accident rate.In this thesis,theoretical modeling and simulation analysis methods are used for research.The main research contents include:Firstly,the finite element model of the scraper conveyor is established based on the discrete element method and the Kelvin-Vogit model,the dynamic equation of the scraper conveyor is deduced,and the finite element model parameters,running resistance and tension of the scraper conveyor are deduced.The force was analyzed,and the dynamic model of the scraper conveyor was established using AMESim.The parameters and vector control strategy of permanent magnet synchronous motor are determined,the Simulink model of vector control of permanent magnet synchronous motor is established,and the machine electric coupling model of permanent magnet direct drive scraper conveyor is established by using the joint simulation interface of AMESim and Simulink.Secondly,using the established mechanical electrical coupling model of permanent magnet direct drive scraper conveyor,the dynamic characteristics of the scraper conveyor under unsteady coal falling,chain jamming and chain breaking conditions are simulated and analyzed.The results show that the variation laws of tension and speed of the scraper conveyor are basically the same,the permanent magnet direct drive system responds quickly to load changes,and large load changes have a great impact on the stability of the drive system,The stability of permanent magnet direct drive system should be improved from the perspective of scraper conveyor tension control and motor drive optimization.Finally,based on the chain tension control principle of scraper conveyor,the hydraulic system is designed and the simulation model is built by AMESim.The fuzzy PID controller is designed by MATLAB / Simulink software.The fuzzy PID controller is applied to the tension control system.The joint simulation shows that the tension control system reduces the tension fluctuation and power imbalance of scraper conveyor under impact load.Compared with conventional PID control,Fuzzy PID control is more suitable for the tension control of scraper conveyor under impact load.The thesis has 60 pictures,9 tables,and 82 references. |
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