| The performance of the scraper conveyor directly affects the production efficiency and mining cost of the coal mine.,the traditional scraper conveyor drive system is mainly asynchronous motor with reducer used together,but the traditional drive method has certain drawbacks.In this thesis,a semi-direct drive drive device of permanent magnet motor and spur gear reducer is proposed,and the permanent magnet motor is used as the driving source to improve the driving mode of scraper conveyor.Under the new structural mode,the dynamic characteristics of the gear system will directly affect the reliability of the permanent magnet semi-direct drive transmission system of the scraper,so the gear bending coupling model is established to study the nonlinear dynamic characteristics.Moreover,considering several common faults of gears,the dynamic characteristics of them are analyzed.In order to ensure the high reliability of the permanent magnet semi-direct drive scraper conveyor system,this thesis studies the dynamic characteristics of the permanent magnet semi-direct drive scraper conveyor system under unsteady working conditions through theoretical mathematical modeling,simulation analysis and experimental verification for the stuck chain and broken chain conditions.The main work includes:(1)The permanent magnet synchronous motor was studied and analyzed,the structure type of the permanent magnet synchronous motor was determined,and its basic mathematical model was established;The vector control method of_di(28)0 was determined,and a double closed-loop control system of speed loop current loop under load of permanent magnet synchronous motor was constructed.According to the characteristics of the mechanical composition structure of the scraper conveyor and the sprocket chain and link drive system,the dynamic model of the double-end drive scraper conveyor was constructed by drawing on the finite element analysis method.Finally,according to the calculation,the permanent magnet synchronous motor and reducer are selected and designed.(2)According to the mass concentration method,the bending and torsion coupling model of the gear is established,and the simulation is carried out in the MATLAB software,and the bifurcation diagram,Lyapunov index diagram,phase diagram,Poincare cross-sectional view,etc.are drawn by the Runge-kuta method;The influence of parameters such as excitation frequency,meshing stiffness ratio and bearing clearance on the vibration characteristics of the system was studied.Then,on the basis of the normal gear,according to several common gear failures,it is mathematically modeled,and then its dynamic characteristics are studied by using MATLAB simulation.(3)From the overall perspective,the dynamic model of the scraper conveyor,the mathematical model of each module of the reducer and the permanent magnet synchronous motor are first established,and the global electromechanical coupling dynamic model of the permanent magnet semi-direct drive scraper conveyor is constructed by linking the parameters such as speed and torque.Simulink was used to construct the electromechanical coupling model,apply specific boundary conditions,and study the dynamic characteristics of the system in the steady-state condition,the stuck chain condition and the broken chain condition under full load.(4)Drawing on dynamic load simulation technology and adopting the method of parameter equal scale reduction,according to the existing permanent magnet synchronous motor and magnetic powder dynamometer system in the laboratory,the software and hardware of the frequency conversion controller were designed,and a small proportion equivalent load simulation test bench was built.The simulated load torque under the three working conditions of full load steady state,broken chain and stuck chain is scaled by parameters,and loaded by the magnetic powder dynamometer,and finally a small proportion equivalent load simulation test bench dynamic characteristic curve is obtained.The experimental results are compared with the simulation results to verify the correctness of the mathematical model and simulation model of the semi-direct drive electromechanical coupling system of permanent magnet motor.This thesis has 54 figures,4 tables,and 100 references. |
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