| According to the status of China's energy resources,coal as the main energy source will not change for a long time.Mining mechanization is the necessary technical means for the coal industry to increase production,improve productivity,the working environment and ensure safe production.With the continuous improvement of coal resource extraction efficiency and comprehensive utilization rate requirements,and the increasing call for industrial energy conservation and emission reduction,the performance higher requirements of the drum type shearer in terms of power,efficiency,reliability and failure rate are proposed.Further research is needed on the efficient control system of the drum shearer including the drive components,transmission mechanism,control system,high reliability and less transmission chain structure design and complex electromechanical system integration.Combined with the development of permanent magnet materials and power electronics technology,high-power permanent magnet synchronous motor(PMSM)and its speed control system are the development direction of mechanical drive and transmission,and research on the drum shearer driven by high-power PMSM is to solve reliable transmission problem.The PMSM has the characteristics of low speed and large torque,so the intermediate reduction transmission mechanism has a smaller transmission ratio.In the severe working condition,the teminal load has a larger impact load on the reduction transmission mechanism and the PMSM,an in-depth study of the the gear reduction system dynamics is needed.The multi-energy domain and multi-parameter coupling are the basic characteristics of complex electromechanical systems in the process of strong shock and large fluctuation load changes.The electromechanical coupling vibration of the system in the nonstationary process will cause the equipment to be in a bad state,affecting the steady state and dynamic performance of the system.In severe cases,it may cause major system failure.Therefore,in-depth study of the dynamic performance and stability of the shearer cutting transmission system a key issue to achieve high efficiency,low consumption,high reliability and safe cutting of the shearer.Under the support of the National Natural Science Foundation of China,in this paper,combined the load characteristics of the shearer cutting section in the actual working condition under the permanent magnet motor drive mode,and the theoretical modeling,numerical simulation analysis and experiment is used to carry out research on dynamics and torsional vibration characteristics of shearer cutting transmission system under the permanent magnet motor drive mode.The research works mainly includes:(1)The working principle of the shearer cutting part in the coal mining process was clarified,and the specific structural composition of the cutting part was shown.The fault distribution and probability of the cutting part were analyzed.When the shearer cutting drum is directly driven by the PMSM,the motor is too large and the rocker arm structure is not matched.The direct impact of the terminal load on the PMSM in the direct drive mode is too large,which affects the safe use of the PMSM.A permanent magnet semi-direct drive cutting transmission system consisting of "PMSM+ threestage spur gear reduction + cutting drum" was proposed.The torque model of the shearer PMSM and the steady-state electromagnetic torque model considering the torsion angle are established.The cutting mechanism of the end drum in shearer was analyzed.The cutting drum load model was established and the load characteristics of the cutting drum are studied by numerical simulation.(2)Combined with the working environment of the shearer semi-direct drive cutting transmission system,considering that the shearer semi-direct drive cutting drive system is a high-power electromechanical device,aiming at the simulation problem of the load characteristics of the cutting drum at the end of the shearer,according to the similar principle and dimension analysis method,a small-scale load simulation experimental platform was built based on the magnetic powder dynamometer.The parameter equivalent scaling principle of the actual system and the small-scale load simulation platform was determined.The performance test of the small-scale test bench of the semi-direct drive cutting transmission system in shearer was completed,which laid the foundation for the study of gear dynamics and torsional vibration characteristics of the shearer semi-direct drive transmission system.(3)For the problem of the shearer semi-direct drive cutting transmission system for a long time under the harsh conditions of the coal mine,under the action of strong impact and large wave load,the gear transmission system is subject to complex impact force and is prone to severe vibration.Considering the gear tooth characteristics and the bearing radial gap coupling function,the bending-torsional coupling multi-degree-offreedom nonlinear dynamic model of the semi-direct drive gear system of shearer was established,and the accuracy of the model was verified by experiments based on the small-scale load simulation platform.According to the established model,the effects of gear excitation frequency,meshing stiffness ratio and bearing clearance on the nonlinear dynamic characteristics of the system were analyzed.For the chaotic interval generated by the system,a proportional integral chaos control method was proposed to shorten or even eliminate the parameter interval of chaos,so that the system can perform stable motion in a larger parameter domain.(4)Considering the electromechanical coupling resonance phenomenon under electromagnetic excitation and end load disturbance,based on the motor theory and Maxwell equation,the electromechanical coupling torsional dynamics model of the rotor shaft of the semi-direct drive section of the shearer was established.The multiscale method was used to solve the approximate solution of the electromechanical coupling model under the condition of main parameter resonance.The steady state solution and stability of the torsional vibration of the motor-rotor system are determined by numerical method.The Hopf bifurcation and chaotic motion of the system under different electromagnetic stiffness are studied.For the system instability vibration caused by the change of the frictional damping of the drive motor of the permanent magnet semi-direct drive cutting drive system in shearer due to temperature and poor working conditions,and the complex electromechanical coupling characteristics of the shearer permanent magnet semi-direct drive cutting drive system,the nonlinear torsional dynamic equation of the shearer permanent magnet semi-direct drive cutting drive system is established.In addition,the q-axis voltage is selected as the control quantity,and a nonlinear speed feedback controller is designed,which can effectively suppress the torsional vibration of the shearer's semi-direct drive transmission system. |
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