| Scraper conveyor is the coal transportation equipment in the mechanized mining face,and its reliable and efficient transportation is an important prerequisite for t the cooperative operation of the‘three machine equipment'in the mechanized mining face.As the key part of scraper conveyor,the drive system usually adopts the form of‘asynchronous motor+soft starter+reducer',and its more transmission links and parts lead to the low efficiency,high failure rate and poor reliability of the drive system.In order to solve the shortcomings of the traditional drive mode of the scraper conveyor,a new drive mode of permanent magnet motor direct-drive is designed,which replaces the low-efficiency asynchronous motor,eliminates the soft starter and reducer,and meets the development requirements of the coal industry for high-yield,high-efficiency,energy-saving and environmental protection.The paper takes the SGZ800/800 conveyor directly driven by permanent magnet motor as the object,establishes the simulation model of permanent magnet direct-drive scraper system,and studies its dynamic response and power balance.The main content of this paper are as follows:Firstly,the dynamics of the scraper conveyor is analyzed using the discrete element method and the Kelvin-Voigt model,and the state equation of the scraper chain system with or without preload is derived,and a simulation model of the scraper chain system is established by MATLAB/Simulink.In addition,based on the control strategy i_d=0,it focuses on the analysis of the motor mathematical equations,coordinate transformation,and other modules in the permanent magnet motor vector control system.Based on this,the simulink model of permanent magnet motor vector control is established;The experimental results of no-load start and sudden load application prove the correctness of the permanent magnet motor vector control system model.Secondly,the electromechanical model of the permanent magnet motor direct-drive scraper system is formed by coupling the scraper chain system model and the permanent magnet motor electrical control model.And in the coupling model,the response of the key parameters is simulated and analyzed,such as the current and torque of the permanent magnet motor and the speed and tension of the scraper chain,in the conditions of preload,no-preload,indefinite coal falling,free stop and controllable stop,and multilateral effect.The results show that the permanent magnet motor responds quickly to the load excitation under various working conditions.there is no reducer buffer,and the vibration and shock are directly used on the motor shaft,therefore,the large shock and vibration should be reduced to improve the control stability of the permanent magnet motor,such as applyong proper pretension to the chain,and appropriately increasing the number of teeth of the sprocket under allowable conditions to weaken the influence of the multilateral effect of the sprocket.Finally,the power balance problem of the head and tail motors in the permanent magnet motor direct-drive scraper system is studied,which mainly the analysis of the factors affecting the power balance during the dual-machine startup process and the design of the power PID controller.The results show that the larger the load on the scraper chain at startup,the more unbalanced the power of the two machines,so the scraper should be started with no load or light load.If the equal load is distributed on the scraper conveyor,the power imbalance is serious when the load is distributed in the area near the nose and tail of the scraper,and the power imbalance is relatively not obvious when the load is distributed in the middle area and whole area of the scraper;therefore,so the scraper should be unloaded properly when it is started to make the load distribute in the middle area.When the head motor is started first,the power imbalance of the two machines will inevitably increase,and the time difference of the two-machine start when the tail motor starts first becomes the key factor in adjusting the power balance effect;and the power balance regulator is well controlled. |
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