| Belt conveyor is one of the most important transportation equipment in the world.It has been widely used in the fields of chemical industry,port,logistics and coal mine.When the belt conveyor starts,it will cause an impact on the power grid,which leads to the reducing service life of belt conveyor.Due to this,the drive system is required to provide adjustable speed and torque,In this paper,a new speed control device is introduced:Controllable Permanent Magnetic Eddy Current Speed Control System(CPMECSC)for mine belt conveyor.Compared with the existing speed control device,it has an incomparable advantage.The magnetic coupler applied to the belt conveyor has several advantages,such as simple structure,convenient installation,safety,environmental protection and so on.The main research contents and characteristics are as follows:1.The way how the double disks magnetic coupler works is analyzed based on its structure.The mathematical model of the double disks variable speed magnetic coupler is established according to the magnetic circuit method and the power loss,and output torque are deduced as well.In addition,the mathematical model of the speed control system of permanent magnet eddy current for mine belt conveyor is built through combining three-phase asynchronous motor,speed reducer and a belt conveyor.2.The belt conveyor controllable permanent magnet eddy current speed control system is analyzed by using Matlab Simulink.At the same time,the mine belt conveyor of permanent magnet eddy current system model is established,and the start of the belt conveyor with Harrison curve is also simulated.The experimental results show that the soft start of the belt conveyor can be realized by adjusting the air gap between the copper and the permanent magnet disk.In the meanwhile,the theory and analysis of the multi machine power balance process of magnetic coupler applied to the belt conveyor is studied theoretically.3.The three-dimensional model of magnetic coupler is established and the simulation of the magnetic coupler is conducted by using three-dimensional finite element software Ansoft Maxwell,in order to analyze the air gap between different copper coil and permanent magnet disk,the number and the area of permanent magnets,and the effects of the permanent magnet disk thickness and copper thickness on the magnetic coupler output speed when the torque are in constant conditions.4.The experimental research is carried out on the permanent magnetic eddy current test platform.Firstly,experimental research on the magnetic coupler speed regulation through air gap under constant torque is carried out and it is found that through air gap adjustment,speed adjustment can be achieved.Then the soft start process of controllable permanent magnetic eddy current of belt conveyor is simulated and through adjusting the air gap,the output speed of the belt conveyor is made to start by the Harrison curve,and the actual running curve is obtained.At the same time,the magnetic coupling of slip is measured and blockage of the belt conveyor is experimented,the result shows that with the increase of air gap,the maximum torque that the magnetic coupler can drive decreases.Finally,the experimental research on the constant load current of the controllable permanent magnetic eddy current of the belt conveyor is carried out.The results show that when the belt conveyor is started with magnetic coupler,the starting current is very low,the impact on the power grid is very small,and the magnetic coupler has "delay starting" with the magnetic coupler,and the power balance process of the belt conveyor is tested at the end. |
