Research On The Control Method Of Belt Conveyor Based On Dynamic Model

Belt conveyors are commonly used in transportation industries such as ports,power plants,mines,and grain.The conveyor is developing in the direction of long distance,high belt speed,energy saving and intelligence,and its dynamic characteristics become more obvious,which brings great challenges to the design work of the belt conveyor system.In order to reduce the tension of conveyor belt,multi-motor drive mode is adopted,but it also brings difficulties to the control of conveyor.Therefore,it is necessary to design a suitable control method so that the conveyor can operate according to a specific curve and ensure the power balance between the motors,thereby achieving smooth running of the belt conveyor system.The wave equation of the conveyor belt is established.It is analyzed that the attenuation coefficient and velocity of the traveling wave in the conveyor belt are both related to the frequency,but the influence can be ignored.Introducing the concept of wave impedance,the product of the wave impedance of the conveyor belt unit and the velocity is equal to the stress of the unit.The wave model of each part of the conveyor is established,and the excitation,refraction and reflection formulas of the wave are theoretically derived.It is proved that it is related to the quality of the drum,the material properties of the conveyor belt,the equivalent speed resistance,etc.,and their mathematical expressions are obtained.According to the propagation mechanism of the upstream wave of the conveyor belt,the wave algorithm of the belt conveyor during the starting and braking process is designed.The three-phase asynchronous AC motor,voltage space vector PWM(SVPWM)control technology and variable frequency speed regulation technology are studied,and a mathematical model is established.Simulation analysis of the motor gives a curve of motor speed,electromagnetic torque and phase current as a function of time during direct start,which proves that the conveyor is not suitable for direct start mode operation.During the operation of the conveyor system,the power imbalance between the motors is easily caused by factors such as the mechanical characteristics of the drive motor and the dimensional deviation between the drive pulley.The dynamic characteristics of the conveyor during the operation are fluctuating cyclically,and the rigid connection and flexible connection are analyzed.The multi-motor drive conveyor system adopts master-slave control and group parallel control strategy to achieve power balance between the motors of the conveyor.The starting and braking operation algorithms of the multi-motor power balance control of the belt conveyor are designed.From the perspective of software engineering,the software input module,calculation algorithm module and output module are designed.The dynamic analysis and calculation software of the belt conveyor control system was developed by using Visual Basic.NET.The example analysis and calculation shows the curve of the speed,driving force,tension,speed and displacement of the tensioning device and the electromagnetic torque of the driving motor with time in the running process of the conveyor system.The conveyor fluctuates periodically at the initial stage of operation and finally tends to be stable.The tension on the driving pulleyof the conveyor belt is greater.The simulation results confirm that the designed multi-motor power balance control system can achieve smooth running of the conveyor.Simulation results show that the designed multi-motor power balance control system to achieve smooth operation of the conveyor.It’s proved that it can meet the requirement of real-time control.