Computer model of electric drive of 1L100K conveying unit

The paper deals with the problems of vibration damping and limiting dynamic loads in the electromechanical system of a belt conveyor by means of an adjustable electric drive. A conveying unit is represented as a three-mass ring system, which corresponds to a conveying unit with cinematically closed tape. The development of the structure of the control system for electric drives of belt conveyors with limited dynamic loads in elastic elements will reduce the dynamic loads on the belt and therefore the wear of the belts. Conditions of damping of oscillations in electromechanical system of belt conveyors are defined.


Introduction
The goal of research is determination of conditions of vibration damping in electromechanical system (EMS) of belt conveyors. It may be considered as homogeneous body consisting of elastic bars with distributed mass, which are subject to action of dry and viscous friction. Elastic vibration propagation in such bars is described by second-order partial differential equations.
Analysis of mechanical properties and synthesis electric drive control system is practically impossible at such description of elastic properties of the belt. It is convenient to perform analysis and synthesis when conveyor belt is presented in the form of lumped masses. At that, number of lumped masses is selected from condition of matching of main natural frequencies of vibrations in system with lumped masses and system with distributed masses.
Researches in this area show that at number of masses equal to six, main natural vibration frequencies correspond to system with distributed masses. Analysis at such number of masses is rather difficult because of high order of differential equations. If vibration damping in the belt with achievement of aperiodic nature of transition process will be provided by means of controlled electric drive, then it is sufficient to apply threemass electromechanical system.

Materials and Methods
Conveying unit may be presented in the form of three-mass calculation model. Kinematic diagrams with three masses may be conditionally divided into linear diagrams and ring diagrams [1][2][3][4][5][6][7]. Ring electromechanical systems (hereafter EMS) correspond to conveying unit with kinematically closed belt.
Ring kinematic chain is characterized by third rigidity with с3 coefficient, which (unlike linear rigidity) realizes elastic connection between outermost masses. Natural vibration frequency of the first mass in this case is defined by To visualize and evaluate dynamic loads resulting from vibrations in the belt of conveying unit, it is necessary to perform computer modelling (MATLAB application package, Simulink subsystem), using parameters of block diagram of TEMS with ring kinematic chain.
Belt conveyor 1L100K is considered as simulation object. This type of conveyor is designed for transportation of rock mass with coal lump size not more than 300 mm and solid not more than 150 mm on rectilinear in plan mine workings with inclination angle from minus 16° to plus 18°.
Technical characteristics of 1L100K according to are shown in Table 1. Conveying unit utilizes fabric-ply belt of 2ShTK-200-4,5x3,5 type which parameters are shown in Table 2. Driver of conveying unit is equipped with asynchronous motor of ВР280S4. Parameters of the motor are shown in Table 3. Electric drive is equipped with explosion-proof frequency converter of PChV-K-110 U5 with the following technical characteristics (Table 4). Flow-chart of control system of three-mass electromagnetic system (TEMS) of conveying unit with ring kinematical scheme containing elastic mechanical constraints is shown in Fig. 1. Fig. 1. The flow-chart of the control system of a three-mass electromechanical system of a conveyor system with an ring kinematic scheme containing elastic mechanical connections, implemented in the MATLAB application software package (Simulink subsystem).

Results and Discussion
Graphs of transient processes of open-loop control system of 1L100K conveying unit obtained during simulation in MATLAB application package (Simulink subsystem) are presented in Fig. 2.