Control method for load distribution of scraper conveyor driven by multiple motors

Abstract

The invention relates to the technical field of coal mining, in particular to a control method for load distribution of a scraper conveyor driven by multiple motors. In order to ensure that the scraper conveyor operates in the optimal state, the load of each motor of the scraper conveyor driven by multiple motors is required to be reasonably distributed under different load conditions. The invention provides a method for distributing loads to motors of a scraper conveyor. The method comprises the steps that in the no-load state, a machine head motor pulls an upper chain, and a machine tail motor pulls a bottom link; along with the increase of the load, before the nose motor reaches the rated output torque, the nose motor pulls the upper chain and the load, and the tail motor only pulls the bottom chain; when the output torque of the machine head motor reaches the rated torque, the machine head motor outputs the rated torque, and the machine tail motor distributes partial load exceeding the rated output torque of the machine head; the machine head and the tail both exceed the output torque of the motors, and the motors of the machine head and the tail jointly distribute loads. According to the control method, the purposes of reducing the local tension of the scraper chain and reducing the total power loss during operation are achieved while load transportation is completed.

Description

Technical Field

[0001] The present invention relates to the technical field of underground coal mining, and specifically to a control method for load distribution of a multi-motor-driven scraper conveyor. Background Art

[0002] The scraper conveyor drives the scraper chain to move by rotating the motor to transport raw coal out of the working face. At present, the drive parts of the scraper conveyor on the working face are all arranged on both sides of the head and the tail. For a double-drive scraper conveyor, there is one motor at each of the head and the tail (mostly arranged in parallel). For a triple-drive scraper conveyor, there are two motors at the head (usually one arranged in parallel and one arranged vertically), and one motor at the tail (usually arranged in parallel). Currently, for the convenience of interchange, each motor of each scraper conveyor mostly uses the same model, and the load distribution all adopts the power balance method, that is, to pursue the dynamic balance of the output torque of each motor.

[0003] The currently adopted multi-motor power balance drive method has certain problems: First, the principle of the scraper conveyor is that the upper scraper chain transports the cargo load, and the bottom chain is basically in an unloaded state. When using the power balance load distribution method, the driving force output by the tail motor, in addition to overcoming the resistance of the bottom chain, needs to act on the load through the head sprocket, increasing the winding resistance, and the overall load of the scraper conveyor increases. Second, the tail motor acting on the upper chain cargo load will cause elastic deformation of the bottom chain, increasing the overall length of the chain, which may cause situations such as chain piling up and chain jumping at the tail. Summary of the Invention

[0004] The purpose of the present invention is to invent a control method for load distribution of a multi-motor-driven scraper conveyor.

[0005] The technical solution adopted by the present invention is: A control method for load distribution of a multi-motor-driven scraper conveyor, without changing the original hardware configuration of the scraper conveyor, changes the output torque of each motor through software according to the load situation to achieve reasonable load distribution. The configuration of the scraper conveyor includes a head parallel drive part 1, a sprocket 2, a chain 3, a scraper 4, a tail drive part 5, a head vertical drive part 6. The two-drive scraper conveyor does not have the head vertical drive part 6. Each drive part includes a motor and a reducer, and the motors are all frequency conversion drives, and the coordinated control can control the output torque.

[0006] The control method of the present invention automatically adjusts the output torque of each motor according to the change of the load detected during the operation of the motor to achieve adaptive control of the motor output.

[0007] Advantageous Effects: The present invention is reasonably designed. By controlling the output torque distribution of each motor of the scraper conveyor, the force on the chain under different load states is reasonably controlled, reducing the winding resistance of the chain passing through the sprocket, and at the same time reducing the elongation caused by the elastic deformation of the bottom chain, realizing the optimization of the scraper conveyor control. Description of the Drawings Figure 1 is a schematic diagram of a scraper conveyor.

[0009] Among them: 1 head parallel drive unit, 2 sprocket, 3 chain, 4 scraper, 5 tail drive unit, 6 head vertical drive unit (this drive unit is not available in two-drive scraper conveyors).

[0010] Figure 2 are the output torque of the motor and the force on the chain under different loads.

[0011] Among them: (1) no load, (2) light load, (3) medium load, (4) heavy load. T t is the output torque of the head, T w is the output torque of the tail, T 0 is the output torque to overcome the chain itself, T tN is the rated torque of the head motor, T wN is the rated torque of the tail motor, F u is the force on each point of the upper chain, F d is the force on each point of the bottom chain.

[0012] Figure 3 is the corresponding curve of the percentage of the motor output torque and the load change.

[0013] Among them: the abscissa L is the load condition, and the ordinate T is the percentage of the output torque. T t is the head torque (the sum of the two head motors in the three-drive configuration), T w is the output torque of the tail motor. Detailed Implementation Modes The present invention will be further described in detail below in conjunction with the drawings and specific implementation modes: As Figure 1 shown, a dumbbell state monitoring system for a scraper conveyor, the components of the scraper conveyor involved include a head parallel drive unit 1, a sprocket 2, a chain 3, a scraper 4, a tail drive unit 5, and a head vertical drive unit 6. The two-drive scraper conveyor does not have the head vertical drive unit 6. Among them, each drive unit includes a motor and a reducer, and the motors are all frequency conversion drives, and the cooperative control can control the output torque.

[0015] According to the conventional configuration of the scraper conveyor, the two-drive and three-drive scraper conveyors will be described separately: (1)When the scraper conveyor is driven by two motors, i.e., one motor at the head and one motor at the tail: ① In the no-load stage, there is no cargo load on both the upper and lower chains, and the lengths of the upper and lower chains are the same. Therefore, in the case of no cargo load, it is approximately considered that the load torque of the upper chain T u is the same as that of the bottom chain T d At this time, calculate the no-load pulling bottom chain torque of the tail motor which are the output torques of the head and tail respectively; ② In the light-load case, the tail motor maintains the output torque T w which is the output torque of the scraper conveyor at no load T 0 The output torque of the head motor T t is used to overcome the load torque of the cargo load T f that is T w =T 0 T t =T 0 +T f ; ③ As the load increases, after the output torque of the head motor T t reaches the rated torque T tN In order to prevent the head motor from overloading, the output torque of the tail motor T w needs to increase to overcome the load torque other than the rated output torque of the head motor T tN that is T t =T tN T w =T 0 +T f -T tN ; ④ When the output torques of the head and tail T t and T wAfter all reach the rated output torque and the load continues to increase, the scraper conveyor is in an overload operation state. To avoid the shutdown due to excessive output torque of a certain motor at the head or tail, each motor needs to output torque according to the rated torque ratio to meet the requirements of the scraper conveyor for instantaneous and small-range overload operation; (2)When the scraper conveyor is triple-driven, that is, two motors at the head and one motor at the tail: ① In the no-load stage, it is the same as the double-motor drive. The calculated no-load pulling bottom-chain torque of the tail motor is still , but the output torque at the head is the sum of the output torques of the two head motors T t1 、 T t2 ; T t =T t1 +T t2 ; ② During light-load operation, the output torque T w of the tail motor is the output torque T 0 of the scraper conveyor at no-load. The output torque T t of the head motor is to overcome the load torque T f of the cargo load, that is, T w =T 0 , T t =T 0 +T f of the two head motors output torques T t1 、 T t2 are coordinated and controlled according to the rated output torque ratio; ③ When the output torque T t of the head motor reaches the sum of the rated torques of the two motors, it maintains the rated torque operation at the head. The output torque T w of the tail motor increases, T w =T 0 +T f -T tN ; ④ When the output torques at the head and tail T t 、 T wAfter all reach the rated output torque, if the load continues to increase, each motor operates in coordination according to the rated torque.

[0016] During the starting process of the scraper conveyor, the motor is in the acceleration stage and requires a large output torque. To avoid the difficult situation of starting with heavy load, during the starting and acceleration stages, the output torques of each motor still operate in balance. After completing the acceleration stage, the load torque is distributed according to the load condition in the operation stage.

Claims

1. A control method for load distribution of a multi-motor driven scraper conveyor, characterized in that: Under different loads of the scraper conveyor, the head and tail motors output different torques to achieve the optimal control of the load distribution of the scraper conveyor. The optimal load distribution of the scraper conveyor is that the force at the separation point after the chain and the sprocket are engaged is zero, that is, the head motor pulls the upper chain and the load, and the tail motor only pulls the bottom chain.

2. The control method for load distribution of a multi-motor driven scraper conveyor according to claim 1, wherein: Currently, most of the driving methods of scraper conveyors are driven by variable-frequency motors. The application of variable-frequency soft start in scraper conveyors can enable each motor to distribute the output torque according to the load conditions. During operation, different torques are controlled for each motor according to different loads, as follows: (1) When the scraper conveyor is driven by two motors, that is, one motor at the head and one motor at the tail: ①In the no-load stage, there is no load on both the upper and lower chains, and the lengths of the upper and lower chains are the same. Therefore, in the case of no load, it is approximately considered that the load torque of the upper chain T u is equal to that of the bottom chain T d . At this time, the no-load pulling torque of the bottom chain by the tail motor of the computer , are the output torques of the head and tail respectively; ② Under light load conditions, the tail motor maintains the output torque T w is the output torque of the scraper conveyor when it is unloaded T 0 , the head motor outputs torque T t to overcome the load torque of the cargo load T f , that is T w =T 0 , T t =T 0 +T f ; ③ As the load increases, the output torque of the head motor T t reaches the rated torque T tN After that, in order to prevent the head motor from overloading, the output torque of the tail motor T w needs to increase to overcome the load torque other than the rated output torque of the head motor T tN That is T t =T tN , T w =T 0 +T f -T tN ; ④ When the output torques of the head and tail T t , T w both reach the rated output torque, and the load continues to increase, the scraper conveyor is in an overload operation state. To prevent a certain motor at the head or tail from having an excessive output torque and causing a protective shutdown, each motor needs to output torque in proportion to the rated torque to meet the requirements of the scraper conveyor for instantaneous and small-range overload operation; (2) When the scraper conveyor is driven by three motors, that is, two motors at the head and one motor at the tail: ① During the no-load stage, it is the same as double-machine drive. The no-load pulling torque of the tail motor of the computer is still , but the output torque of the head is the sum of the output torques of the two head motors T t1 , T t2 . T t =T t1 +T t2 ; ② During light load operation, the output torque of the tail motor T w is the output torque of the scraper conveyor when it is unloaded T 0 , and the output torque of the head motor T t is used to overcome the load torque of the cargo load T f , that is T w =T 0 , T t =T 0 +T f , the output torques of the two head motors T t1 、 T t2 are co - controlled in proportion to the rated output torque; ③ Torque output of the head motor T t After reaching the sum of the rated torques of the two motors, maintain the operation at the rated torque of the head. The torque output of the tail motor T w increases, T w =T 0 +T f -T tN ; ④When the head and tail output torques T t 、 T w both reach the rated output torque, if the load continues to increase, each motor operates in coordination at the rated torque.

3. The control method for load distribution of a multi-motor driven scraper conveyor according to claim 1, characterized in that: During the starting process of the scraper conveyor, the motor is in the acceleration stage and requires a large output torque. To avoid the situation of difficult starting under heavy loads, the output torques of each motor still operate in balance during the starting and acceleration stages. After completing the acceleration stage, the load torque is distributed according to the load conditions during the operation stage.

Images