A method for dynamically controlling a head-tail double drive load of a conveying belt

Abstract

The application discloses a kind of conveying belt head and tail double-drive load dynamic control method, comprising: according to power distribution adjustment target, configuration rotation speed correction curve;With head drive output power minus tail drive output power difference, i.e. the feedback value of actual power distribution, as the input of rotation speed correction curve, obtain correction frequency;With correction frequency respectively to head, tail drive motor set rotation speed value is equal in size, opposite direction correction is implemented, and head and tail drive motor is according to set target Dynamic load distribution;The setting adjustment target of head and tail power distribution, the adjustment effect of rotation speed correction curve and actual feedback value form power distribution control closed loop, can effectively resist various interference factors, and carry out automatic error-free power distribution adjustment.The application can optimize head and tail load distribution, improve belt conveying capacity, reduce the wear of belt, roller and other equipment, improve service life;It can also be applied to multi-head and multi-tail drive system.

Description

Technical Field

[0001] This invention relates to a conveyor belt control method, specifically to a dynamic control method for dual-drive loads at the head and tail of a conveyor belt. Background Technology

[0002] Dual-drive at both ends is a common drive form for long-distance, high-power conveyor belts. It uses a frequency converter to drive the head and tail drive motors separately. The drive motors drive the rollers through a reducer. The rollers drive the belt by friction, thereby realizing the material conveying from the tail to the head.

[0003] like Figure 1 As shown, the head drive motor is currently set to a speed V. 1s and the set speed V of the tail drive motor 2s Using the same setting source, namely the belt set speed V s They employ the same acceleration and deceleration dynamic characteristics to achieve complete "synchronization" between the head and tail drive motors, ensuring that the head and tail belt travel is exactly the same. Under stable load conditions, because the head and tail belt travel is consistent, the belt tension remains unchanged, thus ensuring a stable load on the head and tail drive motors.

[0004] However, the speed control accuracy of frequency converters and the processing accuracy of equipment such as rollers are limited. Furthermore, the travel difference between the head and tail drive motors driving the belts is cumulative, making it difficult to guarantee that the cumulative travel will remain consistent over a long period. If the cumulative travel of the head belt is long, the conveyor belt tension increases, and the load shifts towards the head drive; conversely, if the cumulative travel of the tail belt is long, the conveyor belt tension decreases, and the load shifts towards the tail drive. When the load increases—that is, when material is loaded from the tail towards the head—the overall load on the conveyor belt and on both the head and tail drives increases. However, due to uncertainties such as material distribution, frictional resistance of the idlers between the head and tail, and the transmission of belt elastic tension, it is difficult to ensure that the increase in load on both the head and tail drives is consistent, easily leading to load "deviation." This load "deviation" is random, and once the load stabilizes, the head-tail speed control method cannot correct it.

[0005] Currently, there is no adjustment strategy for the aforementioned load "deviation" to distribute the load between the head and tail drives. The drive motor often operates in an unreasonable state, which limits the conveying capacity of the belt, easily causes equipment wear, and affects the service life of the belt. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to address the problem that under the influence of various disturbance factors, the load at the head and tail of the conveyor belt will "deviate" in both steady-state and dynamic states, making it impossible to achieve the output power distribution according to the set operation. The invention provides a dynamic control method for the load at both the head and tail of the conveyor belt.

[0007] Technical solution: The conveyor belt head and tail dual-drive load dynamic control method of the present invention includes:

[0008] Configure the speed correction curve according to the power distribution adjustment target;

[0009] Read the drive output power from the head and tail drive inverters respectively. The drive output power is in the form of a percentage of the rated power. Use the difference between the head drive output power and the tail drive output power, i.e. the feedback value of the actual power distribution, as the input of the configured speed correction curve to obtain the correction frequency.

[0010] By using the correction frequency, the set speed values ​​of the head and tail drive motors are corrected in equal magnitude and opposite direction, so as to realize the dynamic load distribution of the head and tail drive motors according to the set target. The set speed values ​​of the head and tail drive motors are represented by the frequency.

[0011] The setting and adjustment target of head and tail power distribution, the adjustment effect of speed correction curve, and the actual feedback value form a control closed loop for power distribution, which can effectively resist various interference factors and perform automatic and error-free power distribution adjustment.

[0012] Furthermore, the speed correction curve has an adjustable output dead zone, a proportional output range, and a maximum output range. The adjustable output dead zone sets the correction frequency to 0 to prevent small differences in drive output power from correcting the set speed value, which could cause equipment vibration. When the drive output power difference exceeds the adjustable output dead zone, the set speed values ​​of the head and tail drive motors are corrected, causing the drive output power difference to return to the adjustable output dead zone range. The maximum output range is used to prevent excessive correction, which could cause the drive output power difference to oscillate outside the adjustable output dead zone, resulting in equipment vibration.

[0013] Furthermore, the function expression for the speed correction curve is:

[0014]

[0015] Where f(x) is the output frequency correction value; x is the difference in output power between the head and tail drives, i.e., the feedback value of the actual power distribution; M is the set target for the power distribution between the head and tail, i.e., the difference in the proportion of the head and tail drive power is used as the purpose of power distribution adjustment; M is less than zero, the proportion of the head drive power is less than that of the tail; M is equal to zero, the proportions of the head and tail drive power are the same; M is greater than zero, the proportion of the head drive power is greater than that of the tail.

[0016] Furthermore, when the feedback value of the actual power distribution is within ±1% of the adjustment target M%, the adjustment target is met, and the output frequency correction is 0. When the feedback value of the actual power distribution is greater than (M+1)%, the linear proportional output correction value is positive, the head drive is set to decrease speed, and the tail drive is set to increase speed, that is, the head reduces power and the tail increases power to reduce the power distribution value. When the feedback value of the actual power distribution is greater than (M+4)%, the output frequency correction is 0.3Hz, with the maximum positive value. When the feedback value of the actual power distribution is less than (M-1)%, the linear proportional output correction value is negative, the head drive is set to increase speed, and the tail drive is set to decrease speed, that is, the head increases power and the tail decreases power to increase the power distribution value. When the feedback value of the actual power distribution is less than (M-4)%, the output frequency correction is -0.3Hz, with the minimum negative value.

[0017] Furthermore, the drive output power is replaced by the percentage of drive output torque to rated torque. Since the speed is finely adjusted during regulation, the output torque and output power are approximately the same. Therefore, the output torque is used as a feedback signal to adjust and distribute the output torque, and the control principle and effect are the same as using output power.

[0018] The aforementioned dynamic load control method for dual-drive conveyor belts at both ends can be applied to multi-head drive belt conveyor systems. It combines closely related drives together, and then uses the above method to repeatedly decompose them down to a single drive, thereby achieving multi-drive load distribution.

[0019] The aforementioned dynamic load control method for dual-drive conveyor belts at both ends can be applied to multi-tail drive belt conveyor systems. It combines closely related drives together, and then uses the above method to repeatedly decompose them down to a single drive, thereby achieving multi-drive load distribution.

[0020] The aforementioned dynamic load control method for dual-drive conveyor belts at both ends can be applied to multi-head single-tail drive belt conveyor systems. The multi-head drive is treated as a whole, the set speed of the multi-head drive as a whole is obtained, and then the multi-head drive is repeatedly decomposed in the same way until a single drive is obtained, thereby realizing the multi-drive load distribution.

[0021] The aforementioned dynamic load control method for dual-drive conveyor belts at both ends can be applied to single-head, multi-tail drive belt conveyor systems. The multi-tail drive is treated as a whole, the set speed of the multi-tail drive as a whole is obtained, and then the multi-tail drive is repeatedly decomposed in the same way until a single drive is obtained, thereby realizing the multi-drive load distribution.

[0022] The aforementioned dynamic load control method for dual-drive conveyor belts at both ends can be applied to multi-head and multi-tail drive belt conveyor systems. The multi-head drive is considered as a whole, and the multi-tail drive is considered as a whole. The set speed of the multi-head drive as a whole and the set speed of the multi-tail drive as a whole are obtained separately. The same method is then used to repeatedly decompose the multi-head drive and the multi-tail drive until a single drive is reached, thereby achieving multi-drive load distribution.

[0023] The principle of this invention is as follows:

[0024] Power distribution adjustment method: At the set speed, a slightly faster speed increases the output power, and a slightly slower speed decreases the output power. That is, by applying equal and opposite speed corrections to the head and tail drives, the target power distribution between the head and tail drives can be adjusted.

[0025] Speed ​​correction curve: If the actual power distribution is within the power distribution control target range, the correction is zero; if it exceeds the power distribution control target range, a correction speed is generated towards the power distribution control target, and the head and tail drive set speeds are corrected respectively.

[0026] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0027] (1) By configuring the speed correction curve, it is possible to distribute the head and tail dual drive output power according to the set, and avoid equipment vibration while ensuring control accuracy;

[0028] (2) A closed-loop control loop for output load distribution setting and feedback has been formed, which can effectively counteract various interference factors and realize the stable distribution of head and tail drive output power according to the setting.

[0029] (3) Because the head and tail output loads can be reasonably allocated, the equipment's conveying capacity can be fully utilized, thus improving the conveying capacity;

[0030] (4) The load is effectively distributed to the head and tail drives, which reduces belt tension, reduces wear on belts, rollers and other equipment, and improves the service life of the equipment;

[0031] (5) The power margin of the selected equipment can be reduced, thereby reducing the system cost;

[0032] (6) It can be extended to multi-head drive, multi-tail drive, multi-head single-tail drive, single-head multi-tail drive and multi-head multi-tail drive systems to realize dynamic distribution of multi-drive load. Attached Figure Description

[0033] Figure 1 It is the control logic of the existing head and tail dual-drive belt conveyor system;

[0034] Figure 2 This is the control logic for the head and tail dual-drive belt conveyor system provided in the embodiments of this application;

[0035] Figure 3 This is a schematic diagram of the speed correction curve in an embodiment of this application. Detailed Implementation

[0036] The invention will now be further described with reference to the accompanying drawings.

[0037] Appendix Figures 1 to 3 The attached figures are labeled as follows:

[0038] V s Belt speed setting, unit: Hz;

[0039] V 1s Head drive motor set speed, unit: Hz;

[0040] V 2s Tail drive motor set speed, unit: Hz;

[0041] W1: Head drive output power, unit: %; 100% represents the rated power of the motor.

[0042] W2: Tail drive output power, unit: %; 100% represents the rated power of the motor.

[0043] like Figure 2 As shown in the figure, this application provides a method for dynamic control of the head and tail loads of a conveyor belt, including:

[0044] Configure the speed correction curve according to the power distribution adjustment target;

[0045] Read the drive output power W1 and W2 from the head and tail drive frequency converters respectively. The drive output power in the frequency converter is in percentage form, that is, the output power is the percentage of the rated power.

[0046] The difference between the head drive output power and the tail drive output power is obtained by subtracting the head drive output power from the tail drive output power. This difference is the feedback value of the actual power distribution and is used as the input to the configured speed correction curve y = f(x) to obtain the correction frequency.

[0047] Since the drive motor speed is regulated by a frequency converter, and there is a linear relationship between the frequency converter frequency and the speed, the speed can be expressed in terms of frequency (Hz). The set speed values ​​of the head and tail drive motors are corrected by adjusting the correction frequency in equal magnitude but opposite direction, i.e., at the belt set speed V... s By adding or subtracting the correction frequency from the base, dynamic load distribution of the head and tail drive motors can be achieved according to the set target.

[0048] In this embodiment, the speed correction curve is as follows: Figure 3 As shown, it is divided into 3 parts.

[0049] 1) Adjust the output dead time, which in this example is between (M-1)% and (M+1)%, and the output correction frequency is 0;

[0050] 2) Proportional output range, in this example, is between (M-4)% and (M-1)% and between (M+1)% and (M+4)%. The output correction frequency increases proportionally, and the proportional value is the slope of the straight line.

[0051] 3) Maximum output range: In this example, the maximum output is -0.3Hz when it is less than (M-4)% and the maximum output is 0.3Hz when it is greater than (M+4)%.

[0052] The function expression for the speed correction curve is:

[0053]

[0054] Where f(x) is the output frequency correction value; x is the difference in output power between the head and tail drives, i.e., the feedback value of the actual power distribution; M is the target for the head and tail power distribution, i.e., the difference in the proportion of head and tail drive power is used as the purpose of power distribution adjustment. M is less than zero, the proportion of head drive power is less than that of tail. M equals zero, the proportions of head and tail drive power are the same. M is greater than zero, the proportion of head drive power is greater than that of tail.

[0055] When the feedback value of the actual power distribution is within ±1% of the adjustment target M%, the adjustment target is met, and the output frequency correction is 0. When the feedback value of the actual power distribution is greater than (M+1)%, the linear proportional output correction value is positive, the head drive is set to decrease speed, and the tail drive is set to increase speed, i.e., the head reduces power and the tail increases power to reduce the power distribution value. When the feedback value of the actual power distribution is greater than (M+4)%, the output frequency correction is 0.3Hz, with the maximum positive value. When the feedback value of the actual power distribution is less than (M-1)%, the linear proportional output correction value is negative, the head drive is set to increase speed, and the tail drive is set to decrease speed, i.e., the head increases power and the tail decreases power to increase the power distribution value. When the feedback value of the actual power distribution is less than (M-4)%, the output frequency correction is -0.3Hz, with the minimum negative value.

[0056] The speed correction curve works by adjusting the output speed when the difference in drive output power exceeds the dead zone. This corrects the set speed of the head and tail drive motors, bringing the output power difference back within the dead zone. Essentially, it sets a target for the output power difference. The difference between the actual output power of the head and tail motors is essentially feedback on the output power difference. This combination forms a closed-loop feedback between the target and actual values, effectively counteracting various interference factors and achieving a stable distribution of head and tail drive output power according to the set parameters. The dead zone, when the output power deviation is less than a certain range, sets the correction frequency to 0, preventing small output power differences from correcting the set speed and causing equipment vibration. The maximum output zone prevents excessive correction, which could cause the output power difference to oscillate outside the dead zone, resulting in equipment vibration.

[0057] By utilizing the speed correction curve, this example achieves the operation of the head and tail motors according to the set adjustment target, with the output power of each motor operating at the ratio of their respective rated power, and the error controlled within 1%.

[0058] As shown above, the head and tail dual drives operate according to a specific power distribution, achieving different output power allocations to meet process requirements.

[0059] In the above technical solution, the output power of the head and tail drive is read as the feedback signal. Since the speed is finely adjusted during the adjustment process, the output torque and output power are approximately the same. Therefore, the output torque can also be used as the feedback signal to adjust and distribute the output torque. The control principle and control effect are the same as the output power.

[0060] The conveyor belt head and tail dual-drive load dynamic control method provided in this application embodiment can be extended to multi-head drive or multi-tail drive belt conveyor systems, such as dual-head drive belt conveyor systems, using the same method to determine the actual speed setting values ​​of the two head drives.

[0061] The conveyor belt head-tail dual-drive load dynamic control method provided in this application embodiment can also be extended to multi-head single-tail drive, single-head multi-tail drive, or multi-head multi-tail drive belt conveyor systems. Taking a head-two-drive and tail-one-drive belt conveyor system as an example, the head two drives are first considered as a whole. The ratio of the output power of the head two drives to the total rated power is compared with the tail drive to obtain the overall set speed of the head dual drives. Then, the individual speed settings of the head dual drives are obtained using the same method. In summary, multi-drive systems combine closely related drives together and then repeatedly decompose them down to individual drives to achieve dynamic load distribution across multiple drives.

Claims

1. A method for dynamic load control of dual-drive conveyor belts at both ends, characterized in that, include: Configure the speed correction curve according to the power distribution adjustment target; Read the drive output power from the head and tail drive inverters respectively. The drive output power is in the form of a percentage of the rated power. Use the difference between the head drive output power and the tail drive output power, i.e. the feedback value of the actual power distribution, as the input of the configured speed correction curve to obtain the correction frequency. By using the correction frequency, the set speed values ​​of the head and tail drive motors are corrected in equal magnitude and opposite direction, so as to realize the dynamic load distribution of the head and tail drive motors according to the set target. The set speed values ​​of the head and tail drive motors are represented by the frequency. The setting and adjustment target of head and tail power distribution, the adjustment effect of speed correction curve, and the actual feedback value form a control closed loop for power distribution, which can effectively resist various interference factors and perform automatic and error-free power distribution adjustment. The speed correction curve has adjustable output dead zone, proportional output range and maximum output range; among them, the output dead zone is adjusted by setting the correction frequency to 0, so as to avoid small differences in drive output power also correcting the set speed value, which would cause equipment vibration. When the difference in drive output power exceeds the dead zone range of the adjustment output, the set speed of the head and tail drive motors is corrected so that the difference in drive output power returns to the dead zone range of the adjustment output. The maximum output range is used to avoid excessive correction, which would prevent the difference in drive output power from returning to the dead zone of the adjustment output, and instead cause it to oscillate back and forth outside the dead zone of the adjustment output, resulting in equipment vibration.

2. The conveyor belt head and tail dual-drive load dynamic control method according to claim 1, characterized in that, The function expression for the speed correction curve is: Where f(x) is the output frequency correction value; x is the difference in output power between the head and tail drives, i.e., the feedback value of the actual power distribution; M is the set target for the power distribution between the head and tail, i.e., the difference in the proportion of the head and tail drive power is used as the purpose of power distribution adjustment; M is less than zero, the proportion of the head drive power is less than that of the tail; M is equal to zero, the proportions of the head and tail drive power are the same; M is greater than zero, the proportion of the head drive power is greater than that of the tail.

3. The conveyor belt head and tail dual-drive load dynamic control method according to claim 2, characterized in that, When the feedback value of the actual power distribution is within ±1% of the adjustment target M%, the adjustment target is met, and the output frequency correction is 0. When the feedback value of the actual power distribution is greater than (M+1)%, the linear proportional output correction value is positive, the head drive is set to decrease speed, and the tail drive is set to increase speed, that is, the head reduces power and the tail increases power to reduce the power distribution value. When the feedback value of the actual power distribution is greater than (M+4)%, the output frequency correction is 0.3Hz, with the maximum positive value. When the feedback value of the actual power distribution is less than (M-1)%, the linear proportional output correction value is negative, the head drive is set to increase speed, and the tail drive is set to decrease speed, that is, the head increases power and the tail decreases power to increase the power distribution value. When the feedback value of the actual power distribution is less than (M-4)%, the output frequency correction is -0.3Hz, with the minimum negative value.

4. The conveyor belt head and tail dual-drive load dynamic control method according to claim 1, characterized in that, The drive output power is replaced by the percentage of drive output torque to rated torque.

5. The conveyor belt head and tail dual-drive load dynamic control method according to any one of claims 1 to 4, characterized in that, In multi-head drive belt conveyor systems, closely related drives are combined together, and the above method is used to repeatedly decompose them down to individual drives, thereby achieving multi-drive load distribution.

6. The conveyor belt head and tail dual-drive load dynamic control method according to any one of claims 1 to 4, characterized in that, In multi-tail drive belt conveyor systems, closely related drives are combined together, and the above method is used to repeatedly decompose them down to individual drives, thereby achieving multi-drive load distribution.

7. The conveyor belt head and tail dual-drive load dynamic control method according to any one of claims 1 to 4, characterized in that, This method is applied to multi-head single-tail drive belt conveyor systems. The multi-head drive is treated as a whole, the set speed of the multi-head drive as a whole is obtained, and then the multi-head drive is repeatedly decomposed in the same way until a single drive is obtained, so as to realize the load distribution of multiple drives.

8. The conveyor belt head and tail dual-drive load dynamic control method according to any one of claims 1 to 4, characterized in that, This method is applied to single-head, multi-tail drive belt conveyor systems. The multi-tail drive is treated as a whole, the set speed of the multi-tail drive as a whole is obtained, and then the multi-tail drive is repeatedly decomposed in the same way until a single drive is obtained, so as to realize the load distribution of multiple drives.

9. The conveyor belt head and tail dual-drive load dynamic control method according to any one of claims 1 to 4, characterized in that, This method is applied to multi-head and multi-tail drive belt conveyor systems. The multi-head drive is treated as a whole, and the multi-tail drive is treated as a whole. The set speed of the multi-head drive and the set speed of the multi-tail drive are obtained separately. The same method is then used to repeatedly decompose the multi-head drive and the multi-tail drive until a single drive is obtained, thus realizing the load distribution of multiple drives.

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