Lithium battery pole piece rolling mill pump control AGC hydraulic system, device and control method thereof

Abstract

The present invention relates to a pump-controlled AGC hydraulic system, device and control method of a lithium battery pole piece rolling mill. AGC cylinders are provided on the upper part of the upper bearing seats at both ends of the AGC device. A pump-controlled AGC hydraulic system is provided on the outer side of each AGC cylinder. The host computer gives the AGC pressure / position instruction to the controller, and the controller outputs a speed signal to control the servo motor to drive the double-displacement pump to rotate and build pressure. The first oil port of the double-displacement pump sucks oil from the rod chamber of the AGC cylinder through a low-pressure channel, and the second oil port of the double-displacement pump presses oil to the rodless chamber of the AGC cylinder through a high-pressure channel. The AGC cylinder can realize online real-time adjustment of pressure and position. When rolling single-layer and double-layer alternately coated pole pieces, the single-layer part can also obtain a relatively good rolling effect. The present invention can not only realize high-precision rolling of battery pole pieces with constant pressure and constant roll gap, but also reduce the installation, operation and maintenance costs of the system, and improve the power-to-weight ratio and reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of pole piece roll forming equipment, and in particular to a pump-controlled AGC hydraulic system, device and control method of a lithium battery pole piece rolling mill. Background Art

[0002] As one of the three core components of new energy vehicles, lithium batteries not only account for about 40% of the cost of the entire vehicle, but their performance directly determines the safety and range of the vehicle. From the perspective of the entire vehicle, lithium batteries are required to have technical characteristics such as long life, high energy density, support for fast charging, low cost, large load, and adaptability to harsh environmental conditions. The manufacturing and forming of lithium batteries involves multiple steps, among which the roll-forming of positive and negative electrode sheets is one of the key processes, which has a great impact on the final performance of the battery. The purpose of roll-forming of positive and negative electrode sheets is to increase the compaction density of positive and negative electrode materials. The appropriate compaction density can increase the discharge capacity of the battery, reduce internal resistance, reduce polarization loss, and extend the cycle life of the battery.

[0003] At present, the roll forming of lithium battery pole pieces usually adopts pole piece rolling mill equipment. The rolling of battery pole pieces is a process in which friction is generated between the rollers and the battery pole pieces, and the battery pole pieces are pulled into the rotating rollers, and the battery pole pieces are compressed and deformed. The thickness consistency of pole piece roll forming is an important indicator to measure the stability of lithium batteries. The thickness accuracy of pole pieces is usually required to reach ±0.5 microns, which puts high demands on the automatic control of hydraulic roll gap thickness of pole piece rolling mill (referred to as hydraulic AGC).

[0004] Hydraulic AGC is a technology that achieves online automatic thickness adjustment by controlling the amount of oil entering the AGC cylinder. This method has a simple structure and high sensitivity, can meet very strict thickness accuracy requirements, and can achieve constant pressure and constant roll gap rolling. The introduction of a hydraulic servo control system with high transmitted force and power enables the pole piece rolling mill to achieve online real-time adjustment of pressure and roll gap. When rolling single-layer and double-layer alternating coated pole pieces, the single-layer part can also achieve a relatively good rolling effect, which greatly improves the quality of rolled pole pieces.

[0005] Traditional hydraulic AGC uses electro-hydraulic servo valve-controlled cylinder technology. Valve-controlled AGC consists of hydraulic oil source, pipeline system, servo valve, hydraulic cylinder, sensor and control system. Although valve-controlled AGC has good control performance, the complex system configuration leads to low equipment integration and high installation cost. In addition, the constant pressure operation of the hydraulic oil source and the throttling loss of the pipeline and valve port lead to waste of system energy. In addition, due to the poor anti-pollution ability of the servo valve and the high requirements for the oil cleanliness level (NAS3-5), the system needs to be equipped with a precise filtering device, which increases the installation cost. In order to ensure the reliable operation of the system, stringent requirements are put forward for equipment maintenance. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a lithium battery pole piece rolling mill pump-controlled AGC hydraulic system, device and control method thereof, which can achieve high-precision rolling of pole pieces with constant pressure and constant roll gap, and reduce the installation, operation and maintenance costs of the system, and improve the power-to-weight ratio and reliability.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A pump-controlled AGC hydraulic system for a lithium battery pole piece rolling mill, comprising a controller, a servo motor, a double-displacement pump, a valve block, a filter, an accumulator, a two-position three-way reversing valve, a relief valve, a one-way valve, a pressure sensor, a flow sensor and a displacement sensor; a high-pressure channel and a low-pressure channel are provided in the valve block; the output shaft of the servo motor is connected to the input shaft of the double-displacement pump through a coupling, the oil port surface of the double-displacement pump and the oil port surface of the AGC cylinder are both mounted in contact with the wall surface of the valve block, the first oil port of the double-displacement pump is connected to the rod cavity of the AGC cylinder through the low-pressure channel, the second oil port of the double-displacement pump is connected to the rodless cavity of the AGC cylinder through the high-pressure channel, and the oil drain port of the double-displacement pump is connected to the rodless cavity of the AGC cylinder through the filter. The small displacement control port and the large displacement control port of the dual-displacement pump are connected to the high-pressure channel through a two-position three-way reversing valve, and the two-position three-way reversing valve is connected to the controller; the accumulator is connected to the low-pressure channel; the oil inlet of the overflow valve is connected to the high-pressure channel, and the oil outlet is connected to the low-pressure channel; the oil outlet of the one-way valve is connected to the high-pressure channel, and the oil inlet is connected to the low-pressure channel; the pressure sensor and the flow sensor are arranged on the high-pressure channel, and the displacement sensor is installed on the AGC cylinder; the pressure sensor, the flow sensor and the displacement sensor are all connected to the controller, and the controller is connected to the servo motor via the servo driver to perform closed-loop control on the servo motor.

[0009] Furthermore, it also includes a quick-change joint and a pressure relay, wherein the quick-change joint and the pressure relay are both arranged on the low-pressure channel, and the pressure relay is connected to the controller.

[0010] Furthermore, it also includes a temperature sensor; the temperature sensor is arranged on the low-pressure channel, and the temperature sensor is connected to the controller.

[0011] Furthermore, it also includes a two-position two-way reversing valve, a first damping screw, and a second damping screw; the two-position two-way reversing valve is bridged between the high-pressure channel and the low-pressure channel, the first damping screw is installed between the two-position two-way reversing valve and the low-pressure channel, and the second damping screw is installed between the two-position two-way reversing valve and the high-pressure channel; the controller is connected to the two-position two-way reversing valve.

[0012] An AGC device for a lithium battery pole piece rolling mill comprises a base, a frame mounted on the base and two AGC cylinders, the frame being a left-right symmetrical structure with a crossbeam connected to its top; two upper bearing seats and two lower bearing seats are symmetrically mounted in the inner cavity of the frame, the upper bearing seats being movable bearing seats and the lower bearing seats being fixed bearing seats; the upper rolling roller is mounted in the upper bearing seat through the upper bearing, and the lower rolling roller is mounted in the lower bearing seat through the lower bearing; an AGC cylinder connected to the upper bearing seat and providing downward pressure for the upper bearing seat is mounted on the crossbeam above each upper bearing seat; the base of the AGC cylinder is mounted on the crossbeam, and the cylinder rod of the AGC cylinder is mounted on the corresponding upper bearing seat; a set of any of the above-mentioned lithium battery pole piece rolling mill pump-controlled AGC hydraulic systems is arranged on the outer sides of the two AGC cylinders.

[0013] A pressure closed-loop control method for the pump-controlled AGC hydraulic system of a lithium battery pole piece rolling mill is as follows: a host computer gives an AGC pressure command to a controller via a bus, and the controller receives feedback pressure from a pressure sensor. By comparing the two pressures in real time, a PID controller closed-loop control program outputs a desired speed signal to a servo driver, and the servo driver controls a servo motor to drive a double-displacement pump to rotate. When the rodless cavity pressure exceeds a given pressure, the controller issues a negative speed command, and the second oil port of the double-displacement pump draws oil from the rodless cavity to reduce pressure; when the rodless cavity pressure is lower than a given pressure, the controller issues a positive speed command, and the second oil port of the double-displacement pump injects oil into the rodless cavity to increase pressure, thereby achieving high-precision control of system pressure.

[0014] Furthermore, the system adopts a pressure feedforward compensation controller, a flow nonlinear compensation controller and a leakage compensation controller. The pressure feedforward compensation controller calculates the servo motor speed compensation value by performing trajectory planning for the set pressure; the flow nonlinear compensation controller calculates the flow nonlinear compensation value by receiving pressure, flow and speed signals; the leakage compensation controller calculates the leakage compensation value by receiving pressure and flow signals. All the compensation values ​​act together with the speed signal output by the PID controller in the servo driver, so that the system pressure response speed is faster and the control accuracy is higher.

[0015] A closed-loop position control method for a lithium battery pole piece rolling mill pump-controlled AGC hydraulic system is as follows: a host computer gives an AGC position instruction to a controller via a bus, and the controller receives a position feedback from a displacement sensor. By comparing the two positions in real time, a PID controller closed-loop control program outputs a desired speed signal to a servo driver, and the servo driver controls a servo motor to drive a double-displacement pump to rotate. When the actual position of an AGC cylinder lever is greater than a given position, the controller issues a negative speed instruction, and the second oil port of the double-displacement pump draws oil from a rodless cavity to reduce the extension of the cylinder rod; when the actual position of the AGC cylinder lever is less than a given position, the controller issues a positive speed instruction, and the second oil port of the double-displacement pump injects oil into the rodless cavity to increase the extension of the cylinder rod, thereby achieving high-precision control of the cylinder rod position.

[0016] Furthermore, the system adopts a position feedforward compensation controller, a flow nonlinear compensation controller and a flow dead zone compensation controller. The position feedforward compensation controller calculates the servo motor speed compensation value by performing trajectory planning for the set position; the flow nonlinear compensation controller calculates the flow nonlinear compensation value by receiving pressure, flow and speed signals; the flow dead zone compensation controller calculates the flow dead zone compensation value by receiving pressure, flow and speed signals. All the compensation values ​​act together with the speed signal output by the PID controller in the servo driver, so that the system position response speed is faster and the control accuracy is higher.

[0017] The beneficial effects of adopting the above technical solution are:

[0018] (1) The present invention eliminates the need for a large hydraulic station, complex piping systems, and expensive servo valves, thereby reducing installation costs. It adopts servo-driven energy-saving technology to effectively avoid the overflow and throttling losses of traditional valve-controlled AGCs, thereby reducing operating costs. It also has good anti-pollution capabilities, and does not require frequent replacement of system filters, thereby reducing maintenance costs. (2) The pump-controlled AGC hydraulic system has a high degree of integration, which is convenient for installation on the mechanical body of the pole piece rolling mill, thereby improving the power-to-weight ratio. It effectively avoids servo valve failure problems caused by oil leakage and oil impurity contamination in complex piping systems, thereby improving reliability. (3) The pressure closed-loop control combining classic PID with pressure feedforward compensation, flow nonlinear compensation, and leakage compensation, and the position closed-loop control combining classic PID with position feedforward compensation, flow nonlinear compensation, and flow dead zone compensation are adopted, thereby making the system respond faster and achieving higher control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the AGC device of the lithium battery pole piece rolling mill of the present invention;

[0020] Figure 2 It is the hydraulic principle diagram of the present invention;

[0021] Figure 3It is a logic control flow chart of the present invention;

[0022] Figure 4 It is the block diagram of the pressure closed loop control of the present invention;

[0023] Figure 5 It is the block diagram of position closed-loop control of the present invention;

[0024] In the figure: 1-base, 2-frame, 3-lower roller, 4-upper roller, 5-low-pressure channel, 6-coupling, 7-servo motor, 8-dual-displacement pump, 8.1-first oil port, 8.2-second oil port, 8.3-drain port, 8.4-small-displacement control port, 8.5-large-displacement control port, 9-high-pressure channel, 10-crossbeam, 11-AGC cylinder, 12-upper bearing seat, 13-upper bearing, 14-lower bearing seat, 15-lower bearing, 16-quick-change connector, 17-temperature sensor, 18-pressure relay, 19-accumulator, 20-filter, 21-two-position three-way reversing valve, 22-valve block, 23-check valve, 24-overflow valve, 25-pressure sensor, 26-first damping screw, 27-two-position two-way reversing valve, 28-second damping screw, 29-displacement sensor, 30-flow sensor. DETAILED DESCRIPTION

[0025] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, the present invention is further described below with reference to the accompanying drawings.

[0026] like Figure 1 As shown, an AGC device for a lithium battery pole piece rolling mill includes a base 1, a frame 2 mounted on the base, and two AGC cylinders 11. The frame 2 is divided into two left and right parts and connected together by a crossbeam 10. Two upper bearing seats 12 and two lower bearing seats 14 are symmetrically installed in the inner cavity of the frame 2. The upper bearing seat 12 is a movable bearing seat, and the lower bearing seat 14 is a fixed bearing seat; the upper roller 4 is mounted in the upper bearing seat 12 through the upper bearing 13, and the lower roller 3 is mounted in the lower bearing seat 14 through the lower bearing 15; an AGC cylinder 11 connected to the upper bearing seat 12 and providing pressing power for the upper bearing seat 12 is installed on the crossbeam 10 above each upper bearing seat 12; the base of the AGC cylinder 11 is mounted on the crossbeam 10, and the cylinder rod of the AGC cylinder 11 is mounted on the corresponding upper bearing seat 12; and a set of the above-mentioned pump-controlled AGC hydraulic system is arranged on the outer side of the two AGC cylinders 11. The servo motor 7 , the double-displacement pump 8 , the valve block 22 and the like are all fixedly mounted on the AGC cylinder 11 .

[0027] like Figure 2As shown, a lithium battery pole piece rolling mill pump-controlled AGC hydraulic system includes a controller, a servo motor 7, a double-displacement pump 8, a valve block 22, a filter 20, an accumulator 19, a two-position three-way reversing valve 21, a relief valve 24, a one-way valve 23, a pressure sensor 25, a flow sensor 30 and a displacement sensor 29; a high-pressure channel 9 and a low-pressure channel 5 are provided in the valve block 22; the output shaft of the servo motor 7 is connected to the input shaft of the double-displacement pump 8 through a coupling 6, the oil port surface of the double-displacement pump 8 and the oil port surface of the AGC cylinder 11 are both mounted in contact with the wall surface of the valve block 22, the first oil port 8.1 of the double-displacement pump 8 is connected to the rod cavity of the AGC cylinder 11 through the low-pressure channel 5, the second oil port 8.2 of the double-displacement pump 8 is connected to the rodless cavity of the AGC cylinder 11 through the high-pressure channel 9, and the oil drain of the double-displacement pump 8 is connected to the rodless cavity of the AGC cylinder 11 through the high-pressure channel 9. The port 8.3 is connected to the low-pressure channel 5 through the filter 20, the small-displacement control port 8.4 and the large-displacement control port 8.5 of the dual-displacement pump 8 are connected to the high-pressure channel 9 through the two-position three-way reversing valve 21, and the two-position three-way reversing valve 21 is connected to the controller; the accumulator 19 is connected to the low-pressure channel 5; the oil inlet of the relief valve 24 is connected to the high-pressure channel 9, and the oil outlet is connected to the low-pressure channel 5; the oil outlet of the one-way valve 23 is connected to the high-pressure channel 9, and the oil inlet is connected to the low-pressure channel 5; the pressure sensor 25 and the flow sensor 30 are arranged on the high-pressure channel 9, and the displacement sensor 29 is installed on the AGC cylinder 11; the pressure sensor 25, the flow sensor 30 and the displacement sensor 29 are all connected to the controller, and the controller is connected to the servo motor 7 via the servo driver to perform closed-loop control on the servo motor 7.

[0028] The present invention adopts an integrated volume control scheme in which the servo motor 7 drives the double-displacement pump 8 to directly drive and control the AGC cylinder 11. The pressure value or position value of the AGC cylinder 11 is set according to the rolling quality of the battery electrode sheet. The controller receives the pressure / position instruction and sends a speed signal to the servo driver. The servo driver then controls the servo motor 7 to drive the double-displacement pump 8 to rotate and build pressure. The first oil port 8.1 of the double-displacement pump 8 sucks oil from the rod chamber of the AGC cylinder 11, and the second oil port 8.2 presses oil into the rodless chamber of the AGC cylinder 11. The AGC cylinder can achieve pressure and position. Online real-time adjustment can achieve high-precision rolling of constant pressure and constant roll gap of the pole piece. When rolling the pole piece with single and double layers coated alternately, the single layer part can also get a relatively good rolling effect. The leaked oil in the double displacement pump 8 is stored in the accumulator 19 through the oil drain port 8.3, the filter 20 and the low pressure channel 5 in turn. The filter 20 is used to filter the impurities of the system oil to ensure the cleanliness of the oil; the two-position three-way reversing valve 21 is used to control the oil in the high pressure channel 9 and the small displacement control port 8.4 and the large displacement control port 8.5. When the two-position three-way reversing valve 21 is powered off, the high pressure channel 9 is turned off. The high-pressure channel 9 is connected to the small-displacement control port 8.4 and disconnected from the large-displacement control port 8.5. At this time, the double-displacement pump 8 is in the small-displacement working mode, the oil volume output by the double-displacement pump 8 is reduced, and the AGC cylinder 11 is in the micro-adjustment mode; when the two-position three-way reversing valve 21 is energized, the high-pressure channel 9 is disconnected from the small-displacement control port 8.4 and connected to the large-displacement control port 8.5. At this time, the double-displacement pump 8 is in the large-displacement working mode, the oil volume output by the double-displacement pump 8 is increased, and the AGC cylinder 11 is in the fast action mode; the pressure sensor 25 is used to monitor the high-pressure channel 9 The flow sensor is used to monitor the flow input to the AGC cylinder 11, and the displacement sensor 29 is used to monitor the cylinder rod position of the AGC cylinder 11, and feeds back to the controller in real time. When the pressure of the high-pressure channel 9 exceeds the safety set value, the relief valve 24 overflows the excess oil into the accumulator 19 through the low-pressure channel 5, so that the pressure of the high-pressure channel 9 is stabilized within a safe range; the accumulator 19, as the system's oil replenishment unit, replenishes oil to the system's high-pressure channel 9 through the low-pressure channel 5 and the one-way valve 23 to compensate for internal and external leakage generated during the operation of the system.

[0029] The pump-controlled AGC hydraulic system also includes a quick-change joint 16 and a pressure relay 18, both of which are arranged on the low-pressure channel 5, and the pressure relay 18 is connected to the controller. When the pressure relay 18 detects that the pressure of the low-pressure channel 5 is lower than the minimum allowable value, the system issues an alarm and the equipment shuts down. At this time, oil needs to be replenished to the accumulator 19 through the quick-change joint 16.

[0030] The pump-controlled AGC hydraulic system also includes a temperature sensor 17; the temperature sensor 17 is arranged on the low-pressure duct 5, and the temperature sensor 17 is connected to the controller. When the temperature sensor 17 detects that the oil temperature in the system low-pressure duct 5 is too high, the system issues an alarm and the equipment shuts down. At this time, the equipment needs to be left to stand for a period of time until the oil temperature cools down to the allowable working range.

[0031] The pump-controlled AGC hydraulic system also includes a two-position two-way reversing valve 27, a first damping screw 26, and a second damping screw 28; the two-position two-way reversing valve 27 is connected between the high-pressure channel 9 and the low-pressure channel 5, the first damping screw 26 is installed between the two-position two-way reversing valve 27 and the low-pressure channel 5, and the second damping screw 28 is installed between the two-position two-way reversing valve 27 and the high-pressure channel 9; the controller is connected to the two-position two-way reversing valve 27. When the equipment is ready to shut down or encounters an emergency and needs to be stopped and unloaded, the two-position two-way reversing valve 27 is energized, the high and low pressure channels 5 and 9 are connected, the system is unloaded, and the bending roll cylinder lifts the upper roll 4 back to its original position. The first damping screw 26 and the second damping screw 28 are used to prevent excessive impact vibration during unloading.

[0032] like Figure 3 As shown, the logic control method of the pump control AGC system of the present invention is: after the equipment is started, it is initialized first, and then the system is detected whether there is an unloading and alarm instruction. If there is an unloading instruction, the unloading subroutine is triggered, the two-position two-way reversing valve 27 is opened, the system is unloaded, and the servo motor 7 is in standby mode; if there is an alarm instruction, the open-loop subroutine is triggered, and the servo motor 7 is in standby mode. If there is no unloading and alarm instruction, the system starts temperature and pressure self-checking. When the detected temperature is too low, the open-loop heating program is triggered until the temperature reaches the normal operating temperature of the system. When the detected temperature is too high or the detected pressure is outside the normal operating range of the equipment, the open-loop heating program is triggered. The open-loop subroutine is initiated and the servo motor 7 is in standby mode. If the system temperature and pressure self-test are normal, the equipment can start to work normally and the system selects the control mode. When the system works in the pressure control mode, a pressure command is given and the system calls the pressure closed-loop control subroutine to control the speed of the servo motor 7 so that the system pressure responds quickly to the given pressure and stabilizes it within the required accuracy range. When the system works in the position control mode, a position command is given and the system calls the position closed-loop control subroutine to control the speed of the servo motor 7 so that the cylinder rod of the AGC cylinder 11 responds quickly to the given position and stabilizes it within the required accuracy range.

[0033] like Figure 4As shown, the pressure closed-loop control process of the pump-controlled AGC system of the present invention is: the upper computer gives the AGC pressure instruction to the controller through the bus, and the controller receives the feedback pressure of the pressure sensor 25 at the same time. By comparing the two pressures in real time, the PID controller closed-loop control program outputs the desired speed signal to the servo driver, and the servo driver controls the servo motor 7 to drive the double-displacement pump 8 to rotate. When the rodless chamber pressure exceeds the given pressure, the controller issues a negative speed instruction, and the second oil port 8.2 of the double-displacement pump 8 sucks oil from the rodless chamber to reduce pressure; when the rodless chamber pressure is lower than the given pressure, the controller issues a positive speed instruction, and the second oil port 8.2 of the double-displacement pump 8 8.2 Oil is injected into the rodless cavity to increase the pressure, thereby achieving high-precision control of the system pressure. At the same time, the system adopts a pressure feedforward compensation controller, a flow nonlinear compensation controller and a leakage compensation controller. The pressure feedforward compensation controller calculates the speed compensation value of the servo motor 7 by performing trajectory planning for the set pressure; the flow nonlinear compensation controller calculates the flow nonlinear compensation value by receiving pressure, flow and speed signals; the leakage compensation controller calculates the leakage compensation value by receiving pressure and flow signals. All the compensation values ​​act together with the speed signal output by the PID controller in the servo driver, making the system pressure response faster and the control accuracy higher.

[0034] like Figure 5 As shown, the position closed-loop control process of the pump-controlled AGC system of the present invention is: the upper computer gives the AGC position instruction to the controller through the bus, and the controller receives the feedback position of the displacement sensor 29 at the same time. By comparing the two positions in real time, the PID controller closed-loop control program outputs the desired speed signal to the servo driver, and the servo driver controls the servo motor 7 to drive the double-displacement pump 8 to rotate. When the actual position of the AGC cylinder 11 lever is greater than the given position, the controller issues a negative speed instruction, and the second oil port 8.2 of the double-displacement pump 8 sucks oil from the rodless cavity to reduce the extension of the cylinder rod; when the actual position of the AGC cylinder 11 lever is less than the given position, the controller issues a positive speed instruction, and the second oil port 8.2 of the double-displacement pump 8 The second oil port 8.2 injects oil into the rodless cavity to increase the extension of the cylinder rod, thereby realizing high-precision control of the cylinder rod position. At the same time, the system adopts a position feedforward compensation controller, a flow nonlinear compensation controller and a flow dead zone compensation controller. The position feedforward compensation controller calculates the speed compensation value of the servo motor 7 by performing trajectory planning for the set position; the flow nonlinear compensation controller calculates the flow nonlinear compensation value by receiving pressure, flow and speed signals; the flow dead zone compensation controller calculates the flow dead zone compensation value by receiving pressure, flow and speed signals. All the compensation values ​​act together with the speed signal output by the PID controller in the servo driver to make the system position response faster and the control accuracy higher.

Claims

1. A lithium battery pole piece rolling mill pump control AGC hydraulic system, characterized by: It includes a controller, a servo motor (7), a double-displacement pump (8), a valve block (22), a filter (20), an accumulator (19), a two-position three-way reversing valve (21), a relief valve (24), a check valve (23), a pressure sensor (25), a flow sensor (30) and a displacement sensor (29); The valve block (22) is provided with a high-pressure duct (9) and a low-pressure duct (5); the output shaft of the servo motor (7) is connected to the input shaft of the double-displacement pump (8) through a coupling (6); the oil port surface of the double-displacement pump (8) and the oil port surface of the AGC cylinder (11) are both mounted in contact with the wall surface of the valve block (22); the first oil port (8.1) of the double-displacement pump (8) is connected to the rod chamber of the AGC cylinder (11) through the low-pressure duct (5); the second oil port (8.2) of the double-displacement pump (8) is connected to the rod chamber of the AGC cylinder (11) through the high-pressure duct (9); The rodless chamber of the double-displacement pump (11) is connected, the oil drain port (8.3) of the double-displacement pump (8) is connected to the low-pressure duct (5) through the filter (20), the small-displacement control port (8.4) and the large-displacement control port (8.5) of the double-displacement pump (8) are connected to the high-pressure duct (9) through the two-position three-way reversing valve (21), and the two-position three-way reversing valve (21) is connected to the controller; the accumulator (19) is connected to the low-pressure duct (5); the oil inlet of the overflow valve (24) is connected to the high-pressure duct (9), and the oil outlet is connected to the low-pressure duct (5); The oil outlet of the one-way valve (23) is connected to the high-pressure duct (9), and the oil inlet is connected to the low-pressure duct (5); the pressure sensor (25) and the flow sensor (30) are arranged on the high-pressure duct (9), and the displacement sensor (29) is installed on the AGC cylinder (11); The pressure sensor (25), flow sensor (30) and displacement sensor (29) are all connected to a controller, and the controller is connected to a servo motor (7) via a servo driver to perform closed-loop control on the servo motor (7); It also includes a quick-change connector (16) and a pressure relay (18), wherein the quick-change connector (16) and the pressure relay (18) are both arranged on the low-pressure duct (5), and the pressure relay (18) is connected to the controller; It also includes a temperature sensor (17); the temperature sensor (17) is arranged on the low-pressure duct (5), and the temperature sensor (17) is connected to the controller.

2. The lithium battery pole piece rolling mill pump control AGC hydraulic system according to any one of claim 1, characterized in that: It also includes a two-position two-way reversing valve (27), a first damping screw (26), and a second damping screw (28); the two-position two-way reversing valve (27) is connected between the high-pressure duct (9) and the low-pressure duct (5), the first damping screw (26) is installed between the two-position two-way reversing valve (27) and the low-pressure duct (5), and the second damping screw (28) is installed between the two-position two-way reversing valve (27) and the high-pressure duct (9); and the controller is connected to the two-position two-way reversing valve (27).

3. A lithium battery pole piece rolling mill AGC device, characterized in that: The invention comprises a base (1), a frame (2) mounted on the base (1), and two AGC cylinders (11); the frame (2) is a bilaterally symmetrical structure, and a crossbeam (10) is connected to the top thereof; two upper bearing seats (12) and two lower bearing seats (14) are symmetrically mounted in the inner cavity of the frame (2); the upper bearing seats (12) are movable bearing seats, and the lower bearing seats (14) are fixed bearing seats; the upper roller (4) is mounted in the upper bearing seats (12) through the upper bearing (13), and the lower roller (3) is mounted in the lower bearing seats (15) through the lower bearing (16). ) are installed in the lower bearing seat (14); an AGC cylinder (11) connected to the upper bearing seat (12) and providing downward pressure for the upper bearing seat (12) is installed on the crossbeam (10) above each upper bearing seat (12); the base of the AGC cylinder (11) is installed on the crossbeam (10), and the cylinder rod of the AGC cylinder (11) is installed on the corresponding upper bearing seat (12); the outer sides of the two AGC cylinders (11) are each provided with a set of lithium battery pole piece rolling mill pump control AGC hydraulic system as described in any one of claims 1-2.

4. A pressure closed-loop control method for a pump-controlled AGC hydraulic system of a lithium battery pole piece rolling mill, characterized in that: The invention is realized by the AGC hydraulic system for the pump control of the lithium battery pole piece rolling mill according to any one of claims 1 to 2. The upper computer gives the AGC pressure command to the controller through the bus. At the same time, the controller receives the pressure feedback from the pressure sensor (25). By comparing the two pressures in real time, the PID controller closed-loop control program outputs the desired speed signal to the servo driver. The servo driver controls the servo motor (7) to drive the double-displacement pump (8) to rotate. When the pressure in the rodless chamber exceeds the given pressure, the controller issues a negative speed command, and the second oil port (8.2) of the double-displacement pump (8) absorbs oil from the rodless chamber to reduce the pressure. When the pressure in the rodless chamber is lower than the given pressure, the controller issues a positive speed command, and the second oil port (8.2) of the double-displacement pump (8) injects oil into the rodless chamber to increase the pressure, thereby realizing high-precision control of the system pressure.

5. The pressure closed-loop control method of the pump-controlled AGC hydraulic system of a lithium battery pole piece rolling mill according to claim 4 is characterized in that: The system also adopts a pressure feedforward compensation controller, a flow nonlinear compensation controller and a leakage compensation controller. The pressure feedforward compensation controller calculates the speed compensation value of the servo motor (7) by performing trajectory planning for the set pressure; the flow nonlinear compensation controller calculates the flow nonlinear compensation value by receiving pressure, flow and speed signals; the leakage compensation controller calculates the leakage compensation value by receiving pressure and flow signals. The speed compensation value, flow nonlinear compensation value and leakage compensation value all act together with the speed signal output by the PID controller in the servo driver, so that the system pressure response speed is faster and the control accuracy is higher.

6. A position closed-loop control method for a pump-controlled AGC hydraulic system of a lithium battery pole piece rolling mill, characterized in that: The invention is realized by the pump-controlled AGC hydraulic system of the lithium battery pole piece rolling mill according to any one of claims 1 to 2. The upper computer gives the AGC position instruction to the controller through the bus. At the same time, the controller receives the feedback position of the displacement sensor (29). By comparing the two positions in real time, the PID controller closed-loop control program outputs the expected speed signal to the servo driver. The servo driver controls the servo motor (7) to drive the double-displacement pump (8) to rotate. When the actual position of the AGC cylinder (11) lever is greater than the given position, the controller issues a negative speed instruction, and the second oil port (8.2) of the double-displacement pump (8) sucks oil from the rodless cavity to reduce the extension of the cylinder rod; when the actual position of the AGC cylinder (11) lever is less than the given position, the controller issues a positive speed instruction, and the second oil port (8.2) of the double-displacement pump (8) injects oil into the rodless cavity to increase the extension of the cylinder rod, thereby realizing high-precision control of the cylinder rod position.

7. The position closed-loop control method of the pump-controlled AGC hydraulic system of a lithium battery pole piece rolling mill according to claim 6 is characterized in that: The system also uses a position feedforward compensation controller, a flow nonlinear compensation controller and a flow dead zone compensation controller. The position feedforward compensation controller calculates the speed compensation value of the servo motor (7) by performing trajectory planning for the set position; the flow nonlinear compensation controller calculates the flow nonlinear compensation value by receiving pressure, flow and speed signals; The flow dead zone compensation controller calculates the flow dead zone compensation value by receiving pressure, flow and speed signals. The speed compensation value, flow nonlinear compensation value and flow dead zone compensation value all act together with the speed signal output by the PID controller in the servo driver, making the system position response faster and the control accuracy higher.

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