Demagnetizer, control method and negative material production line

Abstract

The application discloses a magnetic removing machine, a control method and a negative material production line. The magnetic removing machine comprises a mounting frame, an electromagnetic body fixed on the mounting frame, a cylinder body penetrating through the electromagnetic body and connected with the electromagnetic body, a first screen mesh arranged in the cylinder body and corresponding to the electromagnetic body, a tee joint assembly connected with the bottom of the cylinder body, a power module, a permanent magnet coil, a second screen mesh, a vibrating mechanism, a magnetic field detection probe and a control module. The permanent magnet coil is sleeved outside the cylinder body and located above or below the electromagnetic body. The second screen mesh is made of a permanent magnet material and arranged in the cylinder body and corresponding to the permanent magnet coil. The vibrating mechanism is arranged on the cylinder body and used for generating vibration. The magnetic field detection probe is used for detecting the magnetic induction intensity of the second screen mesh. The permanent magnet coil, the control module and the power module are electrically connected. The control module is electrically connected with the magnetic field detection probe, the vibrating mechanism and the tee joint assembly. The application reduces the energy consumption of equipment operation.

Description

Technical Field

[0001] This invention belongs to the field of demagnetization technology, and particularly relates to a demagnetizer, a control method, and a negative electrode material production line. Background Technology

[0002] Magnetic impurities in lithium-ion battery anode materials can increase the self-discharge of lithium-ion batteries, and in severe cases, cause short circuits. Therefore, demagnetization technology plays an increasingly important role in the production of lithium-ion battery anode materials. Generally speaking, demagnetization methods for lithium-ion battery anode materials include chemical demagnetization, physical demagnetization, and electromagnetic field demagnetization. Electromagnetic field demagnetization is the most commonly used and relatively low-cost method, and it is widely used in screening lines for anode material production.

[0003] The application of electromagnetic field demagnetization in the production of lithium-ion battery anode materials makes demagnetization equipment an indispensable core component of anode material production. To ensure product quality, two demagnetization stages are typically arranged on the screening line of anode material production, referred to as primary demagnetization and secondary demagnetization. For products with higher quality and performance requirements, the number of demagnetization stages increases to three, referred to as primary demagnetization, secondary demagnetization, and tertiary demagnetization. The material output from secondary demagnetization exhibits a significant reduction in the content of magnetic materials. To further demagnetize, the tertiary demagnetization stage typically employs demagnetization equipment with higher magnetic field strength, resulting in greater power and higher cost.

[0004] Currently, both two-stage and three-stage demagnetization utilize electromagnetic equipment—the demagnetizer is continuously powered during production, as exemplified by the electromagnetic demagnetizer disclosed in patent document CN218132505U. However, this type of electromagnetic demagnetizer has several shortcomings:

[0005] First, it consumes a lot of energy: the demagnetization process requires a lot of electrical energy, and the higher the magnetic field strength required, the greater the power of the equipment and the greater the energy consumption, which in turn increases the production cost of lithium-ion battery anode materials.

[0006] Secondly, the equipment itself is large and expensive, requiring numerous coils to maintain the magnetic field strength, thus increasing the overall size. Furthermore, for high-magnetic-field demagnetizing equipment, even more coil turns are needed, demanding higher magnetic permeability from the screen material; the selection of ultra-high permeability screen materials further increases the equipment's cost. From another perspective, the removal rate of magnetic materials can be improved by increasing their contact opportunities with the already magnetized screen, i.e., extending the number of screens along the path of the magnetic material. Due to the significant influence of air on magnetic reluctance, this method is actually more effective than simply increasing the magnetic field strength of the screen to remove magnetic materials from the material. Summary of the Invention

[0007] The purpose of this invention is to provide a demagnetizer, a control method, and a negative electrode material production line to solve the problem of high energy consumption in traditional demagnetizing equipment.

[0008] This invention solves the above-mentioned technical problems through the following technical solution: a demagnetizer, comprising a mounting frame, an electromagnetic body fixed on the mounting frame, a cylinder passing through and connected to the electromagnetic body, a first screen disposed inside the cylinder and corresponding to the electromagnetic body, a three-way assembly connected to the bottom of the cylinder via a flexible connector, and a power supply module for supplying power to the electromagnetic coil inside the electromagnetic body; the demagnetizer further comprises:

[0009] The system comprises a permanent magnet coil, a second screen, a vibration mechanism, a magnetic field detection probe, and a control module. The permanent magnet coil is sleeved outside the cylinder and located above or below the electromagnetic body. The second screen is made of permanent magnet material and is disposed inside the cylinder, corresponding to the permanent magnet coil. The vibration mechanism is disposed on the cylinder and is used to generate vibration. The magnetic field detection probe is used to detect the magnetic induction intensity of the second screen. The permanent magnet coil, control module, and power supply module are connected.

[0010] The control module is used to control the power module to energize or de-energize the electromagnetic coil inside the electromagnetic body, so as to enable the first screen to adsorb or expel magnetic materials, and to control the power module to de-energize the permanent magnet coil or to energize the permanent magnet coil according to the magnetic induction intensity detected by the magnetic field detection probe, so as to enable the second screen to adsorb or expel magnetic materials.

[0011] Furthermore, the vibration mechanism includes a vibration motor, a mounting plate, and multiple first transverse support rods located on the same horizontal plane; each first transverse support rod is fixed to the cylinder, the mounting plate is fixedly mounted on the first transverse support rod, and the vibration motor is mounted on the mounting plate.

[0012] Preferably, when the permanent magnet coil is located below the electromagnetic body, the demagnetizer further includes an upper elastic component and a lower elastic component; the upper elastic component includes multiple second horizontal support rods and multiple second elastic parts, each second horizontal support rod corresponding to one second elastic part, and the second horizontal support rods are welded to the cylinder; one end of the second elastic part is disposed on the corresponding second horizontal support rod, and the other end is in contact with the upper surface of the electromagnetic body; the lower elastic component includes multiple first elastic parts and multiple vertical support rods, each first elastic part corresponding to one vertical support rod and one first horizontal support rod; one end of the vertical support rod is fixed to the lower surface of the electromagnetic body, and the other end is connected to the first horizontal support rod through the corresponding first elastic part.

[0013] Furthermore, the three-way assembly includes a flap three-way valve and an electric cylinder; the first port of the flap three-way valve is connected to the bottom of the cylinder through a flexible connector, the second port of the flap three-way valve serves as a magnetic material outlet, and the third port of the flap three-way valve serves as a material outlet; the electric cylinder is connected to the control module, and the telescopic end of the electric cylinder is connected to the crank of the flap three-way valve.

[0014] Furthermore, the demagnetizer also includes a cooling assembly, which includes an oil pump and a heat exchanger mounted on the mounting bracket. The inlet of the oil pump is connected to the cooling medium outlet of the electromagnetic body via a pipe, the outlet of the oil pump is connected to the inlet of the heat exchanger via a pipe, and the outlet of the heat exchanger is connected to the cooling medium inlet of the electromagnetic body via a pipe.

[0015] Furthermore, the distance between the electromagnetic coil and the permanent magnet coil is equal to the diameter of the cylinder.

[0016] Furthermore, the height of the electromagnetic coil is 1.1 to 1.2 times the height of the first screen, or the height of the first screen is 1.1 to 1.2 times the height of the electromagnetic coil; the height of the permanent magnet coil is more than 1.2 times the height of the second screen.

[0017] Furthermore, the power module includes a transformer, a rectifier circuit, a soft-start circuit, a filter circuit, a first bridge circuit composed of a first IGBT module, a second IGBT module, a third IGBT module, and a fourth IGBT module, and a second bridge circuit composed of a fifth IGBT module, a sixth IGBT module, a seventh IGBT module, and an eighth IGBT module; the input terminal of the transformer is connected to an external power source, and its output terminal is connected to the input terminal of the rectifier circuit; the output terminal of the rectifier circuit is connected to the filter circuit through the soft-start circuit; the first bridge circuit and the second bridge circuit are connected in parallel across the filter circuit; the output terminal of the first bridge circuit is connected to the electromagnetic coil, and the output terminal of the second bridge circuit is connected to the permanent magnet coil;

[0018] The control module is connected to the control terminals of the first bridge circuit and the second bridge circuit. The control module is also used to control the on and off of the IGBT module in the first bridge circuit to regulate the direction and magnitude of the output current, and to control the on and off of the IGBT module in the second bridge circuit to regulate the direction and magnitude of the output current.

[0019] Based on the same concept, the present invention also provides a demagnetizer control method as described above, comprising the following steps:

[0020] When the second screen is used for demagnetization, both the electromagnetic coil and the permanent magnet coil are de-energized. When the material passes through the second screen, the magnetic material in the material is adsorbed onto the second screen, and the material is discharged from the third port of the three-way assembly. When the magnetic material is discharged, the control module controls the power module to energize the permanent magnet coil according to the magnetic induction intensity detected by the magnetic field detection probe, so that the magnetic field generated by the permanent magnet coil cancels the magnetic field of the second screen, and the magnetic material is discharged from the second port of the three-way assembly.

[0021] When demagnetizing using the first and second screens, the control module controls the power module to energize the electromagnetic coil and de-energize the permanent magnet coil. When the material passes through the first and second screens, the magnetic substances in the material are adsorbed onto the first and second screens, and the material is discharged from the third port of the three-way assembly. When the magnetic substances are discharged, the electromagnetic coil is de-energized, and the control module controls the power module to energize the permanent magnet coil according to the magnetic induction intensity detected by the magnetic field detection probe, so that the magnetic field generated by the permanent magnet coil cancels the magnetic field of the second screen, and the magnetic substances are discharged from the second port of the three-way assembly.

[0022] Furthermore, the control method also includes magnetizing the second screen using a permanent magnet coil, specifically including:

[0023] When the magnetic field detection probe detects that the magnetic induction intensity of the second screen is lower than the magnetic induction intensity threshold, the control module controls the power module to energize the permanent magnet coil and magnetize the second screen. This ensures that the second screen maintains a high residual magnetic induction intensity after the permanent magnet coil is de-energized, thereby guaranteeing the adsorption effect of magnetic materials.

[0024] Based on the same concept, the present invention also provides a negative electrode material production line, including a screening line, wherein at least one demagnetization stage is provided on the screening line, and a demagnetizer as described above is arranged in each of the demagnetization stages.

[0025] Beneficial effects

[0026] Compared with the prior art, the advantages of the present invention are as follows:

[0027] When using only the second screen for demagnetization, this invention energizes the permanent magnet coil only when the magnetic material is discharged, greatly reducing demagnetization energy consumption. Compared to a single electromagnetic demagnetizer, this invention can employ two-stage demagnetization, namely the first and second screens, which can better achieve the demagnetization effect. In particular, weakly magnetic materials are more easily adsorbed by the screen, effectively improving material quality. Compared to a single electromagnetic demagnetizer, this invention has fewer electromagnetic coil turns, lower energy consumption, reduced cooling requirements for the cooling medium, smaller electromagnetic body size, lower overall equipment cost, and ensures the stability of the equipment during long-term operation. Attached Figure Description

[0028] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the demagnetizer (with mounting bracket) in an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of the demagnetizer (without mounting bracket) in an embodiment of the present invention;

[0031] Figure 3 This is a front view of the demagnetizer in an embodiment of the present invention;

[0032] Figure 4 This is an embodiment of the present invention. Figure 3 AA cross-section view;

[0033] Figure 5 This is a schematic diagram of the cylindrical structure in an embodiment of the present invention;

[0034] Figure 6 This is a schematic diagram of the cooling component in an embodiment of the present invention;

[0035] Figure 7 This is a circuit diagram of the power module in an embodiment of the present invention;

[0036] Figure 8 This is a flowchart of the demagnetization process using a permanent magnet coil in conjunction with a second screen in an embodiment of the present invention;

[0037] Figure 9 This is a hysteresis loop diagram of the permanent magnet material in an embodiment of the present invention;

[0038] Figure 10 This is a flowchart of the demagnetization process using a combined approach in an embodiment of the present invention.

[0039] Among them, 1-mounting bracket, 2-electromagnetic body, 201-cover plate, 202-flange protrusion, 203-third cylinder flange, 204-cooling medium, 205-sealing outer cylinder, 206-electromagnetic coil, 207-base plate, 208-sealing inner cylinder, 209-first screen, 210-sealing ring, 211-auxiliary inner cylinder, 3-cylinder, 301-upper cylinder, 302-lower cylinder, 303-first cylinder flange, 304-locking screw, 305-second horizontal support rod, 306-vertical support rod, 307-second elastic component, 30 8-First elastic component, 309-Fixed shaft, 4-Flexible connector, 5-T-way assembly, 501-Flip three-way valve, 502-Electric cylinder, 503-Crank, 504-Support plate, 6-Vibration mechanism, 601-Vibration motor, 602-Mounting plate, 603-First transverse support rod, 7-Cooling assembly, 701-Oil pump, 702-Heat exchanger, 703-Pipeline, 8-Signal acquisition box, 9-Permanent magnet coil, 901-Limit block, 902-Sealing material, 903-Second screen, 904-Magnetic field detection probe, 10-Outlet box. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] The technical solutions of this application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0042] To address the issues of high energy consumption, large size, and high cost of electromagnetic demagnetizing equipment (such as the electromagnetic demagnetizer disclosed in patent document CN218132505U), this invention provides a demagnetizer combining electromagnetic demagnetization and permanent magnet demagnetization. It adds a permanent magnet coil and a screen made of permanent magnet material (i.e., a second screen) to the electromagnetic demagnetization process. Since the magnetic field generated by the second screen does not require electrical energy, it not only reduces the manufacturing cost of the equipment itself but, more importantly, reduces the energy consumption of the equipment, thereby lowering the production cost of lithium battery anode materials and enhancing the product's market competitiveness.

[0043] Example 1

[0044] like Figures 1 to 3As shown, the demagnetizer provided in this embodiment of the invention includes a mounting frame 1, an electromagnetic body 2 fixed on the mounting frame 1, a cylinder 3 passing through and connected to the electromagnetic body 2, a first screen 209 disposed inside the cylinder 3 and corresponding to the electromagnetic body 2, a three-way assembly 5 connected to the bottom of the cylinder 3 via a flexible connector 4, a power module, a permanent magnet coil 9, a second screen 903, a vibration mechanism 6, a magnetic field detection probe 904, and a control module; the permanent magnet coil 9 is sleeved outside the cylinder 3 and located above or above the electromagnetic body 2. Below (in the diagram, the permanent magnet coil 9 is located below the electromagnetic body 2); the second screen 903 is made of permanent magnet material and is located inside the cylinder 3, corresponding to the permanent magnet coil 9; the vibration mechanism 6 is located on the cylinder 3 and is used to generate vibration, causing the material to fall quickly from the screen; the magnetic field detection probe 904 is used to detect the magnetic induction intensity of the second screen 903; the permanent magnet coil 9, the control module, and the power supply module are electrically connected, and the control module is electrically connected to the magnetic field detection probe 904, the vibration mechanism 6, and the three-way assembly 5. The mounting bracket 1 serves to support the electromagnetic body 2, the cooling assembly 7, the three-way assembly 5, etc., and is used for the on-site installation of the entire demagnetizer on the screening line.

[0045] The control module is used to control the power module to energize or de-energize the electromagnetic coil 206 inside the electromagnetic body 2, so as to realize the first screen 209 adsorbing or expelling magnetic materials, and to control the power module to de-energize the permanent magnet coil 9 or to control the power module to energize the permanent magnet coil 9 according to the magnetic induction intensity detected by the magnetic field detection probe 904, so as to realize the second screen 903 adsorbing or expelling magnetic materials.

[0046] This invention can employ either single-stage or two-stage demagnetization based on the required magnetic content of the material. When the required magnetic content is low, single-stage demagnetization is used, employing a permanent magnet coil 9 and a second screen 903. The power module does not need to energize the permanent magnet coil 9. The material enters the cylinder 3 from the top. Since the electromagnetic coil 206 is not energized, the first screen 209 does not attract the magnetic material in the material. When the material passes through the first screen 209 and falls onto the second screen 903, the second screen 903, made of permanent magnet material, generates a magnetic field. This magnetic field attracts the magnetic material in the material, thus demagnetizing it. The demagnetized material then exits through the three-way assembly. The third port of the three-way assembly 5 discharges the magnetic material (the control module controls the electric cylinder 502 to move, so that the third port of the three-way assembly 5 opens and the second port closes); when discharging the magnetic material, the control module controls the power module to energize the permanent magnet coil 9 according to the magnetic induction intensity detected by the magnetic field detection probe 904, so that the magnetic field generated by the permanent magnet coil 9 cancels the magnetic field generated by the second screen 903, thereby causing the second screen 903 to release the magnetic material, and the released magnetic material is discharged from the second port of the three-way assembly 5 (the control module controls the electric cylinder 502 to move, so that the third port of the three-way assembly 5 closes and the second port opens).

[0047] When a high content of magnetic materials is required in the material, a two-stage demagnetization process is adopted. The first stage involves an electromagnetic coil 206 and a first screen 209, while the second stage involves a permanent magnet coil 9 and a second screen 903. Taking the permanent magnet coil 9 located below the electromagnetic coil 206 as an example, the specific process of the two-stage demagnetization is as follows: The control module controls the power module to energize the electromagnetic coil 206, while the permanent magnet coil 9 is de-energized. The material enters the cylinder 3 from the top. Because the electromagnetic coil 206 is energized, the first screen 209 adsorbs the magnetic materials in the material, performing the first stage of demagnetization. The material passing through the first screen 209 falls onto the second screen 903, where the second screen 903 further adsorbs the magnetic materials (at this time, the permanent magnet coil 9 is de-energized), performing the second stage of demagnetization. The demagnetized material is discharged from the third port of the three-way assembly 5 (the control module controls the electric cylinder 502 to move, so that the third port of the three-way assembly 5 opens and the second port closes); when the magnetic material is discharged, the control module controls the power module to cut off the power to the electromagnetic coil 206, so that the first screen 209 releases the magnetic material. At the same time, the control module controls the power module to energize the permanent magnet coil 9 according to the magnetic induction intensity detected by the magnetic field detection probe 904, so that the magnetic field generated by the permanent magnet coil 9 cancels the magnetic field generated by the second screen 903, thereby causing the second screen 903 to release the magnetic material. The released magnetic material is discharged from the second port of the three-way assembly 5 (the control module controls the electric cylinder 502 to move, so that the third port of the three-way assembly 5 closes and the second port opens).

[0048] This invention employs a single-stage demagnetization process, where the permanent magnet coil 9 is energized only briefly when magnetic materials are discharged, while the electromagnetic coil 206 remains de-energized. This significantly reduces the energy consumption of the demagnetizer during operation, thereby lowering the production cost of the negative electrode material. The invention also utilizes a two-stage demagnetization process, effectively improving the demagnetization effect of the material. Although two-stage demagnetization also requires energizing the electromagnetic coil 206, compared to a single-stage demagnetizer, the electromagnetic coil 206 in this invention has fewer turns. This reduces the energy consumption of the electromagnetic coil 206 and decreases the size of the electromagnetic body 2, lowering the manufacturing cost of the equipment. Therefore, it still maintains advantages in terms of energy consumption, equipment size, and cost.

[0049] During the demagnetization process, the control module also controls the vibration mechanism 6 to vibrate, thereby causing the first screen 209 and the second screen 903 to vibrate, which helps to accelerate the falling of materials and magnetic substances from the screens. In a specific embodiment of the present invention, the vibration mechanism 6 includes two vibration motors 601, two mounting plates 602, and four first transverse support rods 603, which are located on the same horizontal plane; every two first transverse support rods 603 are welded to a semi-circular base, and the two semi-circular bases are fixed to the cylinder 3 by bolts and nuts. One mounting plate 602 is fixed on the two first transverse support rods 603 on the same semi-circular base, and the other mounting plate 602 is fixed on the two first transverse support rods 603 on the other semi-circular base. The two vibration motors 601 are respectively mounted on the two mounting plates 602.

[0050] like Figure 4 and Figure 5 As shown, when the permanent magnet coil 9 is located below the electromagnetic body 2, the demagnetizer also includes an upper elastic component and a lower elastic component. The upper elastic component includes four second horizontal support rods 305 and four second elastic parts 307, each second horizontal support rod 305 corresponding to one second elastic part 307, and the four second horizontal support rods 305 are welded to the cylinder 3. One end of the second elastic part 307 is located on the corresponding second horizontal support rod 305, and the other end is in contact with the upper surface of the electromagnetic body 2 (i.e., the upper surface of the cover plate 201). The lower elastic component includes four first elastic parts 308 and four vertical support rods 306, each first elastic part 308 corresponding to one vertical support rod 306 and one first horizontal support rod 603. One end of the vertical support rod 306 is fixed to the lower surface of the electromagnetic body 2, and the other end is connected to the first horizontal support rod 603 through the corresponding first elastic part 308.

[0051] This invention adds a vibration mechanism 6 and a lower elastic component to the bottom of the electromagnetic body 2. A vertical support rod 306 is welded to the lower surface of the electromagnetic body 2 (i.e., the bottom plate 207 of the electromagnetic body 2). This is not only to match the space occupied by the permanent magnet coil 9, but also to provide a contact support point for the first elastic component 308. The bottom of the vertical support rod 306 contacts the first elastic component 308. When the vibration motor 601 vibrates, the lower elastic component, the upper elastic component, and the cylinder 3 vibrate up and down along the electromagnetic body 2 under the power of the vibration motor 601. This ensures that after the material enters the cylinder 3 from the top, it passes through the first screen 209 and the second screen 903 and smoothly enters the three-way component 5, allowing the material to continuously flow downwards.

[0052] like Figure 5 As shown, the cylinder 3 includes an upper cylinder 301 and a lower cylinder 302. The lower cylinder 302 passes through the electromagnetic body 2 and is connected to the first port of the three-way assembly 5 via a flexible connector 4. A first cylinder flange 303 is provided on the upper cylinder 301, and a second cylinder flange is provided on the top of the lower cylinder 302. The first cylinder flange 303 and the second cylinder flange are connected by a locking screw 304. A second transverse support rod 305 is welded to the top of the lower cylinder 302 and is located below the locking screw 304. A vertical fixed shaft 309 is provided inside the cylinder 3, and multiple crossbars are provided on the fixed shaft 309. The first screen 209 and the second screen 903 are provided on the corresponding crossbars.

[0053] like Figure 4 As shown, in a specific embodiment of the present invention, the electromagnetic body 2 includes a cover plate 201, a base plate 207, a sealed inner cylinder 208, a sealed outer cylinder 205, an auxiliary inner cylinder 211, and an electromagnetic coil 206; the auxiliary inner cylinder 211 is sleeved outside the cylinder body 3 (i.e., the lower cylinder body 302); the base plate 207 is fixed on the mounting bracket 1, the sealed inner cylinder 208 and the sealed outer cylinder 205 are fixed on the inner and outer sides of the base plate 207, the sealed inner cylinder 208 and the base plate 207 are sleeved outside the auxiliary inner cylinder 211, and the sealed outer cylinder 205 is sleeved outside the sealed inner cylinder 208; the sealed inner cylinder 208 and the sealed outer cylinder 205 are connected to the cover plate 201 through a third cylinder flange 203; the electromagnetic coil 206 is disposed in the cavity formed by the base plate 207, the cover plate 201, the sealed inner cylinder 208, and the sealed outer cylinder 205. In this embodiment, the cover plate 201 is connected to the third cylindrical flange 203 by screws. The inner ring of the third cylindrical flange 203 is welded to the flange protrusion 202. The flange protrusion 202 is welded to the sealing inner cylinder 208. The flange protrusion 202 is located on the outside of the auxiliary inner cylinder 211.

[0054] like Figure 1 , Figure 2 and Figure 6As shown, the demagnetizer also includes a cooling assembly 7, which includes an oil pump 701 and a heat exchanger 702 mounted on the mounting frame 1. The inlet of the oil pump 701 is connected to the cooling medium outlet of the electromagnetic body 2 via a pipe 703, and the outlet of the oil pump 701 is connected to the inlet of the heat exchanger 702 via a pipe 703. The outlet of the heat exchanger 702 is connected to the cooling medium inlet of the electromagnetic body 2 via a pipe 703. The cavity formed by the base plate 207, cover plate 201, sealing inner cylinder 208, and sealing outer cylinder 205 is filled with cooling medium 204. Sealing rings 210 are provided between the cover plate 201 and the third cylinder flange, and between the flange protrusion 202 and the cover plate 201, for sealing the cooling medium. The oil pump 701 provides power for the cooling medium. The cooling medium flowing out of the electromagnetic body 2 flows into the oil pump 701 and then into the heat exchanger 702 for heat exchange. The cooled medium then flows into the electromagnetic body 2 to cool the energized electromagnetic coil 206.

[0055] The permanent magnet coil 9 and the second screen 903 can be located either above or below the electromagnetic body 2 (e.g., Figures 1 to 4 (As shown). Typically, a screen with a stronger magnetic field is placed at the bottom. On one hand, when easily attracted magnetic materials (strongly magnetic materials) are attracted by the weakly magnetic screen above, the probability of difficult-to-attract magnetic materials (weakly magnetic materials) being attracted by the strongly magnetic screen below is greater, improving the demagnetization effect. On the other hand, when strongly magnetic materials are attracted by the screen above, the surface magnetic field of the screen above is further weakened, reducing the likelihood of weakly magnetic materials being attracted by the screen above. For example, when the electromagnetic coil 206 is energized and the magnetic field strength of the first screen 209 is greater than or equal to the magnetic field strength of the second screen 903, the permanent magnet coil 9 and the second screen 903 are located above the electromagnetic body 2; when the electromagnetic coil 206 is energized and the magnetic field strength of the first screen 209 is less than the magnetic field strength of the second screen 903, the permanent magnet coil 9 and the second screen 903 are located below the electromagnetic body 2.

[0056] In this embodiment, the first screen 209 is made of magnetically conductive stainless steel, and its surface is passivated to eliminate the influence on the material composition during use and extend the service life of the screen. When the electromagnetic coil 206 is energized, it magnetizes the first screen 209, giving it a high magnetic field strength. When material passes through, it can attract the magnetic substances within, thus achieving demagnetization. The second screen 903 is made of a permanent magnet material with high remanent magnetic induction intensity. Similar to the first screen 209, the surface of the second screen 903 is also passivated. The second screen 903 is used in conjunction with the permanent magnet coil 9. The permanent magnet coil 9 has two functions: First, by energizing the permanent magnet coil 9, it generates a magnetic field of the same magnitude but opposite direction to that of the second screen 903, thus canceling the magnetic field of the second screen 903 and causing the second screen 903 to release the magnetic material adsorbed on it, thereby achieving the removal of the magnetic material; Second, when the magnetic field strength of the second screen 903 decreases or demagnetizes after prolonged use, the permanent magnet coil 9 is used to remagnetize the second screen 903, so that the second screen 903 maintains a high residual magnetic induction intensity after the permanent magnet coil 9 is de-energized, ensuring the removal effect of the magnetic material.

[0057] In this embodiment, the magnetic field detection probe 904 is positioned on a fixed shaft and located in the middle of the second screen 903. The magnetic field detection probe 904 can detect the magnetic field strength of the second screen 903. Based on the detected magnetic field strength, the permanent magnet coil 9 is energized, causing its magnetic field to completely cancel the magnetic field generated by the second screen 903, thus achieving the removal of magnetic materials. The magnetic field strength detected by the magnetic field detection probe 904 is used to determine whether the second screen 903 needs to be magnetized. When the detected magnetic field strength is not zero, the control module adjusts the output current of the power supply module to the permanent magnet coil 9 until the detected magnetic field strength is zero, meaning the magnetic field generated by the permanent magnet coil 9 completely cancels the magnetic field generated by the second screen 903, achieving the removal of magnetic materials. When the detected magnetic field strength is less than the magnetic field strength threshold, the control module controls the power supply module to energize the permanent magnet coil 9, magnetizing the second screen 903 to maintain its adsorption effect on magnetic materials.

[0058] After the permanent magnet coil 9 is wound, it is sealed and fixed by the sealing material 902 and the auxiliary inner cylinder 211, and the limiting block 901 at the bottom of the auxiliary inner cylinder 211 prevents the permanent magnet coil 9 from falling. The lead wire of the permanent magnet coil 9 is connected to the outlet box welded to the bottom plate 207 of the electromagnetic body 2, and the lead wire of the electromagnetic coil 206 is connected to the outlet box 10 welded to the cover plate 201 of the electromagnetic body 2. The other end of the two outlet boxes is connected to the output terminal of the power module.

[0059] The cooling medium outlet oil temperature of the electromagnetic body 2, the vibration frequency of the vibration motor 601, the stroke of the electric cylinder 502 of the three-way assembly 5, and the magnetic field strength of the second screen 903 are all collected by the signal acquisition box 8 and then sent to the control module so that the control module can regulate the power supply module according to the relevant signals collected.

[0060] In one specific embodiment of the present invention, the three-way assembly 5 includes a flap three-way valve 501 and an electric cylinder 502. The first port of the flap three-way valve 501 is connected to the bottom of the cylinder 3 via a flexible connector 4. The second port of the flap three-way valve 501 serves as the magnetic material outlet, and the third port serves as the material outlet. The electric cylinder 502 is connected to a control module, and its telescopic end is connected to the crank 503 of the flap three-way valve 501. Under the action of the control module, the electric cylinder 502 telescopically extends, thereby driving the crank 503 to rotate, realizing the rotation of the flap inside the flap three-way valve 501, thus achieving the switching between the magnetic material outlet and the material outlet. The flexible connector 4 is used to connect the outlet of the cylinder 3 and the first port of the flap three-way valve 501, serving as a transition. The three-way assembly 5 is mounted on the mounting frame 1 via a support plate 504.

[0061] When the magnetic material adsorbed on the screen is discharged, the electromagnetic coil 206 is de-energized. The magnetic field of the second screen 903 must be counteracted by the magnetic field generated by the energized permanent magnet coil 9. Therefore, to avoid the magnetic field generated by the permanent magnet coil 9 affecting the first screen 209, the electromagnetic coil 206 and the permanent magnet coil 9 must maintain a certain distance. In this embodiment, the distance between the electromagnetic coil 206 and the permanent magnet coil 9 is the diameter of the cylinder 3.

[0062] When the dimensions of the demagnetizer in the height direction are relatively compact, that is, when the distance between the electromagnetic coil 206 and the permanent magnet coil 9 is small, both the electromagnetic coil 206 and the permanent magnet coil 9 are energized, and the direction of the magnetic field generated by the electromagnetic coil 206 is consistent with the direction of the magnetic field generated by the permanent magnet coil 9, so as to avoid the magnetic fields generated by both weakening the influence of the corresponding magnetic fields during the process of expelling magnetic materials.

[0063] When the dimension of the demagnetizer in the height direction is relatively large, that is, when the distance between the electromagnetic coil 206 and the permanent magnet coil 9 is greater than or equal to the diameter of the cylinder 3, the influence between the magnetic fields generated by the electromagnetic coil 206 and the permanent magnet coil 9 can be ignored. The direction of the magnetic field generated by the electromagnetic coil 206 and the direction of the magnetic field generated by the permanent magnet coil 9 can be consistent or opposite during the process of expelling magnetic materials.

[0064] Since the magnetic field generated by the DC coil is dispersed at the end of the coil, which weakens the magnetic field strength, the height of the permanent magnet coil 9 is more than 1.2 times the height of the second screen 903. This ensures that the permanent magnet at the end of the second screen 903 is in a region with sufficient magnetic field strength during the magnetization process. It also ensures that when the magnetic material is discharged, the magnetic field of the entire second screen 903 can be completely canceled under the action of the magnetic field excited by the same current, so as to facilitate the discharge of the magnetic material in one go.

[0065] Since the magnetic field of the first screen 209 is generated by the energization of the electromagnetic coil 206 and disappears when the electromagnetic coil 206 is de-energized, the height of the electromagnetic coil 206 is equal to the height of the second screen 903, and can be 1.1 to 1.2 times each other. That is, the height of the electromagnetic coil 206 is 1.1 to 1.2 times the height of the first screen 209, or the height of the first screen 209 is 1.1 to 1.2 times the height of the electromagnetic coil 206.

[0066] Since the magnetic field generated by the electromagnetic coil 206 does not weaken as the temperature of the electromagnetic coil 206 increases, the electromagnetic coil 206 is usually powered by a constant current, with a supply voltage of approximately 200V to 300V. The withstand voltage rating of the electromagnetic coil 206 is relatively low. The permanent magnet coil 9 can be powered by either a constant current or a constant voltage. This is because the power supply time of the permanent magnet coil 9 is extremely short, and the power-off time is very long. The heat generated by the permanent magnet coil 9 during the extremely short power-on period will dissipate during the long power-off period. Constant voltage power supply will not cause changes in the magnetic field. In addition, when the permanent magnet coil 9 magnetizes the second screen 903, it needs to provide a large magnetic field strength, which requires a voltage of approximately 2000V. Therefore, the permanent magnet coil 9 needs a higher withstand voltage rating.

[0067] The demagnetizer of this invention has two coils, typically requiring two independent DC power supplies. Two independent DC power supplies are costly and complex to control. Therefore, this invention provides a power module that outputs two independently adjustable high-voltage DC power supplies with high output accuracy, meeting the functional requirements of the demagnetizer.

[0068] like Figure 7As shown, the power supply module includes a transformer T1, rectifier circuits D1 to D6, a soft-start circuit, a filter circuit, a first bridge circuit composed of IGBT1, IGBT2, IGBT3, and IGBT4, and a second bridge circuit composed of IGBT5, IGBT6, IGBT7, and IGBT8. The input terminal of transformer T1 is connected to an external 380VAC / 50Hz three-phase power supply, and its output terminal is connected to rectifier circuit D1. The input terminals of D1 to D6 are connected; the output terminals of rectifier circuits D1 to D6 are connected to the filter circuit through a soft-start circuit; the first bridge circuit and the second bridge circuit are connected in parallel across the filter circuit; the output terminal of the first bridge circuit is connected to the electromagnetic coil 206, and the output terminal of the second bridge circuit is connected to the permanent magnet coil 9; the control module is connected to the control terminals of the first bridge circuit and the second bridge circuit. The control module is also used to control the conduction and cutoff of the IGBT module in the first bridge circuit to regulate the direction and magnitude of the output current, and to control the conduction and cutoff of the IGBT module in the second bridge circuit to regulate the direction and magnitude of the output current.

[0069] In this embodiment, the soft-start circuit is composed of a resistor R1 and a contactor contact KM1 connected in parallel; the filter circuit includes a first branch composed of a resistor R2 and a capacitor C1 connected in parallel, and a second branch composed of a resistor R3 and a capacitor C2 connected in parallel, with the first branch and the second branch connected in series.

[0070] The three-phase power supply is stepped up to 1500VAC / 50Hz by transformer T1. A three-phase full-bridge rectifier circuit composed of diodes D1-D6 converts the 1500VAC / 50Hz into pulsed DC power. Then, it is converted into stable DC power by high-voltage filtering and energy storage capacitors C1 and C2. Resistors R2 and R3 are connected in parallel with capacitors C1 and C2 respectively to achieve voltage current sharing. The function of resistor R1 and contactor contact KM1 is to achieve soft start. Its function is to charge capacitors C1 and C2 by limiting the current through resistor R1. When fully charged, contactor contact KM1 closes. After rectification and filtering, the theoretical maximum output voltage can be 2121VDC bus DC voltage. Considering the voltage drop of diodes D1, D2, D3, D4, D5, and D6 and the fluctuation of the input voltage, the designed theoretical output is higher than the required 2000VDC, with some margin reserved. Four IGBT modules, IGBT1, IGBT2, IGBT3, and IGBT4, achieve the first DC output through PWM chopper rectification, driving the electromagnetic coil 206 of the demagnetizer. Four IGBT modules, IGBT5, IGBT6, IGBT7, and IGBT8, achieve the second DC output through PWM chopper rectification, driving the permanent magnet coil 9 of the demagnetizer.

[0071] Once fully charged, the resistor R1 is bypassed by closing contactor contact KM1, thus avoiding losses in resistor R1.

[0072] The control module controls the on / off states of IGBT1, IGBT2, IGBT3, and IGBT4 to regulate the first DC output. When IGBT1 and IGBT4 are on, the first output carries a forward current; when IGBT2 and IGBT3 are on, the first output carries a reverse current for reverse demagnetization. By controlling the on-time of the IGBTs, the DC voltage and current can be precisely adjusted, making the output voltage linearly adjustable from 0 to 2000VDC and the output current linearly adjustable from 0 to 100A.

[0073] The control module controls the on / off state of IGBTs 5, 6, 7, and 8 to regulate the second DC output. When IGBTs 5 and 8 are turned on, the second output carries a forward current; when IGBTs 6 and 7 are turned on, the second output carries a reverse current for reverse demagnetization. By controlling the on-time of the IGBTs, the DC voltage and current can be precisely adjusted, making the output voltage linearly adjustable from 0 to 2000VDC and the output current linearly adjustable from 0 to 100A.

[0074] When a forward current is applied to the electromagnetic coil 206, the direction of the magnetic field generated by the electromagnetic coil 206 is the same as the direction of the magnetic field generated by the second screen 903. Therefore, a forward current is applied to the electromagnetic coil 206 during demagnetization. When discharging magnetic material, a momentary reverse current can be applied to the electromagnetic coil 206 to rapidly reduce the magnetic induction intensity of the first screen 209 to 0, causing the magnetic material to fall quickly from the first screen 209. When a reverse current is applied to the electromagnetic coil 206, the direction of the magnetic field generated by the electromagnetic coil 206 is the same as the direction of the magnetic field generated by the second screen 903. Therefore, a reverse current is applied to the electromagnetic coil 206 during demagnetization. When discharging magnetic material, a momentary forward current can be applied to the electromagnetic coil 206 to rapidly reduce the magnetic induction intensity of the first screen 209 to 0, causing the magnetic material to fall quickly from the first screen 209.

[0075] When the magnetic material on the second screen 903 is released, the second power supply module can use constant voltage output, with the output voltage linearly adjustable from 0 to 2000VDC (specifically adjusted according to the magnetic field strength detected by the magnetic field detection probe 904), and the constant voltage output duration is 1 second; the second power supply module can also use constant current output, with the output current linearly adjustable from 0 to 100A, so that the magnetic field generated by the permanent magnet coil 9 can cancel the magnetic field of the second screen 903.

[0076] Based on the original electromagnetic coil 206 for demagnetization, this invention adds a high magnetic field strength permanent magnet coil 9 and a second screen 903 made of permanent magnet material. Combined with the magnetic field generated by the electromagnetic coil 206, this invention reduces equipment cost, size and operating cost while ensuring demagnetization effect, thereby reducing the production cost of lithium-ion battery anode materials and improving the market competitiveness of finished materials.

[0077] Example 2

[0078] This invention provides a demagnetizer control method as described in Embodiment 1. Based on the material's quality requirements (i.e., the required magnetic content), a permanent magnet coil 9 in conjunction with a second screen 903 is used to demagnetize the material; alternatively, a combination of an electromagnetic coil 206 in conjunction with a first screen 209 and a permanent magnet coil 9 in conjunction with a second screen 903 is used to demagnetize the material. Figure 8 As shown, a permanent magnet coil 9 is used in conjunction with a second screen 903 for demagnetization. The specific control method includes:

[0079] When both the electromagnetic coil 206 and the permanent magnet coil 9 are de-energized, the material passes directly through the first screen 209 without being attracted by the magnetic material. When passing through the second screen 903, the magnetic material is attracted to the second screen 903. The control module controls the third port of the flap three-way valve 501 to open and the second port to close, and the material is discharged from the third port of the flap three-way valve 501. When the second screen 903 is full of magnetic material and it is necessary to discharge the magnetic material, the control module controls the power supply module to energize the permanent magnet coil 9 according to the magnetic induction intensity detected by the magnetic field detection probe 904. This causes the magnetic field generated by the permanent magnet coil 9 to cancel the magnetic field of the second screen 903. The control module controls the second port of the flap three-way valve 501 to open and the third port to close, and the magnetic material is discharged from the second port of the flap three-way valve 501.

[0080] The power supply module is energized to the permanent magnet coil 9 based on the magnetic field strength detected by the magnetic field detection probe 904. This causes the magnetic field generated by the permanent magnet coil 9 to cancel the magnetic field of the second screen 903. Specifically, when the magnetic field strength detected by the magnetic field detection probe 904 is not zero, the second output of the power supply module is adjusted to make the magnetic field strength detected by the magnetic field detection probe 904 zero. That is, by adjusting the magnitude of the second output, the magnetic field strength detected by the magnetic field detection probe 904 is made zero. This indicates that the magnetic field generated by the permanent magnet coil 9 completely cancels the magnetic field of the second screen 903, thus ensuring that the magnetic material on the second screen 903 is completely discharged.

[0081] To determine the magnitude and direction of the energizer supplied by the power module to the permanent magnet coil 9, the magnetic property curves of the permanent magnet material used to fabricate the second screen 903 were first measured. Figure 9As shown, the magnetic field strength Hs, remanent magnetic induction Br, coercivity Hc, etc. of the second screen 903 are determined and stored in the control module. Based on the magnitude of the magnetic field strength Hs and coercivity Hc of the second screen 903, the required voltage U1 and voltage U2 (or current I1 and I2) to be applied to the permanent magnet coil 9 are determined to saturate the second screen 903 (the voltage or current when magnetizing the second screen 903) and cancel the magnetic field generated by the second screen 903. Voltage U1 represents the voltage corresponding to the magnetic field strength Hs generated by energizing the permanent magnet coil 9. That is, when the energizing voltage of the permanent magnet coil 9 is U1, the second screen 903 is magnetized, so that the second screen 903 retains the remanent magnetism of Br after the permanent magnet coil 9 is de-energized; when the energizing voltage of the permanent magnet coil 9 is U2, the magnetic field generated by the permanent magnet coil 9 can cancel the magnetic field of the second screen 903, realizing the complete removal of magnetic materials.

[0082] As the usage time increases, the magnetic properties of the second screen 903 will decrease (i.e., the value of the residual magnetic induction intensity Br will decrease), affecting the demagnetization effect. At this time, the power module can supply the permanent magnet coil 9 with the voltage value of U1, which is equivalent to remagnetizing the second screen 903 to make it reach the initial residual magnetic induction intensity Br value, thus ensuring the demagnetization effect.

[0083] like Figure 10 As shown, the material is demagnetized using a combination of electromagnetic coil 206 with first screen 209 and permanent magnet coil 9 with second screen 903. Specific control methods include:

[0084] The control module controls the power supply module to energize the electromagnetic coil 206 and de-energize the permanent magnet coil 9. When the material passes through the first screen 209 and the second screen 903, the magnetic material in the material is attracted to the first screen 209 and the second screen 903. The control module controls the third port of the flap three-way valve 501 to open and the second port to close, and the material is discharged from the third port of the flap three-way valve 501. When the first screen 209 and the second screen 903 are full of magnetic material and it is necessary to discharge the magnetic material, the electromagnetic coil 206 is de-energized. The control module controls the power supply module to energize the permanent magnet coil 9 according to the magnetic induction intensity detected by the magnetic field detection probe 904, so that the magnetic field generated by the permanent magnet coil 9 cancels the magnetic field of the second screen 903. The control module controls the second port of the flap three-way valve 501 to open and the third port to close, and the magnetic material is discharged from the second port of the flap three-way valve 501.

[0085] When the first screen 209 and the second screen 903 are demagnetized together, if it is necessary to remagnetize the second screen 903, which has a weakened magnetic field, the magnetic field directions of the first screen 209 and the second screen 903 must be the same. If they are not the same, it is not allowed to remagnetize the second screen 903 (in this case, remagnetization should be performed when the demagnetizer is stopped) so as to prevent the larger magnetic field during remagnetization from weakening the magnetic field of the first screen 209, thus preventing magnetic materials from entering the material channel (i.e., the third port of the flap three-way valve 501) and causing waste.

[0086] Example 3

[0087] This invention provides a negative electrode material production line, including a screening line, wherein at least one demagnetization stage is provided on the screening line, and a demagnetizer as described in Embodiment 1 is installed in each of the demagnetization stages.

[0088] The above description only discloses specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A demagnetizer, comprising a mounting frame, an electromagnetic body fixed on the mounting frame, a cylinder passing through and connected to the electromagnetic body, a first screen disposed within the cylinder and corresponding to the electromagnetic body, a three-way assembly connected to the bottom of the cylinder via a flexible connector, and a power module for supplying power to an electromagnetic coil within the electromagnetic body, characterized in that, The demagnetizer also includes: The system comprises a permanent magnet coil, a second screen, a vibration mechanism, a magnetic field detection probe, and a control module. The second screen is made of permanent magnet material and is disposed inside the cylinder. The permanent magnet coil is sleeved outside the cylinder and located above or below the electromagnetic body, corresponding to the position of the second screen. The vibration mechanism is disposed on the cylinder and is used to generate vibration. The magnetic field detection probe is used to detect the magnetic induction intensity of the second screen. Both the permanent magnet coil and the control module are electrically connected to the power supply module. The control module is used for: The control power module energizes or de-energizes the electromagnetic coil to cause the first screen to adsorb or release magnetic material. And based on the magnetic induction intensity of the second screen detected by the magnetic field detection probe, the power module is controlled to energize the permanent magnet coil, so that the magnetic field generated by the permanent magnet coil cancels the magnetic field of the second screen, thereby releasing the magnetic material adsorbed by the second screen; or, the power module is controlled to energize the permanent magnet coil to remagnetize the second screen whose magnetic field intensity has weakened. The vibration mechanism includes a vibration motor, a mounting plate, and multiple first transverse support rods located on the same horizontal plane; each first transverse support rod is fixed to the cylinder, the mounting plate is fixed to the first transverse support rod, and the vibration motor is mounted on the mounting plate; When the permanent magnet coil is located below the electromagnetic body, the demagnetizer further includes an upper elastic component and a lower elastic component; the upper elastic component includes multiple second horizontal support rods and multiple second elastic parts, each second horizontal support rod corresponding to one second elastic part, and the second horizontal support rods are welded to the cylinder; one end of the second elastic part is disposed on the corresponding second horizontal support rod, and the other end is in contact with the upper surface of the electromagnetic body; the lower elastic component includes multiple first elastic parts and multiple vertical support rods, each first elastic part corresponding to one vertical support rod and one first horizontal support rod; one end of the vertical support rod is fixed to the lower surface of the electromagnetic body, and the other end is connected to the first horizontal support rod through the corresponding first elastic part; The three-way assembly includes a flap three-way valve and an electric cylinder; the first port of the flap three-way valve is connected to the bottom of the cylinder through a flexible connector, the second port of the flap three-way valve serves as the magnetic material outlet, and the third port of the flap three-way valve serves as the material outlet; the electric cylinder is connected to the control module, and the telescopic end of the electric cylinder is connected to the crank of the flap three-way valve.

2. The demagnetizer according to claim 1, characterized in that: The demagnetizer also includes a cooling assembly, which includes an oil pump and a heat exchanger mounted on the mounting frame. The inlet of the oil pump is connected to the cooling medium outlet of the electromagnetic body via a pipe, the outlet of the oil pump is connected to the inlet of the heat exchanger via a pipe, and the outlet of the heat exchanger is connected to the cooling medium inlet of the electromagnetic body via a pipe.

3. The demagnetizer according to claim 1, characterized in that: The distance between the electromagnetic coil and the permanent magnet coil is equal to the diameter of the cylinder.

4. The demagnetizer according to claim 1, characterized in that: The height of the electromagnetic coil is 1.1 to 1.2 times the height of the first screen, or the height of the first screen is 1.1 to 1.2 times the height of the electromagnetic coil; the height of the permanent magnet coil is more than 1.2 times the height of the second screen.

5. The demagnetizer according to any one of claims 1 to 4, characterized in that: The power supply module includes a transformer, a rectifier circuit, a soft-start circuit, a filter circuit, a first bridge circuit composed of a first IGBT module, a second IGBT module, a third IGBT module, and a fourth IGBT module, and a second bridge circuit composed of a fifth IGBT module, a sixth IGBT module, a seventh IGBT module, and an eighth IGBT module; the input terminal of the transformer is connected to an external power source, and its output terminal is connected to the input terminal of the rectifier circuit; the output terminal of the rectifier circuit is connected to the filter circuit through the soft-start circuit. The first bridge circuit and the second bridge circuit are connected in parallel across the two ends of the filter circuit; the output terminal of the first bridge circuit is connected to the electromagnetic coil, and the output terminal of the second bridge circuit is connected to the permanent magnet coil. The control module is connected to the control terminals of the first bridge circuit and the second bridge circuit. The control module is also used to control the on and off of the IGBT module in the first bridge circuit to regulate the direction and magnitude of the output current, and to control the on and off of the IGBT module in the second bridge circuit to regulate the direction and magnitude of the output current.

6. A demagnetizer control method as described in any one of claims 1 to 5, characterized in that, Includes the following steps: When the second screen is used for demagnetization, both the electromagnetic coil and the permanent magnet coil are de-energized. When the material passes through the second screen, the magnetic material in the material is adsorbed onto the second screen, and the material is discharged from the third port of the three-way assembly. When the magnetic material is discharged, the control module controls the power module to energize the permanent magnet coil according to the magnetic induction intensity detected by the magnetic field detection probe, so that the magnetic field generated by the permanent magnet coil cancels the magnetic field of the second screen, and the magnetic material is discharged from the second port of the three-way assembly. When demagnetizing using the first and second screens, the control module controls the power module to energize the electromagnetic coil and de-energize the permanent magnet coil. When the material passes through the first and second screens, the magnetic substances in the material are adsorbed onto the first and second screens, and the material is discharged from the third port of the three-way assembly. When the magnetic substances are discharged, the electromagnetic coil is de-energized, and the control module controls the power module to energize the permanent magnet coil according to the magnetic induction intensity detected by the magnetic field detection probe, so that the magnetic field generated by the permanent magnet coil cancels the magnetic field of the second screen, and the magnetic substances are discharged from the second port of the three-way assembly.

7. The demagnetizer control method according to claim 6, characterized in that, The control method further includes magnetizing the second screen using a permanent magnet coil, specifically including: When the magnetic field detection probe detects that the magnetic induction intensity of the second screen is lower than the magnetic induction intensity threshold, the control module controls the power module to energize the permanent magnet coil and magnetize the second screen. This ensures that the second screen maintains a high residual magnetic induction intensity after the permanent magnet coil is de-energized, thereby guaranteeing the adsorption effect of magnetic materials.

8. A negative electrode material production line, comprising a screening line, wherein at least one demagnetization stage is provided on the screening line, characterized in that, A demagnetizer as described in any one of claims 1 to 5 is installed in each of the demagnetization stages.

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