Modularized adjustable magnetic flux permanent magnet assembly and assembly process thereof

Abstract

The invention relates to the technical field of permanent magnet assemblies, in particular to a modular adjustable magnetic flux permanent magnet assembly and an assembly process thereof. The permanent magnet assembly comprises at least two groups of permanent magnet module units and a magnetic flux adjusting assembly; each permanent magnet module unit is composed of a main magnet and an auxiliary magnet which are stacked in the magnetic pole direction, an adjusting gap is reserved between the main magnet and the auxiliary magnet, and the main magnet is a neodymium iron boron-based permanent magnet doped with rare earth elements and transition metal. The auxiliary magnet is an aluminum-nickel-cobalt-ferrite composite permanent magnet coated with a nanocrystalline layer, and the auxiliary magnet is composed of aluminum-nickel-cobalt alloy powder and ferrite nano powder; the magnetic flux adjusting assembly comprises a high magnetic conductance insertion piece and a magnetic isolation insertion piece, and the high magnetic conductance insertion piece and the magnetic isolation insertion piece can be selectively inserted into an adjusting gap between the main magnet and the auxiliary magnet. According to the invention, the advantages of different permanent magnet materials are combined, so that the assembly has high magnetic performance and stability while maintaining high magnetic energy product and high residual magnetism.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet component technology, and more specifically, to a modular adjustable flux permanent magnet component and its assembly process. Background Technology

[0002] Rare earth permanent magnet materials are a class of intermetallic compound permanent magnets mainly composed of rare earth metals and transition metals. After being magnetized, these materials can maintain strong magnetism for a long time without the application of an external magnetic field. Their core characteristics lie in their extremely high magnetic energy product, remanence, and coercivity, meaning they can provide very strong magnetic fields and have excellent resistance to demagnetization. Among them, neodymium iron boron (NdFeB) permanent magnets possess the highest magnetic energy product of all commercially available permanent magnet materials, enabling electronic devices and equipment to develop towards miniaturization, lightweighting, and high performance. Currently, rare earth permanent magnet materials are widely used in green and energy-saving fields such as new energy vehicle drive motors, wind power generation, energy-saving elevators, and variable frequency home appliances, as well as in high-tech industries such as consumer electronics, medical equipment, aerospace, and automation control, becoming indispensable key functional materials supporting modern industrial and technological progress. To further improve performance and conserve strategic heavy rare earth resources, the industry continues to innovate technologically.

[0003] The materials used in existing permanent magnet components have limited performance characteristics. Although traditional neodymium iron boron magnets have high energy products, their magnetic flux is prone to decay at high temperatures. AlNiCo magnets have good temperature stability but low energy products, making it difficult to achieve both high energy products and high stability. Summary of the Invention

[0004] The purpose of this invention is to provide a modular adjustable flux permanent magnet component and its assembly process. It uses a neodymium iron boron-based permanent magnet with high coercivity and high energy product as the main magnet, and combines it with an aluminum nickel cobalt-ferrite composite permanent magnet with good temperature stability as the auxiliary magnet, thereby solving the problem of the single performance of permanent magnet components in related technologies.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A modular adjustable flux permanent magnet assembly includes at least two sets of permanent magnet module units and a flux adjustment assembly; The permanent magnet module unit is composed of a main magnet and an auxiliary magnet stacked along the magnetic pole direction, and an adjustment gap is reserved between the main magnet and the auxiliary magnet. The main magnet is a neodymium iron boron based permanent magnet doped with rare earth elements and transition metals. The auxiliary magnet is an AlNiCo-ferrite composite permanent magnet coated with a nanocrystalline layer, and the auxiliary magnet is composed of AlNiCo alloy powder and ferrite nanopowder. The magnetic flux adjustment component includes a high-permeability insert and a magnetic isolation insert. The high-permeability insert and the magnetic isolation insert can be selectively inserted into the adjustment gap between the main magnet and the auxiliary magnet to achieve series superposition or parallel shunting of magnetic flux.

[0006] Optionally, the auxiliary magnet contains 55%-65% aluminum-nickel-cobalt alloy powder and 35%-45% ferrite nanopowder by mass.

[0007] Optionally, the nanocrystalline layer is an oxide nanocrystalline layer, and the thickness of the oxide nanocrystalline layer is 3nm-8nm.

[0008] Optionally, in the main magnet, the rare earth element is selected from at least one of praseodymium, dysprosium, and terbium, and the transition metal is selected from at least one of cobalt, niobium, zirconium, and titanium.

[0009] Optionally, the high magnetic permeability insert is made of an iron-nickel alloy with a nickel content of 75%-80%; the magnetic shielding insert is made of boron nitride ceramic, and the thickness of the magnetic shielding insert is the same as that of the high magnetic permeability insert.

[0010] Optionally, in the aluminum-nickel-cobalt alloy powder, aluminum accounts for 9%-11% by mass, nickel accounts for 16%-19% by mass, cobalt accounts for 8%-12% by mass, and the remainder is iron; the ferrite nanopowder is one of strontium ferrite, barium ferrite, or manganese-zinc ferrite, and the particle size of the ferrite nanopowder is 40nm-80nm.

[0011] Optionally, the width of the adjustment gap is equal to the thickness of the high magnetic permeability insert or the magnetic shielding insert, the depth of the adjustment gap is consistent with the axial length of the permanent magnet module unit, and the inner wall of the adjustment gap is provided with a nickel-phosphorus alloy plating layer.

[0012] Optionally, it also includes a module spacer magnetic component, which is sandwiched between adjacent permanent magnet module units. The spacer magnetic component is made of amorphous alloy strip and its surface is coated with high-temperature resistant insulating paint.

[0013] Optionally, the magnetic flux density when the magnetic flux is superimposed in series is 0.9T-1.2T, and the magnetic flux density when the magnetic flux is splittered in parallel is 0.5T-0.8T.

[0014] An assembly process for a modular adjustable flux permanent magnet assembly includes the following steps: S1: NdFeB raw materials are mixed with rare earth dopants and transition metal additives, and then smelted to form a master alloy; the master alloy is crushed and powdered, oriented and pressed in a magnetic field, and then sintered and tempered before being cut to obtain the main magnet; S2: AlNiCo alloy powder and ferrite nanopowder are mixed in a certain proportion, coated with oxide nanocrystals, pressed into shape, and cut after sintering to obtain auxiliary magnets. S3: Align and stack the main magnet and auxiliary magnet along the magnetic pole direction to form a permanent magnet module unit with an adjustable gap; arrange multiple units along the circumferential direction, with module spacer magnetic components sandwiched between the units; S4: Magnetize the assembled components as a whole. According to the target magnetic flux requirement, insert high-permeability or magnetically shielded inserts into the adjustment gap and detect the magnetic flux density in real time through Hall sensors. When fine adjustment is required, apply pulse current to the auxiliary magnet. After the magnetic flux reaches the target, fix the components to complete the assembly.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention, through modular design, sets an adjustable gap between the main magnet and the auxiliary magnet, and is equipped with high permeability inserts and magnetic isolation inserts; by selectively inserting different inserts, it can switch between two working modes of magnetic flux series superposition and parallel current splitting, so that a single component can adapt to a variety of different working conditions, improving the application adaptability and performance optimization space of permanent magnet components; 2. This invention uses neodymium iron boron-based permanent magnets with high coercivity and high energy product as the main magnet, and combines them with aluminum nickel cobalt-ferrite composite permanent magnets with good temperature stability as auxiliary magnets. This composite structure ingeniously combines the advantages of different permanent magnet materials, taking into account both high magnetic performance and stability, and solving the industry problem that it is difficult for a single material to balance various key performances. Attached Figure Description

[0016] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a flowchart of the assembly process of a modular adjustable flux permanent magnet component according to the present invention. Figure 2 This is a schematic diagram of the permanent magnet component in Embodiment 1 of the present invention.

[0017] The reference numerals in the above figures include: 1-Main magnet, 2-Auxiliary magnet, 21-Nanocrystalline layer, 3-Adjusting gap, 31-Nickel-phosphorus alloy coating. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0019] The present invention will be further explained below with reference to specific embodiments: This invention provides a modular adjustable flux permanent magnet assembly, comprising at least two sets of permanent magnet module units and a flux adjustment component. The permanent magnet module unit is composed of a main magnet and an auxiliary magnet stacked along the magnetic pole direction, with an adjustment gap reserved between the main magnet and the auxiliary magnet. The main magnet is a neodymium iron boron-based permanent magnet doped with rare earth elements and transition metals. The auxiliary magnet is an AlNiCo-ferrite composite permanent magnet coated with a nanocrystalline layer, and the auxiliary magnet is composed of AlNiCo alloy powder and ferrite nanopowder. The flux adjustment component includes a high-permeability insert and a magnetic isolation insert, which can be selectively inserted into the adjustment gap between the main magnet and the auxiliary magnet to achieve series superposition or parallel shunting of the magnetic flux.

[0020] The main magnet is a neodymium iron boron (NdFeB) based permanent magnet doped with rare earth elements (such as praseodymium, dysprosium, and terbium) and transition metals (such as cobalt, niobium, zirconium, and titanium). This is because NdFeB has the highest energy product currently available, providing a strong magnetic field, but its magnetic flux decays easily at high temperatures. Doping with rare earth elements (such as dysprosium) significantly improves coercivity and enhances demagnetization resistance, while transition metals (such as cobalt) improve temperature stability and prevent high-temperature performance degradation. The auxiliary magnet is an AlNiCo-ferrite composite permanent magnet coated with a nanocrystalline layer. AlNiCo magnets have good temperature stability but low energy product, while ferrites are low-cost and have stable magnetic properties; the composite structure offers complementary advantages. The nanocrystalline coating prevents component oxidation and improves interfacial bonding strength. The flux adjustment component uses high permeability inserts (iron-nickel alloy) and magnetic isolation inserts (boron nitride ceramic). This is because iron-nickel alloy (such as permalloy) has high permeability, which can efficiently conduct magnetic flux and achieve series superposition; and boron nitride ceramic has high magnetic reluctance, which can isolate the magnetic circuit and achieve parallel current splitting.

[0021] The auxiliary magnet contains 55%-65% aluminum-nickel-cobalt alloy powder and 35%-45% ferrite nanopowder.

[0022] Among them, AlNiCo alloy powder can provide high remanence and temperature stability, ferrite nanopowder enhances magnetic hardness and cost-effectiveness, and the composite properties are balanced.

[0023] The nanocrystalline layer is an oxide nanocrystalline layer with a thickness of 3nm-8nm.

[0024] Among them, the oxide nanocrystalline layer can coat the powder surface, prevent AlNiCo and ferrite from oxidizing during sintering, and improve density and interfacial bonding. The thickness of the oxide nanocrystalline layer is preferably 3nm-8nm. If it is too thin, the coating will be incomplete and the components will be easily oxidized. If it is too thick, it will increase magnetic resistance and reduce magnetic permeability.

[0025] In the main magnet, rare earth elements are selected from at least one of praseodymium, dysprosium, and terbium, and transition metals are selected from at least one of cobalt, niobium, zirconium, and titanium.

[0026] Rare earth elements (praseodymium, dysprosium, terbium) can improve the coercivity and thermal stability of neodymium iron boron, with dysprosium and terbium particularly enhancing the resistance to demagnetization; transition metals (cobalt, niobium, zirconium, titanium) can refine the grain size and improve corrosion resistance.

[0027] The high-permeability insert is made of an iron-nickel alloy with a nickel content of 75%-80%; the magnetic shielding insert is made of boron nitride ceramic, and the thickness of the magnetic shielding insert is the same as that of the high-permeability insert.

[0028] Among them, iron-nickel alloys (75%-80% nickel) have high magnetic permeability, which is beneficial for magnetic flux conduction; while boron nitride ceramics have good insulation and high magnetic reluctance, making them suitable for magnetic shielding. The same thickness ensures that the inserts can be interchanged in terms of insertion gap.

[0029] In the aluminum-nickel-cobalt alloy powder, aluminum accounts for 9%-11% of the mass, nickel accounts for 16%-19% of the mass, cobalt accounts for 8%-12% of the mass, and the remainder is iron; the ferrite nanopowder is one of strontium ferrite, barium ferrite or manganese-zinc ferrite, and the particle size of the ferrite nanopowder is 40nm-80nm.

[0030] Among them, the AlNiCo composition optimizes magnetic properties, with aluminum improving coercivity and nickel and cobalt enhancing remanence; the ferrite type selection is based on cost and application, with strontium / barium ferrite having high stability and manganese-zinc ferrite having low cost.

[0031] The width of the adjustment gap is equal to the thickness of the high magnetic permeability insert or the magnetic shielding insert, the depth of the adjustment gap is consistent with the axial length of the permanent magnet module unit, and the inner wall of the adjustment gap is provided with a nickel-phosphorus alloy plating.

[0032] Among them, the nickel-phosphorus alloy coating enhances wear resistance and magnetic permeability, prevents gap corrosion, and the width matches the thickness of the insert to ensure that the insert is tightly inserted. If it is too wide, magnetic leakage will increase, and if it is too narrow, the insert will be difficult to insert. Consistent depth can ensure the continuity of the magnetic circuit.

[0033] It also includes module spacer magnetic components, which are sandwiched between adjacent permanent magnet module units. The spacer magnetic components are made of amorphous alloy strip and coated with high-temperature resistant insulating paint.

[0034] Among them, the high magnetic permeability of amorphous alloys reduces magnetic interference between units; insulating varnish (such as polyimide varnish) can prevent short circuits and improve temperature resistance; amorphous tape and insulating varnish ensure mechanical strength and insulation level.

[0035] The magnetic flux density when magnetic fluxes are superimposed in series is 0.9T-1.2T, and the magnetic flux density when magnetic fluxes are shunt in parallel is 0.5T-0.8T.

[0036] Among them, 0.9T-1.2T covers high-power scenarios, while 0.5T-0.8T is suitable for energy-saving modes.

[0037] Furthermore, the present invention also provides an assembly process for a modular adjustable flux permanent magnet assembly, comprising the following steps: S1: NdFeB raw materials are mixed with rare earth dopants and transition metal additives, and then smelted to form a master alloy; the master alloy is crushed and powdered, oriented and pressed in a magnetic field, and then sintered and tempered before being cut to obtain the main magnet; S2: AlNiCo alloy powder and ferrite nanopowder are mixed in a certain proportion, coated with oxide nanocrystals, pressed into shape, and cut after sintering to obtain auxiliary magnets. S3: Align and stack the main magnet and auxiliary magnet along the magnetic pole direction to form a permanent magnet module unit with an adjustable gap; arrange multiple units along the circumferential direction, with module spacer magnetic components sandwiched between the units; S4: Magnetize the assembled components as a whole. According to the target magnetic flux requirement, insert high-permeability or magnetically shielded inserts into the adjustment gap and detect the magnetic flux density in real time through Hall sensors. When fine adjustment is required, apply pulse current to the auxiliary magnet. After the magnetic flux reaches the target, fix the components to complete the assembly.

[0038] It should be noted that the fine adjustment in step S4 refers to magnetizing the assembled component as a whole. After setting the macroscopic magnetic flux value, if fine calibration of the magnetic flux is required based on the setting, such as to compensate for material tolerances, a pulse current with specific parameters can be applied to the auxiliary magnet. Utilizing the low coercivity of the auxiliary magnet, the brief strong magnetic field generated by the pulse current (whose direction is the same as or opposite to the magnetization direction) can cause a slight deflection of its magnetic domains, thereby changing its remanent magnetization contribution and achieving "fine-tuning" of the overall magnetic flux. Since there are unavoidable tolerances in the processing and assembly of mechanical inserts, the pulse current adjustment provides a compensation scheme, ensuring the final accuracy of the magnetic flux output. After the magnetic flux meets the standard, the component is fixed with a fixing agent such as epoxy resin to complete the assembly.

[0039] Taking a drive motor as an example, the reserved mounting slots should be completed during the machining stage of the motor rotor core or base. The slots must match the dimensions and arrangement of the permanent magnet module units. The width and depth of the mounting slots should be consistent with the external dimensions of the permanent magnet module units. Each unit consists of a main magnet and an auxiliary magnet stacked together. The axial length needs to be determined based on the motor rotor diameter, and the width of the adjustment gap is equal to the thickness of the insert. The width of the mounting slot should be slightly larger than the total width of the unit (including the main magnet, auxiliary magnet, and adjustment gap) to accommodate the unit and allow for tolerance clearance, ensuring smooth insertion of the unit and avoiding interference stress. The depth of the mounting slot should match the axial length of the unit, usually consistent with the rotor core thickness, to ensure that the unit end face is flush with the rotor surface, and the slots are positioned and arranged circumferentially. The mounting slots need to be evenly distributed along the rotor circumference, corresponding to the number of permanent magnet module units.

[0040] Example 1: Taking the permanent magnet component of the drive motor as an example, in this example, the component includes two sets of permanent magnet module units and a magnetic flux adjustment component.

[0041] First, the main magnet 1 was prepared. Main magnet 1 uses neodymium iron boron (NdFeB) based permanent magnet material, specifically composed of NdFeB raw materials (mainly Nd, Fe, and B) with the addition of rare earth element dysprosium (Dy) and transition metal cobalt (Co) as dopants. The amount of dysprosium added is 2% of the total mass of NdFeB, and the amount of cobalt added is 1%. The preparation process includes: uniformly mixing the NdFeB raw materials with dysprosium powder and cobalt powder, and melting under argon protection to form a master alloy. After hydrogen crushing, the master alloy is ground into powder by air jet milling to obtain magnetic powder with an average particle size of 5 μm. Orientation pressing is performed in a 1.5T magnetic field to form a green compact. The green compact is sintered at 1080°C for 2 hours, then tempered at 500°C, and finally cut into blocks. The coercivity of the obtained main magnet 1 is measured to be 1150 kA / m, and the magnetic energy product is 44 MGOe. The auxiliary magnet 2 is an AlNiCo-ferrite composite permanent magnet coated with a nanocrystalline layer 21. The AlNiCo alloy powder composition is: 10% aluminum, 17% nickel, 10% cobalt, and the remainder iron. The ferrite nanoparticles are strontium ferrite with a particle size of 60 nm. By mass ratio, the AlNiCo alloy powder accounts for 60% and the ferrite nanoparticles account for 40%. After uniform mixing, a 5 nm thick oxide nanocrystalline layer is coated onto the powder using chemical vapor deposition. The mixed powder is pressed into shape at 800 MPa, then sintered at 1250°C for 1 hour, and cut into blocks of the same size as the main magnet. The coercivity of the resulting auxiliary magnet 2 is measured to be 250 kA / m.

[0042] Assembly of permanent magnet module units: See Figure 1 The main magnet 1 and the auxiliary magnet 2 are aligned and stacked along the magnetic pole direction, with an adjustment gap 3 reserved between them. The width of the adjustment gap 3 is 0.5 mm, and the depth is consistent with the axial length of the module. A nickel-phosphorus alloy plating layer 31 is deposited on the inner wall of the gap by electroplating to enhance wear resistance and magnetic permeability. Each permanent magnet module unit consists of one main magnet 1 and one auxiliary magnet 2. This embodiment uses two such units. Figure 2 Only one set is shown. A module spacer magnetic component is sandwiched between the two sets of units. This spacer magnetic component is made of amorphous alloy strip (iron-based amorphous alloy) and coated with high-temperature resistant insulating varnish (polyimide varnish) with a thickness of 2mm. It is used to isolate magnetic interference between units and improve the overall mechanical strength.

[0043] The magnetic flux adjustment assembly includes a high-permeability insert and a magnetically shielding insert. The high-permeability insert is made of a 78% nickel iron-nickel alloy (permalloy) with a thickness of 0.5 mm, matching the width of the adjustment gap. The magnetically shielding insert is made of boron nitride ceramic, also with a thickness of 0.5 mm, and possesses high magnetic shielding performance. Depending on the application requirements, the inserts can be selectively inserted into the adjustment gap during assembly. When a high magnetic flux density is required, a high-permeability insert is inserted to superimpose the magnetic flux in series, and the measured magnetic flux density is 1.1T. When a low magnetic flux density is required, a magnetic isolation insert is inserted to achieve parallel current splitting of the magnetic flux, and the measured magnetic flux density is 0.6T.

[0044] See Figure 1 The specific assembly process is as follows: S1, S2, and S3 are completed as described above to prepare the main magnet 1 and auxiliary magnet 2 and assemble the module. S4 Magnetization and adjustment: The assembled component is pulse-magnetized (magnetic field strength is 3T). The magnetic flux density is detected in real time using a Hall sensor; when fine adjustment is required, a pulse current is applied to the auxiliary magnet, with a peak current of 100A and a duration of 10ms, to fine-tune the magnetic flux. After the test is passed, the component is fixed with epoxy resin to complete the assembly.

[0045] Example 2: This example is based on Example 1, but with adjustments to the material formulation and process parameters.

[0046] Preparation of the main magnet: The main magnet was prepared on the neodymium iron boron substrate of Example 1, with the doping ratio of the rare earth element dysprosium (Dy) increased to 3%, and the transition metals cobalt (Co) 1.5% and titanium (Ti) 0.5% added. In the preparation process, the melting temperature was increased to 1150°C, and after sintering, a two-stage tempering process (510°C×1h+470°C×2h) was used, followed by cutting into the same dimensions as in Example 1. Testing showed that the coercivity of the obtained main magnet increased to 1200 kA / m, and the energy product remained at 44 MGOe.

[0047] The auxiliary magnet was prepared by adjusting the ratio of AlNiCo alloy powder to ferrite nanoparticles to 65:35. The composition of the AlNiCo alloy powder was slightly adjusted: 10.5% aluminum, 18% nickel, and 11% cobalt. The ferrite nanoparticles remained strontium ferrite (60 nm particle size). The nanocrystalline layer thickness was reduced to 4 nm. The sintering temperature was increased to 1280°C, and the holding time was shortened to 45 minutes to refine the grains. The coercivity of the auxiliary magnet was measured to be 255 kA / m.

[0048] Assembly of permanent magnet module units: The assembly method is the same as in Example 1: the main magnet and auxiliary magnet are aligned and stacked, and the gap width is adjusted to maintain 0.5mm. The spacer magnetic components sandwiched between the units are made of high-temperature resistant amorphous alloy (iron-cobalt based), and the surface is sprayed with polyimide insulating varnish (temperature resistance rating 180°C). The two sets of units are arranged circumferentially.

[0049] Magnetic flux regulation: The high-permeability insert and the magnetically shielding insert of the magnetic flux regulation component are both 0.5 mm thick, and the materials are the same as in Example 1 (iron-nickel alloy and boron nitride ceramic). In high-temperature testing: when the high-permeability insert is inserted, the series magnetic flux density is 1.15 T, slightly higher than 1.1 T in Example 1. When the magnetically shielding insert is inserted, the parallel shunt density is 0.62 T.

[0050] The assembly process follows the steps of claim 10. After S4 is magnetized, it is detected by a Hall sensor and a pulse current (peak value 110A, duration 8ms) is applied for fine adjustment.

[0051] Example 3: This example is based on Example 1, but with adjustments to the material ratios and simplification of the process. The component structure remains unchanged.

[0052] Cost-optimized fabrication of the main magnet: Compared to Example 1, the rare-earth element doping of the main magnet was adjusted to use praseodymium (Pr) alone, with an addition amount of 3% of the total mass of neodymium iron boron. Niobium (Nb, 0.8%) was used to replace part of the cobalt as a transition metal. The fabrication process remained unchanged. The main magnet dimensions were the same as in Example 1, and the coercivity was measured to be 1120 kA / m, and the energy product was 42 MGOe.

[0053] The mass ratio of AlNiCo alloy powder to ferrite nanopowder in the auxiliary magnet was adjusted to 55:45. The composition of the AlNiCo alloy powder was slightly adjusted: aluminum accounted for 9.5% by mass, nickel for 18% by mass, cobalt for 9% by mass, and the remainder was iron. The ferrite nanopowder used was low-cost manganese-zinc ferrite with a particle size of 70 nm. The nanocrystalline layer thickness was set to 6 nm. The rest of the process remained unchanged. Testing showed that the coercivity of the resulting auxiliary magnet was 270 kA / m.

[0054] The assembly method of the permanent magnet module unit is the same as that in Example 1.

[0055] Both the high-permeability and magnetically shielded plates of the flux regulating assembly are 0.5mm thick, but the high-permeability plate uses an iron-nickel alloy with a nickel content of 75% to reduce costs. Under standard operating conditions of the drive motor: when the high-permeability plate is inserted, the series flux density is 0.95T. When the magnetically shielded plate is inserted, the parallel shunt density is 0.65T (within the range of 0.5T-0.8T).

[0056] Example 4: This example is based on Example 1, but with adjustments to the material ratios and simplification of the process. The component structure remains unchanged.

[0057] The rare earth element doping of the main magnet was adjusted to a combination of dysprosium (Dy, 2%) and terbium (Tb, 0.5%), with zirconium (Zr, 1%) and cobalt (Co, 1.2%) added as transition metals. In the preparation process, the powder particle size was refined to 4 μm, the magnetic field orientation pressing strength was increased to 1.8 T, and a rapid heating process (1100°C × 1.5 h) was used during sintering. The resulting main magnet exhibited a coercivity of 1180 kA / m and a magnetic energy product of 46 MGOe.

[0058] In the auxiliary magnet, the mass ratio of AlNiCo alloy powder to ferrite nanoparticles was maintained at 60:40, but ultrafine strontium ferrite with a particle size of 40 nm was selected. The nanocrystalline layer thickness was optimized to 5 nm. The sintering temperature was adjusted to 1250°C. The final auxiliary magnet exhibited a coercivity of 260 kA / m.

[0059] During assembly, the gap width is adjusted to 0.4mm, and the gap depth is adjusted accordingly, while still ensuring that the width equals the thickness of the insert. The inner wall of the gap is coated with a nano-grade nickel-phosphorus alloy. The spacer magnet uses a thin amorphous strip (1.5mm thick) with a corona-resistant coating.

[0060] The high-permeability insert and the magnetically shielding insert of the flux regulating component are both 0.4 mm thick, and the materials are the same as in Example 1. In the high-power test: when the high-permeability insert is inserted, the series flux density reaches 1.18T; when the magnetically shielding insert is inserted, the parallel shunt density is 0.58T. The assembly process remains unchanged.

[0061] Comparative Example 1 Compared with Example 1, this comparative example uses only a single main magnet, without auxiliary magnets and adjustment gap, which is a traditional permanent magnet component solution.

[0062] The permanent magnet assembly in this comparative example consists only of the main magnet and does not include auxiliary magnets, adjustment gaps, or flux adjustment components. The main magnet was prepared following step S1 of Example 1: Neodymium iron boron raw materials (composed of Nd, Fe, and B) were mixed with rare earth dopant dysprosium (Dy, 2% addition) and transition metal cobalt (Co, 1% addition), and then smelted, powdered, magnetically pressed, sintered, and tempered before being cut into shape. The main magnet dimensions were the same as in Example 1, with a coercivity of 1150 kA / m and a magnetic energy product of 44 MGOe. During assembly, a single main magnet was used directly as the assembly, without any spacer magnets or other adjustment structures. After magnetization, the magnetic flux density was detected using a Hall sensor, with a measured value of 0.8 T.

[0063] Comparative Example 2 Compared with Example 1, this comparative example uses a non-composite auxiliary magnet and has no nanocrystalline coating.

[0064] The permanent magnet assembly in this comparative example includes a main magnet and an auxiliary magnet, but the auxiliary magnet uses a traditional AlNiCo alloy (without ferrite composite and nanocrystalline coating). The main magnet is prepared in the same manner as in Example 1. Auxiliary magnet preparation: AlNiCo alloy powder (composition: 10% aluminum, 17% nickel, 10% cobalt, balance iron) is directly pressed into shape, sintered at 1250°C for 1 hour, and cut to the same size as the main magnet. The auxiliary magnet has a coercivity of 200 kA / m and no nanocrystalline coating. The main magnet and auxiliary magnet are stacked, but no adjustment gap is provided, making it impossible to insert inserts. After assembly, it is magnetized, and the magnetic flux density is 0.7 T.

[0065] Comparative Example 3 Compared with Example 1, this comparative example does not have a magnetic flux adjustment component and adopts a fixed gap scheme.

[0066] The permanent magnet assembly in this comparative example includes a main magnet and an auxiliary magnet, with a pre-reserved fixed adjustment gap (0.5 mm wide), but without high-permeability inserts or magnetic isolation inserts. The main magnet and auxiliary magnet are prepared in the same manner as in Example 1. The inner wall of the gap has no nickel-phosphorus alloy plating. During assembly, the main magnet and auxiliary magnet are directly stacked with a fixed gap, preventing the insertion of any inserts. After magnetization, the magnetic flux density is fixed at 0.75 T.

[0067] Performance testing The permanent magnet assemblies prepared and assembled in Examples 1-4 and Comparative Examples 1-3 were subjected to systematic performance testing and analysis. The tests focused on evaluating magnetic properties (coercivity, magnetic energy product, magnetic flux density) and stability (such as temperature adaptability). The testing methods adopted standard industrial procedures, including pulse magnetization, real-time detection of magnetic flux density by Hall sensors, and fine-tuning by applying pulse current when necessary.

[0068] The following is a detailed description of the test results for each embodiment and comparative example. The test environment simulated real-world application conditions, such as room temperature (25°C) and high temperature (80°C) scenarios, to evaluate performance stability. Magnetic flux density was measured using a Hall sensor with an accuracy of ±0.01T; coercivity and magnetic energy product were determined using a BH analyzer.

[0069] Example 1 Test Results: Two sets of permanent magnet module units were used. The main magnet was made of neodymium iron boron-based material with a coercivity of 1150 kA / m and a magnetic energy product of 44 MGOe. The auxiliary magnet was an AlNiCo-ferrite composite with a coercivity of 250 kA / m. The adjustment gap width was 0.5 mm, and the inner wall had a nickel-phosphorus alloy plating. After the entire component was magnetized (magnetic field strength 3T), the magnetic flux was adjusted by inserting high-permeability or magnetically shielded inserts, and fine-tuned using pulsed current (peak value 100A, duration 10ms). In the series superposition mode, i.e., with the high-permeability insert inserted, the magnetic flux density was 1.1T, covering the requirements of high-power applications. In the parallel shunt mode (with the magnetically shielded insert inserted), the magnetic flux density was 0.6T, suitable for energy-saving scenarios. After continuous operation at 80°C for 2 hours, the magnetic flux decay rate was <3%, indicating that the AlNiCo-ferrite composite structure of the auxiliary magnet effectively improved temperature stability. The magnetic energy product remained at 44 MGOe, and the coercivity did not change significantly.

[0070] Example 2 test results: The coercivity of the main magnet was increased to 1200kA / m, and the magnetic energy product was 44MGOe; the auxiliary magnet adjusted the proportion of AlNiCo powder to 65%, the proportion of ferrite nanopowder to 35%, the nanocrystalline layer thickness to 4nm, and the coercivity to 255kA / m; the spacer magnet was made of iron-cobalt based amorphous alloy, which is resistant to 180°C.

[0071] During testing, after magnetization, inserts were inserted for adjustment. The pulse current fine-tuning parameters were set to a peak value of 110A and a duration of 8ms. High-temperature testing focused on evaluating stability. In series superposition mode, the magnetic flux density was 1.15T, slightly higher than in Example 1, thanks to the optimized coercivity of the main magnet. In parallel shunt mode, the magnetic flux density was 0.62T, with high adjustment accuracy. At 80°C, the magnetic flux density fluctuation was <2%, and pulse current fine-tuning further improved magnetic flux stability (attenuation rate <2.5%). Simultaneously, the use of module spacer magnetic components (amorphous alloy strips) effectively reduced inter-unit magnetic interference, and the component structure showed no loosening after vibration testing (frequency 50Hz, duration 1 hour).

[0072] Example 3 Test Results: Example 3 is a cost optimization scheme. The main magnet uses praseodymium doping, with a coercivity of 1120 kA / m and a magnetic energy product of 42 MGOe. The auxiliary magnet has an aluminum-nickel-cobalt powder content of 55%, a ferrite nanopowder content of 45%, a nanocrystalline layer thickness of 6 nm, and a coercivity of 270 kA / m. The high permeability insert uses a 75% nickel-iron alloy to reduce costs.

[0073] During testing, flux regulation was assessed under standard operating conditions, with pulse current parameters referring to Example 1 (peak 100A, duration 10ms). In series superposition mode, the flux density was 0.95T, suitable for low-cost, medium-power applications. In parallel shunt mode, the flux density was 0.65T, also within the target range. However, the material cost was reduced compared to Example 1, while the magnetic energy product remained at 42MGOe, meeting basic application requirements. Simultaneously, pulse current fine-tuning effectively compensated for flux deviation, resulting in higher output stability.

[0074] Test results of Example 4: Example 4 is a high-performance solution. The main magnet is composite doped with dysprosium and terbium, with a coercivity of 1180 kA / m and a magnetic energy product of 46 MGOe. The auxiliary magnet uses ultrafine strontium ferrite (particle size 40 nm) with a nanocrystalline layer thickness of 5 nm and a coercivity of 260 kA / m. The gap is adjusted to be compressed to 0.4 mm, and the insert is correspondingly thinned.

[0075] The ultimate performance was evaluated under high-power testing, with pulse current fine-tuning as in Example 1. In series superposition mode, the magnetic flux density reached 1.18T. In parallel shunt mode, the magnetic flux density was 0.58T, showing good shunt effect. In short-term testing at 100°C, the magnetic flux attenuation rate was <4%, attributed to nanocrystalline coating and gap optimization.

[0076] The testing methods for Comparative Examples 1-3 are the same as those for the Examples. The following table summarizes the test results of all Examples and Comparative Examples for easy comparison:

[0077] As shown in the table above, the magnetic flux density of Comparative Example 1 is fixed at 0.8T, and the magnetic flux attenuation rate at high temperature (80°C) is >8%, making it impossible to adjust the magnetic flux. Comparative Example 1 uses only a single NdFeB main magnet, lacking auxiliary magnets and an adjustment gap. Although NdFeB material has a high energy product (44 MGOe) and high coercivity (1150 kA / m), its magnetic flux output is fixed, making it impossible to achieve series superposition or parallel current splitting through interpolation. Furthermore, a single NdFeB magnet is prone to irreversible magnetic flux attenuation at high temperatures. Moreover, Comparative Example 1 lacks the temperature compensation effect of an AlNiCo-ferrite composite auxiliary magnet, resulting in a significantly higher magnetic flux attenuation rate at high temperatures compared to Example 1.

[0078] The magnetic flux density of Comparative Example 2 was fixed at 0.7T, lower than that of Example 1. At high temperatures, the magnetic flux fluctuation was >5%, and the coercivity of the auxiliary magnet was only 200kA / m. This was because the auxiliary magnet in Comparative Example 2 used a traditional AlNiCo alloy (without ferrite composite and nanocrystalline coating). While AlNiCo magnets have good temperature stability, their magnetic energy product is low; the addition of ferrite nanopowder can enhance magnetic hardness and cost-effectiveness. Comparative Example 2 lacked ferrite composite, resulting in insufficient magnetic performance of the auxiliary magnet (coercivity 200kA / m), failing to effectively complement the main magnet. Furthermore, the lack of nanocrystalline coating made the auxiliary magnet prone to oxidation during sintering, reducing density and interfacial bonding strength. It is evident that nanocrystalline layers (such as oxide layers) can prevent component oxidation and improve interfacial bonding. Although the main and auxiliary magnet stacked structure was retained, no adjustment gap was reserved, making it impossible to insert inserts to adjust the magnetic flux.

[0079] Comparative Example 3 has a fixed magnetic flux density of 0.75T, which is not adjustable. The lack of a coating on the inner wall of the gap results in poor wear resistance. Although Comparative Example 3 has a pre-installed adjustment gap (0.5mm wide), it lacks high-permeability inserts and magnetically shielding inserts. The gap in Comparative Example 3 serves only as a structural void and cannot dynamically change the magnetic circuit. Furthermore, the absence of a nickel-phosphorus alloy coating on the inner wall of the gap makes it prone to wear under mechanical stress and results in poor magnetic permeability. A coating can enhance wear resistance and magnetic permeability, and prevent gap corrosion.

[0080] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A modular adjustable flux permanent magnet assembly, characterized in that: Includes at least two sets of permanent magnet module units and magnetic flux adjustment components; The permanent magnet module unit is composed of a main magnet and an auxiliary magnet stacked along the magnetic pole direction, and an adjustment gap is reserved between the main magnet and the auxiliary magnet. The main magnet is a neodymium iron boron based permanent magnet doped with rare earth elements and transition metals. The auxiliary magnet is an AlNiCo-ferrite composite permanent magnet coated with a nanocrystalline layer, and the auxiliary magnet is composed of AlNiCo alloy powder and ferrite nanopowder. The magnetic flux adjustment component includes a high-permeability insert and a magnetic isolation insert. The high-permeability insert and the magnetic isolation insert can be selectively inserted into the adjustment gap between the main magnet and the auxiliary magnet to achieve series superposition or parallel shunting of magnetic flux.

2. The modular adjustable flux permanent magnet assembly according to claim 1, characterized in that: The auxiliary magnet contains 55%-65% aluminum-nickel-cobalt alloy powder and 35%-45% ferrite nanopowder by mass.

3. The modular adjustable flux permanent magnet assembly according to claim 1, characterized in that: The nanocrystalline layer is an oxide nanocrystalline layer, and the thickness of the oxide nanocrystalline layer is 3nm-8nm.

4. The modular adjustable flux permanent magnet assembly according to claim 1, characterized in that: In the main magnet, the rare earth element is selected from at least one of praseodymium, dysprosium, and terbium, and the transition metal is selected from at least one of cobalt, niobium, zirconium, and titanium.

5. A modular adjustable flux permanent magnet assembly according to claim 1, characterized in that: The high magnetic permeability insert is made of an iron-nickel alloy with a nickel content of 75%-80%; the magnetic shielding insert is made of boron nitride ceramic, and the thickness of the magnetic shielding insert is the same as that of the high magnetic permeability insert.

6. A modular adjustable flux permanent magnet assembly according to claim 2, characterized in that: In the aluminum-nickel-cobalt alloy powder, aluminum accounts for 9%-11% of the mass, nickel accounts for 16%-19% of the mass, cobalt accounts for 8%-12% of the mass, and the remainder is iron; the ferrite nanopowder is one of strontium ferrite, barium ferrite or manganese-zinc ferrite, and the particle size of the ferrite nanopowder is 40nm-80nm.

7. A modular adjustable flux permanent magnet assembly according to claim 1, characterized in that: The width of the adjustment gap is equal to the thickness of the high magnetic permeability insert or the magnetic shielding insert, the depth of the adjustment gap is consistent with the axial length of the permanent magnet module unit, and the inner wall of the adjustment gap is provided with a nickel-phosphorus alloy plating layer.

8. A modular adjustable flux permanent magnet assembly according to claim 1, characterized in that: It also includes module spacer magnetic components, which are sandwiched between adjacent permanent magnet module units. The spacer magnetic components are made of amorphous alloy strip and coated with high-temperature resistant insulating paint.

9. A modular adjustable flux permanent magnet assembly according to claim 1, characterized in that: The magnetic flux density when the magnetic flux is superimposed in series is 0.9T-1.2T, and the magnetic flux density when the magnetic flux is splittered in parallel is 0.5T-0.8T.

10. An assembly process for a modular adjustable flux permanent magnet assembly, used for assembling the modular adjustable flux permanent magnet assembly as described in any one of claims 1-9, characterized in that, Includes the following steps: S1: NdFeB raw materials are mixed with rare earth dopants and transition metal additives, and then smelted to form a master alloy; the master alloy is crushed and powdered, oriented and pressed in a magnetic field, and then sintered and tempered before being cut to obtain the main magnet; S2: AlNiCo alloy powder and ferrite nanopowder are mixed in a certain proportion, coated with oxide nanocrystals, pressed into shape, and cut after sintering to obtain auxiliary magnets. S3: Align and stack the main magnet and auxiliary magnet along the magnetic pole direction to form a permanent magnet module unit with an adjustable gap; arrange multiple units along the circumferential direction, with module spacer magnetic components sandwiched between the units; S4: Magnetize the assembled components as a whole. According to the target magnetic flux requirement, insert high-permeability or magnetically shielding inserts into the adjustment gap and detect the magnetic flux density in real time through Hall sensors. When fine adjustments are required, apply a pulsed current to the auxiliary magnet. Once the magnetic flux reaches the target, fix the component to complete the assembly.

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