A high-frequency transformer nanocrystalline core produced by roll-to-roll and a preparation method thereof

Abstract

The application belongs to the technical field of soft magnetic material and transformer, and particularly relates to a high-frequency transformer nanocrystalline core capable of being produced by roll-to-roll and a preparation method thereof. The preparation method comprises the following steps: performing roll-to-roll annealing treatment on nanocrystalline strip material, applying tensile stress along the length direction of the strip material during the annealing treatment process, and obtaining the annealed nanocrystalline strip material; then coating an organic insulating adhesive coating on the surface of the annealed nanocrystalline strip material, and after the organic insulating adhesive coating is surface-dried, winding the treated nanocrystalline strip material into an iron core with a closed magnetic circuit, dipping and curing to obtain the high-frequency transformer nanocrystalline core. The high-frequency transformer nanocrystalline core has higher saturation magnetic induction intensity and power density compared with ferrite material, and through the synergistic cooperation of the organic insulating adhesive coating and the dipping and curing, the interlayer insulation and the enhancement stability of the nanocrystalline strip material are realized, the high-frequency loss of the iron core can be significantly reduced, and the high-frequency transformer nanocrystalline core has good performance stability.

Description

Technical Field

[0001] This invention belongs to the field of soft magnetic materials and transformer technology, specifically relating to a high-frequency transformer nanocrystalline iron core that can be produced by roll-to-roll and its preparation method. Background Technology

[0002] The essence of a solid-state transformer (SST) lies in replacing the core components of a traditional transformer—the iron core and windings—with entirely solid-state power electronic devices. It leverages power electronic conversion (semiconductor switching) to flexibly adjust output voltage and current, actively control the power factor, and support bidirectional energy flow, upgrading from "passive conversion" to "active control," thus showcasing the advantages of power electronic devices.

[0003] However, in order to ensure the reliable and stable operation of SST, there is also an "isolation transformer" in the system. This transformer contains a small high-frequency iron core (the volume is only 1 / 10 to 1 / 5 of that of a traditional transformer) and fine wire windings. Its operating frequency is consistent with that of power electronic devices (kHz level). It is used in scenarios that require electrical isolation (such as medical equipment with high safety requirements and grid connection of new energy sources) to achieve electrical isolation between the input and output terminals and avoid the risk of leakage.

[0004] Traditional designs use ferrite as the core material for isolation transformers. However, due to its low saturation magnetic flux density, it is very difficult to increase the power density of the transformer. Patent CN 104944933 B describes a method for preparing a high-inductance, high-permeability ferrite core for high-frequency transformers. It uses nanocrystalline manganese-zinc ferrite with a specific composition to improve the inductance and permeability of the core, but its effect on improving the saturation magnetic flux density is relatively limited.

[0005] Nanocrystalline soft magnetic alloys can achieve a saturation magnetic flux density exceeding 1.2T, nearly three times that of ferrites. However, due to their excessively high permeability and the additional interlayer eddy currents between the layers of the nanocrystalline wound core, their high-frequency losses are too high, posing a significant drawback in SST (Silicon-to-Screen) design. Patent CN 113707443 B describes a method for preparing nanocrystalline magnetic cores. This method involves using strip adhesive to bond nanocrystalline strips during core preparation, creating gaps between the strips. The core is then subjected to vacuum impregnation, with the impregnating solution permeating the gaps between the strips. Baking the impregnating solution to solidify it significantly increases the structural strength of the nanocrystalline magnetic core, thereby improving its bending resistance. While this patent achieves good interlayer insulation through strip adhesive and vacuum impregnation, the process is relatively complex. Summary of the Invention

[0006] In view of the shortcomings and deficiencies of the existing technology, the primary objective of this invention is to provide a method for preparing high-frequency transformer nanocrystalline iron cores that can be produced by roll-to-roll manufacturing.

[0007] Another object of the present invention is to provide a high-frequency transformer nanocrystalline iron core prepared by the above method.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A method for preparing a high-frequency transformer nanocrystalline iron core that can be produced by roll-to-roll manufacturing includes the following preparation steps:

[0010] (1) The nanocrystalline ribbon is subjected to roll-to-roll annealing. During the annealing process, tensile stress is applied along the length of the ribbon to obtain the annealed nanocrystalline ribbon.

[0011] (2) Coat the surface of the nanocrystalline strip after the treatment in step (1) with an organic insulating adhesive coating. After the organic insulating adhesive coating is dry, wind the treated nanocrystalline strip into a core with a closed magnetic circuit, impregnate and cure it to obtain a high-frequency transformer nanocrystalline core.

[0012] Furthermore, the composition system of the nanocrystalline ribbon material described in step (1) is Fe. (100-x-y-z-α-β-γ) M x Cu y M' z Si α B β X γ M is at least one element from Co and Ni, M' is at least one element from Nb, V, Mo, Ta, W, Zr, Hf, Ti, Cr, Mn, Al, Sc, Y, Zn, Sn, and X is at least one element from C, Ge, P, Ga, Sb, In, S; 0≤x≤40, 0.5≤y≤1.5, 1≤z≤5, 1≤α≤18, 5≤β≤15, 0≤γ≤3, and satisfies y+z+α+β+γ≤30 (x, y, z, α, β, γ represent the atomic percentage of each element).

[0013] Furthermore, the thickness of the nanocrystalline ribbon in step (1) is 10~30μm.

[0014] Furthermore, the annealing temperature in step (1) is 530~650℃, the annealing time is 10~200 seconds, and the heating method used for annealing is resistance wire heating, laser heating, infrared lamp heating, electrode carbon brush heating, or induction coil heating, etc. Annealing at the above temperatures can optimize magnetic properties and enhance the stability of the magnetic core.

[0015] Furthermore, the tensile stress applied along the length of the strip in step (1) is 1~500 MPa. By simultaneously applying tensile stress during the roll-to-roll annealing process, the magnetic permeability can be continuously adjusted without further heat treatment and magnetic field treatment, making the process simple.

[0016] Further, the initial magnetic permeability of the annealed nanocrystalline ribbon in step (1) is 50~50000; more preferably, the initial magnetic permeability is 1000~30000.

[0017] Further, the organic insulating adhesive in step (2) is an acrylic resin adhesive, an organosilicon adhesive, or an organosilicon-modified acrylic resin adhesive; the thickness of the organic insulating adhesive coating is 0.1~5μm, preferably 0.1~2μm.

[0018] More preferably, the silicone-modified acrylic resin adhesive is prepared by the following method:

[0019] Acrylic ester monomer, acrylonitrile, and vinyl-terminated silicone oil (Vi-PDMS-Vi) are added to an organic solvent and mixed and dissolved. Then, an initiator is added, and after deoxygenation with nitrogen, the temperature is raised to 50~80℃ for copolymerization to obtain an organosilicon-modified acrylic resin adhesive.

[0020] This invention utilizes acrylic resin adhesive, which exhibits good adhesion to nanocrystalline ribbon and impregnated resin, achieving excellent insulating coating and bonding effects. The use of silicone adhesive provides good high-temperature resistance, improving the high-temperature stability of the wound core. Furthermore, the use of silicone-modified acrylic resin adhesive combines the advantages of both, simultaneously achieving good insulating coating, bonding, and high-temperature stability. This reduces high-frequency losses and improves device performance stability, while also offering the advantage of low cost.

[0021] Further, the acrylate monomer is at least one of methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

[0022] Furthermore, the number-average molecular weight of the terminal vinyl silicone oil is in the range of 2000~20000.

[0023] Furthermore, the mass ratio of the added acrylate monomer, acrylonitrile, and vinyl-terminated silicone oil is 10:2~3:0.5~2.

[0024] In the above copolymer raw materials, acrylate monomers are used to improve adhesion, acrylonitrile is used to improve adhesion and corrosion resistance, and vinyl-terminated silicone oil is used to improve high-temperature resistance. The above monomer composition exhibits excellent overall performance.

[0025] Furthermore, the organic solvent is one or more of benzene, toluene, xylene, and ethyl acetate; the amount of organic solvent used is such that the solid content of the obtained organosilicon-modified acrylic resin adhesive is 30-50%.

[0026] Furthermore, the initiator is benzoyl peroxide or azobisisobutyronitrile; the copolymerization reaction time is 3-8 hours.

[0027] Furthermore, the method of applying the organic insulating adhesive coating in step (2) is either spraying (with a nozzle) or brushing (with a brush).

[0028] Furthermore, the coating thickness of the organic insulating adhesive coating in step (2) is 0.1~5μm, more preferably 0.3~3μm.

[0029] Furthermore, the closed magnetic circuit described in step (2) is a ring, a racetrack, or a rectangle.

[0030] Furthermore, the impregnation curing in step (2) is performed using epoxy resin adhesive for vacuum impregnation curing.

[0031] A high-frequency transformer nanocrystalline iron core was prepared by the above method.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] (1) The transformer core of the present invention is made by winding, bonding and curing nanocrystalline strip, which has a higher saturation magnetic induction intensity than ferrite material, and the resulting core has a higher power density.

[0034] (2) The present invention achieves interlayer insulation and enhanced stability of nanocrystalline ribbon by coating the surface of nanocrystalline ribbon with organic insulating adhesive and impregnation curing in a synergistic manner, which can significantly reduce the high frequency loss of iron core and has good performance stability.

[0035] (3) The process of coating the surface with organic insulating adhesive used in this invention can be carried out in one continuous step after the roll-to-roll annealing process. The process is simple and the treatment effect is good. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto. For ease of performance comparison, the iron cores of the following embodiments and comparative examples are all rectangular, with dimensions of 50 mm inner length, 35 mm inner width, 15 mm stack thickness (winding thickness), and 10 mm height.

[0037] Example 1

[0038] A method for preparing a high-frequency transformer nanocrystalline iron core that can be produced by roll-to-roll manufacturing includes the following preparation steps:

[0039] (1) The composition is Fe 73.5 Cu1Nb3Si 15.5 B7. A nanocrystalline ribbon with a thickness of 18 μm and a width of 10 mm was subjected to roll-to-roll annealing at a temperature of 600℃ for 15 seconds. A tensile stress of 17 MPa was applied along the length of the ribbon during the annealing process to obtain the annealed nanocrystalline ribbon. The resulting annealed nanocrystalline ribbon exhibited a permeability of 15000 at 100 kHz.

[0040] (2) Spray an acrylic resin adhesive insulating coating with a thickness of 1 μm onto the surface of the nanocrystalline ribbon treated in step (1) (a polymer product with methyl methacrylate and butyl methacrylate as comonomers in a mass ratio of 10:3, toluene as solvent, and a solid content of 45%). After the insulating coating is surface dry, wind the treated nanocrystalline ribbon into an annular closed magnetic circuit core, and then perform vacuum impregnation and curing in epoxy resin adhesive to obtain a high-frequency transformer nanocrystalline core.

[0041] The core obtained in this embodiment was tested and found to have a saturation magnetic induction intensity of 1.2T (referring to GB / T 13012-2008 Measurement Method of DC Magnetic Properties of Soft Magnetic Materials); a loss of 65W / kg under 100kHz & 0.3T conditions (referring to IEC60404-3:2022 Measurement Method of AC Magnetic Properties of Soft Magnetic Materials); and a loss change rate of 8.6% after high-temperature treatment at 100℃ for 720h.

[0042] Example 2

[0043] A method for preparing a high-frequency transformer nanocrystalline iron core that can be produced by roll-to-roll manufacturing includes the following preparation steps:

[0044] (1) The composition is Fe 73.5 Cu1Nb3Si 15.5 B7. A nanocrystalline ribbon with a thickness of 18 μm and a width of 10 mm was subjected to roll-to-roll annealing at a temperature of 600℃ for 15 seconds. A tensile stress of 20 MPa was applied along the length of the ribbon during the annealing process to obtain the annealed nanocrystalline ribbon. The resulting annealed nanocrystalline ribbon exhibited a permeability of 13000 at 100 kHz.

[0045] (2) Spray an acrylic resin adhesive insulating coating with a thickness of 0.5 μm (a polymer product with methyl methacrylate and butyl methacrylate as comonomers in a mass ratio of 10:3, toluene as solvent, and 45% solid content) onto the surface of the nanocrystalline ribbon after step (1). After the insulating coating is surface dry, wind the treated nanocrystalline ribbon into an annular closed magnetic circuit core, and then vacuum impregnate and cure it in epoxy resin adhesive to obtain a high-frequency transformer nanocrystalline core.

[0046] The core obtained in this embodiment was tested to have a saturation magnetic induction intensity of 1.2T; a loss of 68W / kg under 100kHz & 0.3T conditions; and a loss change rate of 9.5% after high-temperature treatment at 100℃ for 720h.

[0047] Example 3

[0048] A method for preparing a high-frequency transformer nanocrystalline iron core that can be produced by roll-to-roll manufacturing includes the following preparation steps:

[0049] (1) The composition is Fe 73.5 Cu1Nb3Si 15.5 B7. A nanocrystalline ribbon with a thickness of 18 μm and a width of 10 mm was subjected to roll-to-roll annealing at a temperature of 600℃ for 15 seconds. A tensile stress of 36 MPa was applied along the length of the ribbon during the annealing process to obtain the annealed nanocrystalline ribbon. The resulting annealed nanocrystalline ribbon exhibited a permeability of 3000 at 100 kHz.

[0050] (2) Spray an acrylic resin adhesive insulating coating with a thickness of 1.5 μm onto the surface of the nanocrystalline ribbon treated in step (1) (a polymer product with methyl methacrylate and butyl methacrylate as comonomers in a mass ratio of 10:3, toluene as solvent, and a solid content of 45%). After the insulating coating is surface dry, wind the treated nanocrystalline ribbon into an annular closed magnetic circuit core, and then perform vacuum impregnation and curing in epoxy resin adhesive to obtain a high-frequency transformer nanocrystalline core.

[0051] The core obtained in this embodiment was tested to have a saturation magnetic induction intensity of 1.2T; a loss of 70W / kg under 100kHz & 0.3T conditions; and a loss change rate of 9.2% after high-temperature treatment at 100℃ for 720h.

[0052] Example 4

[0053] A method for preparing a high-frequency transformer nanocrystalline iron core that can be produced by roll-to-roll manufacturing, wherein the insulating coating adopts an organosilicone adhesive insulating coating (an adhesive system composed of end vinyl silicone oil, hydrogen-containing silicone oil crosslinking agent and platinum complex catalyst), and the rest is the same as in Example 1.

[0054] The core obtained in this embodiment was tested to have a saturation magnetic induction intensity of 1.2T; a loss of 66W / kg under 100kHz & 0.3T conditions; and a loss change rate of 4.7% after high-temperature treatment at 100℃ for 720h.

[0055] Example 5

[0056] A method for preparing a high-frequency transformer nanocrystalline iron core that can be produced by roll-to-roll manufacturing, wherein the insulating coating uses an organosilicon-modified acrylic resin adhesive, and the rest is the same as in Example 1.

[0057] The preparation method of the organosilicon-modified acrylic resin adhesive is as follows:

[0058] Butyl acrylate, acrylonitrile, and vinyl-terminated silicone oil (Vi-PDMS-Vi, number average molecular weight 9000) in a mass ratio of 10:2.5:1.5 were added to toluene solvent and mixed and dissolved. Then, azobisisobutyronitrile initiator was added, and after deoxygenation with nitrogen, the temperature was raised to 65°C for copolymerization reaction for 5 hours to obtain an organosilicon modified acrylic resin adhesive with a solid content of 45%.

[0059] The core obtained in this embodiment was tested to have a saturation magnetic induction intensity of 1.2T; a loss of 61W / kg under 100kHz & 0.3T conditions; and a loss change rate of 5.0% after high-temperature treatment at 100℃ for 720h.

[0060] The results above show that the silicone-modified acrylic resin adhesive used in this invention can simultaneously achieve good insulation coating effect, bonding effect and high temperature stability.

[0061] Comparative Example 1

[0062] A method for preparing a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy, compared with Example 1, is that the nanocrystalline strip after step (1) is not coated with an acrylic resin adhesive insulating coating, but the rest are the same.

[0063] The iron core obtained in this comparative example showed a loss of 85 W / kg under the conditions of 100 kHz & 0.3T; the loss change rate after high temperature treatment at 100℃ for 720 h was 18.6%.

[0064] The results above show that the present invention achieves interlayer insulation and enhanced stability of nanocrystalline ribbon by coating the surface of nanocrystalline ribbon with organic insulating adhesive and impregnation curing in a synergistic manner. The prepared wound core has significantly reduced losses and significantly improved high-temperature stability.

[0065] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-frequency transformer nanocrystalline iron core that can be produced by roll-to-roll manufacturing, characterized in that... The preparation steps include the following: (1) The nanocrystalline ribbon is subjected to roll-to-roll annealing. During the annealing process, tensile stress is applied along the length of the ribbon to obtain the annealed nanocrystalline ribbon. (2) Coat the surface of the nanocrystalline strip after step (1) with an organic insulating adhesive coating. After the organic insulating adhesive coating is surface dry, wind the treated nanocrystalline strip into a core with a closed magnetic circuit, impregnate and cure it to obtain a high-frequency transformer nanocrystalline core. The organic insulating adhesive mentioned in step (2) is an organosilicon-modified acrylic resin adhesive prepared by the following method: Acrylic ester monomer, acrylonitrile and vinyl-terminated silicone oil are added to an organic solvent and mixed and dissolved. Then an initiator is added, and after deoxygenation with nitrogen, the temperature is raised to 50~80℃ for copolymerization reaction to obtain silicone-modified acrylic resin adhesive. The acrylate monomer is at least one of methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate; the number average molecular weight of the vinyl-terminated silicone oil is in the range of 2000 to 20000. The mass ratio of the acrylate monomer, acrylonitrile, and vinyl-terminated silicone oil is 10:2~3:0.5~2.

2. The method for preparing a high-frequency transformer nanocrystalline core that can be produced by roll-to-roll manufacturing according to claim 1, characterized in that: The composition system of the nanocrystalline ribbon mentioned in step (1) is Fe. (100-x-y-z-α-β-γ) M x Cu y M' z Si α B β X γ Where M is at least one element from Co and Ni, M' is at least one element from Nb, V, Mo, Ta, W, Zr, Hf, Ti, Cr, Mn, Al, Sc, Y, Zn, Sn, and X is at least one element from C, Ge, P, Ga, Sb, In, S; 0≤x≤40, 0.5≤y≤1.5, 1≤z≤5, 1≤α≤18, 5≤β≤15, 0≤γ≤3, and y+z+α+β+γ≤30.

3. The method for preparing a high-frequency transformer nanocrystalline iron core that can be produced by roll-to-roll manufacturing according to claim 1, characterized in that: The thickness of the nanocrystalline ribbon in step (1) is 10~30μm.

4. The method for preparing a high-frequency transformer nanocrystalline core that can be produced by roll-to-roll manufacturing according to claim 1, characterized in that: The annealing temperature in step (1) is 530~650℃, the annealing time is 10~200 seconds, and the heating method used for the annealing is resistance wire heating, laser heating, infrared lamp heating, electrode carbon brush heating or induction coil heating.

5. The method for preparing a high-frequency transformer nanocrystalline core that can be produced by roll-to-roll manufacturing according to claim 1, characterized in that: The tensile stress applied along the length of the strip in step (1) is 1~500MPa; the initial magnetic permeability of the annealed nanocrystalline strip is 50~50000.

6. The method for preparing a high-frequency transformer nanocrystalline core that can be produced by roll-to-roll manufacturing according to claim 1, characterized in that: The thickness of the organic insulating adhesive coating in step (2) is 0.1~5μm.

7. The method for preparing a high-frequency transformer nanocrystalline core that can be produced by roll-to-roll according to claim 1, characterized in that: The organic solvent is one or more of benzene, toluene, xylene, and ethyl acetate; the amount of organic solvent used is such that the solid content of the obtained organosilicon-modified acrylic resin adhesive is 30-50%; the initiator is benzoyl peroxide or azobisisobutyronitrile; the copolymerization reaction time is 3-8 hours.

8. The method for preparing a high-frequency transformer nanocrystalline core that can be produced by roll-to-roll manufacturing according to claim 1, characterized in that: The method of applying the organic insulating adhesive coating in step (2) is by spraying or brushing; the coating thickness of the organic insulating adhesive coating is 0.1~5μm.

9. The method for preparing a high-frequency transformer nanocrystalline core that can be produced by roll-to-roll manufacturing according to claim 1, characterized in that: The closed magnetic circuit mentioned in step (2) is a ring, a racetrack, or a rectangle.

10. The method for preparing a high-frequency transformer nanocrystalline core that can be produced by roll-to-roll manufacturing according to claim 1, characterized in that: The impregnation curing in step (2) is performed by vacuum impregnation curing with epoxy resin adhesive.

11. A high-frequency transformer nanocrystalline iron core, characterized in that: It is prepared by the method described in any one of claims 1 to 10.