High-frequency transformer iron core for SST based on nanocrystalline magnetically soft alloy and preparation method of high-frequency transformer iron core

Abstract

The invention belongs to the technical field of soft magnetic materials and transformers, and particularly relates to a high-frequency transformer iron core for SST based on nanocrystalline soft magnetic alloy and a preparation method of the high-frequency transformer iron core. The preparation method comprises the following steps: carrying out roll-to-roll tension annealing treatment on a nanocrystalline strip, and then coating the surface of the nanocrystalline strip with a sol-gel insulating coating; or firstly coating the surface of the nanocrystalline strip with a sol-gel insulating coating, and then carrying out roll-to-roll tension annealing treatment to obtain the nanocrystalline strip subjected to annealing and insulating treatment; and winding the treated nanocrystalline strip into an iron core of a closed magnetic circuit, and dipping and curing to obtain the high-frequency transformer iron core for the SST. The transformer iron core is formed by winding, bonding and curing the nanocrystalline strip, interlayer insulation and enhanced stability of the nanocrystalline strip are achieved through cooperation of coating of the sol-gel insulation coating on the surface of the nanocrystalline strip and impregnation curing, high-frequency loss of the iron core can be remarkably reduced, and the transformer iron 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 core for SST based on nanocrystalline soft magnetic alloy 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" and 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 large, posing a significant drawback in SST (Silicon-to-Stone) design. Patent CN 113707443 B describes a method for preparing nanocrystalline magnetic cores. This method involves using strip adhesive to bond nanocrystalline strips, creating gaps between the strips. The core is then subjected to vacuum impregnation, with the impregnating solution penetrating the gaps between the strips. Baking the impregnating solution to solidify it significantly increases the structural strength of the nanocrystalline core, thereby improving its bending resistance. While this patent achieves good interlayer insulation through strip adhesive and vacuum impregnation, the process is complex and fails to address the excessively high permeability of nanocrystalline materials in SST applications. 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 a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy.

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

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

[0009] A method for fabricating a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy includes the following fabrication steps:

[0010] (1) The nanocrystalline ribbon is first subjected to roll-to-roll tension annealing, and then coated with a sol-gel insulating coating; or the nanocrystalline ribbon is first coated with a sol-gel insulating coating, and then subjected to roll-to-roll tension annealing to obtain the annealed and insulating nanocrystalline ribbon.

[0011] (2) The nanocrystalline ribbon processed in step (1) is wound into a core with a closed magnetic circuit, and then impregnated with resin and cured to obtain the core of a high-frequency transformer for SST.

[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 roll-to-roll tension annealing treatment mentioned in step (1) refers to applying a tensile stress of 1~500MPa along the length of the strip during the roll-to-roll annealing process. The temperature of the roll-to-roll annealing treatment is 530~650℃, and the time is 10~200 seconds. The heating method used for the annealing treatment is resistance wire heating, laser heating, infrared lamp heating, electrode carbon brush heating, or induction coil heating, etc. Annealing treatment at the above temperatures can optimize magnetic properties and enhance the stability of the magnetic core.

[0015] By applying tensile stress simultaneously during the roll-to-roll annealing process, the magnetic permeability can be continuously adjusted without further 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 sol-gel insulating coating described in step (1) is obtained by drying a sol-gel insulating coating solution composed of the following components in weight percentage:

[0018] Tetraethyl orthosilicate (TEOS) 15-25%, methyltrimethoxysilane (MTMS) 10-16%, silica sol 8-15%, hydrochloric acid 0.2-2%, isopropanol 10-40%, γ-aminopropyltriethoxysilane (KH550) 0.1-1.5%, balance being water.

[0019] The preparation method of the above sol-gel insulating coating solution includes the following steps:

[0020] S1. Premixed silane: TEOS, MTMS and isopropanol are physically mixed to obtain a silane mixture;

[0021] S2. Prepare acid solution: Dilute hydrochloric acid with water to pH=3.8~4.2 to obtain an acidic catalyst solution;

[0022] S3. Catalytic hydrolysis: An acidic catalyst solution is added dropwise to a silane mixture to initiate catalytic hydrolysis, yielding a silanol intermediate solution;

[0023] S4.KH550 hydrolysis: Add KH550 to water for hydrolysis to obtain coupling agent hydrolysate;

[0024] S5. Dispersing filler: Mix and disperse silica sol and coupling agent hydrolysate evenly to obtain filler dispersion;

[0025] S6. Mixing and maturation: Mix the silanol intermediate solution and the filler dispersion evenly, and let it stand to mature, to obtain the sol-gel insulating coating solution.

[0026] The sol-gel insulating coating solution used in this invention exhibits excellent coating uniformity. The dried coating demonstrates strong adhesion to both the nanocrystalline ribbon and the cured organic resin, forming a uniform and stable inorganic (SiO2)-organic composite insulating layer. This results in superior interlayer insulation and curing stability, thereby reducing high-frequency losses and improving device performance stability. The specific working principles of each step and component are as follows:

[0027] In the premixed silane step, TEOS and MTMS provide the basis for the inorganic-organic hybridization, while isopropanol adjusts the viscosity and reaction rate, preparing for subsequent catalytic hydrolysis.

[0028] The catalytic hydrolysis step involves the following reactions: TEOS hydrolysis: Si(OC2H5)4+4H2O→Si(OH)4+4C2H5OH; MTMS hydrolysis: CH3Si(OCH3)3+3H2O→CH3Si(OH)3+3CH3OH; the acidic catalyst catalyzes the above hydrolysis reactions to form a silanol intermediate framework (Si-OH), laying the foundation for subsequent polycondensation.

[0029] The KH550 hydrolysis step involves the following reaction: H2N(CH2)3Si(OC2H5)3 + 3H2O → H2N(CH2)3Si(OH)3 + 3C2H5OH. Hydrolysis of KH550 generates active Si-OH groups and amino groups, which can act as "molecular bridges" to bind with the filler (colloidal SiO2) in subsequent steps, improving the filler's dispersibility and compatibility in the sol.

[0030] The reactions involved in the dispersing filler step include: SiO2−OH+H2N−(CH2)3−Si(OH)3→SiO2−O−Si(OH) )2 -(CH2)3−NH2+H2O, to achieve stable and uniform dispersion of nanofiller (colloidal SiO2) in the system.

[0031] The reactions involved in the mixing and maturation step include: Si(OH)4 + HO-Si≡ (skeleton) → Si-O-Si (crosslinking) + H2O, Si-OH (skeleton) + -O-Si≡ (modified SiO2) → Si-O-Si (covalent bonding), and ≡Si-CH3 (MTMS) + -NH2 (KH550) → hydrogen bonding (flexible phase). This allows the polycondensation reaction to be completed completely under controllable and gentle conditions, forming a stable three-dimensional network wet gel.

[0032] Furthermore, the method of coating the sol-gel insulating coating in step (2) is one or a combination of two or more of the following: (nozzle) spraying, (dipping) coating, and (flat roller) coating. The sol-gel insulating coating is applied to one or both sides of the nanocrystalline ribbon.

[0033] A more preferred method for coating the sol-gel insulating coating is to first dip-coat and then roll-coat, with the strip traction speed during the coating process being 2~4m / min and the tensile stress along the length of the strip being 0~30N / m.

[0034] Furthermore, the thickness of the sol-gel insulating coating in step (2) is 0.1~10μm, more preferably 0.5~3μm.

[0035] Furthermore, the tensile stress of the winding in step (2) is 0~30N / m, the winding speed is 200~2500rpm, and the shape of the closed magnetic circuit is ring, racetrack or rectangular.

[0036] Furthermore, the impregnation curing in step (2) is performed using epoxy resin adhesive for vacuum impregnation curing.

[0037] As an epoxy resin adhesive suitable for use in this invention, it can be formulated using epoxy resin, curing agent and alcohol solution conventional in the art.

[0038] A high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy is prepared by the above method.

[0039] Compared with the prior art, the beneficial effects of the present invention are:

[0040] (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.

[0041] (2) The present invention achieves interlayer insulation and enhanced stability of nanocrystalline ribbon by coating the surface of nanocrystalline ribbon with sol-gel insulating coating and impregnation curing, which can significantly reduce the high frequency loss of iron core and have good performance stability.

[0042] (3) The process of coating the surface with sol-gel insulating coating used in this invention can be carried out in one continuous step before or after the roll-to-roll annealing process. The process is simple and the treatment effect is good. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the roll-to-roll tension annealing process in Example 1 (in the figure, 1 is the feeding wheel; 2 is the clamping wheel; 3 is the furnace heating part; 4 is the clamping wheel; 5 is the winding wheel; and 6 is the nanocrystalline ribbon).

[0044] Figure 2 This is a schematic diagram of the coating process and apparatus for coating nanocrystalline ribbons with sol-gel insulating coatings in Example 1. Detailed Implementation

[0045] 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.

[0046] Example 1

[0047] A method for fabricating a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy includes the following fabrication steps:

[0048] (1) The composition is Fe 73.5 Cu1Nb3Si 15.5 B7. Nanocrystalline ribbons with a thickness of 18μm and a width of 10mm are subjected to roll-to-roll annealing at a temperature of 600℃ for 15 seconds. A tensile stress of 17MPa is applied along the length of the ribbon during the annealing process (see schematic diagram of the roll-to-roll tension annealing process). Figure 1 As shown in the figure, 1 is the feeding wheel; 2 is the clamping wheel; 3 is the furnace heating part; 4 is the clamping wheel; 5 is the winding wheel; and 6 is the nanocrystalline ribbon. The annealed nanocrystalline ribbon has a permeability of 15000 at 100kHz.

[0049] (2) The nanocrystalline ribbon treated in step (1) is coated with a sol-gel insulating coating solution on both sides by dip coating and roll coating in sequence (the coating thickness is designed to be 2.5 μm, and the schematic diagram of the coating process and device is shown in the figure). Figure 2 As shown in the figure, the nanocrystalline ribbon was tractiond at a speed of 2 m / min during the coating process, and the tensile stress along the length of the ribbon was 10 N / m. After the insulating coating solution was surface-dried at 150°C, the treated nanocrystalline ribbon was wound into a core with a closed magnetic circuit. The winding tensile stress was 10 N / m, and the winding speed was 1000 rpm. Then, the wound core was vacuum impregnated and cured with epoxy resin to obtain the core of the high-frequency transformer for SST.

[0050] The composition of the sol-gel insulating coating solution used in this embodiment is as follows (by mass percentage):

[0051] Tetraethyl orthosilicate (TEOS) 20%, methyltrimethoxysilane (MTMS) 10%, silica sol 12%, hydrochloric acid (HCl) 0.5%, isopropanol 25%, γ-aminopropyltriethoxysilane (KH550) 0.2%, and the remainder is water.

[0052] The preparation method of the sol-gel insulating coating solution includes the following steps:

[0053] S1. Premixed silane: TEOS, MTMS and isopropanol are physically mixed to obtain a silane mixture.

[0054] S2. Prepare acid solution: Dilute hydrochloric acid with water to pH=4 to obtain an acidic catalyst solution.

[0055] S3. Catalytic hydrolysis: An acidic catalyst solution is added dropwise to a silane mixture to initiate catalytic hydrolysis, yielding a silanol intermediate solution.

[0056] S4.KH550 hydrolysis: Add KH550 to water for hydrolysis to obtain coupling agent hydrolysate.

[0057] S5. Dispersing filler: Mix and disperse silica sol and coupling agent hydrolysate evenly to obtain filler dispersion.

[0058] S6. Mixing and maturation: Mix the silanol intermediate solution and the filler dispersion evenly, and let it stand to mature, to obtain the sol-gel insulating coating solution.

[0059] The preparation processes of the above sol-gel insulating coating solutions were all carried out at room temperature.

[0060] 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 60W / 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 3.2% after high-temperature treatment at 100℃ for 720h.

[0061] Example 2

[0062] A method for fabricating a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy includes the following fabrication steps:

[0063] (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.

[0064] (2) The nanocrystalline ribbon treated in step (1) was coated with a sol-gel insulating coating solution (coating thickness designed to be 2.0 μm) on both sides by dip coating and roll coating. The traction speed of the nanocrystalline ribbon during the coating process was 2.5 m / min, and the tensile stress along the length of the ribbon was 10 N / m. After the insulating coating solution was surface-dried at 140℃, the treated nanocrystalline ribbon was wound into a core with a closed magnetic circuit. The winding tensile stress was 10 N / m, and the winding speed was 900 rpm. Then, the wound core was vacuum impregnated and cured in epoxy resin to obtain the core of the high-frequency transformer for SST.

[0065] The composition of the sol-gel insulating coating solution used in this embodiment is as follows (by mass percentage):

[0066] Tetraethyl orthosilicate (TEOS) 15%, methyltrimethoxysilane (MTMS) 15%, silica sol 15%, hydrochloric acid (HCl) 0.6%, isopropanol 35%, γ-aminopropyltriethoxysilane (KH550) 0.5%, and the remainder is water.

[0067] The preparation method of the sol-gel insulating coating solution is the same as that in Example 1.

[0068] The core obtained in this embodiment was tested to have a saturation magnetic induction intensity of 1.2T; a loss of 62W / kg under 100kHz & 0.3T conditions; and a loss change rate of 4.1% after high-temperature treatment at 100℃ for 720h.

[0069] Example 3

[0070] A method for fabricating a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy includes the following fabrication steps:

[0071] (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.

[0072] (2) The nanocrystalline ribbon treated in step (1) was coated with a sol-gel insulating coating solution (coating thickness designed to be 1.5 μm) on both sides by dip coating and roll coating. The traction speed of the nanocrystalline ribbon during the coating process was 3.5 m / min, and the tensile stress along the length of the ribbon was 15 N / m. After the insulating coating solution was surface-dried at 120°C, the treated nanocrystalline ribbon was wound into a core with a closed magnetic circuit. The winding tensile stress was 15 N / m, and the winding speed was 1500 rpm. Then, the wound core was vacuum impregnated and cured in epoxy resin to obtain the core of the high-frequency transformer for SST.

[0073] The composition of the sol-gel insulating coating solution used in this embodiment is as follows (by mass percentage):

[0074] Tetraethyl orthosilicate (TEOS) 25%, methyltrimethoxysilane (MTMS) 12%, silica sol 8%, hydrochloric acid (HCl) 0.4%, isopropanol 15%, γ-aminopropyltriethoxysilane (KH550) 0.8%, and the remainder is water.

[0075] The preparation method of the sol-gel insulating coating solution is the same as that in Example 1.

[0076] The core obtained in this embodiment was tested to have a saturation magnetic induction intensity of 1.2T; a loss of 65W / kg under 100kHz & 0.3T conditions; and a loss change rate of 4.8% after high-temperature treatment at 100℃ for 720h.

[0077] Example 4

[0078] A method for fabricating a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy includes the following fabrication steps:

[0079] (1) The composition is Fe 71.5 Co1Ni1Cu1Nb3Si 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 2500 at 100 kHz.

[0080] (2) The nanocrystalline ribbon treated in step (1) was coated with a sol-gel insulating coating solution (coating thickness designed to be 1.0 μm) on both sides by dip coating and roll coating. The traction speed of the nanocrystalline ribbon during the coating process was 4 m / min, and the tensile stress along the length of the ribbon was 20 N / m. After the insulating coating solution was surface dry at 100℃, the treated nanocrystalline ribbon was wound into a core with a closed magnetic circuit. The winding tensile stress was 20 N / m, and the winding speed was 2000 rpm. Then, the wound core was vacuum impregnated and cured in epoxy resin to obtain the core of the high-frequency transformer for SST.

[0081] The composition of the sol-gel insulating coating solution used in this embodiment is as follows (by mass percentage):

[0082] Tetraethyl orthosilicate (TEOS) 20%, methyltrimethoxysilane (MTMS) 16%, silica sol 10%, hydrochloric acid (HCl) 1%, isopropanol 40%, γ-aminopropyltriethoxysilane (KH550) 1%, and the remainder is water.

[0083] The preparation method of the sol-gel insulating coating solution is the same as that in Example 1.

[0084] 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 5.4% after high-temperature treatment at 100℃ for 720h.

[0085] Example 5

[0086] A method for fabricating a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy includes the following fabrication steps:

[0087] (1) The composition is Fe 73.5 Cu1Nb3Si 15.5 B7. A sol-gel insulating coating solution (designed coating thickness 3 μm, composition and preparation method of the sol-gel insulating coating solution are the same as in Example 1) is sprayed onto the upper surface of a nanocrystalline ribbon with a thickness of 18 μm and a width of 10 mm. After the insulating coating solution is surface-dried at 150°C, the nanocrystalline ribbon is subjected to roll-to-roll annealing at 600°C for 15 seconds. A tensile stress of 17 MPa is applied along the length of the ribbon during the annealing process, resulting in an annealed and insulating nanocrystalline ribbon. The obtained annealed and insulating nanocrystalline ribbon has a permeability of 15000 at 100 kHz.

[0088] (2) The nanocrystalline ribbon processed in step (1) is wound into a core with a closed magnetic circuit. The winding tensile stress is 10 N / m and the winding speed is 1000 rpm. Then, the wound core is vacuum impregnated and cured in epoxy resin to obtain the core of the high-frequency transformer for SST.

[0089] The core obtained in this embodiment was tested to have a saturation magnetic induction intensity of 1.2T; a loss of 64W / kg under 100kHz & 0.3T conditions; and a loss change rate of 3.7% after high-temperature treatment at 100℃ for 720h.

[0090] Comparative Example 1

[0091] 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 a sol-gel insulating coating, but the rest are the same.

[0092] 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 18.5%.

[0093] Comparative Example 2

[0094] A method for preparing a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy, compared with Example 2, is that the nanocrystalline strip after step (1) is not coated with a sol-gel insulating coating, but the rest are the same.

[0095] The core obtained in this comparative example showed a loss of 88 W / kg under 100 kHz & 0.3 T conditions; the loss change rate after high-temperature treatment at 100℃ for 720 h was 16.7%.

[0096] Comparative Example 3

[0097] A method for preparing a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy, compared with Example 3, is that the nanocrystalline strip after step (1) is not coated with a sol-gel insulating coating, but the rest are the same.

[0098] The core obtained in this comparative example showed a loss of 92 W / kg under 100 kHz & 0.3 T conditions; the loss change rate after high-temperature treatment at 100℃ for 720 h was 14.2%.

[0099] Comparative Example 4

[0100] A method for preparing a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy, compared with Example 4, is that the nanocrystalline strip after step (1) is not coated with a sol-gel insulating coating, but the rest are the same.

[0101] The core obtained in this comparative example showed a loss of 97 W / kg under 100 kHz & 0.5 T conditions; the loss change rate after high-temperature treatment at 100℃ for 720 h was 12.7%.

[0102] The results of Examples 1-4 and Comparative Examples 1-4 show that the wound iron core prepared by the present invention using a nanocrystalline soft magnetic alloy with high saturation magnetic induction intensity combined with a sol-gel insulating coating has significantly reduced losses and significantly improved high-temperature stability.

[0103] 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 core for SST based on nanocrystalline soft magnetic alloy, characterized in that... The preparation steps include the following: (1) The nanocrystalline ribbon is first subjected to roll-to-roll tension annealing, and then coated with a sol-gel insulating coating; or the nanocrystalline ribbon is first coated with a sol-gel insulating coating, and then subjected to roll-to-roll tension annealing to obtain the annealed and insulating nanocrystalline ribbon. (2) The nanocrystalline ribbon processed in step (1) is wound into a core with a closed magnetic circuit, and then impregnated with resin and cured to obtain the core of a high-frequency transformer for SST.

2. The method for preparing a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy 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 core for SST based on nanocrystalline soft magnetic alloy 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 core for SST based on nanocrystalline soft magnetic alloy according to claim 1, characterized in that: The roll-to-roll tension annealing process mentioned in step (1) refers to applying a tensile stress of 1~500MPa along the length of the strip during the roll-to-roll annealing process. The temperature of the roll-to-roll annealing process is 530~650℃ and the time is 10~200 seconds. The heating method used for the annealing process 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 core for SST based on nanocrystalline soft magnetic alloy according to claim 1, characterized in that: The initial magnetic permeability of the annealed nanocrystalline ribbon in step (1) is 50~50000.

6. The method for preparing a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy according to claim 1, characterized in that: The sol-gel insulating coating described in step (1) is obtained by drying a sol-gel insulating coating solution composed of the following components in weight percentage: Tetraethyl orthosilicate 15-25%, methyltrimethoxysilane 10-16%, silica sol 8-15%, hydrochloric acid 0.2-2%, isopropanol 10-40%, γ-aminopropyltriethoxysilane 0.1-1.5%, with the balance being water.

7. The method for preparing a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy according to claim 6, characterized in that: The preparation method of the sol-gel insulating coating solution includes the following steps: S1. Premixed silane: Tetraethyl orthosilicate, methyltrimethoxysilane and isopropanol are physically mixed to obtain a silane mixture; S2. Prepare acid solution: Dilute hydrochloric acid with water to pH=3.8~4.2 to obtain an acidic catalyst solution; S3. Catalytic hydrolysis: An acidic catalyst solution is added dropwise to a silane mixture to initiate catalytic hydrolysis, yielding a silanol intermediate solution; S4.KH550 hydrolysis: γ-aminopropyltriethoxysilane is added to water for hydrolysis to obtain a coupling agent hydrolysate; S5. Dispersing filler: Mix and disperse silica sol and coupling agent hydrolysate evenly to obtain filler dispersion; S6. Mixing and maturation: Mix the silanol intermediate solution and the filler dispersion evenly, and let it stand to mature, to obtain the sol-gel insulating coating solution.

8. The method for preparing a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy according to claim 1, characterized in that: The method of coating the sol-gel insulating coating in step (1) is one or a combination of two or more of the following: spraying, dipping, and roller coating. The sol-gel insulating coating is applied to one or both sides of the nanocrystalline ribbon.

9. The method for preparing a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy according to claim 8, characterized in that: The method of coating the sol-gel insulating coating is to first dip-coat and then roll-coat, the strip traction speed during the coating process is 2~4m / min, and the tensile stress along the length of the strip is 0~30N / m.

10. The method for preparing a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy according to claim 1, characterized in that: The thickness of the sol-gel insulating coating in step (1) is 0.1~10μm.

11. The method for preparing a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy according to claim 1, characterized in that: The tensile stress of the winding in step (2) is 0~30N / m, the winding speed is 200~2500rpm, and the shape of the closed magnetic circuit is ring, racetrack or rectangular.

12. The method for preparing a high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy according to claim 1, characterized in that: The impregnation curing in step (2) is performed by vacuum impregnation curing with epoxy resin adhesive.

13. A high-frequency transformer core for SST based on nanocrystalline soft magnetic alloy, characterized in that: It is prepared by the method according to any one of claims 1 to 12.

Images