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CN-122000161-A - Low-frequency electrical soft magnetic material, preparation method and low-frequency transformer

CN122000161ACN 122000161 ACN122000161 ACN 122000161ACN-122000161-A

Abstract

The invention relates to the field of electrical soft magnetic materials, and discloses a low-frequency electrical soft magnetic material, a preparation method and a low-frequency transformer. The electrical soft magnetic material comprises, by mass, 68-75% of Fe, 22-26% of Co, 0.5-5% of Ni, 0-1% of Mn and 0.1-1.5% of Si, and the total content of Fe, co and Ni of ferromagnetic elements is controlled to be not lower than 98%. The material is prepared by vacuum smelting and casting, hot rolling and controlled cooling, multi-roller cold rolling, high-temperature annealing under controlled atmosphere and other processes. The material has excellent magnetic performance under the low-frequency condition of 20 Hz, the saturation induction intensity Bs is not lower than 2.30T, the iron loss P 1.7/20 under the condition of the magnetic flux density of 1.7 and T is not higher than 0.70W/kg, and the invention also provides a low-frequency transformer adopting the electrical soft magnetic material as an iron core, which can obviously reduce the cross section area of the iron core and the consumption of main materials under the low-frequency alternating current working condition, thereby effectively reducing the volume, the weight and the loss of the transformer and being suitable for application scenes such as flexible low-frequency alternating current transmission and the like.

Inventors

  • CHENG LING
  • NIE JINGKAI
  • CHEN BAOAN
  • HAN YU
  • MA GUANG
  • HE CHENGXU
  • Tian Congkuan
  • GAO JIE
  • DENG KAIWEI
  • WANG TONGLEI
  • SHI QI

Assignees

  • 中国电力科学研究院有限公司
  • 国网江苏省电力有限公司电力科学研究院

Dates

Publication Date
20260508
Application Date
20251216

Claims (16)

  1. 1. The low-frequency electrical soft magnetic material is characterized in that a casting blank of the low-frequency electrical soft magnetic material comprises, by mass, 68-75% of Fe, 22-26% of Co, 0.5-5% of Ni, 0-1% of Mn and 0.1-1.5% of Si, wherein the total content of Fe, co and Ni is not lower than 98%, and the total content of other impurity elements is lower than 0.01%.
  2. 2. A low frequency electrical soft magnetic material as claimed in claim 1, wherein said low frequency electrical soft magnetic material has an iron loss P1.7/20 of not more than 0.70W/kg at 20 Hz and a magnetic flux density of 1.7T.
  3. 3. A low frequency electrical soft magnetic material as claimed in claim 1, wherein the saturation induction Bs of the low frequency electrical soft magnetic material is not lower than 2.30T.
  4. 4. The low-frequency electrical soft magnetic material according to claim 1, wherein the low-frequency electrical soft magnetic material exists in a cold-rolled thin strip form, and the thickness of the strip is 0.27 mm-0.30 mm and is used for a low-frequency alternating magnetic field working condition.
  5. 5. A method for preparing a low-frequency electrical soft magnetic material, which is characterized by comprising the following steps: Smelting and refining iron, cobalt, nickel, manganese and silicon-containing raw materials under a vacuum condition, and then pouring under the protection of inert gas to obtain a casting blank, wherein the casting blank comprises the components according to any one of claims 1-4; Heating the casting blank to 1250-1300 ℃, carrying out multi-pass hot rolling after heat preservation, wherein the final rolling temperature is not lower than 950 ℃, and carrying out quick cooling after hot rolling to obtain a hot rolled plate; Performing multi-roll cold rolling on the hot rolled plate, and preparing a cold rolled plate after the total reduction rate is 85-89%; and (3) carrying out high-temperature annealing at 850-900 ℃ on the cold-rolled sheet under the controlled protective atmosphere and dew point conditions, and annealing for 2-5 hours to obtain the low-frequency electrical soft magnetic material according to any one of claims 1-4.
  6. 6. The method for producing a low-frequency electrical soft magnetic material according to claim 5, wherein the starting temperature to the ending temperature of the smelting refining is controlled to 1530 ℃ to 1580 ℃.
  7. 7. The method for producing a low frequency electrical soft magnetic material according to claim 5, wherein the cast slab is heat-preserved by not less than 3 h before hot rolling.
  8. 8. A method of producing a low frequency electrical soft magnetic material according to claim 5, wherein the time interval from completion of hot rolling to start of cold rolling is not more than 48 h.
  9. 9. The method for producing a low-frequency electrical soft magnetic material according to claim 5, wherein the multi-roll cold rolling is performed by a rolling mill having not less than four rolls.
  10. 10. The method for producing a low frequency electrical soft magnetic material according to claim 5, wherein the final rolling thickness of the hot rolling is 2.0mm to 2.5 mm.
  11. 11. The method for preparing a low-frequency electrical soft magnetic material according to claim 5, wherein the thickness of the cold-rolled finished product is controlled to be 0.27-0.30 mm.
  12. 12. The method for preparing a low-frequency electrical soft magnetic material according to claim 5, wherein the protective atmosphere is a mixed gas of nitrogen and hydrogen, and the volume fraction of hydrogen is not less than 10%.
  13. 13. A method of producing a low frequency electrical soft magnetic material according to claim 5, wherein the dew point is controlled at-50 ℃ to-30 ℃.
  14. 14. The method for preparing a low-frequency electrical soft magnetic material according to claim 5, wherein the high-temperature annealing adopts a rapid heating mode of more than 100 ℃ per minute, and the temperature is slowly reduced at a speed of 60-120 ℃ per hour after the annealing.
  15. 15. A low frequency transformer, characterized in that the low frequency transformer comprises a core made of the low frequency electrical soft magnetic material according to any one of claims 1 to 4.
  16. 16. The low frequency transformer of claim 15, wherein the low frequency transformer has a nominal operating frequency of no more than 20 Hz.

Description

Low-frequency electrical soft magnetic material, preparation method and low-frequency transformer Technical Field The invention belongs to the field of soft magnetic materials, and particularly relates to a low-frequency electrical soft magnetic material, a preparation method and a low-frequency transformer. Background In a power transmission and transformation system, by selecting proper power transmission frequency between direct current and power frequency, the influence of line impedance on power transmission can be reduced, the advantages of electromagnetic induction transformation, zero crossing switching of current and the like of alternating current transmission can be maintained, and flexible low-frequency alternating current transmission becomes the beneficial supplement of power frequency alternating current and direct current transmission, thus being an important development direction of advanced power transmission technology in the future. At present, a first Taizhou kV flexible low-frequency alternating-current transmission demonstration project and a Hangzhou 220kV flexible low-frequency alternating-current transmission demonstration project are built, a 500kV low-frequency transmission demonstration project with higher normal construction voltage level is built, and the low-frequency transmission frequency is 20Hz. The volume, weight and loss of the low frequency transformer are important factors affecting the economy of the flexible low frequency ac transmission project. The research shows that under the same voltage class and capacity condition, the working frequency is reduced from 50Hz to 20Hz, compared with a power frequency transformer, the 220kV low-frequency transformer has the advantages that the weight is increased by about 70%, the occupied area is increased by about 21%, the volume is increased by about 34%, and the load loss of the transformer is increased by about 33%. At present, the low-frequency transformer mainly has the problems of large weight, large volume, large occupied area and large main material consumption. Particularly, for the application scene of low-frequency transmission of middle-distance offshore wind power, the area and the bearing weight of a platform of an offshore booster station are limited, and the requirements for reducing the volume, the weight and the main material consumption of a low-frequency transformer are urgent. The magnetic properties of low frequency transformer core materials, particularly saturation induction (Bs), are a central factor in limiting weight, volume and load losses. In the 35kV Taizhou and 220kV Hangzhou low-frequency power transmission engineering which is put into operation, the Bs of the oriented electrical steel adopted by the low-frequency transformer are 2.03T, and the Bs reach the physical limit of the oriented silicon steel under the existing 3% Si component system. Meanwhile, in order to ensure that indexes such as the over-excitation capability of the low-frequency transformer and the like meet relevant requirements, the iron core design magnetic flux density Bm in the above-mentioned exemplary engineering is about 1.7T. Through innovative component systems and preparation processes of the electrical soft magnetic material, the novel electrical soft magnetic material with ultrahigh saturation magnetic induction (Bs > 2.20-2.40T) and low frequency and low loss (P1.7/20 < 0.70W/kg) is developed, the design magnetic flux density of a 20Hz low frequency transformer iron core is improved, the product of the iron core cross section and the coil turns is further reduced, the load loss, the weight, the volume and the economic cost of the low frequency transformer are effectively reduced, and the electrical soft magnetic material becomes one of key bottleneck problems to be solved in large-scale popularization and application of the current flexible low frequency transmission technology. Disclosure of Invention The invention aims to solve the problems that the existing magnetic material has low saturation magnetic induction intensity and high low-frequency loss and cannot meet the current flexible low-frequency power transmission requirement. The invention aims at realizing the following technical scheme: The casting blank of the low-frequency electrical soft magnetic material comprises, by mass, 68-75% of Fe, 22-26% of Co, 0.5-5% of Ni, 0-1% of Mn and 0.1-1.5% of Si, wherein the total content of ferromagnetic elements Fe, co and Ni is not less than 98%, and the total content of impurity elements is less than 0.01%. Preferably, the iron loss P1.7/20 of the low-frequency electrical soft magnetic material under the conditions of 20Hz and magnetic flux density of 1.7T is not higher than 0.70W/kg. Preferably, the saturation induction Bs of the low-frequency electrical soft magnetic material is not less than 2.30T. Preferably, the low-frequency electrical soft magnetic material exists in a cold-rolled thin strip form, and the thi