Medium frequency core type isolation transformer based on ultra-low-loss ultra-thin oriented silicon steel core

Abstract

The application provides a medium-frequency core-type isolation transformer based on an ultralow-loss ultrathin oriented silicon steel magnetic core, which comprises a magnetic core, the magnetic core comprises parallel and parallel arranged oriented silicon steel sheets with the same structure, wherein each of the oriented silicon steel sheets is overlapped to form a loop-shaped loop; the center window of the loop-shaped loop constitutes an inner window of the magnetic core, the outer edge of the loop-shaped loop constitutes an outer window of the magnetic core, and the two sides of the loop-shaped loop constitute side columns between the inner window of the magnetic core and the outer window of the magnetic core; and the side columns are wound with windings. The medium-frequency core-type isolation transformer based on the ultralow-loss ultrathin oriented silicon steel magnetic core can realize high-efficiency transmission, high power density, small volume, light weight, low noise and other technical indexes of the transformer.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of transformers, and particularly relates to a medium-frequency core-type isolation transformer based on an ultralow-loss ultrathin oriented silicon steel magnetic core. BACKGROUND

[0002] The traditional power frequency transformer is 50Hz. Z The increase of frequency will cause the loss of the transformer magnetic core under working conditions to increase greatly. Moreover, even if the existing transformer can work at a frequency of 500-1000Hz, the current flow condition of the winding will be obviously different from that under direct current and power frequency, the winding will appear serious skin effect and proximity effect, the alternating current resistance will increase, and the winding loss will increase sharply.

[0003] In addition, according to the previous design standard, the transformer with a single machine capacity of 1.5MVA is designed, which will cause the transformer to have a large volume and increase the loss of the transformer.

[0004] Therefore, the existing domestic manufacturers cannot produce a transformer with a capacity of 1.5MVA and a working frequency of 500-1000Hz, and in view of the working environment of the transformer, the withstand voltage level of the transformer is also high, the primary and secondary insulation, the primary-to-ground insulation and the secondary-to-ground insulation all reach the megawatt-level medium-frequency transformer under the high isolation level of AC 50KV, and there is no relevant national standard and relevant manufacturing specification. SUMMARY

[0005] In view of the above problems, the application provides a medium-frequency core-type isolation transformer based on an ultralow-loss ultrathin oriented silicon steel magnetic core.

[0006] The medium-frequency core-type isolation transformer based on an ultralow-loss ultrathin oriented silicon steel magnetic core provided by the application comprises a magnetic core, the magnetic core comprises oriented silicon steel sheets arranged in parallel and in parallel and having the same structure,

[0007] Among them,

[0008] Each of the oriented silicon steel sheets is overlapped to form a Huizi-shaped loop;

[0009] The empty window at the center of the Huizi-shaped loop constitutes an inner window of the magnetic core, the outer edge of the Huizi-shaped loop constitutes an outer window of the magnetic core, and the two sides of the Huizi-shaped loop constitute side columns between the inner window of the magnetic core and the outer window of the magnetic core.

[0010] The side columns are wound with windings.

[0011] Further,

[0012] The area of the inner window of the magnetic core is 250mm*600mm to 400mm*800mm.

[0013] The magnetic core outer window area is: 500mm*900mm to 700mm*1100mm.

[0014] Further,

[0015] The magnetic core inner window area is: 330mm*730mm;

[0016] The magnetic core outer window area is: 610mm*1010mm.

[0017] Further,

[0018] The cross-sectional area of the magnetic core is: 0.025-0.072m 2 , 250-360mm long, 100-200mm wide.

[0019] Further,

[0020] The cross-sectional area of the magnetic core is: 0.042m 2 , 300mm long, 140mm wide.

[0021] Further,

[0022] The side column comprises: a first side column and a second side column;

[0023] The winding comprises: a first winding and a second winding;

[0024] The first winding is wound on the first side column, and the second winding is wound on the second side column;

[0025] The first winding and the second winding are connected in series.

[0026] Further,

[0027] The winding is 20-40 turns, and the first winding and the second winding are each 10-20 turns.

[0028] Further,

[0029] The winding is 32 turns, and the first winding and the second winding are each 16 turns.

[0030] Further,

[0031] In the winding, the primary winding is a total of 32 turns, and is equally divided into two groups of windings, each of which is 16 turns, and the two groups of windings are wound on the first side column and the second side column respectively, and the winding is connected in series by copper bars.

[0032] Further,

[0033] The winding is a copper foil winding.

[0034] Further,

[0035] The copper foil winding size is 0.3mm*300mm to 0.8mm*800mm.

[0036] Further,

[0037] The copper foil winding size is 0.5mm*550mm.

[0038] Further,

[0039] The material of the copper foil winding is red copper.

[0040] Further,

[0041] The oriented silicon steel sheet is B20R75 silicon steel sheet, and adjacent oriented silicon steel sheets are arranged in close proximity.

[0042] Further,

[0043] The thickness of a single oriented silicon steel sheet is 0.18-0.30mm, the thickness of the magnetic core is 240-380mm, a single layer of the oriented silicon steel sheet is composed of four silicon steel sheets to form a loop, and a total of 4600-6900 silicon steel sheets are required.

[0044] Further,

[0045] The thickness of a single oriented silicon steel sheet is 0.20mm, the thickness of the magnetic core is 300mm, and a total of 6000 silicon steel sheets are required.

[0046] The medium-frequency core-type isolation transformer based on the ultra-low-loss ultra-thin oriented silicon steel magnetic core can realize high-efficiency transmission, high power density, small size, light weight and low noise of the transformer and other technical indicators.

[0047] The capacity of the medium-frequency core-type isolation transformer reaches 1.5MVA per machine, and the working frequency is between 500-1000Hz. Meanwhile, considering the working environment of the transformer, the withstand voltage level of the transformer is also high, and the requirements of the primary and secondary insulation, the primary-to-ground insulation and the secondary-to-ground insulation all reach AC50KV. The theoretical transmission power is 99.2%, and the actual transmission efficiency of the machine is 99.02%, both of which are higher than 99%, realizing the megawatt-level power transmission with an efficiency of up to 99%.

[0048] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the application. The objects and other advantages of the present application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0050] Figure 1 A front view of the ultra-low-loss and ultra-thin oriented silicon steel magnetic core according to the embodiment of the present application is shown;

[0051] Figure 2 A front view of the ultra-low-loss and ultra-thin oriented silicon steel magnetic core according to the embodiment of the present application is shown;

[0052] Figure 3 A front view of the ultra-low-loss and ultra-thin oriented silicon steel magnetic core according to the embodiment of the present application is shown;

[0053] Figure 4 A front view of the ultra-low-loss and ultra-thin oriented silicon steel magnetic core according to the embodiment of the present application is shown;

[0054] Figure 5 A winding model diagram of the medium-frequency core-type isolation transformer based on the ultra-low-loss and ultra-thin oriented silicon steel magnetic core according to the embodiment of the present application is shown,

[0055] Figure 6 A schematic diagram of the joint mode of the bevel staggered joint of the oriented silicon steel sheet at the four diagonal joints of the magnetic core based on the ultra-low-loss and ultra-thin oriented silicon steel magnetic core according to the embodiment of the present application is shown Figure 1 ;

[0056] Figure 7 A schematic diagram of the joint mode of the bevel staggered joint of the oriented silicon steel sheet at the four diagonal joints of the magnetic core based on the ultra-low-loss and ultra-thin oriented silicon steel magnetic core according to the embodiment of the present application is shown Figure 2 ,

[0057] A, first side column; B, second side column; C, first winding; D, second winding; E, outer window of the magnetic core; F, inner window of the magnetic core; H1, first diagonal joint; H2, second diagonal joint; H3, third diagonal joint; H4, fourth diagonal joint; G1, first silicon steel sheet in the single-layer oriented silicon steel sheet; G2, second silicon steel sheet in the single-layer oriented silicon steel sheet; G3, third silicon steel sheet in the single-layer oriented silicon steel sheet; G4, fourth silicon steel sheet in the single-layer oriented silicon steel sheet; X, width direction of the oriented silicon steel sheet; Y, height direction of the oriented silicon steel sheet; Z, thickness direction of the oriented silicon steel sheet. DETAILED DESCRIPTION

[0058] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0059] The medium frequency core type isolation transformer based on the ultra-low-loss ultra-thin oriented silicon steel magnetic core of the present application is designed from two aspects: magnetic core (i.e. core) design and winding design. The medium frequency core type isolation transformer based on the ultra-low-loss ultra-thin oriented silicon steel magnetic core of the present application can realize high efficiency transmission, high power density (small volume and light weight) and low noise and other technical indicators.

[0060] I. Magnetic core design

[0061] Regarding the magnetic core material, considering that the frequency at which the transformer works is between 500-1000 Hz, and comprehensively considering various magnetic core materials, the ultra-low-loss ultra-thin B20R75 silicon steel sheet (i.e. oriented silicon steel sheet) is selected as the magnetic core material of the medium frequency core type isolation transformer of the present application. The saturation magnetic density of the B20R75 silicon steel sheet is 1.8 T, the Curie temperature is 600 degrees Celsius, the thickness is 0.2 mm, and the lamination coefficient is 0.94. The core loss of the magnetic core material is significantly lower than other silicon steel sheets, and the heat generation is significantly lower than other magnetic cores in this frequency range of 500-1000 Hz.

[0062] Figure 1 A model diagram of the medium frequency core type isolation transformer based on the ultra-low-loss ultra-thin oriented silicon steel magnetic core of the present application is shown. Figure 2 Figure 3 Figure 4 A front view, a left view and a global view of the ultra-low-loss ultra-thin oriented silicon steel magnetic core used in the present application are shown respectively.

[0063] As can be seen from Figure 1 , the medium frequency core type isolation transformer of the present application adopts a core type structure, which is constructed by parallel and parallel oriented silicon steel sheets of the same structure. Each oriented silicon steel sheet itself is jointed into a Hui-zi-shaped loop, the empty window in the center of the Hui-zi-shaped loop constitutes a magnetic core inner window F, the outer edge of the Hui-zi-shaped loop constitutes a magnetic core outer window E, and the two sides of the Hui-zi-shaped loop constitute two side columns: a first side column A and a second side column B between the magnetic core inner window F and the magnetic core outer window E. The first side column A is wound with a first winding C, and the second side column B is wound with a second winding D. Among them, the thickness of a single oriented silicon steel sheet is 0.18-0.30 mm, preferably 0.20 mm, and the thickness of the magnetic core is 240-380 mm, preferably 300 mm. As can be seen from Figure 6 ​​, single-layer oriented silicon steel sheet needs four silicon steel sheets (G1, G2, G3 and G4) to form a loop, and for this purpose, the number of silicon steel sheets is 4600-6900 sheets, preferably about 6000 sheets, and adjacent oriented silicon steel sheets are arranged in close proximity.

[0064] Figure 6 and Figure 7 The schematic diagram of the joint mode of the diagonal staggered joint of the single-layer oriented silicon steel sheet based on the ultra-low-loss ultra-thin oriented silicon steel magnetic core of the present application at the four diagonal joints of the magnetic core. Considering that during the operation of the laminated silicon steel transformer, due to the magnetic conductivity of the oriented silicon steel sheet, the magnetic density distribution at the joint is extremely uneven, the magnetic performance will deteriorate, and the magnetic core loss will increase. Therefore, the oriented silicon steel sheet at the four diagonal joints (including the first diagonal joint H1, the second diagonal joint H2, the third diagonal joint H3 and the fourth diagonal joint H4) of the magnetic core adopts the "diagonal staggered joint" joint mode, which means that when the core is connected with the yoke, the oriented silicon steel sheets at the four diagonal angles are arranged in a staggered manner, so that at the four diagonal joints, the air gap between the two adjacent oriented silicon steel sheets in the same plane parallel to the width direction X and the height direction Y of the oriented silicon steel sheet is staggered in the thickness direction Z of the oriented silicon steel sheet, the air gap is 0.05-0.16mm (preferably 0.1mm), and in the thickness direction Z, the distance between the side edges of the two adjacent oriented silicon steel sheets for forming the air gap is 0.20-0.36mm (preferably 0.25mm). In this way, on the one hand, the magnetic core loss can be reduced and the magnetic density distribution can be improved, and on the other hand, this joint mode is relatively simple in manufacturing process compared with other joint modes. In the manufacturing process of the oriented silicon steel sheet joint, it is necessary to avoid the occurrence of the inter-sheet gap between the silicon steel sheets, and to ensure that the silicon steel sheets are as flat as possible. Such operation can further reduce the magnetic core loss of the transformer.

[0065] The magnetic core structure is shown in Figure 2 , Figure 3 and Figure 4 . The size of the magnetic core is related to both the insulation distance of the transformer (the distance between the magnetic core and the primary winding, the distance between the primary winding and the secondary winding, and the insulation distance between the two secondary windings) and the length of the winding. After comprehensive consideration, the size of the magnetic core of the medium-frequency core-type isolation transformer of the present application is designed as:

[0066] The inner window area of the magnetic core is 330mm×730mm.

[0067] The outer window area of the magnetic core is 610mm×1010mm.

[0068] Since the magnetic core area of the transformer is inversely proportional to the number of turns of the transformer winding at a certain working voltage, considering that the working frequency of the medium-frequency core-type isolation transformer of the application is relatively high, there is a serious eddy current effect between the windings, therefore, the number of turns of the winding of the medium-frequency core-type isolation transformer of the application is not easy to be too large, and for this reason, the actual cross-sectional area (the area of the cross section of the magnetic core) of the magnetic core of the medium-frequency core-type isolation transformer of the application is 0.025-0.072 m 2 (0.042 m 2 is preferred), 250-360 mm (300 mm is preferred) in length, and 100-200 mm (140 mm is preferred) in width, and the cross section of the magnetic core is as shown in Figure 7 .

[0069] Under the above magnetic core structure and standard working conditions, the magnetic core loss of the medium-frequency core-type isolation transformer of the application is about 7600 W, accounting for 0.507% of the total capacity of the transformer.

[0070] II. Winding design

[0071] The winding material of the medium-frequency core-type isolation transformer of the application is common red copper. The winding structure is a copper foil winding, and the main reason is that through simulation and actual measurement comparison, it is found that the eddy current effect of the copper tube winding is very serious in the medium frequency band, and the winding loss is huge, and at the same time, the litz wire winding is difficult to meet the heat dissipation requirement in the case of such large capacity and large current, and therefore the copper foil winding structure stands out. Under the medium frequency band, the eddy current effect of the copper foil winding is relatively slight, and at the same time, the copper foil winding has good heat conductivity and low resistivity, and is very suitable as the winding of such a large capacity and large current transformer. And compared with the copper tube winding, the space utilization rate of the copper foil winding is very high, which is of great significance to reduce the size of the large capacity transformer of the application.

[0072] The design of the winding generally selects the magnetic field flux density under a suitable working condition according to the magnetization curve of the magnetic core material, so as to obtain a winding value, and then combines the cross-sectional area of the magnetic core designed in the foregoing to finally calculate the number of turns of the winding. At the same time, considering the eddy current effect in the medium frequency band, the number of turns of the winding should not be too large. According to the working frequency of 500 Hz, the cross-sectional area of the magnetic core of the medium-frequency core-type isolation transformer of the application is selected as 0.042 m 2 , and the magnetic field flux density is selected as 0.1 T, and the number of turns can be calculated as 32 turns. Therefore, the number of turns of the winding is selected as 32 turns.

[0073] Different winding arrangements not only affect the loss of the winding, but also affect the leakage inductance of the transformer. According to the DEWELL model, for a single winding, the more the number of turns of the winding, the more serious the eddy current effect between the windings. Therefore, the medium-frequency core-type isolation transformer of the application adopts the measure of separating the windings. Figure 5The winding model diagram of the medium frequency core type isolation transformer based on the ultra-low-loss and ultra-thin oriented silicon steel magnetic core of the application. Referring to Figure 5 It can be known that the primary and secondary winding of the medium frequency core type isolation transformer of the application adopts the form of series connection of two groups of winding, each group of winding is 16 turns, specifically, the primary winding is totally 32 turns, which is equally divided into two groups of winding each with 16 turns, the two groups of winding are wound on two core columns (i.e. side columns) of the core respectively, and then the winding on the two core columns is connected in series by copper bars.

[0074] Under normal working conditions, the winding current of the medium frequency core type isolation transformer of the application is 500A; through simulation comparison, the copper foil winding size (i.e. the cross section of the copper foil winding) is selected as 0.5mmx550mm in consideration of the factors such as comprehensive loss, electric density and temperature rise. Under the winding cross section area of 275mm 2 , the winding electric density under working condition is 2.18A / mm 2 , which is a relatively low electric density and lower than the maximum magnetic density of copper foil and also does not exist serious temperature rise.

[0075] Under the winding structure and standard working condition mentioned above, the winding loss of the medium frequency core type isolation transformer of the application is about 4400W, accounting for 0.293% of the total capacity of the transformer.

[0076] The medium frequency core type isolation transformer of the application designs the transformer from two aspects: magnetic core design and winding design, which can realize the technical indexes such as high efficiency transmission, high power density (small volume and light weight) and low noise of the transformer.

[0077] The theoretical transmission power of the medium frequency core type isolation transformer of the application is 99.2%, and the transmission efficiency of the actual test is 99.02%, both of which are higher than 99%, realizing the megawatt power transmission with the efficiency of 99%.

[0078] Although the application is described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A medium frequency core type isolation transformer based on ultra-low-loss and ultra-thin oriented silicon steel magnetic core, characterized in that, Comprise: A magnetic core comprising parallel and parallel arranged and structurally identical oriented silicon steel sheets, Wherein, Each of the oriented silicon steel sheets is composed of four silicon steel sheets forming a U-shaped loop; the empty window in the center of the U-shaped loop constitutes the inner window of the magnetic core, the outer edge of the U-shaped loop constitutes the outer window of the magnetic core, and the two sides of the U-shaped loop constitute the side column between the inner window of the magnetic core and the outer window of the magnetic core; The side column is wound with a winding; The oriented silicon steel sheets adopt an inclined angle staggered joint method: at the four inclined angle joints of the magnetic core, the air gap between the two adjacent silicon steel sheets in the same plane parallel to the width direction and height direction of the oriented silicon steel sheet is staggered in the thickness direction of the oriented silicon steel sheet.

2. The medium frequency core type isolation transformer based on the ultra-low loss and ultra-thin oriented silicon steel magnetic core according to claim 1, wherein The area of the inner window of the magnetic core is 250mm×600mm to 400mm×800mm; The area of the outer window of the magnetic core is 500mm×900mm to 700mm×1100mm.

3. The medium frequency core type isolation transformer based on the ultra-low loss and ultra-thin oriented silicon steel magnetic core according to claim 2, wherein The area of the inner window of the magnetic core is 330mm×730mm; The area of the outer window of the magnetic core is 610mm×1010mm.

4. The medium frequency core type isolation transformer based on the ultra-low loss and ultra-thin oriented silicon steel magnetic core according to claim 3, wherein The cross-sectional area of the magnetic core is 0.025-0.072 m 2 , 250-360 mm in length and 100-200 mm in width.

5. The medium frequency core type isolation transformer based on the ultra-low loss and ultra-thin oriented silicon steel magnetic core according to claim 4, wherein The cross-sectional area of the magnetic core is: 0.042 m 2 , 300 mm long, 140 mm wide.

6. The medium frequency core type isolation transformer based on the ultra-low loss and ultra-thin oriented silicon steel magnetic core according to any one of claims 1-5, wherein The side column comprises a first side column and a second side column; The winding comprises a first winding and a second winding; The first winding is wound on the first side column, and the second winding is wound on the second side column; The first winding and the second winding are connected in series.

7. The medium frequency core type isolation transformer based on the ultra-low loss and ultra-thin oriented silicon steel magnetic core according to claim 6, wherein The winding has 20-40 turns, and the first winding and the second winding each have 10-20 turns.

8. The medium frequency core type isolation transformer based on the ultra-low loss and ultra-thin oriented silicon steel magnetic core according to claim 7, wherein The winding has 32 turns, and the first winding and the second winding each have 16 turns.

9. The medium frequency core type isolation transformer based on the ultra-low loss and ultra-thin oriented silicon steel magnetic core according to claim 8, wherein In the winding, the primary winding has a total of 32 turns, which is equally divided into two groups of windings, each having 16 turns, and the two groups of windings are wound on the first side column and the second side column respectively, and the windings are connected in series by copper bars, and the secondary winding is wound in the same way.

10. The medium frequency core type isolation transformer based on the ultra-low loss and ultra-thin oriented silicon steel magnetic core according to claim 9, wherein The winding is a copper foil winding.

11. The medium frequency core type isolation transformer based on the ultra-low loss and ultra-thin oriented silicon steel magnetic core according to claim 10, wherein The copper foil winding size is 0.3mm*300mm to 0.8mm*800mm.

12. The intermediate frequency core-type isolation transformer based on the ultralow-loss and ultrathin oriented silicon steel magnetic core according to claim 11, characterized in that, The copper foil winding size is 0.5mm*550mm.

13. The intermediate frequency core-type isolation transformer based on the ultralow-loss and ultrathin oriented silicon steel magnetic core according to claim 12, characterized in that, The material of the copper foil winding is red copper.

14. The intermediate frequency core-type isolation transformer based on the ultralow-loss and ultrathin oriented silicon steel magnetic core according to any one of claims 1-5, 7-13, characterized in that, The oriented silicon steel sheet is B20R75 silicon steel sheet, and the adjacent oriented silicon steel sheets are arranged in close proximity.

15. The intermediate frequency core-type isolation transformer based on the ultralow-loss and ultrathin oriented silicon steel magnetic core according to claim 14, characterized in that, The thickness of a single oriented silicon steel sheet is 0.18-0.30mm, the thickness of the magnetic core is 240-380mm, a single layer of the oriented silicon steel sheet is composed of four silicon steel sheets to form a loop, and a total of 4600-6900 silicon steel sheets are needed.

16. The intermediate frequency core-type isolation transformer based on the ultralow-loss and ultrathin oriented silicon steel magnetic core according to claim 15, characterized in that, The thickness of a single oriented silicon steel sheet is 0.20mm, the thickness of the magnetic core is 300mm, and a total of 6000 silicon steel sheets are needed.

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