CN111463000A - Combined type shielding structure suitable for wireless power supply system of electric automobile - Google Patents

Abstract

The invention relates to a composite shielding structure suitable for a wireless power supply system of an electric automobile. The structure comprises an aluminum cover, an alumina ceramic heat conducting plate, a magnetic material shielding plate, a receiving coil and a bakelite substrate; the magnetic material shielding plate comprises a shielding plate chamfer and a splicing plate; the spliced plate is formed by splicing plate-shaped structures in various shapes, which are made of two magnetic materials, namely manganese-zinc power ferrite and iron-based nanocrystalline alloy. The receiving coil is arranged between the boundary of the base plate inner frame and the boundary of the base plate outer frame of the bakelite base plate, the magnetic material shielding plate covers the receiving coil, the alumina ceramic heat conducting plate covers the magnetic material shielding plate, and the aluminum cover covers the alumina ceramic heat conducting plate and is fixed with the bakelite base plate into a whole through screws. The invention not only can reasonably utilize magnetic materials to shield electromagnetic radiation, but also can conduct heat generated in the charging process to ensure the effective operation of the system.

Description

A composite shielding structure suitable for electric vehicle wireless power supply system

technical field

The invention relates to the field of electric vehicle wireless power transmission, in particular to a composite shielding structure suitable for an electric vehicle wireless power supply system.

Background technique

Electric vehicle wireless energy transmission technology is a non-contact charging technology. During the charging process, the system will generate a certain degree of electromagnetic radiation, and when the amount of electromagnetic radiation exceeds the human safety standard, it will cause adverse effects on the human body. In order to reduce the electromagnetic radiation of the electric vehicle wireless power transmission system and ensure the safety of the biological body, it is necessary to add electromagnetic shielding design in the process of designing the electric vehicle coupling mechanism.

In the practical application of electric vehicle wireless power supply system, materials with high magnetic permeability and less eddy current loss during charging are generally used to make magnetic shielding structures, and materials with higher electrical conductivity are used to make electrical shielding structures. At present, ferrite materials are usually used as the magnetic shielding structure at home and abroad, and aluminum is used as the electrical shielding structure. However, with the continuous increase of the output power and frequency of the wireless power supply system of electric vehicles, the use of a whole ferrite plate as a magnetic shielding structure can no longer meet the electromagnetic shielding safety radiation standards. In addition, the system will generate a large amount of heat during the charging process, which will affect the power transmission efficiency and shielding effect. How to dissipate heat more effectively is still a problem to be solved.

The square magnetic shielding structure proposed in the literature (Zhaohui. Research on the electromagnetic shielding characteristics of wireless charging system for electric vehicles) is made of PC95 manganese-zinc power ferrite as a whole, and completely covers the receiving coil. This shielding method has a bulky structure. , the magnetic conductive material is not fully utilized, and the shielding effect of using a single ferrite material will affect the transmission efficiency and gradually fail to meet the development needs of future technology. The shielding structure designed in this document does not add a heat sink to conduct conduction. heat generated during charging.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a novel composite magnetic material shielding plate suitable for the wireless power transmission system of an electric vehicle and a suitable heat conduction plate. Among them, the composite magnetic material shielding plate manganese-zinc power ferrite and iron-based nanocrystalline alloy are made of two kinds of magnetic materials. A plate-like structure with chamfers around the edges is placed between the magnetic shielding structure and the aluminum cover. Such a design can not only reasonably use magnetic materials to shield electromagnetic radiation, but also conduct heat generated during the charging process to ensure the effective operation of the system.

The technical scheme that the present invention solves the technical problem is:

A composite shielding structure suitable for an electric vehicle wireless power supply system, the structure comprising an aluminum cover, an alumina ceramic heat-conducting plate, a magnetic material shielding plate, a receiving coil and a bakelite substrate;

The aluminum cover is in the shape of a cube cover, the bottom has an outer edge, and the outer edge is distributed with screw holes;

The alumina ceramic heat-conducting plate includes two parts: a heat-conducting flat plate and a heat-conducting chamfer; the heat-conducting flat plate is a square plate; Angle; the lower end face of the heat conduction plate is attached to the upper end face of the heat conduction chamfer, and the centers of the two are the same;

The magnetic material shielding plate includes shielding plate chamfer, four-corner arrow plate, surrounding trapezoid plate, quasi isosceles trapezoid plate, nanocrystalline rectangular plate, ferrite rectangular plate, inner frame long strip, inner frame triangular plate and center. regular octagonal plate;

Among them, the four shielding plates are chamfered to form a first frame, the first frame is a hollow square isosceles terrace, and the hypotenuse of the terrace is 45°; the end face of the first frame is inlaid with a square split plate ; The composition of the spliced board is: four isosceles trapezoid boards with short sides facing inwards are spliced to form a second frame; a central regular octagon board is placed at the center position inside the second frame, and a regular octagonal board is placed in the center of the second frame. Each side of the shaped plate extends an inner frame long strip, and the length of the inner frame long strip extends from the regular octagon plate to the four corners of the second box and the center of the four inner sides, and the inner frame of the second box The rest of the space is filled with eight inner frame triangular plates; a four-cornered arrow plate is set at the four corners of the outer four corners of the second box to the four corners of the first box, and one four-cornered arrow plate is placed on each side of each four-cornered arrow plate. Trapezoid plate, that is, there are eight surrounding trapezoidal plates, and a nanocrystalline rectangular plate is placed on each of the right-angled sides of the eight surrounding trapezoidal plates, and the inner edge of the first box and the center of the outer edge of the second box are respectively set. There is a nanocrystalline rectangular plate; a ferrite rectangular plate is filled between two adjacent nanocrystalline rectangular plates;

The four-cornered arrow plate, the nanocrystalline rectangular plate, the isosceles trapezoid-like plate, the inner frame elongated plate and the central regular octagon are all made of iron-based nanocrystalline alloy materials; Both the plate and the inner frame triangular plate are made of manganese-zinc power ferrite material;

The bakelite substrate includes the inner frame boundary of the substrate, the outer frame boundary of the substrate, a wire inlet hole, a wire outlet hole, a screw hole and a substrate plate;

The base plate is a square plate as a whole, and two annular protrusions inside and outside are arranged on the upper surface: the inner frame boundary of the base plate and the outer frame boundary of the base plate; the outer edge of the base plate plate is provided with threaded holes;

The receiving coil is wound by using Litz wire, the Litz wire material is copper, the number of strands is 1000-1500, the radius of the wire is 3-5mm, and it is wound into a square shape with rounded four corners. The length is 400mm, and the number of turns is 12 to 18 turns; the width of the coil matches the spacing between the two boundaries; both ends of the coil are drawn inward from the inlet hole and drawn out from the outlet hole respectively;

The side length of the substrate plate is equal to the side length of the outer edge of the aluminum cover;

The bakelite substrate is located at the bottom of the shielding structure, the receiving coil is arranged between the inner frame boundary of the bakelite substrate and the outer frame boundary of the substrate, the magnetic material shielding plate covers the receiving coil, and the alumina ceramic heat conducting plate Covered on the magnetic material shielding plate, the aluminum cover is covered above the alumina ceramic heat-conducting plate, and is fixed as a whole by screws and bakelite base plate.

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

(1) In the present invention, four identical isosceles trapezoids are designed for splicing the shielding structure above the receiving coil. Made of crystalline alloy material, the use of iron-based nanocrystalline alloy material for this structure can enhance the magnetic permeability of this part, so that most of the magnetic flux passes through the shielding material, which can greatly reduce the size of the leakage magnetic field above; This part of the structure is located above the receiving coil, and the magnetic field direction is parallel to the nanocrystalline alloy structure plate, so no large eddy current loss will be generated; in addition, the splicing of four identical isosceles trapezoids can also save materials and simplify the manufacturing process.

(2) In the present invention, a "m"-shaped distributed structure is designed inside the box enclosed by the isosceles trapezoid-like plates in the shielding structure. The center of the structure is a regular octagonal plate. Both extend a long plate-shaped structure, and the m-shaped structure is made of 1K107 iron-based nanocrystalline alloy material. The good magnetic permeability can effectively concentrate the magnetic flux in the middle of the receiving coil to achieve the leakage magnetic field in the center of the shielding coil. The narrow structure can reduce the eddy current effect generated by the vertical magnetic field of the material and control the temperature rise to a certain extent; the rest of the space inside the box is made of TDK PC95 manganese-zinc power ferrite. Eight isosceles right-angled triangle plates are used for filling. This design can generate eddy currents in the inner area of the obstructing square circle, and can restrain the remaining stray magnetic flux from diffusing to the surrounding air.

(3) The present invention is formed by splicing magnetic material shielding plates in three shapes of four-cornered arrow plate, surrounding trapezoidal plate and surrounding rectangular plate around the outside of the box surrounded by the isosceles trapezoidal plate in the shielding structure, wherein the four-cornered arrow plate It is made of 1K107 iron-based nanocrystalline alloy material and placed at the four corners of the outer edge of the shielding plate; the surrounding trapezoidal plates are made of TDK PC95 manganese-zinc power ferrite material and placed on both sides of the four four-corner arrow plates. ; The surrounding rectangular plates are crossed with two materials and placed in the center of the surrounding. The distribution positions and production materials of different structures are obtained through 3D finite element simulation, which can reduce the surrounding eddy current loss and help improve the overall magnetic permeability.

(4) In the present invention, four identical chamfered structures are designed on the surrounding edges of the magnetic material shielding plate. The magnetic leakage at the edge of the shielding plate in the vertical direction and the horizontal direction can guide the magnetic circuit to effectively conduct electromagnetic coupling between the two coils, further improving the transmission efficiency.

(5) The thermal conductivity structure of the present invention adopts alumina ceramic material with good thermal conductivity, high mechanical strength and high temperature resistance. Light weight, which can reduce the load of the vehicle while achieving better heat conduction effect; the heat conduction structure is designed with a chamfered structure around the edge of the lower plane of the heat conduction plate, and the size is consistent with the magnetic material shielding plate, and the increase and shielding The contact area of the plate also retains the contact with the air, which can play a better heat convection and heat conduction.

Description of drawings

1 is a schematic diagram of the relative position of the overall structure of an embodiment of a composite shielding structure suitable for an electric vehicle wireless power supply system according to the present invention;

2 is a top view of the overall structure of an embodiment of a composite shielding structure suitable for an electric vehicle wireless power supply system according to the present invention;

3 is a bottom view of an alumina ceramic heat-conducting plate structure according to an embodiment of a composite shielding structure suitable for an electric vehicle wireless power supply system according to the present invention;

FIG. 4 is a partial schematic diagram of the structure of an alumina ceramic heat-conducting plate according to an embodiment of the composite shielding structure applicable to the wireless power supply system of an electric vehicle;

5 is a top view of a magnetic material shielding structure according to an embodiment of a composite shielding structure suitable for an electric vehicle wireless power supply system according to the present invention;

6 is a plan view of a substrate structure of an embodiment of a composite shielding structure suitable for an electric vehicle wireless power supply system according to the present invention;

FIG. 7 is a simulation comparison diagram of the leakage magnetic field strength of the composite magnetic shielding structure of the present invention and a commonly used PC95 type ferrite magnetic shielding plate of the same size at 10 mm above the shielding plate;

In the picture: 1. Aluminum cover; 2. Alumina ceramic heat-conducting plate; 3. Magnetic material shielding plate; 4. Receiving coil; 5. Bakelite substrate; 6. Screws;

21. Thermally conductive plate; 22. Thermally conductive chamfer;

31. Chamfering of shielding plate; 32. Four-corner arrow plate; 33. Trapezoidal plate around; 34. Isosceles trapezoidal plate; 35. Nanocrystalline rectangular plate; 36. Ferrite rectangular plate; 37. Inner frame long strip; 38. The inner frame triangular plate; 39. The central regular octagonal plate;

51. The boundary of the inner frame of the substrate; 52. The boundary of the outer frame of the substrate; 53, the wire inlet hole; 54, the wire outlet hole; 55, the threaded hole; 56, the substrate plate;

Detailed ways

Specific embodiments of the present invention are given below. The specific embodiments are only used to further illustrate the present invention in detail, and do not limit the protection scope of the claims of the present application.

The present invention provides a composite shielding structure suitable for an electric vehicle wireless power supply system. As shown in FIG. 1 , the structure includes an aluminum cover 1 , an alumina ceramic heat-conducting plate 2 , a magnetic material shielding plate 3 , a receiving coil 4 and an electrical wood board 5;

The relative position and overall structure diagram of the composite shielding structure are shown in Figures 1 and 2, the bakelite substrate 5 is located at the bottom, the receiving coil 4 is located above the bakelite substrate 5, and the receiving coil 4 is placed on the inner frame of the substrate Between the boundary 51 and the boundary 52 of the outer frame of the substrate; the magnetic material shielding plate 3 is located above the receiving coil 4, and the receiving coil 4 is located directly below the square circle surrounded by the isosceles trapezoid-like plate in the magnetic material shielding plate, and the two The center points are located on the same vertical line; the alumina ceramic heat-conducting plate 2 is located above the magnetic material shielding plate 3, and the magnetic material shielding plate 3 is completely attached to the inside of the lower surface of the alumina ceramic heat-conducting plate 2; the aluminum cover 1 is located in the alumina Above the ceramic heat-conducting plate 2, the inner lower surface of the aluminum cover 1 covers the outer upper surface of the alumina ceramic heat-conducting plate 2, and the side inner surface of the aluminum cover 1 just surrounds the alumina ceramic heat-conducting plate 2. The aluminum cover 1 The lower edge of the base plate is attached to the bakelite substrate 5, and the screw holes of the two are aligned with the screw 6 for installation;

The top view of the aluminum cover 1 is shown in FIG. 2, which is a cube without a lower surface flat plate and a hollow interior structure (square cover-like structure), and an edge of a certain width extends from the bottom of the surrounding side of the cube, and is on the edge. Drill holes, the size of the upper plane of the aluminum cover 1 is the same as the size of the heat-conducting flat plate 21 of the alumina ceramic heat-conducting plate 2, and the height of its surrounding sides is the size that can just fit with the bakelite substrate 5 after installation; the thickness of the aluminum cover is 2mm, the height is 30mm, the side length is 848mm; the thickness of the outer edge is 2mm, and the width is 15mm;

The overall bottom view and partial schematic diagram of the structure of the alumina ceramic heat-conducting plate 2 are shown in Figures 3 and 4. The structure includes two parts: a heat-conducting flat plate 21 and a heat-conducting chamfer 22; the heat-conducting flat plate 21 is a square plate, and the heat-conducting inverted feet 22 It is also a cover-like structure, which is a hollow square isosceles terrace (that is, the end face and the bottom surface are square), the hypotenuse of the terrace is 45°, and the inner height of the terrace is shielded from the four shields in the magnetic material shielding plate 3. The inner height of the first box enclosed by the plate chamfer 31 is the same, and the length of the bottom edge of the step is the same as that of the heat conducting plate 21 (also equal to the length of the side of the aluminum cover 1 excluding the outer edge), The side length of the end face is 18-21mm smaller than the side length of the bottom side (the inner height of the ladder is 9-10mm); the lower end face of the heat conducting plate 21 is attached to the upper end face of the heat conducting chamfer 22, and the centers of the two are the same; the heat conducting chamfer 22 The inner surface of the enclosed area is exactly the same as the upper surface of the magnetic material shielding plate 3; the thermal conductivity structure adopts alumina ceramic material with good thermal conductivity, high mechanical strength and high temperature resistance, and the thermal conductivity of the alumina magnetic conductive material can reach 20W /(m·K), and the material has low density and light weight, which can reduce the vehicle load while achieving better thermal conductivity;

The top view of the overall structure of the magnetic material shielding plate 3 is shown in FIG. 5, including the shielding plate chamfer 31, the four-cornered arrow plate 32, the surrounding trapezoidal plate 33, the isosceles trapezoidal plate 34, the nanocrystalline rectangular plate 35, the ferrite Rectangular plate 36, inner frame elongated plate 37, inner frame triangular plate 38 and central regular octagonal plate 39;

Among them, the four shielding plate chamfers 31 enclose a first frame (the shielding plate chamfering 31 is a strip structure), the first frame is a hollow square isosceles terrace, and the hypotenuse of the terrace is a 45° angle, The inner height of the first frame is 1cm, which is the same as the height of the substrate inner frame boundary 51 and the substrate outer frame boundary 52 in the bakelite substrate 5; the first frame is inlaid with a square split board; The side lengths of the embedded grooves on the upper end face of a box are equal; the said spliced plate is composed of: four isosceles trapezoid-like plates 34 are spliced with the short sides facing inward to form a second box; inside the second box The central regular octagonal plate 39 is placed at the center position, an inner frame long strip 37 extends from each side of the regular octagonal plate 39, and the length of the inner frame long strip 37 extends from the regular octagonal plate to the second The four corners of the box and the center of the four inner sides (a central regular octagonal plate 39 and eight inner frame long strips 37 form a "m"-shaped structure), and the remaining space inside the second box is made of eight inner frame triangles. The board 38 is filled; the outer four corners of the second box to the four corners of the first box are respectively provided with a four-corner arrow plate 32 at the four corners, and each four-corner arrow plate 32 is placed on both sides of a surrounding trapezoidal plate 33, that is, There are eight surrounding trapezoidal plates 33, and the right-angled sides of the eight surrounding trapezoidal plates 33 are each fitted with a nanocrystalline rectangular plate 35, and the inner edge of the first frame and the center of the outer edge of the second frame are respectively provided with A nanocrystalline rectangular plate 35; a ferrite rectangular plate 36 is filled between two adjacent nanocrystalline rectangular plates 35; wherein, the side length of the regular octagonal plate 39 is 25mm, and the upper part of the isosceles trapezoid plate 34 is The length of the bottom is 365mm, the length of the bottom is 544mm, the height is 112mm, and the length of the outer chamfer is 28.3mm. The size of the nanocrystalline rectangular plate 35 and the ferrite rectangular plate 36 are the same, and both are rectangular structures with a length of 88mm and a width of 50mm;

The above-mentioned isosceles trapezoid-like plate 34 is processed by chamfering the four corners of the isosceles trapezoid.

The four-cornered arrow plate 32, the nanocrystalline rectangular plate 35, the isosceles-like trapezoid plate 34, the inner frame strip plate 37 and the central regular octagon 39 all use the 1K107 model with higher magnetic permeability and lower high frequency loss. Iron-based nanocrystalline alloy material; shielding plate chamfer 31, surrounding trapezoidal plate 33, ferrite rectangular plate 36 and inner frame triangular plate 38 are all made of TDK PC95 manganese-zinc power ferrite material;

The magnetic material shielding plate 3 uses two magnetic materials, 1K107 iron-based nanocrystalline alloy and TDK PC95 manganese-zinc power ferrite, to perform the composite splicing structure shown in FIG. The magnetic leakage field, and the design of the shielding plate chamfer 31 can reduce the magnetic leakage in the vertical direction and the horizontal direction at the edge of the magnetic material shielding plate 3, and can guide the magnetic circuit to effectively conduct electromagnetic coupling between the two coils, further improving the transmission. efficiency;

The structural schematic diagram of the bakelite substrate 5 is shown in FIG. 6 , including the inner frame boundary 51 of the substrate, the outer frame boundary 52 of the substrate, the wire inlet hole 53 , the wire outlet hole 54 , the screw hole 55 and the substrate plate 56 ;

The substrate plate 56 is a square plate as a whole, and two square protrusions with a thickness of 1 cm are designed on the upper surface, which are the inner frame boundary 51 of the substrate and the outer frame boundary 52 of the substrate. The space between them is used to place and fix the receiving coil 4; a through wire inlet hole 53 is provided at the outer diameter edge of the inner frame boundary 51 of the substrate, and a through wire outlet hole 54 is set at the inner diameter edge of the outer frame boundary 52 of the substrate; A total of 16 threaded holes are arranged at the positions corresponding to the threaded holes of the aluminum cover 1 on the outer edge of the base plate plate 56;

The side length of the substrate plate 56 is equal to the side length of the outer edge of the aluminum cover 1;

The receiving coil 4 is wound by using Litz wire, the Litz wire material is copper, the number of strands is 1300, the radius of the wire is 5mm, and it is wound into a square shape with rounded corners, and the length of the inner side of the winding is 400mm. , the number of turns is 16 turns; both ends of the coil are drawn inward from the wire inlet hole 53 and drawn out from the wire outlet hole 54 respectively, and the two ends of the receiving coil are drawn out and connected to the power electronic conversion device in the power control unit on the vehicle side. The converter performs operations such as compensating, rectifying and filtering the high-frequency alternating current output by the receiving coil, and finally outputs the direct current that meets the requirements of the on-board battery of the electric vehicle to charge the on-board battery;

The bakelite substrate 5 is located at the bottom of the shielding structure, the receiving coil 4 is placed between the substrate inner frame boundary 51 and the substrate outer frame boundary 52 of the bakelite substrate 5, and the magnetic material shielding plate 3 covers the receiving coil 4. The aluminum cover 1 completely covers the top of the alumina ceramic heat-conducting plate 2 (the aluminum cover 1, the alumina ceramic heat-conducting plate 2, and the magnetic material shielding plate 3 are all Fitting); wherein, the center positions of the aluminum cover 1, the alumina ceramic heat-conducting plate 2, the magnetic material shielding plate 3, the receiving coil 4 and the bakelite substrate 5 are located on the same vertical line;

installation steps:

Step 1: Fix the receiving coil 4 in the gap between the inner frame boundary 51 of the bakelite substrate 5 and the outer frame boundary 52 of the substrate. ;

Step 2: Paste each part of the magnetic material shielding plate 3 on the inner surface below the alumina ceramic heat-conducting plate 2 according to the structure shown in FIG. 5 ;

Step 3: Fix the alumina ceramic heat-conducting plate 2 obtained by completing the pasting work of each magnetic material shielding structure in Step 2 on the lower surface of the interior of the aluminum cover 1;

Step 4: Place the aluminum cover 1, the alumina ceramic heat-conducting plate 2 and the magnetic material shielding plate 3 that have been completed in steps 2 and 3 above the coil obtained in step 1, and place the aluminum cover 1 and the threaded holes of the bakelite substrate 5 on top of the coil obtained in step 1. Fix them with screws 6 after corresponding respectively;

Simulation analysis:

Figure 7 shows the simulation of this embodiment and the commonly used complete TDK PC95 manganese-zinc power ferrite board. When 10A alternating current at a frequency of 85 kHz is applied to the current cross section of the transmitting coil, at a height of 10 mm above the magnetic material shielding structure, the alternating current is a peak value. At the moment (ie t=8.88×10 ^-6 s), take the magnetic field intensity comparison curve of each point on a line segment at the center of the magnetic material shielding plate that is symmetrical about the center point and has a length of 1.2m.

It can be seen from Figure 7 that the leakage magnetic field of the composite magnetic shielding structure shown in Figure 5 on the selected line segment is significantly smaller than that of the complete TDK PC95 manganese-zinc power ferrite plate, especially at 0.2m to 0.3m , 0.9m to 1.0m. This shows that the embodiment of the magnetic material shielding plate in the composite shielding structure suitable for the wireless power supply system of electric vehicles is indeed greatly improved in terms of shielding effect compared with the complete TDK PC95 manganese-zinc power ferrite plate, especially The magnetic leakage improvement effect above the edge of the magnetic material shielding plate is remarkable, so it is indeed a great improvement for the current magnetic shielding structure.

What is not described in the present invention applies to the prior art.

Claims (2)

1. a composite shielding structure suitable for an electric vehicle wireless power supply system, characterized in that the structure comprises an aluminum cover, an alumina ceramic heat-conducting plate, a magnetic material shielding plate, a receiving coil and a bakelite substrate; The aluminum cover is in the shape of a cube cover, the bottom has an outer edge, and the outer edge is distributed with screw holes; The alumina ceramic heat-conducting plate includes two parts: a heat-conducting flat plate and a heat-conducting chamfer; the heat-conducting flat plate is a square plate; Angle; the lower end face of the heat conduction plate is attached to the upper end face of the heat conduction chamfer, and the centers of the two are the same; The magnetic material shielding plate includes shielding plate chamfer, four-corner arrow plate, surrounding trapezoid plate, quasi isosceles trapezoid plate, nanocrystalline rectangular plate, ferrite rectangular plate, inner frame long strip, inner frame triangular plate and center. regular octagonal plate; Among them, the four shielding plates are chamfered to form a first frame, the first frame is a hollow square isosceles terrace, and the hypotenuse of the terrace is 45°; the end face of the first frame is inlaid with a square split plate ; The composition of the spliced board is: four isosceles trapezoid boards with short sides facing inwards are spliced to form a second frame; a central regular octagon board is placed at the center position inside the second frame, and a regular octagonal board is placed in the center of the second frame. Each side of the shaped plate extends an inner frame long strip, and the length of the inner frame long strip extends from the regular octagon plate to the four corners of the second box and the center of the four inner sides, and the inner frame of the second box The rest of the space is filled with eight inner frame triangular plates; a four-cornered arrow plate is set at the four corners of the outer four corners of the second box to the four corners of the first box, and one four-cornered arrow plate is placed on each side of each four-cornered arrow plate. Trapezoid plate, that is, there are eight surrounding trapezoidal plates, and a nanocrystalline rectangular plate is placed on each of the right-angled sides of the eight surrounding trapezoidal plates, and the inner edge of the first box and the center of the outer edge of the second box are respectively set. There is a nanocrystalline rectangular plate; a ferrite rectangular plate is filled between two adjacent nanocrystalline rectangular plates; The four-cornered arrow plate, the nanocrystalline rectangular plate, the isosceles trapezoid-like plate, the inner frame elongated plate and the central regular octagon are all made of iron-based nanocrystalline alloy materials; Both the plate and the inner frame triangular plate are made of manganese-zinc power ferrite material; The bakelite substrate includes the inner frame boundary of the substrate, the outer frame boundary of the substrate, a wire inlet hole, a wire outlet hole, a screw hole and a substrate plate; The base plate is a square plate as a whole, and two annular protrusions inside and outside are arranged on the upper surface: the inner frame boundary of the base plate and the outer frame boundary of the base plate; the outer edge of the base plate plate is provided with threaded holes; The receiving coil is wound with Litz wire; The side length of the substrate plate is equal to the side length of the outer edge of the aluminum cover; The bakelite substrate is located at the bottom of the shielding structure, the receiving coil is arranged between the inner frame boundary of the bakelite substrate and the outer frame boundary of the substrate, the magnetic material shielding plate covers the receiving coil, and the alumina ceramic heat conducting plate Covered on the magnetic material shielding plate, the aluminum cover is covered above the alumina ceramic heat-conducting plate, and is fixed as a whole by screws and bakelite base plate. 2. The composite shielding structure suitable for the wireless power supply system of electric vehicles as claimed in claim 1, characterized in that the number of strands of the receiving coil is 1000～1500, the radius of the wire is 3～5mm, and it is wound into a square and The four corners are in the shape of rounded corners, and the number of turns is 12 to 18 turns; the width of the coil matches the spacing between the two boundaries;

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