Magnetizer for high-power wireless charging of automobile and preparation method of magnetizer

Abstract

The invention discloses a magnetizer for high-power wireless charging of an automobile and a preparation method of the magnetizer. The preparation method comprises the following steps: carrying out rapid heat treatment on a nanocrystalline strip in an oxygen-free environment; the nanocrystalline strip subjected to rapid heat treatment is subjected to the following treatment in any sequence: i) surface insulation treatment; ii) winding along the outer surface of the mould. The nanocrystalline strip after rapid heat treatment and surface insulation treatment shows low eddy-current loss, keeps high magnetic conductivity, frequency stability and power stability, can be wound in a user-defined mode to meet the large-size application requirement, meanwhile, when the nanocrystalline strip is wound to be used, the plane of the strip is perpendicular to the plane where a coil is located, and the size of the coil is small. The problem of low magnetic conductivity in the vertical coil direction is effectively solved, a channel with high magnetic conductivity is provided for coil coupling, and the charging efficiency is greatly improved. The preparation method is simple, the production efficiency is high, and continuous production can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology, and specifically relates to a magnetic conductor for high-power wireless charging of automobiles and its preparation method. Background Technology

[0002] With the rapid development of the electric vehicle industry and the increase in driving range, the inconvenience and cumbersome operation of traditional wired charging have become increasingly apparent. Furthermore, wired charging is susceptible to short circuits and open circuits in adverse weather conditions; long-term exposure of charging cables outdoors can lead to insulation damage, resulting in leakage, fire, and other hazards; and the need for manual maintenance of charging stations outdoors increases charging costs. Wireless charging, on the other hand, is convenient, adaptable to various environments, and avoids the problems of interface wear, sparks, and leakage that arise from physical interfaces. It can also achieve high-voltage, high-current, and high-power charging. However, its main drawback is its relatively low charging efficiency. Therefore, improving the charging efficiency of wireless charging systems for electric vehicles is a pressing issue that needs to be addressed.

[0003] Among various wireless charging technologies, magnetically coupled resonant wireless charging technology has been widely studied for its advantages over other technologies, such as longer transmission distance, higher transmission efficiency, and stronger resistance to offset. However, because the magnetically coupled coils at the transmitting and receiving ends are loosely coupled transformers with relatively high leakage inductance, the coupling coefficient between the coils is small, resulting in low energy transmission efficiency. Therefore, it is necessary to design magnetically conductive materials that meet the magnetic requirements of the magnetically coupled coils, reduce the magnetic resistance in the mutual coupling region of the coils, and increase the coupling coefficient to effectively improve energy transmission efficiency.

[0004] CN104900383B discloses a single / multilayer magnetic conductive sheet for wireless charging and its preparation method. The single-layer magnetic conductive sheet includes: a magnetic thin sheet with multiple cracks uniformly distributed on it, dividing the sheet into multiple fragment units; the gaps in the cracks are filled with an insulating medium to insulate the fragment units on both sides of the cracks from each other; and double-sided adhesive, adhered to one side of the magnetic thin sheet, with a protective film composed of the insulating medium formed on the other side of the magnetic thin sheet. The preparation method includes: heat treatment, double-sided adhesive bonding, cracking treatment, impregnation treatment, and drying and curing steps. The magnetic conductive sheet of this invention improves the inductance and quality factor of the charging coil, increases charging efficiency, and reduces losses. The continuous preparation method of the magnetic conductive sheet material for wireless charging proposed in this invention features controllable magnetic permeability, continuous production, convenient operation, and simple insulation treatment. CN209087527U discloses a large-size amorphous nanocrystalline magnetic shielding sheet stack for wireless charging. The splicing gaps of the adjacent nanocrystalline single-unit plates are staggered, which solves the problem of increasing the size of nanocrystalline materials. At the same time, it minimizes the impact of splicing gaps on the overall performance of the product, enabling nanocrystalline materials to be used in wireless charging applications for high-power electrical appliances.

[0005] Existing nanocrystalline magnetic shielding sheets are all stacked in a planar direction. While this can meet the demand for large sizes, the magnetic focusing effect is poor due to the use of a direction perpendicular to the surface. In addition, the soft magnetic material used for magnetic focusing suffers losses mainly from eddy current losses at high frequencies, resulting in low coupling efficiency of the charging coil, low quality factor Q, and low charging efficiency. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention provides a magnetic conductor for high-power wireless charging of automobiles and its preparation method. This magnetic conductor has high permeability and low loss, and can be applied to high-power wireless charging devices for automobiles, significantly improving charging efficiency.

[0007] In a first aspect, the present invention provides a method for preparing a magnetic conductor for high-power wireless charging of automobiles, comprising: rapidly heat-treating a nanocrystalline ribbon in an oxygen-free environment; and processing the rapidly heat-treated nanocrystalline ribbon in any order of the following: i) surface insulation treatment; ii) winding along the outer surface of a mold.

[0008] According to a specific embodiment of the present invention, the preparation method is as follows: The nanocrystalline ribbon is subjected to rapid heat treatment in an oxygen-free environment; one or both sides of the rapidly heat-treated nanocrystalline ribbon are bonded to double-sided adhesive; the nanocrystalline ribbon bonded with double-sided adhesive is wound along the outer surface of the mold to obtain the magnetic conductor for high-power wireless charging of automobiles. Specifically, one or both sides of the rapidly heat-treated nanocrystalline ribbon are first bonded to double-sided adhesive tape with one side of the release film removed. Then, while removing the release film on the other side of the double-sided adhesive tape, it is wound along the outer surface of the mold. At this time, while the substrate attached to the double-sided adhesive provides surface insulation, the wound roll is also shaped.

[0009] According to a specific embodiment of the present invention, the preparation method is as follows: the nanocrystalline ribbon is subjected to rapid heat treatment in an oxygen-free environment; the rapidly heat-treated nanocrystalline ribbon is wound along the outer surface of a mold; adhesive is poured into the interior of the wound nanocrystalline ribbon, and then baked to harden, thereby obtaining the magnetic conductor for high-power wireless charging of automobiles. At this time, the poured adhesive penetrates the gap between every two layers of ribbon, and the inorganic or organic layer formed after curing serves as surface insulation, while baking to harden serves as shaping.

[0010] According to a specific embodiment of the present invention, the thickness of the nanocrystalline ribbon is 15–25 μm, and the width is 0.5–30 mm. Thickness is one of the main factors determining the Q value of the magnetic conductor; the smaller the thickness, the lower the loss.

[0011] According to a specific embodiment of the present invention, the oxygen-free environment includes a vacuum or an inert atmosphere, such as any one of hydrogen, nitrogen, argon, etc.

[0012] According to a specific embodiment of the present invention, rapid heat treatment is performed by pulse heating; preferably, the pulse heating temperature is 600-700°C, and the temperature is held for 5-300 seconds. The heating rate needs to be above 100°C / s to eliminate the brittleness caused by amorphous relaxation during long-term holding as much as possible.

[0013] According to a specific embodiment of the present invention, the winding process matches the size of the cross-section of the resulting roll to the size of the coil for high-power wireless charging of automobiles. Specifically, a magnetic conductor is used to cover the coil, the specific shape of which depends on the shape of the coil. Different winding dies are used for different coil shapes, with the aim of making it the same shape as the coil, and the size can be exactly the same, or 5 to 30 mm larger than the coil around the edges. Generally, the overall size is between 100 mm and 500 mm.

[0014] According to a specific embodiment of the present invention, the shape of the mold is arbitrary, and can be rolled into various custom shapes such as circles, rectangles, trapezoids, etc., preferably cylindrical or prism shapes.

[0015] According to a specific embodiment of the present invention, the thickness of the double-sided adhesive is 1-10 μm.

[0016] In a second aspect, the present invention provides a magnetic conductor for high-power wireless charging of automobiles prepared by the aforementioned method.

[0017] A third aspect of the present invention provides a high-power wireless charging module for automobiles, comprising a coil and the aforementioned magnetic conductor disposed on the back side of the coil, wherein the plane of the nanocrystalline ribbon constituting the magnetic conductor is perpendicular to the plane of the coil.

[0018] The beneficial effects of this invention are as follows:

[0019] The fabrication method provided by this invention produces nanocrystalline ribbons with low eddy current losses after rapid heat treatment and surface insulation, while maintaining high permeability, frequency stability, and power stability. These ribbons can be custom-wound to meet the needs of large-size applications. Furthermore, the winding process ensures that the plane of the ribbon is perpendicular to the plane of the coil during use, effectively solving the problem of low permeability in the direction perpendicular to the coil. This provides a high-permeability channel for coil coupling, significantly improving charging efficiency. The fabrication method of this invention is simple, has high production efficiency, and can be continuously manufactured. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention; wherein, 1-feeding tray; 2-heating furnace; 3-tension roller; 4-double-sided adhesive; 5-winding mold; 6-protective atmosphere vent;

[0021] Figure 2 This is a top view of the magnetic conductor prepared in Embodiment 1 of the present invention;

[0022] Figure 3 This is a bottom view and a schematic diagram of the microstructure of the magnetic conductor prepared in Embodiment 2 of the present invention; wherein, 7-insulating film (substrate carried by double-sided tape); 8-adhesive layer; 9-nanocrystalline tape;

[0023] Figure 4 The power stability test results are for the magnetic conductor prepared in Example 1 of this invention.

[0024] Figure 5 The results of frequency stability testing of the magnetic conductor prepared in Example 1 of this invention;

[0025] Figure 6 The power stability test results are for the magnetic conductor prepared in Example 2 of this invention.

[0026] Figure 7 The results of frequency stability testing of the magnetic conductor prepared in Example 2 of this invention;

[0027] Figure 8The power stability test results are for the magnetic conductor prepared in Example 3 of this invention.

[0028] Figure 9 The results of frequency stability testing of the magnetic conductor prepared in Example 3 of this invention;

[0029] Figure 10 The power stability test results are for the comparative-scale prepared magnetic conductors.

[0030] Figure 11 The frequency stability test results are for the magnetic conductor prepared as a comparative example. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] An alloy of FeCuNbSiB composition was prepared into an amorphous alloy strip with an initial state of 18 μm thickness and 10 mm width using a single-roll rapid quenching method. The initial crystallization temperature and the peak temperature of the first crystallization were measured to be 515 °C and 535 °C, respectively. Rapid heat treatment was then performed in an annealing furnace under a nitrogen atmosphere, using pulse heating to a temperature of 650 °C at a heating rate of 100 °C / s, holding at this temperature for 60 s, and then allowing it to cool naturally. One side of the cooled strip was bonded to a double-sided adhesive tape (with one side of the release film removed). The adhesive material of the double-sided tape was acrylic, and its base material was PET with a thickness of 2 μm. Simultaneously, the other layer of release film was peeled off from the strip bonded with the double-sided tape, and the strip was wound along the outer surface of the side wall of a cylindrical mold to obtain a magnetic conductor, such as... Figure 2 As shown in the diagram, the process flow chart is as follows: Figure 1 As shown.

[0034] Testing revealed that this magnetic conductor exhibits an inductance of 9.5 μH, a Q value of 150, and a permeability of 800 at 100 kHz. It maintains constant permeability within a magnetic field strength of up to 1000 A / m, demonstrating excellent power stability and frequency stability, as shown below. Figure 4 and Figure 5As shown, the magnetic conductor was placed on the back of the coil of a high-power wireless charging system for automobiles (the cross-sectional size of the magnetic conductor matched the size of the coil), with the plane of the strip perpendicular to the plane of the coil. The charging efficiency of the wireless charging system was tested after 30 minutes of operation. The wireless charging system had a power of 11kW and achieved a charging efficiency of 92%. The use of a plane where the strip is perpendicular to the plane of the coil significantly reduces eddy current losses, lowers heat generation during charging, and improves charging efficiency. Furthermore, the nanocrystalline material and double-sided adhesive maintain excellent flexibility after bonding, greatly improving shock resistance compared to brittle ferrite materials, thus significantly enhancing the reliability of the entire electric vehicle system.

[0035] Example 2

[0036] An alloy of FeCuNbSiB composition was prepared into an amorphous alloy strip with an initial state of 18 μm thickness and 10 mm width using a single-roll rapid quenching method. The initial crystallization temperature and the peak temperature of the first crystallization were measured to be 515 °C and 535 °C, respectively. Rapid heat treatment was then performed in an annealing furnace under a nitrogen atmosphere, using pulse heating to 600 °C at a rate of 100 °C / s, holding at this temperature for 5 s, and then allowing it to cool naturally. One side of the cooled strip was bonded to a double-sided adhesive tape (with one side of the release film removed). The adhesive material of the double-sided tape was acrylic, with a PI substrate and a thickness of 5 μm. Simultaneously, the other release film was peeled off from the strip bonded with the double-sided tape, and the strip was wound along the outer surface of the side wall of a cuboid mold to obtain a magnetic conductor, such as... Figure 3 As shown.

[0037] Testing revealed that this magnetic conductor exhibits an inductance of 10.8 μH, a Q value of 138, and a permeability of 1200 at 100 kHz, maintaining constant permeability within a magnetic field strength up to 400 A / m. Power stability and frequency stability are as follows: Figure 6 and Figure 7 As shown. The magnetic conductor was placed on the back of the coil of a high-power wireless charger for a car, with the plane of the strip perpendicular to the plane of the coil. The charging efficiency of the wireless charging system was tested after working for 30 minutes. The power of the wireless charging system was 10.4kW, and the charging efficiency reached 90.2%.

[0038] Example 3

[0039] An alloy with the composition FeCuNbSiB was prepared into an amorphous alloy strip with an initial state by a single-roll rapid quenching method. The strip thickness was 18 μm and the strip width was 10 mm. The initial crystallization temperature and the peak temperature of the first crystallization were tested to be 515 °C and 535 °C, respectively. Rapid heat treatment was performed in an annealing furnace under a nitrogen atmosphere, using pulse heating to a temperature of 700 °C at a heating rate of 100 °C / s, holding at this temperature for 300 s, and then allowing it to cool naturally. The cooled strip was then wound along the outer surface of the side wall of a cylindrical mold, and then resin was poured into the wound nanocrystalline strip. Finally, it was baked to harden, yielding a magnetic conductor.

[0040] Testing revealed that this magnetic conductor exhibits an inductance of 12.5 μH, a Q value of 120, and a permeability of 2000 at 100 kHz, maintaining constant permeability within a magnetic field strength of up to 200 A / m. Power stability and frequency stability are as follows: Figure 8 and Figure 9 As shown. The magnetic conductor was placed on the back of the coil of a high-power wireless charger for a car, with the plane of the strip perpendicular to the plane of the coil. The charging efficiency of the wireless charging system was tested after working for 30 minutes. The power of the wireless charging system was 10.6kW, and the charging efficiency reached 90.8%.

[0041] Comparative Example

[0042] The difference from Example 1 is that the tape for bonding double-sided adhesive tape is cut into multiple nanocrystalline strips, the multiple nanocrystalline strips are horizontally spliced ​​together to form a single-layer nanocrystal, and the multiple single-layer nanocrystals are orthogonally and alternately stacked to obtain a magnetic conductor.

[0043] Testing revealed that this magnetic conductor exhibited an inductance of 8.7 μH, a Q value of 100, and a permeability of 600 at 100 kHz. However, the permeability rapidly decreased with increasing magnetic field strength, resulting in poor power stability. Power stability and frequency stability are shown below. Figure 10 and Figure 11 As shown. The magnetic conductor was placed on the back of the coil of a high-power wireless charger for a car, with the plane of the strip parallel to the plane of the coil. The charging efficiency of the wireless charging system was tested after working for 30 minutes. The power of the wireless charging system was 8.6kW, and the charging efficiency reached 84%.

[0044] As can be seen, compared with the planar superimposed structure, the magnetic field lines of the vertically arranged nanocrystalline ribbon structure provided by this invention pass directly through the plane of the ribbon, resulting in higher magnetic permeability and excellent frequency and power stability, while also having lower losses, effectively improving the efficiency of high-power wireless charging.

[0045] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for preparing a magnetic conductor for high-power wireless charging of automobiles, characterized in that, The preparation method includes: The nanocrystalline ribbon was subjected to rapid heat treatment in an oxygen-free environment; The nanocrystalline ribbon that has undergone rapid heat treatment is processed in any order of the following ways: i) surface insulation treatment; ii) winding along the outer surface of the mold.

2. The preparation method according to claim 1, characterized in that, The preparation method is as follows: The nanocrystalline ribbon was subjected to rapid heat treatment in an oxygen-free environment; One or both sides of the rapidly heat-treated nanocrystalline ribbon are bonded with double-sided adhesive. The nanocrystalline ribbon with double-sided adhesive is wound along the outer surface of the mold to obtain the magnetic conductor for high-power wireless charging of automobiles.

3. The preparation method according to claim 1, characterized in that, The preparation method is as follows: The nanocrystalline ribbon was subjected to rapid heat treatment in an oxygen-free environment; The rapidly heat-treated nanocrystalline ribbon is wound along the outer surface of the mold; The inside of the wound nanocrystalline ribbon is filled with adhesive and then baked to harden, thus obtaining the magnetic conductor for high-power wireless charging of automobiles.

4. The preparation method according to claim 1, characterized in that, The nanocrystalline ribbon has a thickness of 15–25 μm and a width of 0.5–30 mm.

5. The preparation method according to claim 1, characterized in that, The rapid heat treatment is performed using pulse heating; preferably, the pulse heating temperature is 600-700°C, and the temperature is held for 5-300 seconds.

6. The preparation method according to claim 1, characterized in that, The winding process matches the cross-sectional size of the resulting roll to the size of the coil used for high-power wireless charging in automobiles.

7. The preparation method according to claim 1, characterized in that, The shape of the mold can be arbitrary, but it is preferably a cylindrical or prismatic shape.

8. The preparation method according to claim 2, characterized in that, The thickness of the double-sided adhesive is 1-10 μm.

9. A magnetic conductor for high-power wireless charging of automobiles prepared by the method according to any one of claims 1 to 8.

10. A high-power wireless charging module for automobiles, characterized in that, The high-power wireless charging module for automobiles includes a coil and a magnetic conductor as described in claim 9 disposed on the back of the coil, wherein the plane of the nanocrystalline ribbon constituting the magnetic conductor is perpendicular to the plane of the coil.

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