CN112967875B - High-radiation-suppression wireless charging electromagnetic coil for electric vehicle - Google Patents

High-radiation-suppression wireless charging electromagnetic coil for electric vehicle Download PDF

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CN112967875B
CN112967875B CN202110355617.5A CN202110355617A CN112967875B CN 112967875 B CN112967875 B CN 112967875B CN 202110355617 A CN202110355617 A CN 202110355617A CN 112967875 B CN112967875 B CN 112967875B
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coil
ferrite
radiation
square
square frame
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CN112967875A (en
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杨凌升
徐诗豪
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Nanjing University of Information Science and Technology
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Nanjing University of Information Science and Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H01F27/30—Fastening or clamping coils, windings, or parts thereof together; Fastening or mounting coils or windings on core, casing, or other support
    • H01F27/306—Fastening or mounting coils or windings on core, casing or other support
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/36—Electric or magnetic shields or screens
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

The invention discloses a high-radiation-suppression wireless charging electromagnetic coil for an electric vehicle, which comprises an upper ferrite and a lower ferrite which have equal sizes, wherein the ferrite is of a square frame structure, and an X-shaped structure is arranged inside the square frame; upper and lower coils are respectively wound on the square frames of the upper and lower ferrites; and aluminum sheets with the same size as the ferrite are attached to the ferrite. The mutual inductance effect generated by the coil structure is close to the optimal mutual inductance effect generated by completely covering the ferrite. Compared with the full coverage, the material of the ferrite can reduce about 39 percent of the material, and the production cost and the weight of the coil structure are reduced.

Description

High-radiation-suppression wireless charging electromagnetic coil for electric vehicle
Technical Field
The invention belongs to the technical field of wireless charging of electric vehicles, and particularly relates to a high-radiation-suppression electromagnetic coil for wireless charging of an electric vehicle.
Background
For the research of the wireless charging technology of the electric automobile, the most fundamental and basic part is the application of electromagnetic mutual inductance. For the research of electromagnetic mutual inductance, the research on coils is an important ring. The performance of the coil part will not only affect the transmission efficiency and system efficiency of the whole system, but will also ultimately affect the magnitude of the charging current. Therefore, a proper coil structure is designed, and the design is very important for the whole wireless charging system of the electric automobile.
Referring to fig. 11-12, expressions (I) - (III) of transmission power, system efficiency and charging current can be obtained by kirchhoff's law according to an electromagnetic mutual inductance equivalent circuit;
Figure BDA0003003655210000011
Figure BDA0003003655210000012
Figure BDA0003003655210000013
as can be seen from the above three formulas, where ReIs the equivalent resistance, R, behind the second side coil1、R2Is the self-resistance of the two-sided coil, RsIs internal resistance of power supply, UsIs the supply voltage, M is the mutual inductance of the two coils, ω is the frequency of the whole system, so without considering the equivalent resistance, since the resistivity of copper is 0.0172 Ω mm2And/m, the resistance of the coil is calculated to be about 0.04 omega, so that the resistance change of the coil caused by the change of the coil structure is very small, and the value of the formula is basically not influenced, so that the main influence factor of the three formulas is the mutual inductance of the two coils, and the coil mutual inductance with better effect is obtained by setting a proper structure.
For the coil part, the coil structure is generally divided into a coil structure and a ferrite part on the upper side and the lower side of the coil and an aluminum sheet part on the upper side and the lower side of the ferrite.
For the coil structure, a square structure and a circular structure are popular at present, and through comparison of previous research and test, under the same condition, namely that the side length of the square is equal to the diameter of a prototype, and the distance between the upper coil and the lower coil is the same, the mutual inductance of the square coil structure is larger, so the square coil structure is generally selected.
The ferrite part is used for inhibiting the radiation of the magnetic field, and the aluminum sheet is designed according to the same specification of ferrite design and is used for enhancing the radiation inhibition of the magnetic field, so that the specification of the ferrite is only considered in the design.
In most of the existing designs, a ferrite structure completely covering the coil is selected in order to suppress the radiation of the magnetic field as much as possible, and relatively many materials are used, so that the processing cost is relatively high and the weight is relatively large. Therefore, the ferrite structure is optimized on the basis, and the ferrite structure which has better magnetic field radiation inhibition and can reduce materials is obtained by comparing the effects of other common ferrite structures.
Disclosure of Invention
The invention aims to solve the technical problem of providing a wireless charging electromagnetic coil of an electric vehicle with high radiation suppression aiming at the defects of the prior art.
In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:
a high radiation suppression electric vehicle wireless charging electromagnetic coil comprises:
the ferrite is of a square frame structure, and an X-shaped structure is arranged inside the square frame;
upper and lower coils are respectively wound on the square frames of the upper and lower ferrites;
and aluminum sheets with the same size as the ferrite are attached to the ferrite.
In order to optimize the technical scheme, the specific measures adopted further comprise:
the coil is wound on the ferrite in a counterclockwise direction.
The upper coil, the ferrite and the aluminum sheet are symmetrical with the lower coil, the ferrite and the aluminum sheet, and the distance between the upper part and the lower part is 150 mm.
The width of the square frame is 20mm, the outer side length is 200mm, the inner side length is 180mm, and the thickness is 2 mm;
the internal X-shaped structure has a width of 20mm, a length of 186.28mm and a thickness of 2 mm.
The coil is made of litz coil, is made of copper, has a specification of 0.2 x 100, has a diameter of 0.2mm per strand, is bonded with 100 strands, and has a total cross-sectional area of 3.1415mm2。
The upper coil and the lower coil are provided with feed ports.
The feed port is a broken section, and is provided with current source excitation to simulate the charging state of the sightseeing electric automobile.
The cross section is 20mm wide and 100mm away from the adjacent end;
the current source excitation is set at 30A.
The invention has the following beneficial effects:
1. the mutual inductance effect generated by the coil structure is close to the optimal mutual inductance effect generated by completely covering the ferrite.
2. Compared with the full coverage, the material of the ferrite can reduce about 39 percent of the material, and the production cost and the weight of the coil structure are reduced.
Drawings
FIG. 1 is a coil structure without ferrite;
FIG. 2 is a coil with fully coated ferrite added above and below the coil;
FIG. 3 is a view showing the upper and lower sides of the coil only with ferrite covering the coil itself;
FIG. 4 shows a coil and upper and lower ferrite structures designed according to the present invention;
FIG. 5 shows a coil and upper and lower ferrite structures incorporating a peripheral aluminum sheet structure according to the present invention;
FIG. 6 is a diagram of the magnetic field generated by the coil structure of FIG. 1;
FIG. 7 is a diagram of the magnetic fields generated by the coil structure of FIG. 2;
FIG. 8 is a diagram of the magnetic field generated by the coil structure of FIG. 3;
FIG. 9 is a diagram of the magnetic field generated by the coil structure of FIG. 4;
FIG. 10 is a diagram of the magnetic field generated by the coil structure of FIG. 5;
FIG. 11 is an electromagnetic mutual inductance equivalent circuit diagram;
fig. 12 is an electric vehicle wireless charging system.
Detailed Description
Embodiments of the present invention are described in further detail below with reference to the accompanying drawings.
According to the high-radiation-suppression electric vehicle wireless charging electromagnetic coil, the coil structure comprises the upper square coil and the lower square coil, mutual inductance is obtained by comparing the square coil and the circular coil under the same size, namely the side length of the square coil is equal to the diameter of the circular coil, the mutual inductance effect generated by the square coil under the same condition is better than that of the circular coil, and therefore the square coil is selected.
The length of the outer side of the coil is 200mm, the length of the inner side of the coil is 180mm, and the thickness of the coil is 2 mm;
the feeding point is arranged at 100mm from the end point of one side of the upper and lower coils, and the current is set to be 30A.
In order to further improve the mutual inductance effect of the coil, a ferrite structure is added on the upper portion and the lower portion of the coil, and the mutual inductance effect that the ferrite is added to inhibit radiation and strengthen the coil can be obtained through the mutual inductance of the added ferrite and the non-added ferrite and a corresponding magnetic field diagram. The best effect for ferrite is full coverage of the coil, but this is wasteful of material, and by optimising the coil structure, a ferrite structure is obtained which reduces the material as much as possible and which produces a similar effect to full coverage. The X-type ferrite structure is determined by comparing three basic ferrite structures, namely a full-coverage ferrite, a ferrite only covering the size of the coil and a designed X-type ferrite structure and comparing the mutual inductance and the magnetic field diagram of the coil under three conditions, wherein the size of the internal X-type structure is 20mm in width, 186.28mm in length and 2mm in thickness. The coil is made of a litz coil, the specification is 0.2 x 100, the litz coil is made of a copper wire, the ferrite is made of iron, the distance between the upper coil and the lower coil is 150mm commonly used in wireless charging design, and the distance can be specifically adjusted according to actual conditions.
Specifically, a wireless solenoid that charges of high radiation restraines electric motor car includes:
the ferrite is of a square frame structure, and the inside of the square frame is of an X-shaped structure;
upper and lower coils are respectively wound on the square frames of the upper and lower ferrites; the coil is wound along the square frame only and is not wound along the X-shaped structure;
aluminum sheets with the same size as the ferrite are attached to the ferrite, namely the aluminum sheets are attached to the upper surface of the ferrite, the aluminum sheets are attached to the lower surface of the ferrite, and the coil is not in contact with the aluminum sheets.
In the embodiment, the coil is wound on the ferrite in a counterclockwise direction.
In the embodiment, the upper coil, the ferrite and the aluminum sheet are symmetrical to the lower coil, the ferrite and the aluminum sheet, the distance between the upper part and the lower part is 150mm, and the upper distance and the lower distance are common distances in wireless charging design and can be adjusted according to actual conditions.
In the embodiment, the width of the square frame is 20mm, the outer side length is 200mm, the inner side length is 180mm, and the thickness is 2 mm;
the internal X-shaped structure has a width of 20mm, a length of 186.28mm and a thickness of 2 mm.
The width of the coil is 20mm, the side length is 200mm, the thickness is 2mm, namely the diameter of the coil is 2mm, the number of turns is 10 turns, the number of turns of each turn of coil is basically not provided with a gap, the number of turns can be adjusted according to the actual vehicle requirement, the coil is anticlockwise rotated from outside to inside, the side length of the outer square is 200mm, and the square coil shape with the side length of 180mm and the inner square is removed.
In the embodiment, the coil is made of litz coil, the material is copper, the specification is 0.2 x 100, the diameter of each strand is 0.2mm, 100 strands are glued together, and the total cross section area is 3.1415mm2The copper wire is equivalent to a copper wire with the wire diameter of 2mm as a whole;
the aluminum sheet is made of aluminum.
In the embodiment, the feeding ports are arranged at the positions 100mm away from the end points of one sides of the upper coil and the lower coil.
The feed port is a broken section, and is provided with current source excitation to simulate the charging state of the sightseeing electric automobile.
The width of the section is 20mm, the section is 100mm away from the end (namely the side adjacent to the section) close to the section, the section is set as a feed port, the state of electrifying the whole coil is simulated, the position can be adjusted in the actual charging process, the coil is generally connected to the excitation outside the coil, and the set current source excitation is 30A.
Example (b):
as shown in fig. 1 to 4, four coil structures with different ferrites are shown, fig. 5 shows that aluminum sheets are added on the upper part and the lower part of the ferrite structure shown in fig. 4, the radiation suppression of a magnetic field is optimized, the coil sizes are respectively 200mm on the side of an outer square, 180mm on the side of an inner square and 2mm in thickness, a current with the excitation size of 30A is arranged at one end point of 100mm, the upper coil and the lower coil are arranged in the same way, and the distance between the upper coil and the lower coil is 150 mm.
FIG. 1 is a coil without ferrite; FIG. 2 is a coil ferrite monolith covering; FIG. 3 is a coil ferrite covering only the coil size; FIG. 4 is a coil structure designed by the present invention, which adds an X-shaped structure on the basis of a third ferrite structure, wherein the width is 20mm, the length is 186.28mm, the thickness is 2mm, and the coil is wound in a counterclockwise direction (the coil is only wound along a square frame, and is not wound along the X-shaped structure) and fixed on the ferrite structure.
Fig. 6 to 9 are magnetic field diagrams generated after the four coil structures with different ferrites are connected with power supply.
By comparing the first ferrite structure without ferrite and the second ferrite structure completely covered, it can be obtained that the coil structure with ferrite has the function of suppressing the magnetic field, and can effectively reduce the radiation of energy.
By comparing the magnetic field diagrams of the second and third structures, the completely covered ferrite structure can achieve the best radiation effect, and energy can be well converged between the two coils.
By comparing the second ferrite structure with the fourth ferrite structure designed by the present invention, the ferrite structure designed by the present invention can approximately achieve the suppression effect of the structure completely covering the ferrite.
The mutual inductance values obtained for four coil structures with different ferrites are compared with the corresponding ferrite dimensions.
By comparing the first ferrite-free and the second completely covered ferrite structure, it can be seen that the coil mutual inductance increases significantly from 12.88nH to 28.157nH with the ferrite structure, but the size of the ferrite structure is 40000mm2In comparing the mutual inductance structure of the second and third structures, it can be obtained that the material is reduced from 40000 to 14400mm2However, the mutual inductance is also decreased to 19.475nH, and the mutual inductance is decreased too much, and it is found from formulas (I) to (III) that the influence on the transmission power, the system efficiency, and the charging current of the system is large. Compared with the two structures, the coil structure designed by the invention has a mutual inductance value of 25.006nH, is not much different from the second structure with the best radiation suppression effect, and has the same ferrite size of 2450 mm2The material is reduced by about 39 percent, and the equivalent resistance R is reducedeWhen the charging capacitor is set to 3 Ω which is commonly used, the overall system efficiency is 85.04%, and the efficiency is good. After the optimization by adding aluminum sheets above and below the ferrite, the suppression of the magnetic field radiation is increased by comparing with a graph shown in figure 9 and figure 10. Therefore, the coil structure designed by the invention can achieve better radiation inhibition effect, the mutual inductance value is relatively larger, and the material cost and the weight of the coil manufacture can be reduced.
In summary, the coil structure of the invention comprises the shape of the coil, the ferrite structures above and below the coil, and the aluminum sheet structures above and below the ferrite, wherein the sizes of the coil, the ferrite and the aluminum sheet correspond to each other. The coil structure selects a square structure through comparison, the peripheral ferrite is added with an X-shaped structure on the basis of the square structure, the upper coil and the lower coil are provided with feed ports, and then aluminum sheets with the same shape as the ferrite are added up and down on the basis of the ferrite structure, so that the suppression on the radiation of a coil magnetic field is enhanced.
Meanwhile, the mutual inductance, the self-inductance and the coupling coefficient of the coil can be measured by simulating the wireless charging state of the electric automobile, so that the measured value achieves a good mutual inductance effect, and the efficiency is further improved.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.

Claims (1)

1. The utility model provides a wireless solenoid that charges of high radiation restraines electric motor car which characterized in that includes:
the ferrite is of a square frame structure, and an X-shaped structure is arranged inside the square frame;
upper and lower coils are respectively wound on the square frames of the upper and lower ferrites;
an aluminum sheet with the same size as the ferrite is attached to the ferrite;
the coil is wound on the ferrite in the anticlockwise direction;
the coil, the ferrite and the aluminum sheet at the upper part are symmetrical to the coil, the ferrite and the aluminum sheet at the lower part, and the distance between the upper part and the lower part is 150 mm;
the width of the square frame is 20mm, the outer side length is 200mm, the inner side length is 180mm, and the thickness is 2 mm;
the width of the internal X-shaped structure is 20mm, the length is 186.28mm, and the thickness is 2 mm;
the coil is made of litz coilThe material is copper, the specification is 0.2 x 100, the diameter of each strand is 0.2mm, 100 strands are glued together, and the total cross section area is 3.1415mm2；
The upper coil and the lower coil are both provided with feed ports;
the feed port is a broken section, and is excited by a current source to simulate the charging state of the sightseeing electric automobile;
the cross section is 20mm wide and 100mm away from the close end;
the current source excitation is set at 30A.
CN202110355617.5A 2021-04-01 2021-04-01 High-radiation-suppression wireless charging electromagnetic coil for electric vehicle Active CN112967875B (en)

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Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108063044B (en) * 2017-11-30 2024-03-26 亿创智联(浙江)电子科技有限公司 Wireless charging coil and wireless charging system
CN111463000B (en) * 2020-05-20 2021-08-24 河北工业大学 Combined type shielding structure suitable for wireless power supply system of electric automobile
CN112002532A (en) * 2020-08-28 2020-11-27 上海万暨电子科技有限公司 Transmitting assembly and charging assembly structure for wireless charging of electric automobile

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