CN114825650A - Array type wireless power transmission transmitting coil, design method and application - Google Patents

Abstract

The invention belongs to the technical field of wireless power transmission equipment, and discloses an array type wireless power transmission transmitting coil, a design method and application. Calculating the distance of zero mutual inductance of the transmitting coil in the offset process through Maxwell; and designing the overlapping part distance of the two coils according to the calculated distance. When the overlapping distance of the double-coil model is 62mm, the mutual inductance between the coils is zero. According to the calculation result, a 2 x 2 array coil model is designed, and a 3 x 3 array transmitting coil model is further designed. The method solves the key technical problems that the arrangement mode, the connection mode and the switching control strategy of the multi-coil in the prior art are not solved. The array type wireless power transmission device solves the key problems that mutual coupling between array type transmitting coil transmitting units is reduced and real array type wireless power transmission is achieved in the prior art.

Description

Array type wireless power transmission transmitting coil, design method and application

technical field

The invention belongs to the technical field of wireless power transmission equipment, and in particular relates to an array type wireless power transmission transmitting coil, a design method and an application.

Background technique

At present, the magnetic coupling structure is an indispensable core component to realize wireless power transmission, and its design determines the energy transmission level, transmission efficiency and anti-offset capability of the system. Magnetic coupling structures usually consist of high permeability elements and high electrical conductivity elements. Among them, the high permeability element is the carrier of magnetic field energy, which is used to close the magnetic field lines between the transmitting end and the receiving end, improve the coupling performance, and reduce the eddy current loss caused by the magnetic field; the high conductivity element is the carrier of electric energy, usually with high frequency Litz wire is coiled to reduce skin and proximity effects. The performance of the magnetic coupling structure directly determines the power transmission capacity and transmission efficiency of the system, and also determines the volume, total mass, power density, cost, and magnetic field radiation of the system, which in turn affects the practicability and safety of the wireless power transmission system. . According to the moving state of the receiving end of the wireless power transmission system, it can be divided into static wireless charging and dynamic wireless charging.

(1) Static wireless charging magnetic coupling mechanism

According to the number of transmitting coils, it can be divided into dual-coil and multi-coil wireless power transmission systems. The commonly used single-transmitting coil structures are mainly circular coils and square coils, and the anti-offset ability of square coils is generally more advantageous than that of circular coils. Compared with the square coil, the coupling coefficient of the circular coil decreases faster with the increase of the offset. The effective magnetic flux path of the circular coil is only a quarter of the diameter, and the offset of the circular coil is 38% of its diameter, the magnetic coupling coefficient of the magnetic coupling structure is about zero, and the coupling coefficient of the circular coil is about The offset decreases faster as the offset increases. In order to increase the energy transmission distance, it is necessary to increase the diameter of the primary coil, which will increase the system cost, mass and loss, while reducing the power density of the system. On this basis, the research team from the University of Auckland proposed a DD coil whose effective magnetic flux path is half of its coil diameter, so the DD coil has a larger coupling coefficient than a circular coil. However, when both the primary and secondary sides of the wireless power transmission system use DD coils, when the offset on the X-axis is 34% of the coil length, the magnetic flux of the secondary coil is zero, which becomes an induction blind spot. Therefore, Professor John proposed a DDQ coil, adding a quadrature square coil on the basis of the DD coil, but this will increase the manufacturing cost and increase the number of compensation circuits. The BBP coil has the advantages of eliminating blind spots of induction, higher coupling coefficient and anti-offset of the DDQ coil, and at the same time, compared with the DDQ coil, the amount of litz wire is reduced by about 25.17%, and the manufacturing cost is reduced. For the multi-transmitting and multi-receiving system, it is an extension of the traditional single-transmitting and single-receiving system, which can provide a larger charging plane and supply power for more loads. But for each load state change will affect the working performance of the system. Therefore, there are power distribution and efficiency optimization problems between different loads that need to be solved, as well as decoupling control problems between loads to eliminate mutual interference between multiple loads, so that each load can work stably. For multi-load wireless power transmission systems, the extended reactance compensation method can be used to eliminate the influence of cross-coupling between receiving coils, and to improve the transmission efficiency by increasing the number of receivers. For a multi-transmitting wireless power transmission system, the transmitting end is composed of a plurality of transmitting coils arranged to form a transmitting surface, thereby realizing wireless energy transmission to the load at any position on the transmitting surface. However, for the multi-transmission wireless power transmission system, it is necessary to design the mechanism and arrangement of the transmitting coil to form a uniform magnetic field on the transmitting surface, and at the same time, it is necessary to consider the connection method between the transmitting coil units and the switching control strategy to achieve independent control of the coil. .

(2) Dynamic wireless charging magnetic coupling mechanism

Compared with static wireless charging, dynamic wireless charging can continuously and timely replenish electric energy for electric vehicles in motion, which is convenient for electric vehicles to be connected to the power grid for charging anytime and anywhere, effectively increases the mileage of electric vehicles, and overcomes the bottleneck problem of existing power batteries. According to the composition of the transmitting coil, it can be divided into a long rail type wireless power transmission system and a segmented coil chain type wireless power transmission system. The long-rail layout structure will bring unnecessary loss and magnetic field leakage problems in the global power supply, which leads to the dynamic wireless charging scheme of segmented coil chain. In the traveling direction of the trolley, it is composed of a plurality of concentrated planar coils of the same structure arranged in sequence, and an appropriate power supply management strategy is added to the primary power supply, and only the coils below the trolley are excited and powered. However, with the surge in the number of primary coils in the segmented layout, the power supply mode of the primary coil chain is complicated, and it is necessary to realize the precise positioning of the electric vehicle at the receiving end, realize the real-time excitation of the corresponding primary coil and the effective medium of the primary coil chain. Continue the relay. Therefore, it involves the exploration of the position detection method of the load coil and the relay relay strategy between the transmitter coils.

Through the above analysis, the existing problems and defects in the prior art are:

(1) At this stage, the research on the transmission mechanism and compensation network topology of the traditional single-transmission single-receive wireless power transmission system is quite mature. However, the research on the circuit model and system transmission characteristics of the multi-transmitting and multi-receiving wireless power transmission system is not yet clear. For the coupling between multiple loads and the relationship between the reflected impedance and the number of loads on the transmitting side of the multiple loads, as well as the influence of the reflected impedance on the transmission efficiency and stability of the system, no clear formula has been given yet; for the coupling between multiple transmitting coil units, the system The influence of working performance and how to reduce the mutual coupling between the transmitting coils are also the focus and difficulty of the research.

(2) There is also no agreement on the electrical connection method between the multiple transmitter coils and the guidelines for the switching control strategy. Therefore, for the structure design of the coil unit of the multi-coil array wireless power transmission system, the arrangement mode, connection mode and switching control strategy of the multi-coil are the key technical problems that have not yet been solved.

(3) The mutual coupling of the transmitting coil in the direction of travel of the primary coil chain of the receiving coil in dynamic wireless power transmission needs to be eliminated by design, and the mutual coupling between the coil units of the array transmitting coil exists not only in the travel direction of the load coil but also in the direction of travel of the load coil. Therefore, reducing the mutual coupling between the transmitting units of the array transmitting coil is a key issue in the design and realization of the array wireless power transmission.

(4) The wireless power transmission equipment in the prior art has poor signal transmission performance and poor practicability.

The difficulty of solving the above problems and defects is that the circuit model and system transmission characteristics of the multi-transmitting and multi-receiving wireless power transmission system are not yet clear. The coupling between multiple loads and the relationship between the reflected impedance and the number of loads on the transmitting side of multiple loads, as well as the influence of the reflected impedance on the transmission efficiency and stability of the system, have not yet given a clear formula.

The significance of solving the above problems and defects is that it is beneficial to reduce the efficiency drop of the transceiver coil, improve the transmission efficiency and the transmission stability in a special environment, and further help to enhance the applicability of wireless power transmission.

SUMMARY OF THE INVENTION

In order to overcome the problems existing in the related art, the disclosed embodiments of the present invention provide an array type wireless power transmission transmitting coil, a design method and application thereof, and specifically an array type wireless power transmission transmitting coil that eliminates cross coupling is designed.

The technical solution is as follows: a design method for an array wireless power transmission transmitting coil that eliminates cross-coupling includes: calculating the distance where the mutual inductance of the two transmitting coils is zero during the offset process through simulation;

Obtain the overlapping position of the two transmitting coils according to the distance where the calculated mutual inductance is zero. The simulation calculation is carried out by computer simulation software, and the calculation method is the internal calculation formula of the program.

In one embodiment, the method for obtaining the overlapping position of two transmitting coils includes: fixing a single coil by simulating, moving the overlapping distance between another coil and the target coil, and obtaining the overlapping position where the mutual inductance curve is zero, and the overlapping position is double transmitting The decoupling distance of the coil;

When the overlapping distance of the two transmitting coils is 62mm, the mutual inductance between the two transmitting coils is zero.

Another object of the present invention is to provide a 2×2 array coil model designed by using the design method of the array wireless power transmission transmitting coil eliminating cross-coupling.

Another object of the present invention is to provide a 2×2 array transmitting coil unit structure constructed by using the 2×2 array coil model. The 2×2 array transmitting coil unit structure is sequentially laid with: a first Layer resin board, small magnetic board, second layer resin board, 2×2 array transmitting coil and plexiglass.

In one embodiment, the total height of the 2×2 array transmitting coil unit structure is 33mm.

Another object of the present invention is to provide a 3×3 array transmitting coil model designed by using the design method of the array wireless power transmission transmitting coil eliminating cross-coupling.

Another object of the present invention is to provide a 3×3 array transmitting coil unit structure constructed by using the 3×3 array transmitting coil model, wherein the 3×3 array transmitting coil unit structure is sequentially laid with: One layer of resin plate, small magnetic plate, second layer of resin plate, 3×3 array transmitting coil and plexiglass.

In one embodiment, the total height of the 3×3 array transmitting coil unit structure is 33mm.

Another object of the present invention is to provide an application of the 2×2 array coil model in charging an electric vehicle connected to a power grid anytime and anywhere.

Another object of the present invention is to provide an application of the 3×3 array coil model in charging an electric vehicle connected to a power grid anytime, anywhere.

Combined with all the above-mentioned technical solutions, the advantages and positive effects possessed by the present invention are:

The invention calculates (computer simulation) the distance where the mutual inductance of the transmitting coil is zero during the offset process through Maxwell calculation (computer simulation);

According to the calculated distance, design the distance of the overlapping part of the two coils. When the double-coil model has an overlap distance of 62mm, the mutual inductance between the coils is zero. According to the calculation results, a 2×2 array coil model is designed, and a 3×3 array transmitter coil model is further designed. It solves the unresolved key technical problems of the prior art multi-coil arrangement, connection and switching control strategy. The invention solves the problem of reducing the mutual coupling between the transmitting units of the array transmitting coil in the prior art, and solving the key problem of the wireless power transmission of the real array type.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and do not limit the disclosure of the present invention.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the disclosure and together with the description serve to explain the principles of the disclosure.

FIG. 1 is a flowchart of a method for designing an array wireless power transmission transmitting coil for eliminating cross-coupling provided by an embodiment of the present invention.

FIG. 2 is an effect diagram of a double-coil model provided by an embodiment of the present invention.

3 is a diagram of the mutual inductance and overlapping distance of the double coils provided by the embodiment of the present invention; wherein, the abscissa is the coil spacing; the ordinate is the coil mutual inductance; the upper right corner is the mutual inductance of coil 7 and coil 4, operating frequency: 85KhZ.

FIG. 4 is a diagram of a 2×2 array coil model provided by an embodiment of the present invention.

FIG. 5 is a model diagram of a 3×3 array transmitting coil provided by an embodiment of the present invention.

FIG. 6 is a graph of mutual inductance between 2×2 array coils provided by an embodiment of the present invention; wherein, FIG. 6(a) the mutual inductance diagram of coil 1; FIG. 6(b) the mutual inductance diagram of coil 2; FIG. 6(c) the mutual inductance diagram of coil 3 ; Figure 6 (d) mutual inductance diagram of coil 4.

FIG. 7 is a graph of mutual inductance between coils in a typical position of a 3×3 array provided by an embodiment of the present invention; wherein, FIG. 7(a) the mutual inductance diagram of coil 1; FIG. 7(b) the mutual inductance diagram of coil 3; FIG. 7(c) coil 5 Mutual inductance diagram; Fig. 7(d) Mutual inductance diagram of coil 7; Fig. 7(e) Mutual inductance diagram of coil 9.

FIG. 8 is a structural diagram of a single transmitting coil unit provided by an embodiment of the present invention; wherein, FIG. 8(a) is a detailed layout diagram of the structure of a single transmitting coil unit; FIG. 8(b) is a partial enlarged view of FIG. 8(a).

FIG. 9 is a structural diagram of the arrangement of a single transmitting coil provided by an embodiment of the present invention.

In the figure: 1. The first layer of resin plate; 2. Small magnetic plate; 3. The second layer of resin plate; 4. The transmitting coil; 5. The plexiglass.

Detailed ways

In order to make the above objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific implementation disclosed below.

In the prior art, the magnetic coupling mechanism is a key link in the wireless power transmission system, and the performance of the coupling mechanism directly affects the working performance of the wireless power transmission system. At present, wireless power transmission can be divided into two categories: static wireless power transmission and dynamic wireless power transmission according to the state of the receiving end. Most of the static wireless power transmission is a single transmitter and a single receiver coil. It is necessary to optimize the shape structure and structural parameters of the transceiver coil to meet the relevant index parameters. For dynamic wireless power transmission, the coupling mechanism is divided into two types: long guide rail design and segmented coil structure design. Among them, due to the use of a segmented coil structure, there is mutual coupling between the transmitting coils 4, and the coil coupling between adjacent coils has a large influence on the output characteristics of the receiving end, thus causing the output power of the receiving end to fluctuate greatly. However, in an array wireless power transmission system, multiple transmitting units need to be used to supply energy to the receiving coils, so there is mutual coupling between the transmitting coils 4 between various operating modes.

In order to improve the transmission efficiency and working efficiency between the transceiver coils and facilitate the performance analysis of the magnetic coupling mechanism in the later stage, it is necessary to realize the decoupling between the array transceiver coils and reduce the mutual inductance between the 4 units of the transmitting coils.

The technical solutions of the present invention will be further described below in conjunction with the embodiments.

Example

According to the idea of BPP coil, the magnetic field generated by the coil passes through the coil plane in one direction inside the coil, and passes through the same plane in the opposite direction outside the coil, so that the decoupling of the partially overlapped coil can be realized. The degree of overlap of the two coils in the BPP structure depends on the overall coil structure. Adding ferrite on the back of the coil increases power transfer and avoids magnetic radiation on the back of the coil. The ferrite provides a low reluctance channel for the magnetic flux. Add an aluminum plate behind the aluminum plate to prevent and limit electromagnetic interference. Therefore, this idea is used for reference in the design of the array transmitting coil 4 . By partially overlapping two square coils of the same size, in order to compensate for the weak coupling between adjacent transmitting units of traditional connected array coils, overlapping array coils can be constructed through an overlapping structure. According to the size of the transmitting coil unit, the overlap size between the coils is designed and calculated.

As shown in FIG. 1 , the present invention provides a design method for an array wireless power transmission transmitting coil that eliminates cross-coupling, including:

S101, through Maxwell calculation (computer simulation calculation), the distance at which the mutual inductance of the two transmitting coils 4 appears to be zero during the offset process is obtained.

S102, the overlapping position of the two transmitting coils is obtained according to the calculated distance where the mutual inductance is zero.

In step S102, the method for obtaining the overlapping position of the two transmitting coils 4 includes: fixing a single coil by simulating, moving the overlapping distance between the other coil and the target coil, and obtaining the overlapping position where the mutual inductance curve is zero, and the overlapping position is the double transmitting coil. 4 decoupling distances.

In the present invention, the effect of the double coil model is shown in Figure 2, and the size is: 300mm*300mm.

The mutual inductance and overlapping distance of the double coils are shown in Figure 3. According to Figure 3, it is found that the mutual inductance between the coils is zero when the overlap distance is 62mm for the double-coil model. According to this calculation result, a 2×2 array coil model is designed, as shown in Figure 4; and a 3×3 array transmitting coil 4 model is further designed. As shown in Figure 5.

Fig. 6 is a graph of mutual inductance between coils in a 2×2 array, in which Fig. 6(a) is the mutual inductance diagram of coil 1; Fig. 6(b) is the mutual inductance diagram of coil 2; Fig. 6(c) is the mutual inductance diagram of coil 3; 4 Mutual inductance diagram.

According to the calculation results of the coil mutual inductance in Figure 4, the mutual inductance between the target coil and the coil in the overlapping direction is almost zero, and the coil in the non-connected coil is almost zero. Mutual inductance is also zero. Therefore, 2×2 transmitting coils 4 can be designed, and the overlapping distances are both 62mm. And this extends to the 3×3 target transmitting array coil design.

Figure 7 is a graph of mutual inductance between coils in a typical position of a 3×3 array. Figure 7(a) mutual inductance diagram of coil 1; Figure 7(b) mutual inductance diagram of coil 3; Figure 7(c) mutual inductance diagram of coil 5; Figure 7(d) mutual inductance diagram of coil 7; Figure 7(e) mutual inductance diagram of coil 9 .

According to the mutual inductance calculation curve of a typical coil selected in Figure 7, the mutual inductance between the coils is almost near 0. This shows that the transmitting coil 4 can effectively eliminate the mutual inductance between the array coils. It is helpful to go to the next step for the position and angle detection of the receiving coil and the selection of switching timing.

Through the simplification of the coil, a simplified model of the array transmitting coil 4 is obtained, and through numerical calculation and simulation calculation, the overlapping distance of the double coils to achieve zero mutual coupling is obtained, and then the overlapping distance of the 2×2 array transmitting coil 4 is adjusted. , to achieve decoupling between its array transmitting units. Finally, it is extended to a 3×3 array transmitting coil 4 to ensure that the overlapping distance at the side length of the array transmitting unit is the overlapping distance that the above-mentioned double coils achieve decoupling. At the same time, the coil adopts 0.04×800 Litz wire, and ferrite and aluminum plate are laid on the back of this coil. The 4-unit structure of a single transmitting coil is shown in Figure 8. Among them, in Figure 8(a), from top to bottom are laid: the first layer of resin plate 1, the small magnetic plate 2, the second layer of resin plate 3, the transmitting coil 4 and the plexiglass 5; the first layer of resin plate 1 The thickness of 6mm, the thickness of the small magnetic plate 2 is 5mm, the thickness of the second layer of resin plate 3 is 5mm, and the thickness of the plexiglass is 10mm. Fig. 8(b) is a partial enlarged view of Fig. 8(a), the total height of a single transmitting coil unit structure is 33mm.

In a preferred embodiment, the present invention provides a 2×2 array transmitting coil unit structure constructed by using the 2×2 array coil model. The 2×2 array transmitting coil unit structure is sequentially laid with: One layer of resin plate 1 , small magnetic plate 2 , second layer of resin plate 3 , 2×2 array transmitting coils (a mode of transmitting coil 4 , as shown in FIG. 4 ) and plexiglass 5 .

In a preferred embodiment, the present invention also provides a 3×3 array transmitting coil unit structure constructed by using the 3×3 array transmitting coil model, wherein the 3×3 array transmitting coil unit structure is sequentially laid with : The first layer of resin plate 1 , the small magnetic plate 2 , the second layer of resin plate 3 , the 3×3 array transmitting coil 4 (another mode of transmitting coil 4 , as shown in FIG. 5 ), and the plexiglass 5 .

At the same time, the transmitting coil 4 adopts a square winding method, and the arrangement structure of a single transmitting coil 4 is shown in FIG. 9 .

This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or techniques in the technical field not disclosed by the present disclosure . The specification and examples are to be regarded as exemplary only, with the true scope and spirit of the disclosure being indicated by the appended claims. It is to be understood that the present disclosure is not limited to the precise structures described above and illustrated in the accompanying drawings, and that various modifications and changes may be made without departing from the scope thereof.

Claims (10)

1. A design method for an array wireless power transmission transmitting coil for eliminating cross coupling is characterized in that the design method for the array wireless power transmission transmitting coil for eliminating the cross coupling comprises the following steps: the distance of zero mutual inductance of the two transmitting coils (4) in the offset process is calculated through simulation; and acquiring the overlapping position of the two transmitting coils (4) according to the distance with the calculated mutual inductance being zero.

2. The design method of the array wireless power transmission transmitting coil for eliminating the cross coupling according to claim 1, wherein the method for obtaining the overlapping position of the two transmitting coils (4) comprises: the overlapping position with a mutual inductance curve of zero is obtained by fixing a single coil in a simulation way and moving the overlapping distance between the other coil and a target coil, and the overlapping position is the decoupling distance of the double transmitting coils (4);

when the overlapping distance of the two transmitting coils (4) is 62mm, the mutual inductance between the two transmitting coils (4) is zero.

3. A 2 x 2 array coil model designed by the design method of the array wireless power transmission transmitting coil (4) for eliminating the cross coupling as claimed in any one of claims 1-2.

4. A 2 x 2 array transmitting coil unit structure built by using the 2 x 2 array coil model of claim 3, wherein the 2 x 2 array transmitting coil unit structure is sequentially laid from top to bottom: the magnetic field sensor comprises a first layer of resin plate (1), a small magnetic plate (2), a second layer of resin plate (3), a 2 x 2 array transmitting coil (4) and organic glass (5).

5. The 2 x 2 array transmit coil unit structure of claim 4, wherein the 2 x 2 array transmit coil unit structure has a total height of 33 mm.

6. A 3 x 3 array transmitting coil model designed by the method for designing the array wireless power transmission transmitting coil for eliminating the cross coupling as claimed in any one of claims 1 to 2.

7. A 3 x 3 array transmitting coil unit structure built by using the 3 x 3 array transmitting coil model of claim 6, wherein the 3 x 3 array transmitting coil unit structure is sequentially laid from top to bottom: the magnetic field sensor comprises a first layer of resin plate (1), a small magnetic plate (2), a second layer of resin plate (3), a 3 x 3 array transmitting coil and organic glass (5).

8. A33 array transmit coil unit structure according to claim 6 wherein the 3 x 3 array transmit coil unit structure has a total height of 33 mm.

9. An application of the 2 x 2 array coil model of claim 3 in charging the electric vehicle connected to the power grid anytime anywhere.

10. An application of the 3 x 3 array coil model of claim 6 in charging electric vehicles connected to the power grid at any time and any place.

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