Quasi-static resonant cavity magnetic field distribution coil, wireless power supply system and coil winding method

Abstract

The invention provides a quasi-static resonant cavity magnetic field distribution coil, a wireless power supply system and a coil winding method. The technical problems that an existing quasi-static resonant cavity structure is high in cost and complex in structure and control are solved. The quasi-static resonant cavity magnetic field distribution coil is formed by winding a wire and comprises at least two coil square frames formed by bending and winding the wire, and the plurality of coil square frames are uniformly arranged in a spatial range at equal angles, so that the magnetic field distribution of a region enclosed by the plurality of coil square frames is similar to that of a quasi-static resonant cavity; the magnetic field is distributed around the center of the area enclosed by the coil frames. Through a special winding mode of the wire, a distributed magnetic field similar to a quasi-static resonant cavity is formed. The structure is simpler, the cost is saved, and wireless communication inside and outside a space range can be realized; and the transmitting end is only of a structure powered by a single power supply, active control of any amplitude or phase is not needed, and the complexity of system control is reduced.

Description

Technical Field

[0001] The present invention relates to the field of wireless charging, in particular to a quasi-static resonant cavity magnetic field distribution coil, a wireless power supply system, and a coil winding method. Background Art

[0002] Wireless power transmission in space has the advantages of being unrestricted by space, having a relatively high degree of freedom, and being able to supply power to multiple devices simultaneously. As a branch direction among them, a resonant cavity can realize wireless energy transmission for multiple devices within its internal space.

[0003] Currently, the research on resonant cavities is mostly based on the cavity resonance principle. The cavity needs to be excited by an excitation device to reach the resonant state, thereby generating a magnetic field inside the cavity, and different modes have different electromagnetic field distributions. Most of the theoretical research on resonant cavities is based on coupled-mode and magnetic resonance theories. However, the analysis based on the coupled-mode theory is relatively complex, and problems such as slow convergence will occur when using finite element simulation tools to analyze traditional models. Therefore, some research has proposed a general circuit model for traditional resonant cavity systems, hoping to describe the complex cavity system with simple circuit elements. The proposed circuit model is a three-coil wireless power transmission system, where the excitation device of the cavity is the source coil, the cavity body is the relay coil, and the receiving device is the receiving coil. However, this model ignores the existence of the electric field inside the cavity, and there is still a gap between the efficiency calculation of the circuit model and the actual measurement. In addition, some research has proposed a multi-modal quasi-static resonant cavity based on a quasi-static resonant cavity. On the basis of the original quasi-static resonant cavity body, four corners of the three-dimensional structure are vertically cut off to form a column with an octagonal bottom surface with openings. The so-called multi-modal actually only adds one resonant mode. Under the new excitation mode, the current flows around the opening of the cavity, forming a new distributed magnetic field. Combining the two modes can achieve a uniform magnetic field within a certain range. Some research has also proposed a mesh cavity resonator composed of a mesh metal wall. Its working mechanism and principle are the same as those of traditional resonant cavities, and it can generate and confine electromagnetic waves of natural resonant modes inside its mesh cavity. Compared with traditional cavities that are completely enclosed and use a large amount of metal materials, the metal mesh structure avoids excessive costs and waste of metal materials. Some research has also proposed using a metal mesh to construct one or more cavity walls of the resonator cavity and wirelessly power the receiver inside the cavity through electrical coupling. However, due to the high density of the metal mesh, the wireless communication signal attenuation between devices inside and outside the cavity is quite large. Therefore, it becomes very difficult to truly achieve both power transmission inside the cavity and wireless communication with the outside at the same time.

[0004] In summary, whether it is a traditional or a quasi-static resonator, its cavity uses an aluminum sheet as the structural surface. When applied to a room-sized space, the large amount of aluminum sheet used results in a high construction cost, and the issues of the use and waste of metal materials and radiation on human safety remain to be solved. The proposed mesh cavity resonator based on the working mechanism and theory of traditional resonators can solve the cost problem caused by the large amount of metal materials used in traditional resonators and also solve the communication signal isolation problem caused by the closed cavity. However, the structure of the mesh cavity is more complex. Summary of the Invention

[0005] The purpose of the present invention is to provide a magnetic field distribution coil for a quasi-static resonator, a wireless power supply system, and a coil winding method, which are used to solve the technical problems of high cost, complex structure, and complex control of the existing quasi-static resonator structure.

[0006] A magnetic field distribution coil for a quasi-static resonator includes at least two coil frames formed by bending and winding a wire. A number of coil frames are evenly arranged at equal angles within a spatial range, such that the magnetic field distribution in the enclosed area by the coil frames is similar to the magnetic field distribution of a quasi-static resonator, and the magnetic field is distributed around the center of the enclosed area by the coil frames.

[0007] Optionally, a number of coil frames are all wound by one wire.

[0008] Optionally, the coil frames are all approximately rectangular coil frames.

[0009] Optionally, the coil frames are all single-turn coils.

[0010] Optionally, the current directions of the wires wound on one side of a number of coil frames close to the central axis of the enclosed area are the same, all vertically upward or downward.

[0011] A wireless power supply system includes the above-mentioned magnetic field distribution coil for a quasi-static resonator.

[0012] Optionally, it further includes a transmitter circuit, and both ends of the magnetic field distribution coil for a quasi-static resonator are connected to the transmitter circuit;

[0013] The transmitter circuit includes a DC power supply, a high-frequency inverter, and a primary compensation circuit connected in sequence. Both ends of the magnetic field distribution coil for a quasi-static resonator are respectively connected to the two output ends of the primary compensation circuit.

[0014] Optionally, it further includes a wireless charging receiver. The wireless charging receiver includes a receiving coil, a secondary compensation circuit, a rectifying and filtering circuit, and a load connected in sequence;

[0015] When the receiving coil is located at any position within the enclosed area of several coil frames, the receiving coil is magnetically coupled with the quasi-static resonant cavity magnetic field distribution coil to supply power to the load.

[0016] A coil winding method is used for winding the above-mentioned quasi-static resonant cavity magnetic field distribution coil. Select any one of several coil frames as the first coil frame, and define the coil frames that rotate in one direction with the first coil frame as the rotation starting point as the second to the Nth coil frames in sequence. Define the side of the coil frame array close to the center of the enclosed area as the axis side, and the outer side of the frame forming the cavity area range as the starting side. The specific winding steps are as follows:

[0017] S1: Take any position on the starting side of the first coil frame as the winding starting point, and select the clockwise or counterclockwise direction as the winding direction.

[0018] S2: Starting from the winding starting point selected in step S1, wind the first coil frame along the winding direction until the winding on the axis side of the first coil frame is completed.

[0019] S3: Bend and rotate the winding wire to the axis direction of the top or bottom side of the (i + 1)th coil frame, and wind the (i + 1)th coil frame along the winding direction until i + 1 = N, where: at the initial moment, i = 1.

[0020] S4: Bend and rotate the winding wire from the end position at the top or bottom of the Nth coil frame to the axis direction of the top or bottom of the axis side of the first coil frame, and wind the remaining part of the first coil frame and return to the winding starting point to form a coil structure with a magnetic field distribution similar to that of a quasi-static resonant cavity.

[0021] Due to the adoption of the above technical solution, the present invention has the following advantages:

[0022] 1. Through the special winding method of the wire, the present application forms a distributed magnetic field similar to a quasi-static resonant cavity. And the transmitting end is only a structure powered by a single power supply, without the need for any active control of amplitude or phase, reducing the complexity of system control.

[0023] 2. Compared with the traditional closed cavity using metal materials as the structure surface, the present application has a simpler structure and saves costs. The coil structure designed based on the magnetic coupling theory can achieve wireless communication inside and outside the space range.

[0024] Other advantages, objectives and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. Description of the Drawings

[0025] The accompanying drawings of the present invention are described as follows.

[0026] Figure 1 This is a physical diagram of the magnetic field distribution coil of the quasi-static resonator when the number of coil frames of the present invention is four.

[0027] Figure 2 This is a schematic structural diagram of the present invention when the number of coil frames is 2, 3, 4, and 8.

[0028] Figure 3 This is a circuit diagram of the wireless power supply system of the present invention.

[0029] Figure 4 This is an equivalent circuit diagram of the transmitting end circuit of the wireless power supply system of the present invention.

[0030] Figure 5 This is a simulation diagram of the magnetic field distribution of the transmitting coil of the present invention.

[0031] In the figure: L p1 -L p8 are all coil frames. Specific embodiments

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0033] Embodiment 1:

[0034] As Figure 1 shown, a kind of magnetic field distribution coil of a quasi-static resonator includes at least two coil frames bent and wound by a wire. A plurality of coil frames are evenly arranged at equal angles within a spatial range, so that the magnetic field distribution in the enclosed area of the plurality of coil frames is similar to the magnetic field distribution of a quasi-static resonator, and the magnetic field is distributed around the center of the enclosed area of the plurality of coil frames.

[0035] In this embodiment, as Figure 2 shown, they are respectively the distribution diagrams of the coil frames L pi when the number of coil frames is 2, 3, 4, and 8. Among them: i ∈ (1 - m), where m is the number of coil frames. The m coil frames are wound by a single wire, so that the m coil frames can generate a uniform magnetic field distributed around the center of the structure. Further, the magnetic field distribution in the enclosed area of the m coil frames is similar to the magnetic field distribution of a quasi-static resonator. pi In this embodiment, the coil frames L

[0036] are all approximately rectangular coil frames, and the coil frames L pi are all single-turn coils. The current directions of the wires wound on one side of the plurality of coil frames L pi close to the axis of the annular array are the same, all vertically upward. pi ​

[0037] Embodiment 2:

[0038] As Figure 3 shown, a wireless power supply system includes a quasi-static resonant cavity magnetic field distribution coil described in Embodiment 1.

[0039] Optionally, it further includes a transmitter circuit, and both ends of the quasi-static resonant cavity magnetic field distribution coil are connected to the transmitter circuit;

[0040] The transmitter circuit includes a DC power supply, a high-frequency inverter, and a primary compensation circuit connected in sequence. Both ends of the quasi-static resonant cavity magnetic field distribution coil are respectively connected to two output ends of the primary compensation circuit.

[0041] Optionally, the wireless charging receiver includes a receiving coil, a secondary compensation circuit, a rectifier filter circuit, and a load connected in sequence;

[0042] When the receiving coil is at any position within the enclosed area of several coil frames, the receiving coil is magnetically coupled with the quasi-static resonant cavity magnetic field distribution coil to supply power to the load.

[0043] In this embodiment, the DC voltage source includes an AC / DC conversion circuit and a power plug connected to the input end of the AC / DC conversion circuit. During use, the power plug is connected to the mains power. As Figure 3 shown in the system circuit diagram, it includes n wireless charging receivers. Figure 3 In which V D is the DC power supply after being converted by the AC / DC conversion circuit. Four MOS transistors S1 - S4 constitute the high-frequency inverter. The primary compensation circuit includes primary compensation elements Z p1 , Z p2 and Z p3 , L1 is a quasi-static resonant cavity magnetic field distribution coil composed of several coil frames L pi ; L s1 -L sn is the receiving coil. The secondary compensation circuit includes secondary compensation elements Z S11 -Z Sn1 , Z S12 -Z Sn2 and Z S13 -Z Sn3 , the load includes Z L1 -Z Ln . The rectifier filter circuit includes a rectifier (not shown in the figure) and a filter capacitor (not shown in the figure). Figure 4 In which M ij is the mutual inductance between the primary and secondary sides, and M Sij is the mutual inductance between the secondary sides. As an embodiment of the present application, the primary compensation circuit and the secondary compensation circuit adopt an LCC - LCC topology structure. That is: Zp1 and Z S11 -Z Sn1 To compensate the inductance, Z p2 , Z p3 , Z S12 -Z Sn2 and Z S13 -Z Sn3 Both are compensation capacitors.

[0044] In this embodiment, since there are multiple receiving devices in the system, it is necessary to make the receiving device load obtain the effect of constant current input. Convert multiple complex sides, that is, the receiving device side, to the primary side, and solve the conditions for the load to obtain constant current. The equivalent circuit is as follows: Figure 4 As shown. 总 It is the total load converted from the secondary side to the primary side.

[0045] Depend on Figure 4 The equivalent circuit diagram shown in the figure lists the KVL equations of the two loops as follows:

[0046]

[0047] From the above formula, we can get:

[0048]

[0049] Obviously, to make the output current independent of the load, let Z P1 +Z P3 = 0. That is, for any compensation topology system, when the primary side topology satisfies Z P1 +Z P3 =0, multiple receiving loads can obtain a constant current input effect.

[0050] For a four-frame structure with four transmitting coils, COMSOL finite element simulation software was used for simulation. The structure was wound with a single-turn closed cylindrical wire with a cross-sectional diameter of 5 mm, and the wound structure frame was a square frame with a single side length of approximately 200 mm. A 15A DC excitation was applied to the coil. The magnetic field distribution simulation results are shown in Figure 1. Figure 5 As shown, a distributed uniform magnetic field is formed around the center.

[0051] In this embodiment, if Figure 1 As shown, several wireless charging receiving terminals are respectively installed on a tablet computer, a robot, a laptop computer and a drone. When the above devices are located in the area formed by the quasi-static resonant cavity magnetic field distribution coil, the wireless charging receiving terminal is coupled with the receiving terminal to transmit electric energy.

[0052] Embodiment 3:

[0053] A coil winding method is used for winding the quasi-static resonant cavity magnetic field distribution coil described in Example 1, selecting any one of a plurality of coil frames as the first coil frame, defining the coil frames rotating in one direction with the first coil frame as the rotation starting point as the second to Nth coil frames in sequence, defining the side of the frame near the center of the enclosed area of ​​the plurality of coil frame arrays as the axis side, and the outer side of the frame constituting the cavity area range as the starting side, and the specific winding steps are:

[0054] S1: Take any position on the starting side of the first coil frame as the winding starting point, and select clockwise or counterclockwise as the winding direction;

[0055] In this embodiment, if Figure 2 (c) shows the coil box L on the left side of the selected space range. p1 The first coil block is defined counterclockwise from the second to the fourth coil blocks (L p2 -L p4 ), with coil frame L p1 The middle of the starting side is the starting point for winding, and the counterclockwise rotation is the starting point for winding.

[0056] S2: Starting from the winding starting point selected in step S1, winding the first coil frame along the winding direction until the winding is completed on the axis side of the first coil frame;

[0057] In this embodiment, if Figure 2 As shown in (c), the winding distance is determined according to the size of the coil frame. The specific steps of winding are:

[0058] S2.1: Wind vertically downward from the starting point to the coil frame L p1 The bottom of

[0059] S2.2: Bend the winding wire and wind the coil frame L p1 from the bottom edge to the center;

[0060] S2.3: Bend the winding wire and wind the coil frame L p1 from the axis side to its top end.

[0061] S3: The winding conductor is bent and rotated to the axis direction of the top or bottom side of the i+1th coil frame, and the i+1th coil frame is wound along the winding direction until i+1=N, wherein: at the initial moment i=1;

[0062] In this embodiment, if Figure 2 (c) As shown, when the coil frame L p1 After the winding is completed on the axis side, the winding wire is bent and rotated to the coil frame L p2 The top axis direction and the coil frame L p2 The starting position at the top of the axis side starts to bend counterclockwise to wind the coil frame Lp2 ; When the coil frame L p2 is wound, the winding wire is bent and rotated to the axial direction of the top side of the coil frame L p3 and starts to bend counterclockwise to wind the coil frame L p3 , and so on until the coil frame L p4 is wound.

[0063] S4: The winding wire bends and rotates from the end position at the top or bottom of the Nth coil frame to the axial direction at the top or bottom on the axial side of the first coil frame, and winds the remaining part of the first coil frame and returns to the winding starting point, forming a coil structure with a magnetic field distribution similar to that of a quasi-static resonant cavity.

[0064] In this embodiment, as Figure 2 (c) shows, when the coil frame L p4 is wound, the winding guide bends and rotates to the axial direction of the top side of the coil frame L p1 and winds the top side of the coil frame L p1 and the remaining part of the starting side of the coil frame L p1 .

[0065] In this embodiment, the coil with the magnetic field distribution of the quasi-static resonant cavity is wound by a single guide wire, and only a set of transmitting end circuits needs to be set, without any active control of amplitude or phase, reducing the complexity of system control. Compared with the traditional closed cavity using metal materials as the structural surface, the structure is simpler, the cost is saved, and the utilization rate is high.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement without departing from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A quasi-static resonant cavity magnetic field distribution coil, characterized in that, It includes at least two coil frames formed by bending and winding a wire. A number of coil frames are evenly arranged at equal angles within a spatial range, such that the magnetic field distribution in the enclosed area by the number of coil frames is similar to the magnetic field distribution of a quasi-static resonant cavity, and the magnetic field is distributed around the center of the enclosed area by the number of coil frames.

2. The magnetic field distribution coil of a quasi-static resonant cavity according to claim 1, characterized in that, A number of coil frames are all formed by winding a single wire.

3. A quasi-static resonant cavity magnetic field distribution coil according to claim 1 or 2, characterized in that, The coil frames are all approximately rectangular coil frames.

4. A quasi-static resonant cavity magnetic field distribution coil according to claim 3, characterized in that, The coil frames are all single-turn coils.

5. A quasi-static resonant cavity magnetic field distribution coil according to claim 3, characterized in that, The current directions of the winding wires on one side of the number of coil frames close to the central axis of the enclosed area are the same, either all vertically upward or downward.

6. A wireless power supply system, characterized in that, It includes a coil for the magnetic field distribution of a quasi-static resonant cavity according to any one of claims 1-5.

7. A wireless power supply system according to claim 6, wherein It further includes a transmitting-end circuit, and both ends of the coil for the magnetic field distribution of the quasi-static resonant cavity are connected to the transmitting-end circuit; The transmitting-end circuit includes a DC power supply, a high-frequency inverter, and a primary compensation circuit connected in sequence. Both ends of the coil for the magnetic field distribution of the quasi-static resonant cavity are respectively connected to two output ends of the primary compensation circuit.

8. A wireless power supply system according to claim 6, characterized in that, It further includes a wireless charging receiving end, and the wireless charging receiving end includes a receiving coil, a secondary compensation circuit, a rectifying and filtering circuit, and a load connected in sequence; When the receiving coil is at any position within the enclosed area by the number of coil frames, the receiving coil is magnetically coupled with the coil for the magnetic field distribution of the quasi-static resonant cavity to supply power to the load.

9. A coil winding method, characterized in that, For the winding of the coil for the magnetic field distribution of a quasi-static resonant cavity according to any one of claims 1-5, select any one of the number of coil frames as the first coil frame. Define the coil frames that rotate in one direction starting from the first coil frame as the second to the Nth coil frames in sequence. Define the side of the square close to the center of the enclosed area of the number of coil frame arrays as the axis side, and the outer side of the square constituting the cavity area range as the starting side. The specific winding steps are as follows: S1: Take any position on the starting side of the first coil frame as the winding starting point, and select the clockwise or counterclockwise direction as the winding direction; S2: Starting from the winding starting point selected in step S1, wind the first coil frame along the winding direction until the winding on the axis side of the first coil frame is completed; S3: Bend and rotate the winding wire to the axis direction of the top or bottom side of the (i + 1)th coil frame, and wind the (i + 1)th coil frame along the winding direction until i + 1 = N, where: initially i = 1; S4: Bend and rotate the winding wire from the end position at the top or bottom of the Nth coil frame to the axis direction of the top or bottom of the axis side of the first coil frame, and wind the remaining part of the first coil frame and return to the winding starting point to form a coil structure with a magnetic field distribution similar to that of a quasi-static resonant cavity.

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