A cube corner anti-offset wireless charging device and method

Abstract

This invention discloses a three-dimensional angle-resistant wireless charging device and method, belonging to the field of wireless charging technology. The device includes first to sixth transmitting coils and first to third receiving coils. The six transmitting coils form a cubic spatial structure, with the first and second transmitting coils facing each other and serving as the front and back faces of the cubic space; the third and fourth transmitting coils facing each other and serving as the left and right faces of the cubic space; and the fifth and sixth transmitting coils facing each other and serving as the top and bottom faces of the cubic space. The three receiving coils form a sphere located at the center of the cubic space. This invention achieves omnidirectional, dead-angle-free magnetic field energy radiation.

Description

Technical Field

[0001] This invention belongs to the field of wireless charging technology, and particularly relates to a three-dimensional angle-resistant wireless charging device and method. Background Technology

[0002] Wireless charging technology originates from the concept of wireless power transmission. Its essence lies in using electromagnetic induction, electromagnetic resonance, and radio frequency to achieve contactless power transfer. Wireless charging technology is gradually changing the way society supplies and manages energy, and its application prospects are broad, covering many fields such as healthcare, smart cities, space exploration, industrial robots, automated transportation systems, and electric vehicles.

[0003] Research on Wireless Power Transfer (WPT) began as early as the 19th century, pioneered by Nikola Tesla, a Serbian-American scientist. Following the failure of Tesla's experiments, a long period of stagnation ensued. In the 21st century, high-frequency resonance technology enabled the first successful lighting of a 60W incandescent bulb at a distance of 2 meters. However, this technology remained largely a conceptual demonstration, as it employed a repeater coil and utilized a high frequency in the MHz range, hindering its industrialization. Inspired by these experiments, numerous research institutions have undertaken research into more practical wireless charging technologies. Electric vehicles are among the most widely used applications, and applying this technology to the automotive sector aims to address the shortcomings of traditional wired charging in terms of convenience, durability, and continuous power supply for onboard devices.

[0004] Currently, the global wireless charging industry has formed a technological landscape in which electromagnetic induction technology dominates the low-power consumer electronics market, while magnetic resonance technology focuses on medium- and high-power and long-distance scenarios. The wireless charging industry is continuously evolving towards higher efficiency, greater positional tolerance, stronger compatibility, and lower cost.

[0005] However, electromagnetic induction power transmission has a short range and requires the two coils to be directly aligned; otherwise, the efficiency is extremely low. Magnetic resonance can improve the axial transmission distance to some extent, but its ability to resist radial and angular offsets remains insufficient. Virtual coils with a large effective area created by multiple coils have limitations in resisting offsets in three-dimensional space. The magnetic field optimization range of this technology is limited to a plane or a single dimension, and can only enhance the anti-offset performance in the horizontal or vertical directions, failing to achieve omnidirectional magnetic field coverage in three-dimensional space. When the receiving coil and transmitting coil are offset at multiple angles, the effective coupling area between the coils decreases significantly, and the coupling coefficient decays sharply, resulting in significant fluctuations in system output power and transmission efficiency, making it difficult to cope with the randomness of parking offsets during parking, and for robots and drones. Summary of the Invention

[0006] Purpose of the invention: In order to solve the problems of existing technologies such as inability to achieve efficient coupling in all directions in three-dimensional space, high cost, poor stability and narrow adaptability, this invention provides a three-dimensional angle anti-offset wireless charging device and method.

[0007] Technical Solution: This invention provides a three-dimensional angle-resistant wireless charging device, comprising first to sixth transmitting coils and first to third receiving coils; the six transmitting coils form a cubic spatial structure, wherein the first and second transmitting coils are opposite each other and serve as the front and rear of the cubic space; the third and fourth transmitting coils are opposite each other and serve as the left and right sides of the cubic space; the fifth and sixth transmitting coils are opposite each other and serve as the top and bottom of the cubic space; the three receiving coils form a sphere, which is located at the center of the cubic space, with the first and second transmitting coils corresponding to the first receiving coil, the third and fourth transmitting coils corresponding to the second receiving coil, and the fifth and sixth transmitting coils corresponding to the third receiving coil.

[0008] Furthermore, the six transmitting coils and three receiving coils are all wound into a ring, with half of the cubic space located underground and the receiving coils set on the ground surface; ideally, the first and second transmitting coils are coaxial and parallel to the first receiving coil; the third and fourth transmitting coils are coaxial and parallel to the second receiving coil; and the fifth and sixth transmitting coils are coaxial and parallel to the third receiving coil.

[0009] Furthermore, the current flowing through the transmitting coil is equal, the mutual inductance coefficients between the transmitting coils are equal, and the mutual inductance coefficients between the transmitting coil and the corresponding receiving coil are equal.

[0010] Furthermore, a three-dimensional Cartesian coordinate system is constructed with the center point of the cubic space as the origin. All receiving coils are two-layered. For the first receiving coil, from... The first layer is spirally wound along the positive y-axis, and the second layer is spirally wound along the negative y-axis until... Up to the port; for the second receiving coil, from The first layer is spirally wound along the negative x-axis, and the second layer is spirally wound along the positive x-axis until... Up to the port; for the third receiving coil, from The first layer is spirally wound along the positive z-axis, and the second layer is spirally wound along the negative z-axis until... Up to the port.

[0011] Furthermore, the device also includes first to third double-pole double-throw switches, first to seventh capacitors and a first resistor; the first to sixth capacitors and six transmitting coils constitute the transmitting circuit, three receiving coils, three double-pole double-throw switches, the seventh capacitor and the first resistor constitute the receiving circuit.

[0012] One end of each of the first to sixth capacitors is connected to the signal generator, and the other end of each of the first to sixth capacitors is connected to one end of the corresponding transmitting coil. The other end of all the transmitting coils is connected to the signal generator.

[0013] Three double-pole double-throw switches correspond one-to-one with three receiving coils. The two ends of any receiving coil are connected to the receiving circuit through a double-pole double-throw switch. One common terminal of the first double-pole double-throw switch is connected to one common terminal of the second double-pole double-throw switch. The other common terminal of the second double-pole double-throw switch is connected to one common terminal of the third double-pole double-throw switch. The other common terminal of the third double-pole double-throw switch is connected to one end of the seventh capacitor. The other end of the seventh capacitor is connected to one end of the first resistor. The other end of the first resistor is connected to the other common terminal of the first double-pole double-throw switch.

[0014] Furthermore, the radius of the transmitting coil is larger than the radius of the receiving coil, and the radius of the transmitting coil is equal to the distance between the receiving coil and the corresponding transmitting coil. Kirchhoff's equations are constructed based on the following principles:

[0015] The mutual inductance between the transmitting coil and its non-corresponding receiving coil is 0; taking any transmitting coil as the central transmitting coil, the sum of the mutual inductances between the two transmitting coils adjacent to the central transmitting coil on the left and right and the central transmitting coil is 0, and the sum of the mutual inductances between the two transmitting coils adjacent to the central transmitting coil on the top and bottom and the central transmitting coil is 0.

[0016] Impedance matching is performed on the transmitter circuit to make Impedance matching is performed on the receiving circuit to make Thus, we obtain the following expression:

[0017] ;

[0018] Where j represents the imaginary unit, It is the angular frequency of the signal generator. Let be the mutual inductance between two opposing transmitting coils. This is the capacitance value of the seventh capacitor; This is the equivalent inductance value of the transmitting coil; These are the capacitance values ​​of capacitors one through six; These are the equivalent inductance values ​​of the first, second, and third receiving coils, respectively.

[0019] The expressions for Kirchhoff's equations are as follows:

[0020] ;

[0021] in, For the voltage phasor of the signal generator, The mutual inductance coefficient between the transmitting coil and the corresponding receiving coil. This represents the equivalent resistance value of the three receiving coils; This is the resistance value of the first resistor; This is the equivalent resistance value of the transmitting coil; This is the total current phasor of the transmitting circuit; For the current phasor of the receiving circuit;

[0022] Solving the Kirchhoff equations yields: ;

[0023] Obtain input power and output power The expression is as follows:

[0024] ;

[0025] Efficiency ;

[0026] Mutual intuition related items Recorded as Simplify the expression for efficiency by taking the derivative, let 0, get The expression is ; due to Efficiency is maximized at the extreme point, thus obtaining The value is .

[0027] A charging method for a three-dimensional angle-resistant wireless charging device specifically involves: when a car enters a cubic space formed by transmitting coils, obtaining the angle between the second receiving coil in the car and the second receiving coil under ideal conditions. According to the included angle Different modes can be selected by a double-pole double-throw switch; the ideal state is that the first and second transmitting coils are coaxial and parallel to the first receiving coil; the third and fourth transmitting coils are coaxial and parallel to the second receiving coil; and the fifth and sixth transmitting coils are coaxial and parallel to the third receiving coil.

[0028] when When selecting mode one: use the double-pole double-throw switch to... End and End connection, End and End connection; or End and End connection, End and End connection;

[0029] when When selecting mode two: use the double-pole double-throw switch to... End and End connection, End and End connection; or End and End connection, End and End connection;

[0030] when When selecting mode three: use the double-pole double-throw switch to... End and End connection, End and End connection; or End and End connection, End and End connection;

[0031] when When selecting mode four: use the double-pole double-throw switch to... End and End connection, End and End connection; or End and End connection, End and End connection.

[0032] Furthermore, efficiency under the four modes The expression is:

[0033] .

[0034] Beneficial effects:

[0035] 1. This invention designs a cubic three-dimensional coil coupling architecture, with circular transmitting coils arranged on the six outer surfaces of the cube, and three mutually orthogonal circular coils set inside the cube. By utilizing the synergistic effect of the outer surface coils and the inner orthogonal coils, it breaks through the limitations of magnetic field coverage of traditional planar coils or single-dimensional composite coils, and realizes omnidirectional, dead-angle-free magnetic field energy radiation.

[0036] 2. This invention uses a double-pole double-throw switch to select the connection method of the receiving coil. While achieving optimal efficiency, it fundamentally solves the technical problem that existing technologies cannot handle arbitrary angles and large-range offsets between the transmitter and receiver during parking from the hardware structure level. It maintains the mutual inductive coupling strength between the transmitter and receiver in a stable range, ensuring that the system output power and transmission efficiency do not decrease significantly, and completely eliminates the dependence on precise parking alignment. Attached Figure Description

[0037] Figure 1 This is a structural diagram of the transmitting coil of the present invention.

[0038] Figure 2 This is a structural diagram of the receiving coil of the present invention.

[0039] Figure 3 This is a schematic diagram of wireless charging for electric vehicles according to the present invention.

[0040] Figure 4 This is the hardware circuit schematic diagram of the present invention.

[0041] Figure 5 This is a top view of the magnetic field of the receiving coil.

[0042] Figure 6 This is a top view of the magnetic field of the transmitting coil in the vertical direction.

[0043] Figure 7 This is a graph showing the relationship between efficiency and load resistance.

[0044] Figure 8 A schematic diagram showing the direction of the transmitting coil current at a certain moment;

[0045] Figure 9 This is a schematic diagram showing the direction of the current in the receiving coil at a certain moment.

[0046] Figure 10 This is a schematic diagram of the current in the receiving coil after rotating 90°.

[0047] Figure 11 This is a top view of the coil when it is rotating.

[0048] Figure 12 This is a graph showing the efficiency distribution under different modes.

[0049] Figure 13 This is a flowchart of the charging process. Detailed Implementation

[0050] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0051] This invention aims to realize a high-efficiency wireless charging technology that has strong omnidirectional anti-offset capability and excellent compatibility, meeting the convenient use needs of daily parking that "does not require precise alignment", promoting the development of wireless charging technology for electric vehicles towards a more efficient, convenient and practical direction, and accelerating its large-scale application in the civilian and commercial fields.

[0052] When the magnetic flux through a closed conductor loop changes, an electromotive force (EMF) is generated in the loop, which drives the generation of a current. Therefore, the process of generating current at the receiving end in a wireless power transmission system can be summarized as follows: the alternating current at the transmitting end generates a changing magnetic field, which is coupled into the receiving coil through electromagnetic induction, generating an induced EMF, and then generating an induced current.

[0053] This invention proposes a three-dimensional multi-directional wireless charging station design, with the transmitting coil structure as follows: Figure 1 As shown, six transmitting coils ( , , , , , The coils are located on six faces, forming a cubic spatial structure. The receiving coil structure is as follows: Figure 2 As shown, three receiving coils ( , , The coil is wound into a spherical shape; the arrow in the diagram indicates a single-layer structure. During winding, each coil consists of two layers, first... Single-layer winding, wound to a specified number of turns. Then, play on the ball. Single-layer winding, wound to a specified number of turns. After that, proceed Single-layer winding, wound to a specified number of turns. After that, directly in Wind a second layer onto the already wound coil to the specified number of turns. Then wrap Second layer to the specified number of turns Finally entangled Second layer to the specified number of turns . Number of turns of the receiving coil 1 / 2. The first receiving coil of the present invention. from The port begins to spirally wind the first layer in the +y direction. The second layer spirals in the -y direction. Up to the port, coil from The port begins to spirally wind the first layer in the -x direction. The second layer spirals in the +x direction. Up to the port, coil from The port begins to spirally wind the first layer in the +z direction. The second layer spirals in the -z direction. Up to the port.

[0054] like Figure 3 As shown, during use, part of the transmitting coil is located underground while the receiving coil is placed on the ground with the receiving coil at the center of the transmitting coil. Ideally, the first and second receiving coils are coaxial and parallel to the first receiving coil, the third and fourth transmitting coils are coaxial and parallel to the second receiving coil, and the fifth and sixth transmitting coils are coaxial and parallel to the third receiving coil.

[0055] The hardware circuit diagram of this invention is as follows: Figure 4 As shown, , , It is a double-pole double-throw switch, A B The two ports, C D The two ports, E F The two ports are represented by 0 and 1 respectively, indicating that each port is open and closed. , , , , , It is the equivalent inductance of the six transmitting coils, designed to be equal to ; , , , , , These are the equivalent resistances of the six transmitting coils, designed to be equal to... ; , , , , , These are the capacitors on each transmitting circuit; they are designed to be equal to... Simultaneously, all transmitting coils are made identical in all parameters (number of turns, radius, etc.) except for their spatial position, and all receiving coils are also made identical in all parameters except for their spatial position. Therefore:

[0056] ;

[0057] in, , , , , , This represents the current values ​​of each branch in the transmitting circuit, which is also the total current of the transmitting circuit. , , , , , The values ​​are all , , , , , , This represents the current phasor of each branch in the transmitter circuit. This is the total current phasor of the transmitting circuit; Characterizes the ability of a change in current in coil i to induce an electromotive force in coil j. This is called the mutual inductance coefficient between coils i and j. , It is the mutual inductance coefficient between the first and second transmitting coils; , It is the mutual inductance coefficient between the third and fourth transmitting coils; , It is the mutual inductance coefficient between the fifth and sixth transmitting coils; they are designed to be equal to ;at the same time It is the mutual inductance coefficient between the first transmitting coil and the first receiving coil. It is the mutual inductance coefficient between the second transmitting coil and the first receiving coil. It is the mutual inductance coefficient between the third transmitting coil and the second receiving coil. Fourth is the mutual inductance between the transmitting coil and the second receiving coil. It is the mutual inductance coefficient between the fifth transmitting coil and the third receiving coil. It is the mutual inductance coefficient between the sixth transmitting coil and the third receiving coil, designed to be equal to .

[0058] Now consider the magnetic flux received by a transmitting coil from the magnetic fields of other coils. Taking the third transmitting coil as an example, draw... Figure 5 From the top view, it can be seen that the magnetic flux of the magnetic field lines of the first receiving coil passing through the third transmitting coil from left to right cancels out the magnetic flux of the magnetic field lines of the first receiving coil passing through the third transmitting coil from right to left. Similarly:

[0059] .

[0060] Considering the magnetic flux generated by the first and second transmitting coils in the third transmitting coil, such as... Figure 6 As shown, the magnetic flux generated by the second transmitting coil in the third transmitting coil flows from left to right, while the magnetic flux generated by the first transmitting coil in the third transmitting coil flows from right to left. This is because... Therefore, these two magnetic fluxes are equal in magnitude and opposite in direction, thus canceling each other out. Similarly:

[0061] .

[0062] Write Kirchhoff's equations based on the circuit diagram:

[0063] ;

[0064] in, It is the voltage phasor of the signal generator. It is the angular frequency of the signal generator. This refers to the value of the capacitor in the receiving circuit. This refers to the value of the external resistor in the receiving circuit. This is the current phasor of the receiving circuit.

[0065] Impedance matching is performed on the transmitter circuit to make Impedance matching is performed on the receiving circuit to make .

[0066] From the above two equations, we get:

[0067] ;

[0068] Ultimately, Kirchhoff's equations can be simplified to

[0069] ;

[0070] in Let be the equivalent resistance value of the receiving coil, then we can solve for... ;

[0071] Define the input power as The output power is ,but ;

[0072] have to ;

[0073] By efficiency Finally, the solution was obtained. .

[0074] Analysis efficiency With load resistance In this embodiment, the given efficiency formula needs to be considered as relating to... The relationship between the function and the extreme values ​​can be clarified by finding the derivative, analyzing the monotonicity and limit behavior.

[0075] First, consider the mutual intuition-related items. Recorded as If (constant), then the efficiency formula can be simplified to:

[0076] ;

[0077] Let the molecule denominator ,but Its derivative is:

[0078] ;

[0079] Molecular derivative: ;

[0080] Expand the denominator and differentiate: ;

[0081] ;

[0082] Substitute into the derivative formula:

[0083] ;

[0084] Substitute D and simplify the molecule:

[0085] ;

[0086] make 0, meaning the molecule is 0:

[0087] ;

[0088] Expand and organize:

[0089] ;

[0090] because Therefore, the extreme point is:

[0091] ;

[0092] Discussion by section:

[0093] 1. When hour:

[0094] The numerator of the derivative is positive. 0, Follow Increase monotonically.

[0095] 2. When hour:

[0096] The derivative is 0. It has reached its maximum value.

[0097] 3. When hour:

[0098] The numerator of the derivative is negative. 0, Follow Increases monotonically and decreases.

[0099] Therefore, this embodiment selects This maximizes efficiency.

[0100] This embodiment sets the radius of the ring-shaped transmitting coil. The radius of the ring receiving coil Number of turns per transmitting coil Total number of turns per receiving coil = , , The graph showing the relationship between efficiency and load resistance is shown below. Figure 7 As shown.

[0101] Assume that at any given moment the direction of the current in the transmitting coil is as follows Figure 8 As shown, and with the current decreasing, the first and second transmitting coils will generate a magnetic field decreasing along the positive y-axis, the third and fourth transmitting coils will generate a magnetic field decreasing along the positive x-axis, and the fifth and sixth transmitting coils will generate a magnetic field decreasing along the negative z-axis. Correspondingly, this will generate a magnetic field in the receiving coil as follows: Figure 9 The direction of the current is indicated by the number of coil turns, which is only for structural illustration and does not represent the actual number of turns.

[0102] To prevent the induced currents from canceling each other out, the current inflow and outflow ports of the two receiving coils need to be connected. Six methods for determining the direction of current flow, under ideal conditions, taking into account... Figure 3 The restrictions on the positions of the three transmitting coils are only... Two equivalent connection methods are referred to as Mode 1 in this case, A and B. The two ports, C and D The two ports, E and F The two ports are represented by 0 and 1, respectively, indicating that each port is open and closed. This invention uses sinusoidal alternating current. When the current in the transmitting coil is opposite to the alternating current and increases, the current in the receiving coil flows in the same direction as the current at that moment. When the current in the transmitting coil is in the same direction as the alternating current and increases or opposite to the alternating current and decreases, the current in the receiving coil flows in the opposite direction as the current at that moment, but the connection method can remain unchanged.

[0103] Now consider rotating the transmitting coil 90° counterclockwise (viewed from above, also from a top-down perspective) around the vertical line at the center of the third receiving coil plane. The direction of the current in the receiving coil is as follows: Figure 10 As shown. You can see and The current flow direction has reversed, therefore it is necessary to reverse the above six connection methods. and An exchange is necessary; otherwise, the current in the first receiving coil will cancel out with that in the second or third receiving coil, leading to reduced efficiency. Ultimately, there is... The two equivalent connection methods are called Mode 2.

[0104] When rotating 180°, the connection of the receiving coil needs to be changed at the 90° rotation position. and The location has The two equivalent connection methods are called Mode 3.

[0105] When rotating 270°, the connection of the receiving coil needs to be changed on the non-rotated side. and The location has The two equivalent connection methods are called Mode 4.

[0106] Assuming the transmitting coil in mode one is not rotating, the angle of counterclockwise rotation from the initial position (ideal state) is... ,like Figure 11 As shown, the dashed line represents the initial position, and the solid line represents the position after rotation.

[0107] Input power of the signal generator The constant, induced electromotive force of the receiving coil is entirely used to power the load, and the induced electromotive force generated by each transmitting coil relative to each receiving coil at the initial position is... Under these conditions, the initial output power is At this point, the efficiency is According to the law of electromagnetic induction, induced electromotive force... ,in It is the magnetic flux. B is the magnetic induction intensity. Under the condition that the magnetic field of the transmitting coil is not affected by the rotation of the receiving coil and its direction is perpendicular to the plane of the coil, then The induced electromotive force remains constant and is proportional to the effective area S. For the second receiving coil, the direction of the magnetic field remains unchanged, while the effective area of ​​the magnetic field in the third and fourth transmitting coils becomes... The effective area of ​​the magnetic field of the first and second transmitting coils becomes For the first receiving coil, the direction of the magnetic fields passing through the third and fourth transmitting coils changes, and the effective area of ​​the magnetic fields of the third and fourth transmitting coils becomes... The direction of the magnetic fields passing through the first and second transmitting coils remains unchanged, and the effective area becomes The induced electromotive force of the third receiving coil is unaffected by rotation. After final rotation, the induced electromotive force becomes... Then the output power is Efficiency becomes the initial position times.

[0108] For mode two, the initial position lags behind mode one by 90°, so the efficiency is... of Times. Similarly, the efficiency of mode three is... of The efficiency of Mode 4 is times that of the previous mode. of times.

[0109] Efficiency formula from initial position Efficiency formulas for different modes are obtained:

[0110] .

[0111] In this embodiment, 220 strands of Litz wire are used to make the receiving and transmitting coils. The transmitting coil has a diameter of 0.35m, and the receiving coil has a diameter of 0.25m, with 18 turns of each. , measured , , , The optimal load was calculated. The initial position efficiency was ultimately calculated to be 94.0%, and the efficiencies of each mode are as follows: Figure 12 As shown.

[0112] Therefore, in order to maintain high-efficiency transmission during angular offset, when... When, select mode one; when When, select mode two; when When, select mode three; when When that happens, select mode four.

[0113] When wirelessly charging other vehicles such as cars, the following should be followed: Figure 13 The process.

[0114] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A charging method for a three-dimensional angle-resistant wireless charging device, characterized in that, The device includes first to sixth transmitting coils and first to third receiving coils; the six transmitting coils form a cubic spatial structure, wherein the first and second transmitting coils are opposite each other and serve as the front and rear of the cubic space; the third and fourth transmitting coils are opposite each other and serve as the left and right sides of the cubic space; the fifth and sixth transmitting coils are opposite each other and serve as the top and bottom of the cubic space; the three receiving coils form a sphere, which is located at the center of the cubic space, with the first and second transmitting coils corresponding to the first receiving coil, the third and fourth transmitting coils corresponding to the second receiving coil, and the fifth and sixth transmitting coils corresponding to the third receiving coil. A three-dimensional Cartesian coordinate system is constructed with the center point of the cubic space as the origin. All receiving coils are two-layered. For the first receiving coil, from... The first layer is spirally wound along the positive y-axis, and the second layer is spirally wound along the negative y-axis until... Up to the port; for the second receiving coil, from The first layer is spirally wound along the negative x-axis, and the second layer is spirally wound along the positive x-axis until... Up to the port; for the third receiving coil, from The first layer is spirally wound along the positive z-axis, and the second layer is spirally wound along the negative z-axis until... Up to the port; The device also includes first to third double-pole double-throw switches, first to seventh capacitors and a first resistor; the first to sixth capacitors and six transmitting coils constitute the transmitting circuit, and three receiving coils, three double-pole double-throw switches, the seventh capacitor and the first resistor constitute the receiving circuit. One end of each of the first to sixth capacitors is connected to the signal generator, and the other end of each of the first to sixth capacitors is connected to one end of the corresponding transmitting coil. The other end of all the transmitting coils is connected to the signal generator. Three double-pole double-throw switches correspond one-to-one with three receiving coils. The two ends of any receiving coil are connected to the receiving circuit through a double-pole double-throw switch. One common terminal of the first double-pole double-throw switch is connected to one common terminal of the second double-pole double-throw switch. The other common terminal of the second double-pole double-throw switch is connected to one common terminal of the third double-pole double-throw switch. The other common terminal of the third double-pole double-throw switch is connected to one end of the seventh capacitor. The other end of the seventh capacitor is connected to one end of the first resistor. The other end of the first resistor is connected to the other common terminal of the first double-pole double-throw switch. The method is specifically as follows: When the car enters the cubic space formed by the transmitting coil, the angle between the second receiving coil in the car and the second receiving coil under ideal conditions is obtained. According to the included angle Different modes can be selected by a double-pole double-throw switch; the ideal state is that the first and second transmitting coils are coaxial and parallel to the first receiving coil; the third and fourth transmitting coils are coaxial and parallel to the second receiving coil; and the fifth and sixth transmitting coils are coaxial and parallel to the third receiving coil. when When selecting mode one: use the double-pole double-throw switch to... End and End connection, End and End connection; or End and End connection, End and End connection; when When selecting mode two: use the double-pole double-throw switch to... End and End connection, End and End connection; or End and End connection, End and End connection; when When selecting mode three: use the double-pole double-throw switch to... End and End connection, End and End connection; or End and End connection, End and End connection; when When selecting mode four: use the double-pole double-throw switch to... End and End connection, End and End connection; or End and End connection, End and End connection.

2. The method according to claim 1, characterized in that, The six transmitting coils and three receiving coils are all wound into a ring, with half of the cubic space located underground and the receiving coils set on the ground surface; ideally, the first and second transmitting coils are coaxial and parallel to the first receiving coil; the third and fourth transmitting coils are coaxial and parallel to the second receiving coil; and the fifth and sixth transmitting coils are coaxial and parallel to the third receiving coil.

3. The method according to claim 1, characterized in that, The current flowing through the transmitting coil is equal, the mutual inductance coefficients between the transmitting coils are equal, and the mutual inductance coefficients between the transmitting coil and the corresponding receiving coil are equal.

4. The method according to claim 1, characterized in that, The radius of the transmitting coil is greater than the radius of the receiving coil, and the radius of the transmitting coil is equal to the distance between the receiving coil and the corresponding transmitting coil. Kirchhoff's equations are constructed based on the following principles: Design the following constraints: ； in, , , , , , This represents the current values ​​of each branch in the transmitting circuit, which is also the total current of the transmitting circuit. , , , , , This represents the current phasor of each branch in the transmitter circuit. This is the total current phasor of the transmitting circuit; Characterizes the ability of a change in current in coil i to induce an electromotive force in coil j. This is called the mutual inductance coefficient between coils i and j. , It is the mutual inductance coefficient between the first and second transmitting coils; , It is the mutual inductance coefficient between the third and fourth transmitting coils; , It is the mutual inductance coefficient between the fifth and sixth transmitting coils; they are designed to be equal to ;at the same time It is the mutual inductance coefficient between the first transmitting coil and the first receiving coil. It is the mutual inductance coefficient between the second transmitting coil and the first receiving coil. It is the mutual inductance coefficient between the third transmitting coil and the second receiving coil. Fourth is the mutual inductance between the transmitting coil and the second receiving coil. It is the mutual inductance coefficient between the fifth transmitting coil and the third receiving coil. It is the mutual inductance coefficient between the sixth transmitting coil and the third receiving coil, designed to be equal to ; The mutual inductance between the transmitting coil and its non-corresponding receiving coil is 0; taking any transmitting coil as the central transmitting coil, the sum of the mutual inductances between the two transmitting coils adjacent to the central transmitting coil on the left and right and the central transmitting coil is 0, and the sum of the mutual inductances between the two transmitting coils adjacent to the central transmitting coil on the top and bottom and the central transmitting coil is 0. Impedance matching is performed on the transmitter circuit to make Impedance matching is performed on the receiving circuit to make Thus, we obtain the following expression: ； Where j represents the imaginary unit, It is the angular frequency of the signal generator. Let be the mutual inductance between two opposing transmitting coils. This is the capacitance value of the seventh capacitor; This is the equivalent inductance value of the transmitting coil; These are the capacitance values ​​of capacitors one through six; These are the equivalent inductance values ​​of the first, second, and third receiving coils, respectively. The expressions for Kirchhoff's equations are as follows: ； in, For the voltage phasor of the signal generator, The mutual inductance coefficient between the transmitting coil and the corresponding receiving coil. This represents the equivalent resistance value of the three receiving coils; This is the resistance value of the first resistor; This is the equivalent resistance value of the transmitting coil; This is the total current phasor of the transmitting circuit; For the current phasor of the receiving circuit; Solving the Kirchhoff equations yields: ; Obtain input power and output power The expression is as follows: ； Efficiency ; Mutual intuition related items Recorded as Simplify the expression for efficiency by taking the derivative, and let... 0, get The expression is ; due to Efficiency is maximized at the extreme point, thus obtaining The value is .

5. The charging method according to claim 4, characterized in that, Under the condition that the magnetic field of the transmitting coil is not affected by the rotation of the receiving coil and its direction is perpendicular to the plane of the coil, the efficiency in the four modes. The expression is: 。

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