Wireless charging alignment guidance system and alignment method

Abstract

The present invention discloses a wireless charging alignment guidance system and method. The wireless charging alignment guidance system includes a transmitter and a receiver. The transmitter includes a transmitter aluminum plate, a transmitter magnetic core, and a transmitter coil. The receiver includes a receiver aluminum plate, a receiver magnetic core, and a receiver coil. The transmitter also includes a loop coil. The receiver also includes a positioning coil. When the positioning coil approaches the loop coil, the impedance of the loop coil changes. The wireless charging alignment guidance system determines the position of the receiver based on the impedance change of the loop coil to achieve alignment guidance. Compared with the existing technology, the present invention can better align the receiver and transmitter before parking and charging, thereby improving charging efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless charging of electric vehicles, and in particular to a wireless charging alignment guiding system and an alignment method. Background Art

[0002] With the rapid development of electric vehicles in my country in recent years, achieving safe, convenient, and fast charging for electric vehicles is of great significance. The traditional method for charging electric vehicles is to directly obtain power from the power grid through charging piles. However, when charging electric vehicles with wires, the charging sockets or cables are often exposed. During high-power charging, sparks and arcs are easily generated, posing a major safety hazard. At the same time, traditional wired charging requires manual operation by the user. Human negligence and hardware wear caused by frequent plugging and unplugging of the charging socket can easily lead to poor contact, resulting in personal safety incidents in high-power environments.

[0003] To address these issues, short-range wireless power transmission technology is often used to achieve wireless charging for electric vehicles. This technology typically involves installing a receiver on the vehicle's chassis. A transmitter installed above or below the ground generates an induced current through a magnetic field. This current is rectified into direct current and then used to charge the vehicle's battery. To maximize energy transmission, the receiver on the vehicle's chassis must be aligned as closely as possible with the center of the transmitter. Relying solely on the driver to park the vehicle correctly can be inaccurate.

[0004] Therefore, how to design a wireless charging alignment guidance system and alignment method to achieve better alignment between the receiving end and the transmitting end before charging and improve charging efficiency is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] In view of the problem in the prior art that the alignment accuracy between the receiving end and the transmitting end during wireless charging is poor, which affects the charging efficiency, the present invention proposes a wireless charging alignment guidance system and alignment method.

[0006] The technical solution of the present invention is to propose a wireless charging alignment guidance system, including a transmitting end and a receiving end, the transmitting end including a transmitting end aluminum plate, a transmitting end magnetic core, and a transmitting end coil, the receiving end including a receiving end aluminum plate, a receiving end magnetic core, and a receiving end coil, the transmitting end also including a loop coil, the receiving end also including a positioning coil, and the positioning coil can change the impedance of the loop coil when it is close to the loop coil. The wireless charging alignment guidance system determines the position of the receiving end according to the impedance change of the loop coil to achieve alignment guidance.

[0007] Furthermore, the Loop coil includes a plurality of coil units wound on a PCB board, and each of the coil units can be used as an independent coil.

[0008] Furthermore, the positioning coil includes two positioning coil plates, and the connection line of the two positioning coil plates is perpendicular to the setting direction of the receiving end;

[0009] Or the positioning coil includes four positioning coil plates, and the four positioning coil plates are respectively installed at the four vertex corners of the receiving end.

[0010] Furthermore, the loop coil and the positioning coil are both connected to a resonant circuit, and the resonant circuit at the loop coil and the resonant circuit at the positioning coil have similar resonant frequencies.

[0011] Furthermore, when the positioning coil includes two positioning coil plates, each positioning coil plate is connected to a resonant circuit, and the two resonant circuits have the same resonant frequency and different switching frequencies.

[0012] Furthermore, the impedance variation of each coil unit is:

[0013]

[0014] Wherein, ΔZs is the impedance of the coil unit, w0 is the angular frequency, M is the mutual inductance between the coil unit and the positioning coil, and RMO is the equivalent resistance of the positioning coil coupled to the coil unit.

[0015] The present invention also proposes an alignment method for a wireless charging alignment guide system, comprising:

[0016] Establish a two-dimensional coordinate system with the center of the Loop coil as the origin;

[0017] Calculating the impedance change of each coil unit on the loop coil;

[0018] Calculating the coordinates of the positioning coil according to the impedance change;

[0019] The receiving end is guided in alignment according to the coordinates of the positioning coil.

[0020] Furthermore, the coordinates of the positioning coil are calculated according to the impedance change, and the formula is:

[0021]

[0022]

[0023] Wherein, x and y are the horizontal and vertical coordinates of the positioning coil, respectively, ΔZ1 to ΔZ n The impedance change of each coil unit, ΔZ avg is the average impedance change of the coil unit, X1 to X nThe horizontal coordinates of each coil unit, Y1 to Y n is the ordinate of each coil unit.

[0024] Furthermore, when the positioning coil includes two positioning coil plates, calculating the coordinates of the positioning coil according to the impedance change includes:

[0025] Calculating the coordinates of the two positioning coil plates according to the impedance change;

[0026] The coordinates of the midpoint of the line connecting the two positioning coil plates are calculated as the coordinates of the positioning coil.

[0027] Furthermore, the calculation formula for the coordinates of the midpoint of the line connecting the two positioning coil plates is:

[0028]

[0029]

[0030] Among them, x1, x2, and x3 are the horizontal coordinates of the two positioning coil plates and the positioning coil respectively, and y1, y2, and y3 are the vertical coordinates of the two positioning coil plates and the positioning coil respectively.

[0031] Compared with the prior art, the present invention has at least the following beneficial effects:

[0032] By setting up a wireless charging alignment guidance system, the receiving end and the transmitting end can be better aligned before parking charging, thereby improving charging efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 This is a structural diagram of the wireless charging alignment guidance system;

[0035] Figure 2 It is a structural diagram of the Loop coil;

[0036] Figure 3 Schematic diagram of the structure of the positioning coil;

[0037] Figure 4 This is the equivalent circuit diagram of the inductor coil when a non-ferromagnetic metal foreign object approaches;

[0038] Figure 5This is a structural block diagram of the wireless charging alignment guidance system;

[0039] Figure 6 Schematic diagram of establishing a two-dimensional coordinate system on a loop coil according to an embodiment;

[0040] Figure 7 Schematic diagram of the structure of a wireless charging alignment guidance system according to an embodiment;

[0041] Figure 8 Schematic diagram of the connection between the positioning coil and the positioning coil plate when there are two positioning coil plates. DETAILED DESCRIPTION

[0042] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0043] Thus, a feature indicated in this specification is intended to illustrate one of the features of one embodiment of the present invention, rather than to imply that every embodiment of the present invention must have the described feature. In addition, it should be noted that this specification describes many features. Although certain features can be combined together to illustrate possible system designs, these features can also be used in other, not explicitly described, combinations. Thus, unless otherwise noted, the described combinations are not intended to be limiting.

[0044] The principle and structure of the present invention are described in detail below with reference to the accompanying drawings and embodiments.

[0045] In the prior art, during wireless charging, the alignment between the receiving end and the transmitting end is poor due to the self-alignment performed by the vehicle owner. The idea of the present invention is to propose a wireless charging alignment guidance system and alignment method, which can determine the position of the receiving end by the impedance change of the loop coil to achieve alignment guidance, thereby improving the alignment accuracy between the receiving end and the transmitting end and improving charging efficiency.

[0046] See Figure 1The wireless charging alignment guidance system proposed in the present invention includes a transmitter and a receiver. The transmitter includes a transmitter aluminum plate, a transmitter magnetic core, and a transmitter coil, and the receiver includes a receiver aluminum plate, a receiver magnetic core, and a receiver coil. During operation, the transmitter coil and the receiver coil are magnetically coupled to each other, thereby achieving wireless charging. A loop coil is provided on the side of the transmitter facing the receiver, and a positioning coil is provided on the side of the receiver facing the transmitter. When the positioning coil approaches the loop coil, the impedance of the loop coil changes. The change in the loop coil impedance can be used to determine the position of the positioning coil relative to the loop coil, thereby determining the position of the receiver relative to the transmitter, thereby achieving precise alignment between the transmitter and receiver.

[0047] See Figure 2 The loop coil includes multiple coil units wound on the PCB board, each of which can be used as an independent coil, so that each coil can be coupled with the positioning coil, thereby changing its own impedance to achieve the purpose of determining the position of the positioning coil.

[0048] Furthermore, the positioning coil can be composed of a single positioning coil. When the positioning coil is close to the loop coil, the impedance of each coil unit changes. The specific position of the positioning coil can be determined by the impedance change of the coil unit, thereby determining the specific position of the receiving end, and then performing alignment guidance;

[0049] In another embodiment of the present invention, the positioning coil can be composed of two positioning coil plates, and the connection of the two positioning coil plates is perpendicular to the setting direction of the receiving end. The conduction frequencies of the two positioning coils are kept staggered to prevent interference with the LOOP coil at the same time, so that the center of the receiving end is located at the midpoint of the connecting line. In this case, the positions of the two positioning coil plates can be first determined by the coil unit, and then the position of the receiving end can be determined based on the position of the midpoint of the connecting line between the two positioning coil plates, thereby performing positioning guidance.

[0050] In another embodiment of the present invention, the positioning coil may be formed of four positioning coil plates, which are respectively mounted at the four corners of the receiving end. During positioning, the positions of the four positioning coils may be first determined by the coil unit, and then the position of the receiving end may be determined based on the centers of the four positioning coil plates, thereby providing positioning guidance.

[0051] See Figure 3 The shape of the positioning coil can be any one of circular, square, and elliptical.

[0052] See Figure 4, which is the equivalent circuit diagram of the inductor coil when a non-ferromagnetic metal foreign object is close to it. During alignment, the positioning coil at the receiving end can be equivalent to the metal foreign object. Among them, the inductance of the inductor coil is Lcoil, the equivalent resistance is Rcoil, and the metal foreign object can be regarded as an inductor L coupled with the inductor coil. MO and the equivalent resistance R MO When a metal foreign body approaches, the impedance of the coil can be expressed as:

[0053]

[0054]

[0055] Right now

[0056]

[0057]

[0058] Where w is the angular frequency, and M is the mutual inductance between the inductor and the metal foreign object. This formula shows that the proximity of a non-ferromagnetic metal foreign object reduces the inductor's equivalent inductance and increases its equivalent impedance. In a wireless charging system, the loop coil can be considered the inductor coil, and the positioning coil can be considered the metal foreign object. During charging, the proximity of the positioning coil to the loop coil increases its impedance. This impedance change can be used to determine the position of the positioning coil, and thus the receiver's position, enabling precise positioning.

[0059] See Figure 5 In order to facilitate the detection of impedance, a resonant circuit is connected to both the loop coil and the positioning coil in the present invention, and the resonant frequency of the resonant circuit at the loop coil is close to that of the resonant circuit at the positioning coil (within 500K), so that the inductive reactance of the circuit is 0, that is, L MO is 0, and the impedance of each coil unit is expressed as follows:

[0060]

[0061] Among them, Z s is the impedance of the coil unit, R coil is the equivalent resistance of the coil unit, w0 is the angular frequency, M is the mutual inductance coefficient between the coil unit and the positioning coil, R MO It is the equivalent resistance of the positioning coil coupled to the coil unit.

[0062] To determine the position of the positioning coil, it is actually necessary to determine the distance between the positioning coil and each coil unit. This distance is reflected in the impedance change of the coil unit. Therefore, the present invention determines the actual position of the positioning coil by the impedance change of the coil unit. The formula for the impedance change is:

[0063]

[0064] Where ΔZ s is the impedance change of the coil unit, w0 is the angular frequency, M is the mutual inductance coefficient between the coil unit and the positioning coil, R MO It is the equivalent resistance of the positioning coil coupled to the coil unit.

[0065] During measurement, since the impedance of the coil unit cannot be measured directly, the present invention reflects its impedance change by detecting the voltage amplitude change of the coil unit in real time. The voltage and impedance satisfy Ohm's law, and the voltage amplitude change can be converted into impedance change through Ohm's law.

[0066] Specifically, the alignment method of the wireless charging alignment guidance system includes:

[0067] Establish a two-dimensional coordinate system with the center of the Loop coil as the origin;

[0068] Calculate the impedance change of each coil unit on the Loop coil;

[0069] Calculate the coordinates of the positioning coil according to the impedance change;

[0070] The receiving end is guided according to the coordinates of the positioning coil.

[0071] See Figure 6 The alignment method of the present invention is described using a loop coil comprising 16 coil units as an example. A two-dimensional coordinate system is first established with the center point o of the loop coil as the coordinate origin. Each coil unit corresponds to a two-dimensional coordinate. When the receiving end and the transmitting end are aligned, the impedance of each coil unit will change. When a sinusoidal current flows through it, the voltage change of each coil unit is also different. The voltage change is proportional to the impedance, and therefore the distance from the positioning coil is also proportional. The position of the coil unit from the positioning coil is different, and the amplitude of its impedance increase is also different. During alignment, the controller first detects the voltage change of each coil unit and converts it into an impedance change. Then, a weighted calculation is performed based on its two-dimensional coordinates. The formula can be expressed as:

[0072]

[0073]

[0074] Among them, x and y are the horizontal and vertical coordinates of the positioning coil, respectively, ΔZ1 to ΔZ n The impedance change of each coil unit, ΔZ avg is the average impedance change of the coil unit, X1 to X n The horizontal coordinates of each coil unit, Y1 to Y n is the vertical coordinate of each coil unit.

[0075] After calculating the coordinates of the positioning coil, the positioning coil can be moved to the origin of the two-dimensional coordinate system. Since the origin of the two-dimensional coordinate system is also the midpoint of the loop coil, and the loop coil is located on the transmitter and the positioning coil is located on the receiver, by aligning the positioning coil with the origin, the receiver and transmitter can be accurately aligned. To facilitate user positioning guidance, a display screen can also be set up on the vehicle to display the position of the receiver in the two-dimensional coordinate system. The user can directly determine the position of the receiver and transmitter based on the display screen (the origin can be regarded as the transmitter), so as to facilitate positioning guidance of the receiver and transmitter.

[0076] For the solution of aligning a single positioning coil, it cannot determine the angle between the transmitter on the ground and the receiver on the car. Therefore, it cannot ensure whether the wireless charging receiver and transmitter are completely aligned during charging. The deviation between the angles will lead to a decrease in charging efficiency. To solve this problem, the present invention proposes an alignment method for two positioning coil plates.

[0077] See Figure 7 This is a schematic diagram of the wireless charging alignment guidance system with two positioning coil plates. When the alignment function is enabled, to prevent the two positioning coil plates from having a cumulative effect on the loop coil impedance change, resulting in inaccurate test results, the present invention controls the resonant circuits connected to the two positioning coil plates to conduct at different switching frequencies, thereby avoiding the cumulative effect. In this case, the coordinates of the positioning coils are calculated based on the impedance change, including:

[0078] Calculate the coordinates of the two positioning coil plates according to the impedance change;

[0079] Calculate the coordinates of the midpoint of the line connecting the two positioning coil plates as the coordinates of the positioning coil.

[0080] See Figure 8 , m and n are the coordinates of the two positioning coil plates, q is the midpoint of the line connecting m and n, then their distance and offset angle are:

[0081]

[0082]

[0083]

[0084]

[0085] Where d is the distance between the positioning coil and the origin, θ1 is the offset angle of the car, x1, x2, and x3 are the horizontal coordinates of the two positioning coil plates and the positioning coil respectively, and y1, y2, and y3 are the vertical coordinates of the two positioning coil plates and the positioning coil respectively.

[0086] Through this method, the position of the positioning coil and the offset angle of the car can be determined simultaneously. According to the position of the positioning coil and the offset angle of the car, the position of the wireless charging receiver can be adjusted, thereby achieving precise positioning between the receiver and the transmitter.

[0087] Compared with the prior art, the wireless charging alignment guidance system and alignment method proposed in the present invention can better align the receiving end and the transmitting end before charging, thereby improving charging efficiency.

[0088] The above embodiments are only used to illustrate the specific implementation methods of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and changes can be made without departing from the concept of the present invention. These modifications and changes should all fall within the scope of protection of the present invention.

Claims

1. A method for aligning a wireless charging alignment guide system, characterized in that: The wireless charging alignment guidance system includes a transmitter and a receiver, wherein the transmitter includes a loop coil and the receiver includes a positioning coil; The alignment method of the wireless charging alignment guide system includes: Establish a two-dimensional coordinate system with the center of the Loop coil as the origin; Calculating the impedance change of each coil unit on the loop coil; Calculating the coordinates of the positioning coil according to the impedance change; Performing alignment guidance on the receiving end according to the coordinates of the positioning coil; The coordinates of the positioning coil are calculated according to the impedance change, and the formula is: ； ； Wherein, x and y are the horizontal and vertical coordinates of the positioning coil respectively. to is the impedance change of each coil unit, is the average impedance change of the coil unit, X1 to X n The horizontal coordinates of each coil unit, Y1 to Y n is the ordinate of each coil unit.

2. The alignment method according to claim 1, wherein: When the positioning coil includes two positioning coil plates, calculating the coordinates of the positioning coil according to the impedance change includes: Calculating the coordinates of the two positioning coil plates according to the impedance change; The coordinates of the midpoint of the line connecting the two positioning coil plates are calculated as the coordinates of the positioning coil.

3. The alignment method according to claim 2, wherein: The two positioning coil plates The calculation formula for the coordinates of the midpoint of the connecting line is: ； ； in, 、 、 They are the two positioning coil plates and the horizontal coordinates of the positioning coils, 、 、 They are the two positioning coil plates and the vertical coordinates of the positioning coils respectively.

4. A wireless charging alignment guiding system using the alignment method according to any one of claims 1 to 3, characterized in that: The transmitting end includes a transmitting end aluminum plate, a transmitting end magnetic core, and a transmitting end coil; the receiving end includes a receiving end aluminum plate, a receiving end magnetic core, and a receiving end coil; when the positioning coil approaches the loop coil, the impedance of the loop coil can change; the wireless charging alignment guidance system determines the position of the receiving end according to the impedance change of the loop coil to achieve alignment guidance.

5. The wireless charging alignment guidance system according to claim 4, characterized in that: The Loop coil includes a plurality of coil units wound on a PCB board, and each of the coil units can be used as an independent coil.

6. The wireless charging alignment guidance system according to claim 5, characterized in that: The positioning coil includes two positioning coil plates, and the connection line of the two positioning coil plates is perpendicular to the setting direction of the receiving end; Or the positioning coil includes four positioning coil plates, and the four positioning coil plates are respectively installed at the four vertex corners of the receiving end.

7. The wireless charging alignment guidance system according to claim 5, characterized in that: The loop coil and the positioning coil are both connected to a resonant circuit, and the resonant frequency of the resonant circuit at the loop coil is similar to the resonant frequency of the resonant circuit at the positioning coil.

8. The wireless charging alignment guidance system according to claim 6, characterized in that: When the positioning coil includes two positioning coil plates, each positioning coil plate is connected to a resonant circuit, and the two resonant circuits have the same resonant frequency and different switching frequencies.

9. The wireless charging alignment guidance system according to claim 7, characterized in that: When the positioning coil is close to the loop coil, the impedance change of each coil unit is: ； in, is the impedance change of the coil unit, is the angular frequency, is the mutual inductance coefficient between the coil unit and the positioning coil, It is the equivalent resistance of the positioning coil coupled to the coil unit.

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