A method for guiding and aligning a wireless charging system and a vehicle

Abstract

The present invention provides a method for guiding and aligning a wireless charging system and a vehicle, belonging to the field of wireless charging devices. The wireless charging system includes a charging transmitting coil connected to a charging power supply in a ground transmitting device, a charging receiving coil connected to a vehicle power battery in a vehicle receiving device, a transmitting coil in the ground transmitting device, and a receiving coil in the vehicle receiving device. The transmitting coil generates an alternating identification magnetic field covering the charging transmitting coil, and the intensity of the identification magnetic field changes with the distance from the center position of the charging transmitting coil in space. There are multiple receiving coils arranged around the center position of the charging receiving coil, or there is 1 receiving coil arranged in the middle of the charging receiving coil, which is used to induce the identification magnetic field to generate an induced electromotive force. The induced electromotive force at the optimal charging position is calibrated and compared with the intensity of the induced electromotive force of the receiving coil detected in real time, so as to infer the relative position relationship between the ground device and the vehicle-mounted device.

Description

Technical Field

[0001] The present invention relates to a method for guiding and aligning a wireless charging system and a vehicle, belonging to the technical field of wireless charging. Background Art

[0002] The conventional charging method commonly used for electric vehicles is wired charging. This charging method has problems such as complex operation and easy occurrence of poor contact. The wireless charging technology can provide a convenient and safe charging method for the power battery of electric vehicles, and can solve the deficiencies existing in the existing wired charging technology.

[0003] However, the existing wireless charging technology requires relatively accurate alignment between the ground-end device and the vehicle-end device. If the alignment is inaccurate, it will have a great impact on the power, efficiency, and electromagnetic radiation of wireless charging, and it is very difficult to achieve alignment only through the manual operation of the driver. The existing wireless charging models in the market do not have a fully automated alignment guidance function. Most of the guidance methods use radar detection methods, but they are not cost-effective due to high prices and are not suitable for large-scale commercial use; the existing low-frequency coil solutions do not have a guidance function and cannot realize the guidance of the charging position. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for guiding and aligning a wireless charging system and a vehicle, which is used to solve the problem that the existing low-frequency coil solution cannot guide the alignment of wireless charging.

[0005] To achieve the above purpose, the present invention provides a method for guiding and aligning a wireless charging system. The wireless charging system includes a charging transmitting coil connected to a charging power supply in a ground transmitting device and a charging receiving coil connected to a vehicle power battery in a vehicle receiving device; it is characterized in that the wireless charging system further includes a transmitting coil provided in the ground transmitting device and a receiving coil provided in the vehicle receiving device; the transmitting coil generates an alternating identification magnetic field covering the charging transmitting coil, and the intensity of the identification magnetic field changes with the distance from the center position of the charging transmitting coil in space; there are multiple receiving coils arranged around the charging receiving coil, or there is 1 receiving coil provided in the middle of the charging receiving coil, which is used to induce the identification magnetic field to generate an induced electromotive force.

[0006] When the vehicle reaches the optimal charging position, the induced electromotive forces of each receiving coil are collected as the reference induced electromotive force of the receiving coil; the optimal charging position is the vehicle position when the charging transmitting coil and the charging receiving coil are directly opposite.

[0007] During the vehicle alignment process, calculate in real time the difference between the induced electromotive force of each receiving coil and the corresponding reference induced electromotive force; the differences of each receiving coil at the same moment reflect the distance from the current position of the vehicle to the optimal charging position, and determine whether the vehicle has reached the optimal charging position according to the differences of each receiving coil.

[0008] The alternating current in the transmitting coil forms an alternating magnetic field, and the receiving coil induces the alternating magnetic field to generate an induced electromotive force. Therefore, the change in the intensity of the induced electromotive force in the receiving coil can reflect the change in the intensity of the alternating magnetic field. Since the intensity of the alternating magnetic field changes with the distance from the center position of the charging transmitting coil in space, the change in the intensity of the induced electromotive force in the receiving coil can reflect the change in the distance between the receiving coil and the center of the charging transmitting coil. By measuring the induced electromotive force of the receiving coil corresponding to the optimal charging position, the distance between the receiving coil and the center of the charging transmitting coil, that is, the optimal charging position, can be obtained, so as to judge whether the vehicle has reached the optimal charging position.

[0009] Further, in the above wireless charging system guiding and alignment method, calculate the eigenvalue according to the differences of each receiving coil; when the eigenvalue is 0, it is considered that the vehicle has reached the optimal charging position; the eigenvalue is the sum of the absolute values of the differences of each receiving coil, or the sum of the squares of the differences of each receiving coil.

[0010] The difference of the above single receiving coil can represent the distance between the position of the corresponding receiving coil and the position of the corresponding receiving coil when the vehicle reaches the optimal charging position. Therefore, by statistically combining the differences of each receiving coil to obtain the eigenvalue, then the eigenvalue has a unique minimum value indicating that the position of the receiving coil at the current position of the receiving coil coincides with the position at the optimal charging position, and at this time the eigenvalue is 0.

[0011] Further, in the above wireless charging system guiding and alignment method, when the eigenvalue shows an increasing trend, take parking braking to make the vehicle reach the optimal charging position.

[0012] The increasing trend of the eigenvalue represents that the distance between the charging transmitting coil and the charging receiving coil reaches the minimum value, indicating that the vehicle has reached the optimal charging position. At this time, apply parking braking to stop the vehicle at the optimal charging position.

[0013] Further, in the above wireless charging system guiding and alignment method, the setting positions of the transmitting coils are arranged in central symmetry with the charging transmitting coil as the center.

[0014] Further, in the above wireless charging system guiding and alignment method, the setting positions of the receiving coils are arranged in central symmetry with the charging receiving coil as the center.

[0015] The present invention also provides a vehicle. A vehicle receiving device for wireless charging includes a charging receiving coil connected to a vehicle power battery. It is characterized in that a receiving coil is further provided in the vehicle receiving device. The receiving coil is used to generate an induced electromotive force in an alternating identification magnetic field. The identification magnetic field covers a charging transmitting coil of a wireless charging system ground transmitting device. The intensity of the identification magnetic field changes with the distance from the center position of the charging transmitting coil in space. There are multiple receiving coils arranged around the charging receiving coil, or there is 1 receiving coil provided in the middle of the charging receiving coil.

[0016] When the vehicle reaches the optimal charging position, the induced electromotive forces of each receiving coil are collected as the reference induced electromotive force of the receiving coil. The optimal charging position is the vehicle position when the charging transmitting coil and the charging receiving coil are directly opposite.

[0017] During the vehicle alignment process, the difference between the induced electromotive force of each receiving coil and the corresponding reference induced electromotive force is calculated in real time. The differences of each receiving coil at the same moment reflect the distance from the current vehicle position to the optimal charging position. According to the differences of each receiving coil, it is judged whether the vehicle reaches the optimal charging position.

[0018] The alternating current in the transmitting coil forms an alternating magnetic field. The receiving coil induces the alternating magnetic field to generate an induced electromotive force. Therefore, the change in the intensity of the induced electromotive force in the receiving coil can reflect the change in the intensity of the alternating magnetic field. Since the intensity of the alternating magnetic field changes with the distance from the center position of the charging transmitting coil in space, the change in the intensity of the induced electromotive force in the receiving coil can reflect the change in the distance between the receiving coil and the center of the charging transmitting coil. By measuring the induced electromotive force of the receiving coil corresponding to the optimal charging position, the distance between the receiving coil and the center of the charging transmitting coil, that is, the optimal charging position, can be obtained. The vehicle uses this to judge whether it reaches the optimal charging position.

[0019] Further, in the above vehicle, by calculating the sum of the absolute values of the differences of each receiving coil or the sum of the squares of the differences of each receiving coil, a characteristic value is obtained. When the characteristic value is the smallest and is 0, it indicates that the vehicle reaches the optimal charging position.

[0020] The difference of the above single receiving coil can represent the distance between the position of the corresponding receiving coil and the position of the corresponding receiving coil when the vehicle reaches the optimal charging position. Therefore, by obtaining the characteristic value through a statistical combination of the differences of each receiving coil, there is a unique minimum value of the characteristic value indicating that the position of the receiving coil at the current position of the vehicle coincides with the position of the receiving coil at the optimal charging position, and at this time the characteristic value is 0.

[0021] Further, in the above vehicle, when the characteristic value shows an increasing trend, the vehicle takes parking braking to achieve the purpose of reaching the optimal charging position.

[0022] The increasing trend of the eigenvalue indicates that the distance between the charging transmitting coil and the charging receiving coil reaches the minimum value, indicating that the vehicle has reached the optimal charging position. At this time, parking braking is performed to stop the vehicle at the optimal charging position.

[0023] Further, in the above vehicle, the identification magnetic field is generated by a transmitting coil arranged around the charging transmitting coil of the ground transmitting device, and the arrangement position of the transmitting coil is centrosymmetrically arranged with the charging transmitting coil as the center.

[0024] Further, in the above vehicle, the arrangement position of the receiving coil is centrosymmetrically arranged with the charging receiving coil as the center. Description of the Drawings

[0025] Figure 1 It is a flowchart of the present invention;

[0026] Figure 2 It is a schematic diagram of the distribution of 4 groups of transmitting coils on the ground end device;

[0027] Figure 3 It is a schematic diagram of the distribution of 4 groups of receiving coils on the vehicle-mounted end device;

[0028] Figure 4 It is a schematic diagram of the position of the ideal alignment state;

[0029] Figure 5 It is a schematic diagram of the relative position of the devices at a certain moment t during the alignment process;

[0030] Figure 6 It is a schematic diagram of the relative position of the devices after a certain moment (t + Δt) during the alignment process;

[0031] Figure 7 It is a schematic diagram of the relationship between the electromotive force difference ΔE and the distance Δr from the center position;

[0032] Figure 8 It is the root mean square value s 2 and the schematic diagram of the relationship between the distance Δr from the center position;

[0033] Figure 9 It is a schematic diagram of the distribution of 3 groups of transmitting coils on the ground end and 2 groups of receiving coils on the vehicle-mounted end. Detailed Embodiment

[0034] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments.

[0035] Method Embodiment:

[0036] In the wireless charging system of the present invention, in addition to the charging transmitting coil on the ground device and the charging receiving coil on the vehicle-mounted device, there are also a transmitting coil on the ground device and a receiving coil on the vehicle-mounted device. The setting of the transmitting coil on the ground device should at least meet the following conditions: the transmitting coil generates an induced magnetic field that covers the charging transmitting coil and changes alternately over time, and the intensity of the induced magnetic field changes with the distance from the center position of the charging transmitting coil in space. In order to form the above-mentioned induced magnetic field, the transmitting coil on the ground device can adopt, for example, Figure 2 the arrangement method of the transmitting coil shown, Figure 2 in which 4 groups of transmitting coils (Transmitting 1, 2, 3, 4) are arranged around the charging transmitting coil on the ground device and are centrosymmetric with the center of the charging transmitting coil. As the receiving coil, it can be arranged around the charging receiving coil. For example, if there is 1 receiving coil, it can be set at the center of the charging receiving coil; if there are multiple receiving coils, they can be arranged around the charging receiving coil. The receiving coil is used to induce the above-mentioned induced magnetic field to generate an induced electromotive force to identify the positional relationship between the charging receiving coil and the charging transmitting coil. Figure 3 Figure 4 shows the distribution diagram of 4 groups of receiving coils on the vehicle-mounted device, and the receiving coils are centrosymmetric with the center of the charging receiving coil.

[0037] As other embodiments, in order to judge the positional relationship between the current position of the vehicle and the optimal charging position through the induced electromotive force of the receiving coil in the induced magnetic field, the induced magnetic field should be centered on the charging transmitting coil; the receiving coil and the charging receiving coil only need to have a relatively close and fixed positional relationship. Therefore, the transmitting coil and the receiving coil can also adopt the arrangement positions shown in Figure 9 Figure 5, Figure 9 in which there are 3 transmitting coils on the ground device and 2 receiving coils on the vehicle-mounted device and are distributed as shown in the figure. The present invention does not limit the number and positional distribution of the transmitting coil and the receiving coil, as long as the above conditions are met.

[0038] As shown in Figure 4 Figure 6, when the ground device and the vehicle-mounted device are opposite to each other, indicating that the charging transmitting coil and the charging receiving coil are opposite to each other, that is, in the optimal position for wireless charging, calculate the induced electromotive force generated by each receiving coil:

[0039]

[0040] Among them, E1 is the induced electromotive force of receiving coil 1, and the unit is V; N 接1 is the number of turns of receiving coil 1; S 接1 is the area of receiving coil 1, and the unit is m²; B 1总 is all the magnetic induction intensities received by receiving coil 1, and the unit is T; B 11The magnetic induction intensity received by the receiving coil 1 from the transmitting coil 1, with the unit of T; B 12 The magnetic induction intensity received by the receiving coil 1 from the transmitting coil 2, with the unit of T; B 13 The magnetic induction intensity received by the receiving coil 1 from the transmitting coil 3, with the unit of T; B 14 The magnetic induction intensity received by the receiving coil 1 from the transmitting coil 4, with the unit of T.

[0041] Set the induced electromotive force of each receiving coil at the optimal charging position as the reference induced electromotive force E ref , since the parameters of each receiving coil are the same, at this time, the magnetic induction intensities received by the 4 receiving coils from the 4 transmitting coils are the same, that is, E ref = E1 = E2 = E3 = E4. The reference induced electromotive force E needs to be measured and corrected multiple times for the same wireless charging system ref . Those skilled in the art should understand that in the case of an asymmetric distribution of receiving coils, the reference induced electromotive forces of each receiving coil should be different.

[0042] As Figure 1 shown in the flowchart of the method of the present invention, after the vehicle enters the detection area, the alignment detection system is started, and the alignment process begins.

[0043] During the alignment process, the ground-end device and the vehicle-mounted device perform relative movement within the time Δt, as follows Figures 5 to 6 process. According to the calculation formulas of the induced electromotive force and the magnetic induction intensity, it can be known that:

[0044]

[0045] In the formula, E is the induced electromotive force of a single receiving coil, with the unit of V; N 接 is the number of turns of this receiving coil; S 接 is the area of this receiving coil, with the unit of ㎡; B 总 is the magnetic induction intensity at the corresponding receiving coil formed by the magnetic fields of all transmitting coils, with the unit of T; μ0 is the magnetic permeability in vacuum, with the unit of N·A -2 ; N is the number of turns of the transmitting coil; I is the current of the transmitting coil, with the unit of A; r is the distance from the receiving coil to the center position of the ground-end device, with the unit of m.

[0046] The above formula shows that the induced electromotive force is related to the slope of the magnetic induction intensity per unit time, that is, E is proportional to Δr. And according to the above formula, when the distance from the center position of the ground-end device is r, the induced electromotive force of the receiving coil at this time is E. Therefore, when the distance from the center position of the ground end is 0, the induced electromotive force of the receiving coil at this time is E ref , the difference E - Eref = ΔE ∝ Δr. The relationship between the electromotive force difference ΔE and the distance Δr from the receiving coil to the center of the ground-end device is as follows Figure 7 shown. When the receiving coil is at the center position of the ground-end device, i.e., Δr is 0, the electromotive force difference ΔE has a minimum value of 0, indicating that the vehicle is in the optimal charging position. During the movement of the vehicle, the movements of the 4 receiving coils are consistent. Therefore, for the same time period Δt, the distances Δr between each receiving coil and the center position of the ground-end device are the same.

[0047] Transmit the induced electromotive force differences ΔE of each receiving coil after Δt time to the controller, and the controller calculates the mean square value s of the real-time induced electromotive force differences ΔE 2 , and the calculation formula is as follows:

[0048] s 2 = (ΔE1 2 + ΔE2 2 + ΔE3 2 + ΔE4 2 )

[0049] In the formula, ΔE1 is the difference between the current induced electromotive force of receiving coil 1 and the reference induced electromotive force, with the unit of V; ΔE2 is the difference between the current induced electromotive force of receiving coil 2 and the reference induced electromotive force, with the unit of V; ΔE3 is the difference between the current induced electromotive force of receiving coil 3 and the reference induced electromotive force, with the unit of V; ΔE4 is the difference between the current induced electromotive force of receiving coil 4 and the reference induced electromotive force, with the unit of V.

[0050] The relationship between the root mean square difference s 2 and the distance Δr from the center position of the charging receiving coil is as follows Figure 8 shown. When the receiving coil is at the center position of the ground-end device, i.e., Δr is 0, the root mean square value s 2 has a minimum value of 0, indicating that the vehicle is in the optimal charging position. The controller calculates the current root mean square value in real time and compares it with the root mean square value calculated at the previous moment. When it is found that the root mean square value has a tendency to increase, the system determines that the current is about to deviate from the optimal alignment position. The controller activates the parking brake function, completes the parking, and transmits a signal to the ground-end device to cut off power and stop working, thus completing the alignment process.

[0051] Those skilled in the art should understand that due to reasons such as calculation accuracy and errors, it is difficult to ensure that the calculated value of the final s 2 is absolutely equal to zero during the implementation of the solution. Therefore, the calculated value of s 2 should also be considered equal to zero within the range that meets the error requirements near zero.

[0052] In addition, through other statistical methods, such as calculating the sum of the absolute values of each induced electromotive force, the same relationship as that with the distance Δr from the center position of the device at the ground end can be obtained, achieving the same effect.

[0053] Vehicle embodiment:

[0054] The present invention also provides a vehicle that adopts the wireless charging system guiding and alignment method described in the above method embodiment. Since the wireless charging system guiding and alignment method has been completely described in the above method embodiment, it will not be elaborated here.

Claims

1. A method for guiding and alignment of a wireless charging system, the wireless charging system comprising a charging transmitting coil connected to a charging power supply in a ground transmitting device and a charging receiving coil connected to a vehicle power battery in a vehicle receiving device; characterized in that, The wireless charging system further includes a transmitting coil disposed in the ground transmitting device and a receiving coil disposed in the vehicle receiving device; the transmitting coil generates an alternating identification magnetic field covering the charging transmitting coil, and the intensity of the identification magnetic field varies spatially with the distance from the center position of the charging transmitting coil; there are multiple receiving coils arranged around the charging receiving coil, or there is 1 receiving coil disposed in the middle of the charging receiving coil, for inducing the identification magnetic field to generate an induced electromotive force; When the vehicle reaches the optimal charging position, the induced electromotive forces of each receiving coil are collected as the reference induced electromotive force of the receiving coil; the optimal charging position is the vehicle position when the charging transmitting coil and the charging receiving coil are facing each other; During the vehicle alignment process, the differences between the induced electromotive forces of each receiving coil and the corresponding reference induced electromotive forces are calculated in real time; the differences of each receiving coil at the same moment reflect the distance from the current vehicle position to the optimal charging position, and based on the differences of each receiving coil, it is judged whether the vehicle has reached the optimal charging position.

2. The method for guiding and aligning a wireless charging system according to claim 1, wherein A characteristic value is calculated according to the differences of each receiving coil; when the characteristic value is 0, it is considered that the vehicle has reached the optimal charging position; the characteristic value is the sum of the absolute values of the differences of each receiving coil, or the sum of the squares of the differences of each receiving coil.

3. The method for guiding and aligning a wireless charging system according to claim 2, wherein When the characteristic value shows an increasing trend, parking braking is taken to enable the vehicle to reach the optimal charging position.

4. The method for guiding and aligning a wireless charging system according to claim 3, wherein The setting position of the transmitting coil is arranged in central symmetry with the charging transmitting coil as the center.

5. The method for guiding and aligning a wireless charging system according to claim 4, wherein The setting position of the receiving coil is arranged in central symmetry with the charging receiving coil as the center.

6. A vehicle, wherein a vehicle receiving device for wireless charging includes a charging receiving coil connected to a vehicle power battery; characterized in that, A receiving coil is further disposed in the vehicle receiving device, and the receiving coil is used to generate an induced electromotive force in the alternating identification magnetic field, and the identification magnetic field covers the charging transmitting coil of the ground transmitting device of the wireless charging system, and the intensity of the identification magnetic field varies spatially with the distance from the center position of the charging transmitting coil; there are multiple receiving coils arranged around the charging receiving coil, or there is 1 receiving coil disposed in the middle of the charging receiving coil; When the vehicle reaches the optimal charging position, the induced electromotive forces of each receiving coil are collected as the reference induced electromotive force of the receiving coil; the optimal charging position is the vehicle position when the charging transmitting coil and the charging receiving coil are facing each other; During the vehicle alignment process, the differences between the induced electromotive forces of each receiving coil and the corresponding reference induced electromotive forces are calculated in real time; the differences of each receiving coil at the same moment reflect the distance from the current vehicle position to the optimal charging position, and based on the differences of each receiving coil, it is judged whether the vehicle has reached the optimal charging position.

7. The vehicle according to claim 6, characterized in that, By calculating the sum of the absolute values of the differences of each receiving coil or the sum of the squares of the differences of each receiving coil, a characteristic value is obtained; when the characteristic value is the smallest and is 0, it indicates that the vehicle has reached the optimal charging position.

8. The vehicle according to claim 7, characterized in that, When the characteristic value shows an increasing trend, the vehicle takes parking braking to achieve the purpose of reaching the optimal charging position.

9. The vehicle according to claim 8, characterized in that The identification magnetic field is generated by a transmitting coil disposed around the charging transmitting coil of the ground transmitting device, and the setting position of the transmitting coil is arranged in central symmetry with the charging transmitting coil as the center.

10. The vehicle according to claim 9, characterized in that, The set positions of the receiving coils are arranged in central symmetry with the charging receiving coil as the center.

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