A precise positioning method for planar array coils of wireless power transmission system

Abstract

The application discloses a wireless power transmission system plane array coil precision positioning method, and belongs to the wireless power transmission field, which comprises a wireless power transmission plane array transmitting coil and receiving coil coupling mechanism, a transmitting coil precision positioning method and positioning precision required by the system m Method; preliminarily divide the positioning area according to the positioning precision; find the reference point in the area A ij According to the formula, correct the positioning area A ij , find the reference point in the next area combined with the correction result, obtain all the positioning areas and the positioning reference points in the areas, and then obtain the accurate position of the transmitting coil. The application reduces the influence of the position change of the receiving coil and the transmitting coil on the transmission power fluctuation in the wireless power transmission process, and improves the stability of the wireless charging.

Description

Technical Field

[0001] This invention belongs to the field of wireless power transmission, and specifically relates to a method for precise positioning of planar array coils in a wireless power transmission system. Background Technology

[0002] As wireless power transfer technology for electric vehicles (EVs) gradually develops, changes in the positions of the receiving and transmitting coils during wireless charging will affect fluctuations in the transmitted power. Therefore, the positioning of the receiving coil installed in the EV plays a crucial role. Summary of the Invention

[0003] The purpose of this invention is to provide a method for locating the receiving coil of a wireless power transmission system, thereby solving the problem of locating the relative positions of the receiving coil and the transmitting coil in an electric vehicle.

[0004] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0005] A method for precise positioning of planar array coils in a wireless power transmission system includes: a coupling mechanism between the transmitting and receiving coils of the planar array wireless power transmission system, a precise positioning method for the transmitting coil, and the positioning accuracy required by the system. method;

[0006] The wireless power transmission planar array transmitting and receiving coil coupling mechanism includes transmitting coils that are stacked and positioned to minimize the cross-coupling coefficient. The parameters of the transmitting coils include the power supply frequency, amplitude, internal resistance, internal resistance of the transmitting coil, mutual inductance, and compensation capacitor, and all parameters are identical. The receiving coil is positioned above the transmitting coils.

[0007] Model for calculating the coordinates of the transmitting coil positioning point:

[0008] When the center point of the receiving coil is located at O p At point 1, the current in the four transmitting coils is 1. When the center point of the receiving coil is located At point 1, the current in the four transmitting coils is 1. In clustering, a set of samples can be viewed as a set of points in a vector space, and the similarity between samples can be represented by the distance in that space.

[0009] Preferably, to describe the current change from point p to point q at the center of the receiving coil, the Euclidean distance between the currents at the two points is taken, and denoted as... Its expression is: ,when At that time, it must be satisfied , , , This indicates that point p and point q coincide; if there are two or more points... , making When the positioning error is the smallest, select the point with the smallest positioning error.

[0010] Preferably, a reference point is determined in the positioning area, and the coordinate information of the reference point and the corresponding current information of the four transmitting coils are established in a database; during the actual positioning process, the current information of the four transmitting coils of the point to be positioned is compared with the reference point, and the coordinates of the point to be positioned are calculated based on the coordinate information of the reference point.

[0011] Preferably, the specific method for calculating the coordinates of the positioning point is as follows:

[0012] The curves showing the relationship between the y-axis coordinate and the current value I differ under different x-coordinate values. The variation patterns of the curves for currents I1, I2, I3, and I4 with x-axis coordinate values ​​under different y-axis coordinate values ​​were observed. Using the CurveFitting toolbox in MATLAB, the curves of currents I1, I2, I3, and I4 with y-axis coordinate values ​​were fitted to obtain the functional relationship between current I and the y-axis. The derivative of this function was then derived, allowing for an approximate calculation of the current change caused by changes in the y-axis. Therefore, the region is obtained. Middle Reference Point To the testing point Current change caused by change in the vertical coordinate The reference point is obtained by measuring the change in current between two points and the Euclidean distance between the currents at those two points. To the testing point Changes in the vertical axis and changes in the horizontal axis ;

[0013] The current of each transmitting coil varies significantly in different areas. To ensure high positioning accuracy, different positioning areas are defined, and a reference point is located within each area. The required positioning accuracy... This determines the number of positioning areas, the size of the positioning areas, and the positioning reference points within the areas.

[0014] The preferred method for precise positioning of planar array coils is as follows:

[0015] Step 1: Determine the required positioning accuracy for the system. Based on the determined positioning accuracy, the system initially and roughly divided the system into m×n positioning areas. This represents the region in the i-th row and j-th column of the divided region;

[0016] Step 2: Find the best reference point in different areas. The coordinates of the top left corner are The step size is l, the length in the x-axis direction is l1, and the length in the y-axis direction is l2, where l1 and l2 are multiples of the step size l. All reference points in the region are obtained according to the step size. For all reference points, (m+n) constraints are proposed to optimize the reference points, thereby selecting the best reference point.

[0017] Step 3: Optimize the positioning area using reference points. The correction is performed by dynamically adjusting the lengths of l1 and l2, and arranging and combining the six possible cases of the constraint results to obtain a total of nine regional correction results.

[0018] Step 4: Results of the area correction in Step 3. Return to Step 2 to continue optimizing the reference point for the next area.

[0019] Repeat steps 2 to 4 until all positioning areas and the best reference point within each area are obtained that meet the positioning accuracy requirements.

[0020] Compared with the prior art, the present invention, employing the above technical solution, has the following beneficial effects:

[0021] This invention provides a method for precise positioning of planar array coils in a wireless power transmission system, which optimizes the positioning problem of the relative positions of the receiving coil and the transmitting coil in an electric vehicle, reduces the fluctuation of transmission power during wireless power transmission caused by changes in the positions of the receiving coil and the transmitting coil, and thus improves the stability of wireless charging. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a flowchart of a planar array coil precise positioning strategy based on region division provided by the present invention;

[0024] Figure 2 This is a structural diagram of the wireless power transmission planar array transmitting coil and receiving coil coupling mechanism provided by the present invention;

[0025] Figure 3 This is the equivalent circuit diagram of the wireless power transmission planar array transmitting coil and receiving coil coupling mechanism provided by the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] See Figure 1 , Figure 2 and Figure 3 The present invention provides a method for locating a receiving coil in a wireless power transmission system, comprising: a coupling mechanism between a wireless power transmission planar array transmitting coil and a receiving coil, a specific calculation method for the coordinates of the positioning point, and a precise positioning method for the planar array coil;

[0028] A wireless power transmission planar array transmitting coil and receiving coil coupling mechanism includes: the transmitting coils are stacked, positioned to minimize the cross-coupling coefficient, and all parameters of the transmitting coils are identical, including: the frequency, amplitude, and internal resistance of the power supply; the internal resistance, mutual inductance, and compensation capacitor of the transmitting coils; and the receiving coil is positioned above the transmitting coils.

[0029] Optionally, in some embodiments, the transmitting coil consists of four square coils stacked together, and the placement position minimizes the cross-coupling coefficient. The four transmitting coils are stacked, and by properly placing the transmitting coils, the cross-coupling coefficient can be minimized. The receiving coil is at a certain height from the four transmitting coils.

[0030] In this embodiment, the KVL equations for the four transmitting coils and one receiving coil are written as follows:

[0031] (1)

[0032] In the formula, An AC voltage source supplies power to the four transmitting coils, and all four AC voltage sources have the same frequency. These are the currents in the four transmitting loops, It is the current in the receiving coil circuit, R S1 R S2 R S3 R S4R1, R2, R3, R4, and R5 represent the internal resistances of the four voltage sources, respectively; R1, R2, R3, R4, and R5 represent the internal resistances of the first, second, third, and fourth transmitting coils and the receiving coil, respectively; L1, L2, L3, L4, and L5 represent the inductances of the first, second, third, and fourth transmitting coils and the receiving coil, respectively; C1, C2, C3, C4, and C5 represent the compensation capacitors of the first, second, third, fourth, and receiving coils, respectively; M represents the internal resistance of the four voltage sources, respectively; R1, R2, R3, R4, and R5 represent the internal resistances of the first, second, third, and fourth transmitting coils and the receiving coil, respectively; C1, C2, C3, C4, and C5 represent the compensation capacitors of the first, second, third, fourth, and receiving coils, respectively. 15 M 25 M 35 M 45 The mutual inductance M between the first transmitting coil and the receiving coil, the second transmitting coil and the receiving coil, the third transmitting coil and the receiving coil, and the fourth transmitting coil and the receiving coil, respectively. 12 M 13 M 14 M 23 M 24 M 34 The cross-coupling mutual inductances R between the first and second transmitting coils, the first and third transmitting coils, the first and fourth transmitting coils, the second and third transmitting coils, the second and fourth transmitting coils, and the third and fourth transmitting coils, respectively. load This is the load for the receiving coil circuit.

[0033] After properly placing the four transmitting coils, the cross-coupling mutual inductance between the transmitting coils can be ignored in theoretical analysis, that is... Furthermore, the parameters, structure, and function of each transmitting coil element are completely identical, that is... The internal resistance of each transmitting coil and the internal resistance of the receiving coil are approximately equal, that is... Formula (1) can be simplified to

[0034] (2)

[0035] make

[0036] (3)

[0037] At this point, formula (2) can be simplified to

[0038] (4)

[0039] The expression for the current I5 in the receiving coil circuit can be obtained as follows:

[0040] (5)

[0041] The loop current expressions for the four transmitting coils can be obtained as follows:

[0042] (6)

[0043] As can be seen from equation (5), there is a corresponding relationship between the current of each transmitting coil and the mutual inductance between the receiving coils. In the planar array transmitting coil WPT system, when the spatial position of the receiving coil changes, the mutual inductance M between each transmitting coil and the receiving coil increases. 15 M 25 M 35 M 45 The currents I1, I2, I3, and I4 of each transmitting coil will change, meaning there will be a corresponding relationship between the center coordinates (x, y) of the receiving coil.

[0044] The specific calculation method for the coordinates of the positioning point includes:

[0045] The curves showing the relationship between the y-axis coordinate and the current value I differ under different x-coordinate values. We can observe the changing patterns of the curves for currents I1, I2, I3, and I4 with different y-axis coordinate values. By fitting the curves of currents I1, I2, I3, and I4 with the y-axis coordinate values ​​using the CurveFitting toolbox in MATLAB, we can obtain the functional relationship between current I and the y-axis. Furthermore, we can derive the derivative of this function, thereby approximately calculating the current change caused by changes in the y-axis. Therefore, the region can be obtained. Middle Reference Point To the testing point Current change caused by change in the vertical coordinate The reference point can be obtained by measuring the change in current between two points and the Euclidean distance between those currents. To the testing point Changes in the vertical axis and changes in the horizontal axis .

[0046] Precise positioning methods for planar array coils include:

[0047] See Figure 1 As a specific embodiment of the wireless power transmission system receiving coil positioning method provided by the present invention, the specific process of the planar array coil precise positioning method is as follows:

[0048] Step 1: Determine the required positioning accuracy for the system. Based on the determined positioning accuracy, the system initially and roughly divided the system into m×n positioning areas. This represents the region in the i-th row and j-th column of the divided region;

[0049] Step 2: Find the best reference point in different areas. The coordinates of the top left corner are The step size is l, the length in the x-axis direction is l1, and the length in the y-axis direction is l2, where l1 and l2 are multiples of the step size l. All reference points in the region are obtained according to the step size. For all reference points, (m+n) constraints are proposed to optimize the reference points and select the best reference point.

[0050] Step 3: Optimize the positioning area using reference points. The correction is performed by dynamically adjusting the lengths of l1 and l2, and arranging and combining the six possible cases of the constraint results to obtain a total of nine regional correction results.

[0051] Step 4: Combining the regional correction results from Step 3, return to Step 2 to continue optimizing reference points for the next region.

[0052] Step 5: Repeat steps 2 to 4 until all positioning areas and the best reference point within each area are obtained that meet the positioning accuracy requirements.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for precise positioning of planar array coils in a wireless power transmission system, characterized in that, include: Step S1: Construct a wireless power transmission planar array transmitting coil and receiving coil coupling mechanism. The coupling mechanism includes transmitting coils, which are stacked and positioned to minimize the cross-coupling coefficient. The parameters of the transmitting coils include: power supply frequency, amplitude, internal resistance, internal resistance of the transmitting coil, mutual inductance, and compensation capacitor, and all parameters are identical. The receiving coil is placed above the transmitting coils. Step S2: Establish a calculation model for the coordinates of the transmitting coil positioning point: When the center point of the receiving coil is located At point 1, the current in the four transmitting coils is 1. When the center point of the receiving coil is located At point 1, the current in the four transmitting coils is 1. In clustering, the sample set is viewed as a set of points in a vector space, and the similarity between samples is represented by the distance in that space. Step S3: Determine the required positioning accuracy for the system. And based on the determined positioning accuracy, a preliminary rough division was made. One location area; Step S4: Find the best reference point in different areas. The coordinates of the top left corner are Step size is , axial length is , axial length is ,in and Step size The reference points are obtained by taking multiples of the step size to find all reference points within the region, and then the optimal reference point is selected. The region... Indicates the first region in the partition. Line 1 The column area; Step S5: Optimize the positioning area using reference points. Make corrections, i.e., make dynamic adjustments. and The length of the region is used to obtain the region correction result; Step S6: Combining the regional correction results from step S5, return to step S4 to continue optimizing the reference point for the next region; Step S7: Repeat steps S4 to S6 until all positioning areas and the best reference point within each area are obtained that meet the positioning accuracy requirements. Step S8: Establish the coordinate information of the optimal reference point and the corresponding current information of the four transmitting coils into the database; Step S9: During the actual positioning process, the current information of the four transmitting coils of the point to be positioned is compared with that of the reference point, and the coordinates of the point to be positioned are calculated based on the coordinate information of the reference point.

2. The method for precise positioning of planar array coils in a wireless power transmission system as described in claim 1, characterized in that, To describe the center point of the receiving coil from Click The change in current at two points is taken as the Euclidean distance between the currents at those two points, and denoted as... Its expression is: ,when At that time, it must be satisfied , , , ,illustrate Point and Points coincide; if there are two or more points , making When the positioning error is the smallest, select the point with the smallest positioning error.

3. The method for precise positioning of planar array coils in a wireless power transmission system as described in claim 1, characterized in that, The specific method for calculating the coordinates of the positioning point is as follows: different Coordinate values Axis coordinate values ​​and current values The curves showing the changes are different; observe the loop currents of the four transmitting coils. and Follow The curves of varying axis coordinate values ​​are in different The variation pattern of the axis coordinate values ​​was analyzed using the Curve Fitting toolbox in MATLAB to study the current. and and The current is obtained by fitting the curve of the axis coordinate values. and By establishing the functional relationship between the axes, and then deriving the derivative of this function, the change in current caused by the change in the ordinate can be approximately calculated. Therefore, the region is obtained. Middle Reference Point To the testing point Current change caused by change in the vertical coordinate ; The reference point is obtained by measuring the change in current at two points and the Euclidean distance between those currents. To the testing point Changes in the vertical axis and changes in the horizontal axis ;in, Indicates the first region in the partition. Line 1 The column area, Indicates the region Reference point in The row number representing the location area The column number represents the location area; The current of each transmitting coil varies greatly in different areas. In order to ensure high positioning accuracy, different positioning areas are divided, and reference points are found in each area. Required positioning accuracy This determines the number of positioning areas, the size of the positioning areas, and the positioning reference points within the areas.

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