CN110645883B - Positioning method for four-detection-coil wireless charging positioning system - Google Patents

Abstract

The invention provides a positioning method for a four-detection-coil wireless charging positioning system, which is used for the wireless charging positioning system with a four-detection-coil structure, and realizes positioning work by calculating the proximity degree of a point to be positioned from a gridding reference point, wherein the proximity degree is described by using a membership function model in a fuzzy mathematical theory. The positioning accuracy is determined by the selection of the membership function and the density of the gridding reference points, and the high-accuracy positioning of the wireless charging system on the receiving coil can be realized.

Description

Positioning method for four-detection-coil wireless charging positioning system

The technical field is as follows:

the invention is used in the field of wireless power transmission, in particular to a positioning method for a four-detection-coil wireless charging positioning system.

Background art:

with the progress and development of human science and technology, the demand of human society for electric energy is increasing day by day, and the electric energy transmission technology is developing rapidly. In recent years, wireless power transmission technology is gaining favor of people with higher safety and convenience, and a plurality of researchers research the wireless power transmission technology, apply basic theories of the wireless power transmission technology to practice and put forward a wireless charging product which can be applied in a marketization mode.

However, during the operation of the wireless charging system, the position of the receiving coil directly affects the operation performance of the system. When the receiving coil and the transmitting coil are misaligned, the mutual inductance between the receiving coil and the transmitting coil is significantly reduced, thereby affecting the transmission power and transmission efficiency of the system, increasing the loss of the system, and adversely affecting the reliability and stability of the system. Especially in the application scenario of wireless charging of electric vehicles, it is difficult to ensure that the transmitting coil is aligned with the receiving coil every time the vehicle is parked due to uncertainty of the behavior of the driver when parking. Therefore, a wireless charging positioning device with reasonable design is needed, which can detect the relative position of the transmitting coil and the receiving coil and feed back the relative position to an operator or a processor, so as to adjust the relative position of the transmitting coil and the receiving coil to realize efficient wireless power transmission.

At present, a four-detection coil positioning scheme is a reasonable wireless power transmission positioning scheme, but the positioning algorithm for the scheme is not researched much, and the positioning accuracy of the system is not high. Therefore, the research of the positioning algorithm is carried out aiming at the device, the positioning precision can be effectively improved, and a simple, quick and feasible wireless charging system positioning scheme is realized.

The invention content is as follows:

the invention aims to solve the problems, and aims to provide: the invention provides a positioning method for a four-detection-coil wireless charging positioning device aiming at a four-detection-coil wireless charging positioning system, which describes the proximity degree of a position to be detected and a reference position through the combination of parameters measured in advance and a membership function model in a fuzzy mathematical theory, thereby realizing the positioning work of the position to be detected.

In order to achieve the purpose, the method adopted by the invention is as follows: a positioning method for a four-detection coil wireless charging positioning system is realized based on a four-coil positioning system, the four-coil positioning device comprises four small detection coils, the four small detection coils are arranged on a plane with the same height as a receiving coil, the central connecting lines of the four balance coils are intersected at the center of the receiving coil, and the relative positions of the detection coils and the receiving coil are fixed; the positioning method comprises the following steps:

1) dividing the space in the positioning range into a plurality of grids;

2) measuring and recording the effective values of the induced voltages of the four detection coils at each gridding reference point and storing the information in a storage device;

3) reading the effective values of the induced voltages of the four coils at the current position after the positioning work is started;

4) and representing the change of the current position and the reference point position by using all the induced voltage information of the four detection coils, as shown in the following formula:

ΔU＝|u_p1-u_r1|+|u_p2-u_r2|+|u_p3-u_r3|+|u_p4-u_r4|

wherein u is_p1,u_p2,u_p3,u_p4Induced voltage values, u, for the four detection coils at the current position_r1,u_r2,u_r3,u_r4Is a certain parameterLighting the stored induction voltage value;

4) describing the proximity degree of the current point and the reference point by using a membership function model and delta U, and defining:

5) and calculating the proximity degree of each reference point and the current point to form a matrix:

6) searching four minimum elements in the matrix delta, and calculating the current position according to the following formula to finish the positioning work:

wherein (x)_a,y_a),(x_b,y_b),(x_c,y_c),(x_d,y_d) Are the coordinates of the corresponding location.

When the system works, the current position detection coil voltage value is compared with the voltage value stored in the memory and is subjected to related operation, so that the positioning work of the current position coil is realized. The basic principle of the positioning method is that the effective value of the induction voltage on the mutual induction coil is determined by the current of the transmitting coil and the mutual inductance between the coils, and the formula (1) is shown as follows:

u＝ωMI (1)

obviously, only the current of the transmitting coil needs to be kept unchanged in each positioning process, the change of the mutual inductance value can be represented by the change of the induced voltage, and the change of the mutual inductance value is related to the relative position of the transmitting coil and the receiving coil, so that the positioning of the receiving coil can be realized by detecting the induced voltage of the coil.

Has the advantages that:

the invention provides an algorithm for a four-detection-coil wireless charging positioning system. The algorithm estimates the current position information through the information of the gridding reference point, is simple to realize, is accurate in positioning, and has certain positive significance for improving the working performance of the wireless power transmission system.

Description of the drawings:

FIG. 1 is a schematic diagram of a four-search coil wireless charging positioning system;

FIG. 2 is a top view of a four-search coil wireless charging positioning system;

FIG. 3 is a grid diagram of a localization space;

FIG. 4 is a schematic diagram of a gridding positioning algorithm;

fig. 5 is a flow chart of a positioning process.

The specific implementation scheme is as follows:

embodiments of the apparatus of the present invention will be described in further detail below with reference to the accompanying drawings.

As shown in fig. 1 to 5, the present invention discloses a positioning method for a four-coil wireless charging positioning system, which is implemented based on a four-coil positioning device, wherein the four-coil positioning system includes four small detection coils, the four small detection coils are arranged on a plane at the same height as a receiving coil, central connecting lines of the four balance coils intersect at the center of the receiving coil, and the relative positions of the detection coils and the receiving coil are fixed.

The four detection coils are arranged on a plane with the same height as the receiving coil, are symmetrically distributed and are fixed relative to the receiving coil, and the induced voltage values of the four detection coils are used as a positioning basis in the positioning process. For each reference point in the grid, effective values of the induced voltages of the four detection coils are obtained when the center of the receiving coil is at the reference point, denoted as u₁,u₂,u₃,u₄And stores these values in the storage device.

And after the positioning process is started, acquiring the voltage values of the four induction coils at the current position. After the actual positioning operation is started, the center of the receiving coil cannot be located at a certain reference point each time, and therefore, a variable is required to be defined to describe the "proximity degree" of the center of the receiving coil from a certain reference point. For the space magnetic field established by the transmitting coil, the space magnetic field has certain symmetry, so that the voltage difference information of a single detecting coil cannot completely represent the change of a space position, and therefore, all induced voltage information of four detecting coils is used for representing the positions of a current position and a reference point, and the following steps are provided:

ΔU＝|u_p1-u_r1|+|u_p2-u_r2|+|u_p3-u_r3|+|u_p4-u_r4| (2)

in order to calculate the coordinates of the center of the receiving coil to be positioned by using the coordinates of the existing reference point, a parameter needs to be defined, the 'proximity degree' of the center of the receiving coil from a certain reference point is described by using a delta U, and the 'proximity degree' of the center of the receiving coil from the certain reference point is described by using a membership function of a fuzzy mathematical theory. Obviously, the smaller Δ U, the greater the proximity of the center of the receiver coil to the reference point, so a membership function with a smaller distribution is selected, and is described here with a normal distribution. When the delta U is less than or equal to 0.01, the approach degree is considered to be 1, and a normal distribution type membership function is selected for description and defined as follows:

after obtaining the voltage effective values of the four detection coils at the current position, calculating the closeness degree of the current position to all reference points according to the formula (3), thereby obtaining an n × n matrix:

operating the elements in the matrix, traversing each element in the matrix, searching for four elements with the maximum value, and recording as the four elements_A,_B,_C,_DThat is, find four reference points nearest to the center of the actual receiving coil position, and its corresponding coordinates are known and are denoted as A (x)_a,y_a),B(x_b,y_b),C(x_c,y_c),D(x_d,y_d) As shown in figure two.

The center coordinates of the receiving coil to be positioned can be determined by the coordinates of the four points and the corresponding proximity degree, namely, the larger the proximity degree is, the higher the weight of the coordinate information is. Thus, the resulting calculations yield the receive coil coordinates:

Claims (1)

1. a positioning method for a four-detection-coil wireless charging positioning system is characterized by comprising the following steps: the positioning method is realized based on a four-coil positioning system, the four-coil positioning system comprises four small detection coils, the four small detection coils are arranged on a plane with the same height as that of a receiving coil, the central connecting lines of the four small detection coils are intersected at the center of the receiving coil, and the relative positions of the detection coils and the receiving coil are fixed; the positioning method comprises the following steps:

1) dividing the space in the positioning range into a plurality of grids;

2) measuring and recording the effective values of the induced voltages of the four detection coils at each gridding reference point and storing the information in a storage device;

3) reading the effective values of the induced voltages of the four coils at the current position after the positioning work is started, and recording u₁,u₂,u₃,u₄；

4) And representing the change of the current position and the reference point position by using all the induced voltage information of the four detection coils, as shown in the following formula:

ΔU＝|u_p1-u_r1|+|u_p2-u_r2|+|u_p3-u_r3|+|u_p4-u_r4|

wherein u is_p1,u_p2,u_p3,u_p4Induced voltage values, u, for the four detection coils at the current position_r1,u_r2,u_r3,u_r4Faradic stored for a certain reference pointA pressure value;

4) describing the proximity degree of the current point and the reference point by using a membership function model and delta U, and defining:

wherein Δ U is the sum of absolute values of differences between induced voltages of the four detection coils and the voltage stored at a certain reference point, as described above;

5) and calculating the proximity degree of each reference point and the current point to form a matrix:

6) searching four minimum elements in the matrix delta, and calculating the current position according to the following formula to finish the positioning work:

wherein (x)_a,y_a),(x_b,y_b),(x_c,y_c),(x_d,y_d) Are the coordinates of the corresponding location.

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