Method and device for measuring magnetic field intensity of high-temperature superconducting maglev transportation system

Abstract

A method and device for measuring the magnetic field intensity of a high-temperature superconducting maglev transportation system. The method comprises: determining the upper surface of a permanent magnet track as a magnetic field intensity reference (S1); constructing a chord reference-multi-point chord measurement system to detect irregularities on the upper surface of the permanent magnet track, chord measurement system configurations including a system sampling interval, a system order and a chord measurement configuration (S2); calculating chord measurement values of a plurality of measurement point positions in middle on the basis of the multi-point chord measurement system, and in combination with a least squares method, constructing an inversion model of the measurement system, wherein the inversion model refers to reconstructing an original track irregularity waveform from the chord measurement values of the chord reference, and track irregularities recovered on the basis of the inversion model represent the vertical displacement of the chord reference (S3); on the basis of an optimal chord measurement configuration of the multi-point chord system, determining arrangement positions of gap sensors, and arranging a Hall sensor array in a magnetic field intensity measurement direction (S4); and correcting a reference position on the basis of the vertical displacement of the chord reference, and on the basis of Hall sensor measurement results, using an interpolation method to calculate a magnetic field intensity distribution at any height above the reference (S5). The present invention proposes for the first time to combine a multi-point chord measurement principle to measure magnetic field intensity distribution irregularities of the permanent magnet track in high-temperature superconducting maglev transportation, and the measurement results can be used for evaluating magnetic field intensity irregularities of the permanent magnet track of a high-temperature superconducting maglev transportation system and adjusting the attitude of the permanent magnet track.

Description

A method and device for measuring magnetic field strength of a high-temperature superconducting maglev transportation system Technical Field

[0001] The present invention relates to the technical field of maglev transportation, and in particular to a method and device for measuring the magnetic field intensity of a high-temperature superconducting maglev transportation system. Background Art

[0002] The high-temperature superconducting maglev transportation system is a self-stabilizing system without suspension-guidance control. Its basic principle is to utilize the pinning effect of Type II non-ideal high-temperature superconducting materials. The permanent magnetic track provides a magnetic source for the high-temperature superconducting bulk material. The magnetic flux lines pass through the pinning centers in the superconductor, causing the superconductor to obtain a portion of the magnetic flux. When the high-temperature superconductor in a mixed state moves, according to Lenz's law, the magnetic field environment in which the superconductor is located changes, resulting in the generation of induced current inside it. The interaction between the induced current and the permanent magnetic track generates a pinning force that prevents the superconductor from returning to its initial position. It manifests as a suspension force in the vertical direction and as a guiding force in the horizontal direction.

[0003] High-temperature superconducting maglev transportation systems are currently at a critical stage of transitioning from the laboratory to engineering applications. For these systems, the levitation and guidance forces required for safe and high-speed operation of maglev vehicles are provided by the interaction between the superconductor's induced magnetic field and the magnetic field of the permanent magnet track. This presents a new challenge: the uneven magnetic field intensity in the permanent magnet track. The permanent magnet track system provides the sole magnetic field input source for the high-temperature superconducting maglev system. This uneven magnetic field intensity directly alters the levitation gap of the maglev vehicle. Given the strong nonlinear relationship between the superconductor's levitation force and the levitation gap, even small changes in the levitation gap caused by magnetic field unevenness can cause the superconductor to continuously oscillate. Furthermore, superconductors are subject to unavoidable issues such as magnetostriction, stress concentration caused by pinning defects, and alternating induced current losses. These defects, when combined with the influence of magnetic field unevenness, can, in severe cases, cause the superconductor's levitation and guidance functions to fail, compromising the safety of maglev train operations.

[0004] Measuring magnetic field strength irregularities in permanent magnet tracks of high-temperature superconducting maglev systems is a challenging issue, affecting the entire lifecycle of maglev systems, from design and optimization to construction and operation and maintenance. Measurements of permanent magnet track magnetic field strength provide data support and a scientific basis for evaluating magnetic field irregularities and optimizing track posture. Currently, a detection method with high efficiency, high accuracy, and low cost is urgently needed. To improve the technical framework for measuring permanent magnet track strength in high-temperature superconducting maglev systems, this paper proposes a method and device for measuring magnetic field strength in high-temperature superconducting maglev systems.

[0005] Summary of the Invention

[0006] In order to solve the problem of uneven detection of magnetic field strength in high-temperature superconducting maglev transportation systems in the prior art, the present invention provides a method and device for measuring magnetic field strength in high-temperature superconducting maglev transportation systems, which solves the problem of magnetic field strength detection above the permanent magnet track mentioned in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for measuring the magnetic field strength of a high-temperature superconducting maglev transportation system, comprising the following steps:

[0008] S1. Determine the upper surface of the permanent magnet rail as the reference for magnetic field strength;

[0009] S2. Construct a chord benchmark-multi-point chord measurement system to detect surface irregularities on the permanent magnet rail. The chord measurement system configuration includes the system sampling interval, system order, and chord measurement configuration.

[0010] S3. Calculate the chordal measurements at multiple intermediate measurement points based on the multi-point chordal measurement system and construct an inversion model of the measurement system using the least squares method. The inversion model reconstructs the original track irregularity waveform from the chordal measurements of the chordal reference. The track irregularity restored according to the inversion model is the vertical displacement of the chordal reference.

[0011] S4. Based on the optimal string measurement configuration of the multi-point string system, determine the layout position of the gap sensor and arrange the Hall sensor array along the direction of measuring the magnetic field strength;

[0012] S5. Correct the reference reference position based on the up and down displacement of the chord reference, and calculate the magnetic field intensity distribution at any height above the reference reference using an interpolation method based on the Hall sensor measurement results.

[0013] Preferably, in step S2, the system sampling interval is Δs, and the system order calculation formula is as follows: γ=L / Δs

[0014] Where γ represents the system order, L represents the system chord length, and Δs represents the sampling step size.

[0015] Preferably, in step S3, the chord measurement values ​​of the middle multiple measuring points are calculated based on the multi-point chord measurement system, and the formula is as follows: G = H·Z Z

[0016] Where G is the chord measurement matrix, H is the measurement matrix, and Z Z is the irregularity vector matrix of the permanent magnet track;

[0017] The chord measurement matrix G is expressed as follows:

[0018] Where G(i) is the chord measurement value of all measuring points when the chord reference starting point is at measuring point i, g n-1,i is the chord measurement value of measuring point n-1 when the chord reference starting point is measuring point i;

[0019] The corresponding measurement matrix H of the chord reference full configuration is as follows:

[0020] The measurement matrix H has n-1 rows and n+1 columns. The number of rows corresponds to the number of fully configured measurement points, and the number of columns is consistent with the dimension of the irregularity vector covered by the chord datum including the endpoints. n-1 [k] is the convolution kernel corresponding to the measurement point n-1, and the elements in the first and n+1 columns correspond to the segmentation ratio γ of the measurement point i i and The middle columns 2 to n are unit matrices with a dimension of (n-1);

[0021] The permanent magnet track irregularity vector matrix Z corresponding to each column of the chord measurement matrix G Z As shown below:

[0022] Where z i is the irregularity vector corresponding to the chord reference position i.

[0023] Preferably, the inversion model is constructed in combination with the least squares method, and the optimal solution is obtained under the condition that the track irregularity waveform reconstructed and restored by the inversion model is closest to the actual track irregularity to ensure the accuracy of the measurement results. The optimal solution satisfies the following formula:

[0024] Where H is the measurement matrix, G is the chord measurement matrix, and Z * The optimal solution is the restored waveform of the uneven permanent magnet track.

[0025] Preferably, the operator ζ is constructed in the inversion model of the measurement system to ensure the stability of the solution and output the permanent magnet track unevenness recovery waveform Z * , the operator expression is as follows:

[0026] Where H is the measurement matrix, T is the matrix transpose operation, β is the regularization coefficient, ranging from 0.001 to 0.005, I is the unit matrix, and i is the measurement point position;

[0027] The restored waveform output is as follows: Z * =ζ·G

[0028] Where Z * is the permanent magnet track unevenness recovery waveform, G is the chord measurement matrix, and ζ is the operator.

[0029] Preferably, in step S4, based on the optimal string measurement configuration of the multi-point string system, the gap sensor arrangement position is determined, and the Hall sensor array is arranged along the direction of measuring the magnetic field strength, and j Hall sensors are arranged at each measuring point position to obtain the Hall sensor measurement matrix B;

[0030] Where B n-1,j is the measurement value of the jth sensor at the measuring point n-1 and in the measuring direction.

[0031] Preferably, the optimal chord measurement configuration is the optimal sensor installation position, and the optimal chord measurement configuration meets the following conditions: (1) the common divisor of the distance between each measuring point is 1, ensuring the stability of the measurement system and the subsequent inversion model, thereby ensuring the accuracy of the chord measurement value and the restored track irregularity; (2) the measurable wavelength is maximized under the measurement accuracy requirement to ensure the availability of the measurement results; (3) the measurement error requirement is met to ensure the accuracy of the measurement results.

[0032] Preferably, in step S5, the corrected reference reference position is obtained by subtracting the vertical displacement from the initial position of the string reference, and the magnetic field intensity distribution at any height above the reference reference is calculated using the interpolation method based on the Hall sensor measurement result, and the formula is expressed as follows: R * =RZ * B * =interpl(R * ,B,s)

[0033] Where R * is the corrected string reference position, R is the initial position, B * is the magnetic field intensity at position s in the interpolated measurement direction.

[0034] On the other hand, to achieve the above-mentioned purpose, the present invention further provides the following technical solution: a device for measuring the magnetic field strength of a high-temperature superconducting maglev transportation system, the device comprising:

[0035] Trolley main frame, running wheels, sensor mounting bracket, measuring string mounting bracket, measuring string, Hall sensor mounting hole, gap sensor mounting hole, encoder;

[0036] The traveling wheel is connected to the trolley main frame through a bearing; the sensor mounting bracket and the measuring string mounting bracket are both fixedly connected to the trolley main frame; the sensor mounting bracket is provided with a Hall sensor mounting hole for fixedly mounting a Hall sensor and a gap sensor mounting hole for fixedly mounting a gap sensor; the measuring string mounting bracket is fixedly connected to a measuring string; the encoder is connected to the bearing and rotates coaxially with the bearing.

[0037] The present invention has the following beneficial effects: the method of the present invention is the first to apply the multi-point chord measurement method to a high-temperature superconducting maglev transportation system. Compared with traditional inertial measurement methods and optical camera methods, the method has high measurement accuracy, good stability, and resistance to external interference. In particular, when the measuring device passes through the permanent magnet track joint, a large impact is generated. At this time, the gap measurement value reaches the maximum range saturation value of the sensor. This means that when the gap sensors carried by the multi-point chord reference pass through the joint successively, the gap sensor measurement amplitude changes alternately. When the end sensor of the chord reference passes through the joint, the amplitude reaches the sensor range saturation value, which is equivalent to the chord reference "failure", causing "distortion" of the chord measurement value at the intermediate measurement point. In the method of the present invention, only the rows of the measurement matrix corresponding to the chord reference "failure" are eliminated to maintain the accuracy of the measurement matrix H, thereby ensuring the accuracy of the restored track irregularity waveform, thereby ensuring that the measurement accuracy of the multi-point chord measurement method is not affected by vibration and impact. The measurement device designed by the present invention can measure the magnetic field intensity at any position above the permanent magnet track of the high-temperature superconducting maglev transportation system. The device is lightweight, easy to disassemble and transport, and has controllable and low economic costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG1 is a schematic flow chart of the steps of the method of the present invention;

[0039] FIG2 is a schematic diagram of a device for measuring the magnetic field strength above a permanent magnet track of a high-temperature superconducting maglev transportation system according to an embodiment of the present invention.

[0040] FIG3 is a schematic diagram of a device for measuring the magnetic field strength above a permanent magnet track of a high-temperature superconducting maglev transportation system according to an embodiment of the present invention.

[0041] FIG4 is a schematic diagram of a flow chart showing the magnetic field strength measurement process at any position above a permanent magnet track in a high-temperature superconducting maglev transportation system according to an embodiment of the present invention;

[0042] In the figure, 1-trolley main frame; 2-traveling wheel; 3-sensor mounting bracket; 4-measuring string mounting bracket; 5-measuring string; 6-Hall sensor mounting hole; 7-gap sensor mounting hole; 8-encoder; 11-uneven magnetic field strength; 12-uneven track; 13-Hall sensor; 14-gap sensor. DETAILED DESCRIPTION

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] Example 1

[0045] High smoothness of functional components in high-temperature superconducting maglev transportation systems is an important prerequisite for ensuring safe, stable, and comfortable operation of maglev vehicles across all speed ranges. Due to the coupling effects of factors such as rain, climate changes such as high and low temperatures, track foundation settlement, concrete structure creep, and cyclic loads on maglev vehicles, the spatial distribution of the permanent magnet track's magnetic field and the flatness of the traction DC motor change. If problems such as uneven magnetic field intensity with a large rate of change occur, this will directly affect the safety and stability of maglev vehicle operation. As shown in Figure 1, the method proposed in the present invention can measure the magnetic field intensity at any position above the permanent magnet track of a high-temperature superconducting maglev system. A method for measuring the magnetic field intensity of a high-temperature superconducting maglev transportation system specifically includes the following:

[0046] S1. Determine the upper surface of the permanent magnet rail as the reference for magnetic field strength.

[0047] In this embodiment, the present invention is used to detect the uneven distribution of magnetic field intensity above the permanent magnet track of a high-temperature superconducting maglev transportation system. The upper surface of the permanent magnet track is determined as the measurement reference datum plane. The ideal operating height position of the high-temperature superconducting maglev operation is 10 mm. In this example, the vertical magnetic field intensity is measured at a position 10 mm above the upper surface of the permanent magnet track.

[0048] S2. Construct a chord reference-multi-point chord measurement system to detect surface irregularities on the permanent magnet rail. The chord measurement system configuration includes the system sampling interval, the system order, and the chord measurement configuration (i.e., the gap sensor installation position).

[0049] The system sampling interval is Δs, and the system order calculation formula is as follows: γ=L / Δs

[0050] Where γ represents the system order, L represents the system chord length, and Δs represents the sampling step size.

[0051] S3. Calculate the chord measurement values ​​at multiple intermediate measuring points based on the multi-point chord measurement system, and construct an inversion model of the measurement system using the least squares method. The inversion model reconstructs the original track irregularity waveform from the chord measurement values ​​of the chord datum. The track irregularity restored according to the inversion model is the upper and lower displacement of the chord datum.

[0052] The chord measurement values ​​of multiple measuring points in the middle are calculated based on the multi-point chord measurement system. The formula is as follows: G = H·Z Z

[0053] Where G is the chord measurement matrix, H is the measurement matrix, and Z Z is the irregularity vector matrix of the permanent magnet track;

[0054] The chord measurement matrix G is expressed as follows:

[0055] Where G(i) is the chord measurement value of all measuring points when the chord reference starting point is at measuring point i, gn-1,i is the chord measurement value of measuring point n-1 when the chord reference starting point is measuring point i;

[0056] The corresponding measurement matrix H of the chord reference full configuration is as follows:

[0057] The measurement matrix H has n-1 rows and n+1 columns. The number of rows corresponds to the number of fully configured measurement points, and the number of columns is consistent with the dimension of the irregularity vector covered by the chord datum including the endpoints. n-1 [k] is the convolution kernel corresponding to the measurement point n-1, and the elements in the first and n+1 columns correspond to the segmentation ratio γ of the measurement point i i and The middle columns 2 to n are unit matrices with a dimension of (n-1);

[0058] The permanent magnet track irregularity vector matrix Z corresponding to each column of the chord measurement matrix G Z As shown below:

[0059] Where z i is the irregularity vector corresponding to the chord reference position i.

[0060] The inversion model is constructed by combining the least squares method. The optimal solution is obtained under the condition that the track irregularity waveform reconstructed by the inversion model is closest to the actual track irregularity to ensure the accuracy of the measurement results. The optimal solution satisfies the following formula:

[0061] Where H is the measurement matrix, G is the chord measurement matrix, and Z * The optimal solution is the restored waveform of the uneven permanent magnet track.

[0062] When the condition number of the measurement matrix H is too large, it is an ill-conditioned matrix, which leads to the solution Z * Therefore, the present invention constructs the operator ζ in the inversion model of the measurement system to ensure the stability of the solution, thereby ensuring the accuracy of the subsequent calculated chord reference position and outputting the permanent magnet track unevenness recovery waveform Z * , the operator expression is as follows:

[0063] Where H is the measurement matrix, T is the matrix transpose operation, β is the regularization coefficient, ranging from 0.001 to 0.005, I is the unit matrix, and i is the measurement point position;

[0064] The restored waveform output is as follows: Z * =ζ·G

[0065] Where Z * is the permanent magnet track unevenness recovery waveform, G is the chord measurement matrix, and ζ is the operator.

[0066] S4. Based on the optimal string measurement configuration of the multi-point string system, determine the layout position of the gap sensor and arrange the Hall sensor array along the direction of measuring the magnetic field strength.

[0067] The optimal chord measurement configuration is the optimal sensor installation position. The optimal chord measurement configuration meets the following conditions: (1) the common divisor of the distance between each measuring point is 1, which ensures the stability of the measurement system and the subsequent inversion model, thereby ensuring the accuracy of the chord measurement value and the restored track irregularity; (2) the measurable wavelength is maximized under the measurement accuracy requirement to ensure the availability of the measurement results; (3) the measurement error requirement is met to ensure the accuracy of the measurement results;

[0068] The formula is as follows:

[0069] Where d is the common divisor of the distance between measuring points, GCD is the common divisor calculation function, min is the minimum value calculation function, z e is the waveform error of track irregularity restoration, σ is the standard deviation of the error waveform under the required measurement accuracy, σ k is the standard deviation of the error waveform when the measurable wavelength is λ, σ k The expression is as follows:

[0070] Where z j is the amplitude of the error waveform at position j, Δs is the sampling step, n-1 is the number of wavelength domain divisions, and N is the length of the error waveform.

[0071] In this embodiment, the measurement object is the vertical magnetic field intensity 10 mm above the upper surface of the permanent magnet rail. The gap sensor arrangement position is determined by the optimal chord measurement configuration, and a Hall sensor is arranged vertically at each measuring point.

[0072] Arrange j Hall sensors at each measuring point to obtain the Hall sensor measurement matrix B;

[0073] Where B n-1,j is the measurement value of the jth sensor at the measuring point n-1 and in the measuring direction.

[0074] S5. Correct the reference reference position based on the up and down displacement of the chord reference, and calculate the magnetic field intensity distribution at any height above the reference reference using an interpolation method based on the Hall sensor measurement results.

[0075] In step S5, the corrected reference reference position is obtained by subtracting the vertical displacement from the initial position of the string reference, and the magnetic field intensity distribution at any height above the reference reference is calculated using the interpolation method based on the Hall sensor measurement results. The formula is as follows: R * =RZ * B *=interpl(R * ,B,s)

[0076] Where R * is the corrected chord reference position, R is the initial position, interp1 is the interpolation function, B * is the magnetic field intensity at position s in the interpolated measurement direction.

[0077] If we calculate the vertical magnetic field strength at 10 mm above the reference datum, then B * =interpl(R * ,B,10), represents the vertical magnetic field intensity at 10 mm from the reference plane after interpolation.

[0078] In this embodiment, based on the proposed optimal chord measurement configuration, a device for measuring the vertical magnetic field intensity above the permanent magnet track of a high-temperature superconducting maglev transportation system was designed. The measurement device design is shown in Figure 2. Component 7, the gap sensor mounting hole, aligns with the optimal chord measurement configuration and is used to mount a gap sensor 14 to sense the gap between the collection and measurement surfaces. Component 6, the Hall sensor mounting hole, is vertically arranged with Hall sensors 13 to measure the vertical magnetic field intensity. Step S3 calculates the chord measurement value and the permanent magnet track irregularity recovery waveform. Then, step S5 corrects the reference plane and calculates the vertical magnetic field intensity 10 mm above the permanent magnet track. Figure 3 illustrates the measurement of the vertical magnetic field intensity above the permanent magnet track of a high-temperature superconducting maglev system. The measurement device can move along the permanent magnet track surface. During this movement, the encoder triggers the acquisition card at evenly spaced pulse intervals, records the gap sensor measurements, and uploads them to a host computer for subsequent offline processing. The measurement results can be used to assess the magnetic field intensity irregularity of the high-temperature superconducting maglev permanent magnet track and adjust the permanent magnet track's posture. The measurement process is shown in Figure 4.

[0079] In order to achieve scientific maintenance of the smooth state of functional parts of the high-temperature superconducting maglev transportation system and meet the requirements of safe, stable and comfortable operation of high-speed maglev trains, based on the same inventive concept as the above-mentioned method embodiment, the embodiment of the present application also provides a high-temperature superconducting maglev transportation system magnetic field strength measurement device, which is used to implement the high-temperature superconducting maglev transportation system magnetic field strength measurement method described in the above embodiment.

[0080] Furthermore, this embodiment provides a device for measuring the smoothness of the magnetic field intensity distribution above the permanent magnet track of a high-temperature superconducting maglev transportation system. As shown in Figure 2, the device includes a trolley main frame 1, a running wheel 2, a sensor mounting bracket 3, a measuring string mounting bracket 4, a measuring string 5, a Hall sensor mounting hole 6, a gap sensor mounting hole 7, and an encoder 8; the running wheel 2 of the measuring device is connected to the trolley main frame 1 through a bearing, and the encoder 8 is also connected to the bearing and rotates coaxially. The measuring string 5 is installed on the measuring string mounting bracket 4, and the measuring string mounting bracket 4 is connected to the trolley main frame 1. The Hall sensor mounting hole 6 and the gap sensor mounting hole 7 are located on the sensor mounting bracket 3.

[0081] Trolley main frame 1: The trolley main frame is the main part of the measuring device, and other hardware of the device are connected to the trolley main frame, as shown in Figure 2.

[0082] Running wheel 2: The two running wheels at the front and rear of the measuring device are connected to the trolley main frame through bearings, which can realize the function of moving the device along the surface of the permanent magnet rail, and the running speed can reach 3m / s.

[0083] Sensor mounting bracket 3: Mainly used to install gap sensors and Hall sensors, and connected to the vehicle main frame by welding.

[0084] Measuring string mounting bracket 4: It is mainly used to fix the measuring string. It should be ensured to have sufficient rigidity. The trolley main frame is connected to the measuring string mounting bracket by welding.

[0085] Measuring string 5: Based on the optimal string measurement configuration scheme, a measuring string with a certain bending stiffness is processed, and the measuring string is connected to the measuring string mounting bracket by welding or bolts.

[0086] Hall sensor mounting hole 6: used to fix the Hall sensor 13 and measure the magnetic field strength. It is necessary to select a suitable Hall sensor and ensure the installation accuracy.

[0087] Gap sensor mounting hole 7: used to fix the gap sensor 14 to measure the unevenness of the upper surface of the permanent magnet rail. It is necessary to select a suitable gap sensor and ensure the installation accuracy.

[0088] Encoder 8: The encoder rotates coaxially with the trolley bearing. The encoder pulse triggers the acquisition card at equal distances along the forward direction of the measuring device to record the mileage information, ensuring that the sensor gap value corresponds to the mileage, which is convenient for subsequent data analysis.

[0089] The device designed in this invention can measure magnetic field strength at any location above the permanent magnet track in a high-temperature superconducting maglev transportation system. The device is lightweight, easy to disassemble, and transport, with manageable costs and low economical costs. This marks the first application of multi-point string measurement in a high-temperature superconducting maglev system. Compared to the traditional inertial reference method, this method offers higher measurement accuracy, better stability, and greater resistance to external interference. This is particularly true when the measuring device passes over joints in the permanent magnet track, which can generate significant impact. The multi-point string measurement method ensures that the measurement accuracy is unaffected by vibration.

[0090] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for measuring magnetic field strength of a high-temperature superconducting maglev transportation system, characterized in that: The following steps are involved: S1. Determine the upper surface of the permanent magnet rail as a reference for magnetic field strength; S2. Constructing a chord reference-multi-point chord measurement system to detect the unevenness of the upper surface of the permanent magnet rail. The chord measurement system configuration includes the system sampling interval, the system order and the chord measurement configuration; S3. Calculate the chord measurement values ​​at multiple measuring points in the middle based on the multi-point chord measurement system, and build an inversion model of the measurement system in combination with the least squares method. The inversion model refers to reconstructing the original track irregularity waveform from the chord measurement values ​​of the chord reference. The track irregularity restored according to the inversion model is the up and down displacement of the chord reference. S4. Based on the optimal string measurement configuration of the multi-point string system, determine the layout position of the gap sensor, and arrange the Hall sensor array along the direction of measuring the magnetic field strength; S5. Correct the reference reference position based on the up and down displacement of the chord reference, and calculate the magnetic field intensity distribution at any height above the reference reference by using an interpolation method according to the measurement result of the Hall sensor; In step S3, the chord measurement values ​​of the middle multiple measuring points are calculated based on the multi-point chord measurement system, and the formula is expressed as follows: G=H·Z Z Where G is the chord measurement matrix, H is the measurement matrix, and Z Z is the irregularity vector matrix of the permanent magnet track; The chord measurement matrix G is expressed as follows: Where G(i) is the chord measurement value of all measuring points when the chord reference starting point is at measuring point i, g n-1,i is the chord measurement value of measuring point n-1 when the chord reference starting point is at measuring point i; The corresponding measurement matrix H for the full configuration of the chord reference is as follows: The measurement matrix H has n-1 rows and n+1 columns. The number of rows corresponds to the number of fully configured measurement points, and the number of columns is consistent with the dimension of the irregularity vector covered by the chord datum including the endpoints. n-1 [k] is the convolution kernel corresponding to the measurement point n-1, and the elements in the first and n+1 columns correspond to the segmentation ratio γ of the measurement point i i and The middle columns 2 to n are unit matrices with a dimension of n-1; The permanent magnet track irregularity vector matrix Z corresponding to each column of the chord measurement matrix G Z As shown below: Where z i is the irregularity vector corresponding to the chord reference position i.

2. The method for measuring magnetic field strength of a high-temperature superconducting maglev transportation system according to claim 1, characterized in that: In step S2, the system sampling interval is Δs, and the system order calculation formula is as follows: γ=L / Δs Among them, γ represents the system order, L represents the system chord length, and Δs represents the sampling step.

3. The method for measuring magnetic field strength of a high-temperature superconducting maglev transportation system according to claim 1, characterized in that: The inversion model is constructed by combining the least squares method. The optimal solution is obtained under the condition that the track irregularity waveform reconstructed and restored by the inversion model is closest to the actual track irregularity to ensure the accuracy of the measurement results. The optimal solution satisfies the following formula: Where H is the measurement matrix, G is the chord measurement matrix, and Z * The optimal solution is the restoration waveform of the uneven permanent magnet track.

4. The method for measuring magnetic field strength of a high-temperature superconducting maglev transportation system according to claim 1, characterized in that: The operator ζ is constructed in the inversion model of the measurement system to ensure the stability of the solution and output the permanent magnet track unevenness recovery waveform Z * , the operator expression is as follows: Where H is the measurement matrix, T is the matrix transposition operation, β is the regularization coefficient, ranging from 0.001 to 0.005, I is the unit matrix, and i is the measurement point position; The restored waveform output is as follows: WITH * =ζ G Where Z * is the permanent magnet track unevenness recovery waveform, G is the chord measurement matrix, and ζ is the operator.

5. The method for measuring magnetic field strength of a high-temperature superconducting maglev transportation system according to claim 1, characterized in that: In step S4, based on the optimal string measurement configuration of the multi-point string system, the gap sensor arrangement position is determined, and the Hall sensor array is arranged along the direction of measuring the magnetic field strength, and j Hall sensors are arranged at each measuring point to obtain the Hall sensor measurement matrix B; Where B n-1,j is the measurement value of the jth sensor in the measurement direction at the measurement point n-1.

6. The method for measuring magnetic field strength of a high-temperature superconducting maglev transportation system according to claim 1, characterized in that: In step S5, the corrected reference reference position is obtained by subtracting the up and down displacement from the initial position of the string reference, and the magnetic field intensity distribution at any height above the reference reference is calculated using the interpolation method according to the measurement result of the Hall sensor. The formula is as follows: * =RZ * B * =interpl(R * ,B,s) Where R * is the corrected string reference position, R is the initial position, B * is the magnetic field intensity at position s in the interpolated measurement direction.

7. A measuring device for measuring magnetic field strength of a high-temperature superconducting maglev transportation system according to any one of claims 1 to 6, characterized in that: The measuring device comprises: A trolley main frame (1), a running wheel (2), a sensor mounting bracket (3), a measuring string mounting bracket (4), a measuring string (5), a Hall sensor mounting hole (6), a gap sensor mounting hole (7), and an encoder (8); The running wheel (2) is connected to the trolley main frame (1) via a bearing; the sensor mounting bracket (3) and the measuring string mounting bracket (4) are both fixedly connected to the trolley main frame (1); the sensor mounting bracket (3) is provided with a Hall sensor mounting hole (6) for fixedly mounting a Hall sensor (13) and a gap sensor mounting hole (7) for fixedly mounting a gap sensor (14); the measuring string (5) is fixedly connected to the measuring string mounting bracket (4); the encoder (8) is connected to the bearing and rotates coaxially with the bearing.

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