A method for measuring small distances using eddy current

Abstract

The present application provides an eddy current micro-distance measurement method, which relates to the field of distance measurement technology. The device includes: a main coil, multiple secondary coils, multiple programmable phase shifters, multiple coil drivers, an oscillation circuit and a controller; the multiple secondary coils and the main coil are arranged on the same plane, and the multiple secondary coils are arranged around the main coil, the main coil is connected to the oscillation circuit, the oscillation circuit is also connected to the multiple programmable phase shifters, and the multiple programmable phase shifters are respectively connected to the multiple secondary coils through the multiple coil drivers; the oscillation circuit and the multiple programmable phase shifters are both connected to the controller, the device uses the eddy currents generated by the multiple secondary coils to enhance or offset the eddy currents generated by part of the main coil, which can offset the adverse effects of non-parallel installation on measurement. Compared with manual correction, the measurement accuracy of eddy current micro-distances can be improved through automation.

Description

Technical Field

[0001] The present application relates to the technical field of distance measurement, and in particular to a method for measuring small distances using eddy currents. Background Art

[0002] The distance from the excitation coil to the target conductor can be measured by the eddy current inductance method, in which the magnetic field generated by the excitation coil forms eddy currents in the target metal, which can generate a magnetic field, so that an induced electromotive force can be generated in the excitation coil, thereby changing the inductance of the excitation coil. The change in inductance can reflect the distance between the excitation coil and the target conductor.

[0003] When the excitation coil is strictly parallel to the surface of the target conductor, the change in the small distance between the two is linearly related to the change in the inductance of the excitation coil. The change in the small distance can be calculated by measuring the change in inductance. When the excitation coil is not parallel to the surface of the target conductor, the change in the small distance is no longer linearly related to the change in inductance. In the prior art, when the excitation coil is not parallel to the surface of the target conductor, it is usually necessary to adjust the excitation coil and the surface of the target conductor to be strictly parallel through repeated manual correction, which has low execution efficiency and inaccurate measurement results. Summary of the invention

[0004] The purpose of the present invention is to provide an eddy current small distance measurement method to address the deficiencies in the above-mentioned prior art, so as to solve the technical problem in the prior art that when the excitation coil and the surface of the target conductor are not parallel, the excitation coil and the surface of the target conductor need to be adjusted to be strictly parallel through manual correction, resulting in low execution efficiency and low measurement accuracy.

[0005] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0006] In a first aspect, an embodiment of the present application provides an eddy current micro-distance measuring device, the eddy current micro-distance measuring device comprising: a main coil, a plurality of secondary coils, a plurality of programmable phase shifters, a plurality of coil drivers, an oscillation circuit and a controller;

[0007] The multiple secondary coils and the main coil are arranged on the same plane, and the multiple secondary coils are arranged around the main coil. The main coil is connected to the oscillation circuit, and the oscillation circuit is also connected to the multiple programmable phase shifters. The multiple programmable phase shifters are respectively connected to the multiple secondary coils through the multiple coil drivers; the oscillation circuit and the multiple programmable phase shifters are both connected to the controller.

[0008] Optionally, the eddy current micro-distance measuring device further includes: the multiple coil drivers are respectively connected to the multiple auxiliary coils through the multiple switches.

[0009] Optionally, each programmable phase shifter is a phase shifter based on a third-order phase-locked loop.

[0010] Optionally, coil parameters of the multiple secondary coils are all the same.

[0011] Optionally, circuit parameters of the multiple coil drivers are the same.

[0012] In a second aspect, an embodiment of the present application provides an eddy current micro-distance measurement method, which is applied to a controller in the eddy current micro-distance measurement device described in the first aspect above, and the method includes:

[0013] Adjusting the phase of at least one programmable phase shifter in the eddy current micro-distance measuring device to calibrate the main coil in the eddy current micro-distance measuring device;

[0014] After the main coil is calibrated, a plurality of switches in the eddy current micro-distance measuring device are controlled to be turned on, and a measurement frequency signal generated by an oscillation circuit in the eddy current micro-distance measuring device is obtained;

[0015] Calculating the measured inductance of the main coil according to the measured frequency of the measured frequency signal;

[0016] The distance between the target conductor to be measured and a preset position in the main coil is determined according to the measured inductance.

[0017] Optionally, adjusting the phase of at least one programmable phase shifter in the eddy current micro-distance measuring device to calibrate the main coil in the eddy current micro-distance measuring device includes:

[0018] Controlling the switch between the programmable phase shifter and the corresponding secondary coil to be turned on, and controlling the switches between other programmable phase shifters and the corresponding secondary coils to be turned off;

[0019] Acquiring a calibration frequency signal generated by the oscillation circuit under the action of the programmable phase shifter;

[0020] Calculating the equivalent inductance of the main coil under the action of the programmable phase shifter according to the calibration frequency of the calibration frequency signal;

[0021] According to the equivalent inductance and a preset reference inductance, the phase of the programmable phase shifter is adjusted so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase adjustment is equal to the reference inductance.

[0022] Optionally, before adjusting the phase of the programmable phase shifter according to the equivalent inductance and a preset reference inductance, the method further includes:

[0023] Controlling the switch between the reference programmable phase shifter and the corresponding secondary coil to be turned on, and controlling the switch between other programmable phase shifters and the corresponding secondary coils to be turned off, wherein the reference programmable phase shifter is a preset reference programmable phase shifter among the multiple programmable phase shifters, and at least one of the programmable phase shifters includes: all other programmable phase shifters except the reference programmable phase shifter among the multiple programmable phase shifters;

[0024] Acquiring a calibration frequency signal generated by the oscillation circuit under the action of the reference programmable phase shifter;

[0025] According to the calibration frequency of the calibration frequency signal, the equivalent inductance of the main coil under the action of the reference programmable phase shifter is calculated as the reference inductance.

[0026] Optionally, adjusting the phase of the programmable phase shifter according to the equivalent inductance and a preset reference inductance so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase adjustment is equal to the reference inductance includes:

[0027] If the equivalent inductance is greater than the reference inductance, the phase of the programmable phase shifter is increased so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase increase is equal to the reference inductance.

[0028] Optionally, adjusting the phase of the programmable phase shifter according to the equivalent inductance and a preset reference inductance so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase adjustment is equal to the reference inductance includes:

[0029] If the equivalent inductance is smaller than the reference inductance, the phase of the programmable phase shifter is reduced so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase reduction is equal to the reference inductance.

[0030] Compared with the prior art, this application has the following beneficial effects:

[0031] The present application provides an eddy current micro-distance measuring device, which includes a main coil, multiple secondary coils, multiple programmable phase shifters, multiple coil drivers, an oscillation circuit and a controller. The multiple secondary coils and the main coil are arranged on the same plane, and the multiple secondary coils are arranged around the main coil. The main coil is connected to the oscillation circuit, and the oscillation circuit is also connected to multiple programmable phase shifters. The multiple programmable phase shifters are respectively connected to multiple secondary coils through multiple coil drivers, and the oscillation circuit is also connected to the controller. The eddy current micro-distance measuring device can adjust the magnitude of the current in the multiple secondary coils through the phase of the multiple programmable phase shifters and the multiple coil drivers, and the eddy current magnitude can be finely adjusted through the phase difference between the current in the secondary coil and the current in the main coil. The eddy current generated by the multiple secondary coils is used to enhance or offset the eddy current generated by part of the main coil, which can offset the adverse effect of the non-parallel installation on the measurement, and does not need to adjust the main coil to be strictly parallel to the surface of the target conductor through manual correction. In addition, compared with manual correction, the measurement accuracy of the eddy current micro-distance can be improved through automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A schematic diagram of the structure of an eddy current micro-distance measuring device provided in an embodiment of the present application;

[0034] Figure 2 A schematic diagram of the spatial structure of an eddy current micro-distance measurement device provided in an embodiment of the present application;

[0035] Figure 3 A schematic diagram of the spatial structure of another eddy current micro-distance measuring device provided in an embodiment of the present application;

[0036] Figure 4 A schematic diagram of the structure of another eddy current micro-distance measuring device provided in an embodiment of the present application;

[0037] Figure 5 A schematic diagram of a flow chart of an eddy current micro-distance measurement method provided in an embodiment of the present application;

[0038] Figure 6 A schematic diagram of a flow chart of another eddy current micro-distance measurement method provided in an embodiment of the present application;

[0039] Figure 7A schematic diagram of a flow chart of another eddy current micro-distance measurement method provided in an embodiment of the present application;

[0040] Figure 8 A schematic diagram of a flow chart of another eddy current micro-distance measurement method provided in an embodiment of the present application;

[0041] Fig. 9 A waveform diagram of a main coil and multiple secondary coils provided in an embodiment of the present application;

[0042] Fig.10 Another waveform diagram of a main coil and multiple secondary coils provided in an embodiment of the present application;

[0043] Fig.11 A schematic diagram of an eddy current micro-distance measuring device applied to a controller provided in an embodiment of the present application;

[0044] Fig.12 A schematic diagram of a controller provided in an embodiment of the present application.

[0045] Icons: main coil 100; first secondary coil 210; second secondary coil 220; third secondary coil 230; fourth secondary coil 240; first programmable phase shifter 310; second programmable phase shifter 320; third programmable phase shifter 330; fourth programmable phase shifter 340; first secondary coil driver 410; second secondary coil driver 420; third secondary coil driver 430; fourth secondary coil driver 440; oscillation circuit 500; controller 600; first switch 710; second switch 720; third switch 730; fourth switch 740. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0048] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0049] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0050] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0051] When the excitation coil is not parallel to the surface of the target conductor, it is necessary to adjust the excitation coil and the surface of the target conductor to be strictly parallel through repeated manual correction. The execution efficiency is low, and the manual correction method cannot guarantee strict parallelism, resulting in inaccurate measurement of the eddy current micro-distance.

[0052] In order to improve the efficiency of eddy current small-distance measurement and the accuracy of measurement results, the present application provides an eddy current small-distance measurement method, in which an excitation coil and multiple other coils, that is, a main coil and multiple auxiliary coils work together, and the eddy currents generated by the multiple auxiliary coils are used to enhance or offset part of the eddy currents generated by the main coil, thereby offsetting the adverse effects of non-parallel installation on the measurement. The efficiency of measurement and the accuracy of measurement results can be improved in an automated manner.

[0053] The following is an explanation of an eddy current micro-distance measuring device provided in an embodiment of the present application through a specific example. Figure 1 A schematic diagram of the structure of an eddy current micro-distance measuring device provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the eddy current micro-distance measuring device includes: a main coil 100 , a plurality of secondary coils, a plurality of programmable phase shifters, a plurality of secondary coil drivers, an oscillating circuit 500 and a controller 600 .

[0054] The main coil 100 is connected to the oscillating circuit 500 to form an oscillator, which generates a sinusoidal signal of a specific frequency. The oscillating circuit 500 is connected to the controller 600, so that the controller 600 can measure the frequency of the sinusoidal signal generated by the oscillator.

[0055] Optionally, in the embodiment of the present application, the oscillator may adopt a Clappe oscillator with smaller transistor parasitic parameters, or other oscillators, which are not specifically limited in the embodiment of the present application.

[0056] Wherein, a resonant capacitor is provided in the oscillation circuit 500 .

[0057] The magnetic field generated by the main coil 100 can also form eddy currents in the target conductor to be measured. The eddy currents generate a magnetic field, which generates an induced electromotive force in the main coil 100, thereby changing the inductance of the main coil 100. The changed inductance of the main coil 100 and the resonant capacitor designed in the oscillation circuit 500 can jointly determine the frequency generated by the oscillator.

[0058] The oscillator circuit 500 is also connected to a plurality of programmable phase shifters. In the embodiment of the present application, four programmable phase shifters are used as an example for explanation, wherein the four programmable phase shifters are respectively a first programmable phase shifter 310, a second programmable phase shifter 320, a third programmable phase shifter 330, and a fourth programmable phase shifter 340. The sinusoidal signal generated by the oscillator can be used as an input signal of the plurality of programmable phase shifters, and the programmable phase shifter can shift the phase of the input sinusoidal signal by a corresponding angle to generate a sinusoidal signal after the phase is shifted, thereby outputting the sinusoidal signal.

[0059] Multiple programmable phase shifters are connected to multiple secondary coils through multiple secondary coil drivers. In the embodiment of the present application, four coil drivers and four secondary coils are used as examples for explanation. The four coil drivers are respectively the first secondary coil driver 410, the second secondary coil driver 420, the third secondary coil driver 430, and the fourth secondary coil driver 440. The four secondary coils are respectively the first secondary coil 210, the second secondary coil 220, the third secondary coil 230, and the fourth secondary coil 240, wherein the first programmable phase shifter 310 is connected to the first secondary coil 210 through the first secondary coil driver 410, the second programmable phase shifter 320 is connected to the second secondary coil 220 through the second secondary coil driver 420, the third programmable phase shifter 330 is connected to the third secondary coil 230 through the third secondary coil driver 430, and the fourth programmable phase shifter 340 is connected to the fourth secondary coil 240 through the fourth secondary coil driver 440. Multiple secondary coil drivers can receive sinusoidal signals transmitted from the programmable phase shifters connected thereto, and drive and control the multiple secondary coils according to the sinusoidal signals.

[0060] The multiple programmable phase shifters are phase shifters that can be digitally programmed or controlled by the controller 600. In the embodiment of the present application, the programmable phase shifter can be a phase shifter based on a third-order phase-locked loop, which can track the frequency and phase of the sinusoidal signal generated by the oscillator, and can generate a sinusoidal signal with a desired phase. The controller 600 is also connected to multiple programmable phase shifters to control the phases of multiple programmable controllers.

[0061] Optionally, the structures of the multiple programmable phase shifters are the same.

[0062] In the embodiment of the present application, the multiple programmable phase shifters can be desktop instruments, rack-mounted instruments, integrated connection instruments or surface-mounted components, and can also be other programmable phase shifters, which are not specifically limited in the embodiment of the present application.

[0063] In the embodiment of the present application, the coil parameters of the multiple secondary coils are the same. For example, the coil parameters such as material, line width, spacing, shape, number of turns, etc. of the first secondary coil 210, the second secondary coil 220, the third secondary coil 230, and the fourth secondary coil 240 are the same. For example, the multiple secondary coils 200 can be made of a PCB (Printed Circuit Board) with a thickness of 1.6 mm and a FR4 process material to produce a planar spiral inductor with a line width of 0.2 mm, a spacing of 0.2 mm, and the same number of turns. The planar spiral inductor based on the PCB process has low cost, excellent consistency, and can be manufactured together with the measurement circuit, and can be used in space scenarios with limited thickness.

[0064] In the embodiment of the present application, the circuit parameters of the multiple secondary coil drivers are the same. For example, the circuit parameters of the multiple secondary coil drivers, such as voltage, current, output impedance, frequency response curve, etc., are the same.

[0065] In the embodiment of the present application, four programmable phase shifters are taken as an example to explain the spatial structure of the eddy current micro-distance measuring device. By way of example, Figure 2 A schematic diagram of the spatial structure of an eddy current micro-distance measuring device provided in an embodiment of the present application, Figure 3 A schematic diagram of the spatial structure of another eddy current micro-distance measuring device provided in an embodiment of the present application is shown in FIG. Figure 2 and Figure 3 As shown, the plurality of secondary coils and the main coil 100 are arranged on the same plane, and the plurality of secondary coils are arranged around the main coil 100 , and the positions of the plurality of secondary coils 200 are rotationally symmetric with the main coil as the center.

[0066] If the currents of the adjacent wires of the main coil 100 and the secondary coil are the same, eddy currents in opposite directions are generated at corresponding positions on the target conductor to be measured, and the total eddy current decreases. If the currents of the adjacent wires of the main coil and the secondary coil are opposite, eddy currents in the same direction are generated at corresponding positions on the target conductor to be measured, and the total eddy current increases. The size of the eddy current can be finely adjusted by adjusting the phase difference between the current in the secondary coil and the current in the main coil.

[0067] Optionally, the signal amplitude generated by the multiple secondary coils under the corresponding coil drivers can be a multiple of the signal amplitude of the main coil, or can be the same as the signal amplitude of the main coil. In the embodiment of the present application, the signal amplitude generated by the multiple secondary coils under the corresponding coil drivers is a multiple of the signal amplitude of the main coil, that is, different from the signal amplitude of the main coil.

[0068] The present application provides an eddy current micro-distance measuring device, which can adjust the magnitude of the current in multiple secondary coils through the phases of multiple programmable phase shifters and multiple coil drivers, and can finely adjust the magnitude of the eddy current through the phase difference between the current in the secondary coil and the current in the main coil. The eddy currents generated by the multiple secondary coils are used to enhance or offset part of the eddy currents generated by the main coil, which can offset the adverse effects of non-parallel installation on the measurement, and does not require the main coil to be adjusted to be strictly parallel to the surface of the target conductor through manual correction. In addition, compared with manual correction, the measurement accuracy of the eddy current micro-distance can be improved through automation.

[0069] Furthermore, in the above Figure 1 Based on the eddy current micro-distance measuring device shown, the embodiment of the present application also provides another eddy current micro-distance measuring device. Optionally, Figure 4 A schematic diagram of the structure of another eddy current micro-distance measuring device provided in an embodiment of the present application is shown in FIG. Figure 4 As shown, the eddy current micro-distance measuring device also includes: a plurality of switches.

[0070] Multiple coil drivers are connected to multiple secondary coils through multiple switches. For example, four switches are used as an example for explanation in the embodiment of the present application. The four switches can be a first switch 710, a second switch 720, a third switch 730, and a fourth switch 740, respectively, wherein the first secondary coil driver 410 is connected to the first secondary coil 210 through the first switch 710, the second secondary coil driver 420 is connected to the second secondary coil 220 through the second switch 720, the third secondary coil driver 430 is connected to the third secondary coil 230 through the third switch 730, and the fourth secondary coil driver 440 is connected to the fourth secondary coil 240 through the fourth switch 740.

[0071] In the embodiment of the present application, the parameters of the multiple switches are the same.

[0072] Optionally, multiple switches may be connected to the controller 600 so that the states of the multiple switches, such as closed or open states, can be controlled by the controller 600 .

[0073] In the embodiment of the present application, the first programmable phase shifter 310, the first secondary coil driver 410, the first switch 710, and the first secondary coil 210 may constitute a first calibration branch, the second programmable phase shifter 320, the second secondary coil driver 420, the second switch 720, and the second secondary coil 220 may constitute a second calibration branch, the third programmable phase shifter 330, the third secondary coil driver 430, the third switch 730, and the third secondary coil 230 may constitute a third calibration branch, and the fourth programmable phase shifter 340, the fourth secondary coil driver 440, the fourth switch 740, and the fourth secondary coil 240 may constitute a fourth calibration branch. Through the four calibration branches, the eddy current generated by the secondary coil can be used to enhance or offset part of the eddy current generated by the main coil, thereby offsetting the adverse effects of the non-parallel installation on the measurement.

[0074] An eddy current micro-distance measuring device provided in an embodiment of the present application also includes: multiple switches, multiple coil drivers are respectively connected to multiple auxiliary coils through multiple switches to control the state of the auxiliary coils, and then use the eddy currents generated by the auxiliary coils to enhance or offset part of the eddy currents generated by the main coils, thereby offsetting the adverse effects of non-parallel installation on measurement.

[0075] In the above Figure 1~Figure 4 Based on the above embodiment, the present application also provides an eddy current micro-distance measurement method. Figure 5 A schematic diagram of a flow chart of an eddy current micro-distance measurement method provided in an embodiment of the present application, which is applied to the above Figure 4 The controller in the eddy current micro-distance measuring device shown in the figure may be a device with computing and processing functions, such as an MCU (microcontroller unit). Figure 5 As shown, the method includes:

[0076] S501, adjusting the phase of at least one programmable phase shifter in the eddy current micro-distance measuring device to calibrate the main coil in the eddy current micro-distance measuring device.

[0077] In an embodiment of the present application, calibration is performed after the target conductor to be measured and the eddy current micro-distance measuring device are installed, wherein the initial phases of the plurality of programmable phase shifters are the same, and by way of example, the initial phase may be 90°.

[0078] By adjusting the phase of at least one programmable phase shifter, multiple calibration branches corresponding to multiple programmable phase shifters generate the same equivalent main coil inductance. At this time, the calibration of the main coil in the eddy current micro-distance measuring device is completed.

[0079] Among them, phase adjustment is performed through at least one programmable phase shifter. When the currents at adjacent positions of the main coil and the secondary coil are in phase, the eddy current generated in the target conductor below is the strongest. When the currents at adjacent positions of the main and secondary coils are in anti-phase, the eddy current generated in the target conductor below is the weakest. By adjusting the phase of at least one programmable phase shifter, the superimposed eddy currents generated on the target conductor can be controlled.

[0080] When the phase is 0°, the vortex reaches its maximum, when the phase is 180°, the vortex reaches its minimum, and when the phase is 90°, the vortex is at a medium value.

[0081] S502, after the main coil calibration is completed, multiple switches in the eddy current micro-distance measuring device are controlled to be turned on, and a measurement frequency signal generated by an oscillation circuit in the eddy current micro-distance measuring device is obtained.

[0082] After the main coil calibration is completed, the phases of multiple calibrated programmable phase shifters are obtained, and all multiple switches are turned on, that is, the first switch, the second switch, the third switch, and the fourth switch are all turned on. The controller can measure the frequency of the measurement frequency signal generated by the oscillator to obtain the measurement frequency of the measurement frequency signal generated by the oscillation circuit in the eddy current micro-distance measurement device.

[0083] S503, calculating the measured inductance of the main coil according to the measured frequency of the measured frequency signal.

[0084] According to the measurement frequency of the measurement frequency signal and the resonant capacitance in the oscillation circuit, the measurement inductance of the main coil can be obtained by calculation. The measurement inductance of the main coil can be calculated by the following formula (1).

[0085] Formula (1)

[0086] in, represents the measurement frequency of the measurement frequency signal, Represents the capacitance value of the resonant capacitor, Represents the measured inductance of the primary winding.

[0087] S504: Determine the distance between the target conductor to be measured and a preset position in the main coil according to the measured inductance.

[0088] In an embodiment of the present application, the correspondence between the measured inductance and the distance between the target conductor to be measured and the preset position in the main coil is pre-calibrated, and the correspondence is obtained through multiple experiments, wherein the correspondence between the measured inductance and the distance between the target conductor to be measured and the preset position in the main coil can be a linear relationship.

[0089] According to the correspondence between the pre-calibrated measurement inductance and the distance between the target conductor to be measured and the preset position in the main coil, the distance between the target conductor to be measured and the preset position in the main coil can be obtained according to the measurement inductance, thereby realizing the measurement of small distances of eddy currents when the main coil and the target conductor to be measured are not parallel.

[0090] The present application provides an eddy current micro-distance measurement method, which calibrates the main coil in the eddy current micro-distance measurement device by adjusting the phase of at least one programmable phase shifter in the eddy current micro-distance measurement device. After the calibration is completed, multiple switches in the eddy current micro-distance measurement device are controlled to be turned on, and the signal measurement frequency generated by the oscillation circuit in the eddy current micro-distance measurement device is obtained. According to the signal measurement frequency, the measurement inductance of the main coil is calculated, and according to the measurement inductance, the distance between the target conductor to be measured and the preset position in the main coil is determined. By adjusting the phase of at least one programmable phase shifter, the eddy current generated by the secondary coil is enhanced or partially offset by the eddy current generated by the main coil, thereby offsetting the adverse effects of non-parallel installation on the measurement, and determining the distance between the target conductor to be measured and the preset position in the main coil.

[0091] Furthermore, in the above Figure 5 Based on the eddy current micro-distance measurement method shown, the present application embodiment also provides another eddy current micro-distance measurement method. Optionally, Figure 6 A schematic diagram of a flow chart of another eddy current micro-distance measurement method provided in an embodiment of the present application, such as Figure 6 As shown, the above method S501, i.e. adjusting the phase of at least one programmable phase shifter in the eddy current micro-distance measuring device to calibrate the main coil in the eddy current micro-distance measuring device, includes:

[0092] S601, controlling the switch between the programmable phase shifter and the corresponding secondary coil to be turned on, and controlling the switches between other programmable phase shifters and the corresponding secondary coils to be turned off.

[0093] When adjusting the phase of a programmable phase shifter in the eddy current micro-distance measuring device, the switch between the programmable phase shifter and the corresponding secondary coil is turned on, and the switches between other programmable phase shifters and the corresponding secondary coils are controlled to be turned off.

[0094] For example, if the programmable phase shifter is a fourth programmable phase shifter, the fourth switch between the fourth programmable phase shifter and the fourth secondary coil is controlled to be turned on, the third switch between the third programmable phase shifter and the third secondary coil is disconnected, the second switch between the second programmable phase shifter and the second secondary coil is disconnected, and the first switch between the first programmable phase shifter and the first secondary coil is disconnected.

[0095] S602, obtaining a calibration frequency signal generated by an oscillation circuit under the action of a programmable phase shifter.

[0096] Before controlling the switch between the programmable phase shifter and the corresponding secondary coil to be turned on, the primary coil oscillates to generate a sinusoidal signal, and after the sinusoidal signal is input into the programmable phase shifter, a sinusoidal signal with an initial phase shift is generated.

[0097] The switch between the programmable phase shifter and the corresponding secondary coil is controlled to be turned on. After passing through the secondary coil driver and the switch corresponding to the programmable phase shifter, a current is generated in the secondary coil, thereby generating an induced electromotive force in the main coil, changing the inductance of the main coil. The controller can measure the frequency of the calibration frequency signal generated by the oscillator to obtain the calibration frequency of the calibration frequency signal generated by the oscillation circuit in the eddy current micro-distance measuring device.

[0098] S603, calculating the equivalent inductance of the main coil under the action of the programmable phase shifter according to the calibration frequency of the calibration frequency signal.

[0099] According to the calibration frequency of the calibration frequency signal, the equivalent main coil inductance of the main coil under the action of the programmable phase shifter can be calculated. The equivalent main coil inductance of the main coil can be calculated by the following formula (2).

[0100] Formula (2)

[0101] in, represents the calibration frequency of the calibration frequency signal, Represents the capacitance value of the resonant capacitor, Represents the equivalent inductance of the main coil.

[0102] S604, adjusting the phase of the programmable phase shifter according to the equivalent inductance and the preset reference inductance, so that the equivalent inductance calculated by the programmable phase shifter after the phase adjustment is equal to the reference inductance.

[0103] Compare the equivalent inductance and the preset reference inductance, and adjust the phase of the programmable phase shifter according to the comparison result, wherein, the closer the phase of the programmable phase shifter is to 180°, the more eddy currents that cancel each other out are generated on the target conductor to be measured, the eddy currents have a reduced effect on the inductance of the main coil, and the equivalent inductance is reduced; the closer the phase of the programmable phase shifter is to 0°, the more eddy currents that increase are generated on the target conductor to be measured, the eddy currents have a greater effect on the inductance of the main coil, and the equivalent inductance is increased.

[0104] By adjusting the phase of the programmable phase shifter, the equivalent inductance is increased or decreased until the equivalent inductance calculated under the action of the programmable phase shifter after the phase adjustment is equal to the reference inductance.

[0105] If the equivalent inductance is greater than the reference inductance, the phase of the programmable phase shifter is increased so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase increase is equal to the reference inductance.

[0106] If the equivalent inductance is smaller than the reference inductance, the phase of the programmable phase shifter is reduced so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase reduction is equal to the reference inductance.

[0107] An eddy current micro-distance measurement method provided in an embodiment of the present application controls the switch between a programmable phase shifter and a corresponding secondary coil to be turned on, and controls the switch between other programmable phase shifters and corresponding secondary coils to be turned off, thereby obtaining a signal calibration frequency generated by an oscillation circuit under the action of the programmable phase shifter, and calculating the equivalent inductance of the main coil under the action of the programmable phase shifter based on the signal calibration frequency, and adjusting the phase of the programmable phase shifter based on the equivalent inductance and a preset reference inductance, so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase adjustment is equal to the reference inductance, thereby completing the calibration of the programmable phase shifter for the main coil.

[0108] Furthermore, in the above Figure 6 Based on the eddy current micro-distance measurement method shown, the present application embodiment also provides another eddy current micro-distance measurement method. Optionally, Figure 7 A schematic diagram of a flow chart of another eddy current micro-distance measurement method provided in an embodiment of the present application, such as Figure 7 As shown, before the above method S604, that is, before adjusting the phase of the programmable phase shifter according to the equivalent inductance and the preset reference inductance, the method further includes:

[0109] S701, controlling the switch between the reference programmable phase shifter and the corresponding secondary coil to be turned on, and controlling the switches between other programmable phase shifters and the corresponding secondary coils to be turned off.

[0110] The reference programmable phase shifter is a preset reference programmable phase shifter among the plurality of programmable phase shifters. The at least one programmable phase shifter includes: all other programmable phase shifters except the reference programmable phase shifter among the plurality of programmable phase shifters.

[0111] For example, if the reference programmable phase shifter is a first programmable phase shifter, the at least one programmable phase shifter includes a second programmable phase shifter, a third programmable phase shifter, and a fourth programmable phase shifter. A first switch between the first programmable phase shifter and the corresponding first secondary coil is controlled to be turned on, a second switch between the second programmable phase shifter and the corresponding second secondary coil is controlled to be turned off, a third switch between the third programmable phase shifter and the corresponding third secondary coil is controlled to be turned off, and a fourth switch between the fourth programmable phase shifter and the corresponding fourth secondary coil is controlled to be turned off.

[0112] S702, obtaining a calibration frequency signal generated by an oscillation circuit under the action of a reference programmable phase shifter.

[0113] Before controlling the switch between the reference programmable phase shifter and the corresponding secondary coil to be turned on, the main coil oscillates to generate a sinusoidal signal, and after the sinusoidal signal is input into the reference programmable phase shifter, a sinusoidal signal with an initial phase shift is generated.

[0114] The switch between the control reference programmable phase shifter and the corresponding secondary coil is turned on. After passing through the secondary coil driver and the switch corresponding to the reference programmable phase shifter, current is generated in the secondary coil, and then an induced electromotive force is generated in the main coil, thereby changing the inductance of the main coil. The controller can measure the calibration frequency of the calibrated calibration frequency signal generated by the oscillator.

[0115] S703, calculating the equivalent inductance of the main coil under the action of the reference programmable phase shifter as the reference inductance according to the calibration frequency of the calibration frequency signal.

[0116] According to the calibration frequency of the calibration frequency signal, the equivalent main coil inductance of the main coil under the action of the reference programmable phase shifter can be calculated by the above formula (2).

[0117] An eddy current micro-distance measurement method provided in an embodiment of the present application controls the switch between a reference programmable phase shifter and a corresponding secondary coil to be turned on, and controls the switch between other programmable phase shifters and corresponding secondary coils to be turned off, thereby obtaining a signal calibration frequency generated by an oscillation circuit under the action of a reference programmable phase shifter. Based on the signal calibration frequency, the equivalent inductance of the main coil under the action of the reference programmable phase shifter is calculated as a reference inductance, and then the phase of at least one programmable phase shifter can be calibrated based on the reference inductance, so that the equivalent inductance calculated under the action of the programmable phase shifter after phase adjustment is equal to the reference inductance.

[0118] In the above-mentioned embodiments of the present application Figure 5 , Figure 6 and Figure 7 On the basis of the provided eddy current micro-distance measurement method, the eddy current micro-distance measurement method is specifically explained and illustrated by a complete embodiment in combination with the accompanying drawings as follows. By way of example, the preset reference programmable phase shifter is specifically explained by taking the first programmable phase shifter as an example, and at least one programmable phase shifter is specifically explained by taking the second programmable phase shifter, the third programmable phase shifter, and the fourth programmable phase shifter as examples. It can be understood that the preset reference programmable phase shifter can also be other programmable phase shifters, and at least one programmable phase shifter can also be other programmable phase shifters, which are not specifically limited in the embodiments of the present application. Figure 8 A schematic diagram of another eddy current micro-distance measurement method provided in an embodiment of the present application. Figure 8As shown, the method includes:

[0119] S801, controlling the first switch to be turned on, controlling the other switches to be turned off, obtaining a calibration frequency signal generated by the oscillation circuit under the action of the first programmable phase shifter, and calculating a reference inductance.

[0120] The specific implementation and effect description of S801 refer to the above Figure 7 S701, S702, and S703 are not described in detail here.

[0121] S802, controlling the second switch to be turned on, controlling other switches to be turned off, obtaining a calibration frequency signal generated by the oscillation circuit under the action of the second programmable phase shifter, and calculating an equivalent inductance corresponding to the first programmable phase shifter.

[0122] For the specific implementation and effect description of S802, see the above Figure 6 S601, S602, and S603 are not described in detail here.

[0123] S803, adjusting the phase of the second programmable phase shifter according to the equivalent inductance corresponding to the first programmable phase shifter and the preset reference inductance, so that the equivalent inductance calculated by the second programmable phase shifter after the phase adjustment is equal to the reference inductance.

[0124] For the specific implementation and effect description of S803, see the above Figure 6 S604 in the description will not be described in detail here.

[0125] S804, control the third switch to be turned on, control the other switches to be turned off, obtain the calibration frequency signal generated by the oscillation circuit under the action of the third programmable phase shifter, and calculate the equivalent inductance corresponding to the third programmable phase shifter.

[0126] For the specific implementation and effect description of S804, see the above Figure 6 S601, S602, and S603 are not described in detail here.

[0127] S805, adjusting the phase of the third programmable phase shifter according to the equivalent inductance corresponding to the third programmable phase shifter and the preset reference inductance, so that the equivalent inductance calculated under the action of the third programmable phase shifter after the phase adjustment is equal to the reference inductance.

[0128] For the specific implementation and effect description of S805, see the above Figure 6 S604 in the description will not be described in detail here.

[0129] Optionally, the phase of the third programmable phase shifter can be adjusted according to the equivalent inductance corresponding to the third programmable phase shifter and the equivalent inductance corresponding to the second programmable phase shifter, so that the equivalent inductance calculated under the action of the third programmable phase shifter after the phase adjustment is equal to the equivalent inductance corresponding to the second programmable phase shifter.

[0130] S806, controlling the fourth switch to be turned on, controlling the other switches to be turned off, obtaining the calibration frequency signal generated by the oscillation circuit under the action of the fourth programmable phase shifter, and calculating the equivalent inductance corresponding to the fourth programmable phase shifter.

[0131] The specific implementation and effect description of S806 refer to the above Figure 6 S601, S602, and S603 are not described in detail here.

[0132] S807, adjusting the phase of the fourth programmable phase shifter according to the equivalent inductance corresponding to the fourth programmable phase shifter and the preset reference inductance, so that the equivalent inductance calculated under the action of the fourth programmable phase shifter after the phase adjustment is equal to the reference inductance.

[0133] The specific implementation and effect description of S807 refer to the above Figure 6 S604 in the description will not be described in detail here.

[0134] Optionally, the phase of the fourth programmable phase shifter can also be adjusted according to the equivalent inductance corresponding to the fourth programmable phase shifter and the equivalent inductance corresponding to the third or second programmable phase shifter, so that the equivalent inductance calculated under the action of the fourth programmable phase shifter after the phase adjustment is equal to the equivalent inductance corresponding to the third or second programmable phase shifter.

[0135] Optionally, the order of adjusting the phase of the second programmable phase shifter, adjusting the phase of the third programmable phase shifter, and adjusting the phase of the fourth programmable phase shifter can be adjusted. It is also possible to first adjust the phase of the third programmable phase shifter, then adjust the phase of the second programmable phase shifter, and finally adjust the phase of the fourth programmable phase shifter. The order of adjustment is not specifically limited in the embodiments of the present application.

[0136] S808, after the main coil calibration is completed, all switches in the eddy current micro-distance measuring device are controlled to be turned on, and a measurement frequency signal generated by an oscillation circuit in the eddy current micro-distance measuring device is obtained, and the measurement inductance of the main coil is calculated according to the measurement frequency of the measurement frequency signal, and the distance between the target conductor to be measured and the preset position in the main coil is determined according to the measurement inductance.

[0137] For the specific implementation and effect description of S808, see the above Figure 5 S502, S503, and S504 are not described in detail here.

[0138] Optionally, Figure 2 The figure shows the situation where the eddy current coil is parallel to the surface of the target conductor to be measured, where the initial phases of the four phase shifters are all set to 90°. Fig. 9 A waveform diagram of a main coil and multiple secondary coils provided in an embodiment of the present application, such as Fig. 9 As shown, since the four secondary coils are at the same distance from the target conductor to be measured and have rotational symmetry with respect to the main coil, the calibrated phases of the programmable phase shifters corresponding to the four secondary coils are all 90°.

[0139] Optionally, Figure 3 The figure shows that the eddy current coil is tilted to the right. At this time, the second secondary coil is closest to the plane of the target conductor to be measured, and the eddy current generated by the adjacent main coil position in the target conductor to be measured is the strongest. The fourth secondary coil is farthest from the plane of the target conductor to be measured, and the eddy current generated by the adjacent main coil position in the target conductor to be measured is the weakest. The first secondary coil is centered at the plane of the target conductor to be measured, and the eddy current intensity generated by the adjacent main coil position in the target conductor to be measured is centered. The third secondary coil is centered at the plane of the target conductor to be measured, and the eddy current intensity generated by the adjacent main coil position in the target conductor to be measured is centered, but slightly higher than that of the first secondary coil.

[0140] Fig.10 Another waveform diagram of a main coil and multiple secondary coils provided in an embodiment of the present application is as follows: Fig.10 As shown, after calibration, the phase of the first secondary coil is 90°, the eddy current generated by the second secondary coil will offset a considerable part of the eddy current generated by the main coil, so the phase of the second secondary coil is greater than 90°, the eddy current generated by the third secondary coil will offset part of the eddy current generated by the main coil, so the phase of the third secondary coil is slightly greater than 90°, and the eddy current generated by the fourth secondary coil will enhance part of the eddy current generated by the main coil, so the phase of the fourth secondary coil is less than 90°.

[0141] The present application provides an eddy current small distance measurement method, which adopts a main coil and multiple auxiliary coils to work together, and uses the eddy currents generated by the auxiliary coils to enhance or offset part of the eddy currents generated by the main coils, thereby offsetting the adverse effects of non-parallel installation on measurement.

[0142] The following describes an eddy current micro-distance measuring device, a controller and a storage medium provided by the present application for executing the present application. The specific implementation process and technical effects are described above and will not be repeated below.

[0143] Fig.11 A schematic diagram of an eddy current micro-distance measuring device applied to a controller provided in an embodiment of the present application is shown in FIG. Fig.11 As shown, the device comprises:

[0144] The calibration module 1101 is used to adjust the phase of at least one programmable phase shifter in the eddy current micro-distance measuring device to calibrate the main coil in the eddy current micro-distance measuring device.

[0145] The control module 1102 is used to control the conduction of multiple switches in the eddy current micro-distance measuring device after the main coil calibration is completed, and obtain the measurement frequency signal generated by the oscillation circuit in the eddy current micro-distance measuring device.

[0146] The calculation module 1103 is used to calculate the measured inductance of the main coil according to the measured frequency of the measured frequency signal.

[0147] The determination module 1104 is used to determine the distance between the target conductor to be measured and a preset position in the main coil according to the measured inductance.

[0148] Optionally, the calibration module 1101 is specifically used to control the conduction of the switch between the programmable phase shifter and the corresponding secondary coil, and control the disconnection of the switch between other programmable phase shifters and the corresponding secondary coils, obtain the calibration frequency signal generated by the oscillation circuit under the action of the programmable phase shifter, calculate the equivalent inductance of the main coil under the action of the programmable phase shifter according to the calibration frequency of the calibration frequency signal, and adjust the phase of the programmable phase shifter according to the equivalent inductance and a preset reference inductance, so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase adjustment is equal to the reference inductance.

[0149] Optionally, the calibration module 1101 is also used to control the conduction of the switch between the reference programmable phase shifter and the corresponding secondary coil, and control the disconnection of the switch between other programmable phase shifters and the corresponding secondary coils, wherein the reference programmable phase shifter is a preset reference programmable phase shifter among multiple programmable phase shifters, and at least one programmable phase shifter includes: all other programmable phase shifters other than the reference programmable phase shifter among the multiple programmable phase shifters, obtain the calibration frequency signal generated by the oscillation circuit under the action of the reference programmable phase shifter, and calculate the equivalent inductance of the main coil under the action of the reference programmable phase shifter according to the calibration frequency of the calibration frequency signal as the reference inductance.

[0150] Optionally, the calibration module 1101 is specifically configured to increase the phase of the programmable phase shifter if the equivalent inductance is greater than the reference inductance, so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase increase is equal to the reference inductance.

[0151] Optionally, the calibration module 1101 is specifically configured to reduce the phase of the programmable phase shifter if the equivalent inductance is smaller than the reference inductance, so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase reduction is equal to the reference inductance.

[0152] The above modules may be one or more integrated circuits configured to implement the above methods, such as one or more application specific integrated circuits (ASIC), or one or more digital singnal processors (DSP), or one or more field programmable gate arrays (FPGA). For another example, when a module is implemented in the form of a processing element scheduling program code, the processing element may be a general-purpose processor, such as a central processing unit (CPU) or other processor that can call program code. For another example, these modules may be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0153] Fig.12 A schematic diagram of a controller provided in an embodiment of the present application, wherein the controller may be a device with computing and processing functions.

[0154] The controller includes: a processor 1201 , a storage medium 1202 , and a bus 1203 . The processor 1201 and the storage medium 1202 are connected via the bus 1203 .

[0155] The storage medium 1202 is used to store programs, and the processor 1201 calls the programs stored in the storage medium 1202 to execute the above method embodiment. The specific implementation method and technical effect are similar and will not be repeated here.

[0156] Optionally, the present invention also provides a program product, such as a computer-readable storage medium, comprising a program, which is used to execute the above method embodiment when executed by a processor.

[0157] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the scheme of this embodiment.

[0158] The above-mentioned integrated unit implemented in the form of a software functional unit can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor (English: processor) to perform some steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (English: Read-Only Memory, referred to as: ROM), random access memory (English: Random Access Memory, referred to as: RAM), disk or optical disk and other media that can store program codes.

[0159] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for measuring small distances using eddy currents, characterized in that: A controller used in an eddy current micro-distance measuring device, wherein the eddy current micro-distance measuring device comprises: a main coil, a plurality of secondary coils, a plurality of programmable phase shifters, a plurality of coil drivers, an oscillation circuit, a controller and a plurality of switches; The multiple secondary coils and the main coil are arranged on the same plane, and the multiple secondary coils are arranged around the main coil, the main coil is connected to the oscillation circuit, the oscillation circuit is also connected to the multiple programmable phase shifters, and the multiple programmable phase shifters are respectively connected to the multiple secondary coils through the multiple coil drivers; the oscillation circuit and the multiple programmable phase shifters are both connected to the controller; Wherein, the plurality of coil drivers are respectively connected to the plurality of auxiliary coils through the plurality of switches; The method comprises: Adjusting the phase of at least one programmable phase shifter in the eddy current micro-distance measuring device to calibrate the main coil in the eddy current micro-distance measuring device; After the main coil is calibrated, a plurality of switches in the eddy current micro-distance measuring device are controlled to be turned on, and a measurement frequency signal generated by an oscillation circuit in the eddy current micro-distance measuring device is obtained; Calculating the measured inductance of the main coil according to the measured frequency of the measured frequency signal; Determining the distance between the target conductor to be measured and a preset position in the main coil according to the measured inductance; Wherein, each of the programmable phase shifters is a phase shifter based on a third-order phase-locked loop; the coil parameters of the multiple secondary coils are all the same; and the circuit parameters of the multiple coil drivers are all the same.

2. The eddy current micro-distance measurement method according to claim 1, characterized in that: The step of adjusting the phase of at least one programmable phase shifter in the eddy current micro-distance measuring device to calibrate the main coil in the eddy current micro-distance measuring device comprises: Controlling the switch between the programmable phase shifter and the corresponding secondary coil to be turned on, and controlling the switches between other programmable phase shifters and the corresponding secondary coils to be turned off; Acquiring a calibration frequency signal generated by the oscillation circuit under the action of the programmable phase shifter; Calculating the equivalent inductance of the main coil under the action of the programmable phase shifter according to the calibration frequency of the calibration frequency signal; According to the equivalent inductance and a preset reference inductance, the phase of the programmable phase shifter is adjusted so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase adjustment is equal to the reference inductance.

3. The eddy current micro-distance measurement method according to claim 2, characterized in that: Before adjusting the phase of the programmable phase shifter according to the equivalent inductance and the preset reference inductance, the method further includes: Controlling the switch between the reference programmable phase shifter and the corresponding secondary coil to be turned on, and controlling the switch between other programmable phase shifters and the corresponding secondary coils to be turned off, wherein the reference programmable phase shifter is a preset reference programmable phase shifter among the multiple programmable phase shifters, and at least one of the programmable phase shifters includes: all other programmable phase shifters except the reference programmable phase shifter among the multiple programmable phase shifters; Acquiring a calibration frequency signal generated by the oscillation circuit under the action of the reference programmable phase shifter; According to the calibration frequency of the calibration frequency signal, the equivalent inductance of the main coil under the action of the reference programmable phase shifter is calculated as the reference inductance.

4. The eddy current micro-distance measurement method according to claim 2, characterized in that: The adjusting the phase of the programmable phase shifter according to the equivalent inductance and the preset reference inductance, so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase adjustment is equal to the reference inductance, comprises: If the equivalent inductance is greater than the reference inductance, the phase of the programmable phase shifter is increased so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase increase is equal to the reference inductance.

5. The eddy current micro-distance measurement method according to claim 2, characterized in that: The adjusting the phase of the programmable phase shifter according to the equivalent inductance and the preset reference inductance, so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase adjustment is equal to the reference inductance, comprises: If the equivalent inductance is smaller than the reference inductance, the phase of the programmable phase shifter is reduced so that the equivalent inductance calculated under the action of the programmable phase shifter after the phase reduction is equal to the reference inductance.

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