Inductive magnetic field sensor multi-resonance point equivalent circuit model and establishment method

Abstract

The disclosure provides a multi-resonance point equivalent circuit model of an inductive magnetic field sensor and a method for establishing the same. The inductive magnetic field sensor comprises an electromagnetic induction component, a feedback coil, and an amplification circuit. The multi-resonance point equivalent circuit model comprises: an output terminal; an RLC equivalent circuit of the electromagnetic induction component, comprising an equivalent model of a magnetic core and an RLC equivalent circuit coupled to the magnetic core; an equivalent circuit of the amplification circuit, one end of which is connected to the RLC equivalent circuit and the other end of which is connected to the output terminal; an equivalent circuit of the negative feedback coil, one end of which is connected to the output terminal and the other end of which is coupled to the RLC equivalent circuit of the electromagnetic induction component; and at least one parallel resonance equivalent circuit, which is connected between the RLC equivalent circuit of the electromagnetic induction component and the equivalent circuit of the amplification circuit and is configured to suppress a resonance peak corresponding to a resonance point in a working frequency band of the sensor.

Description

Technical Field

[0001] This disclosure relates to the field of electromagnetic technology, and in particular to an equivalent circuit model of a multi-resonant point inductive magnetic field sensor and a method for establishing it. Background Technology

[0002] Inductive magnetic field sensors are sensors that measure changes in magnetic fields using Faraday's law of electromagnetic induction. They are widely used in geophysics, medicine, and defense, and are among the most common magnetic field sensors. In geophysical electromagnetic methods, they are widely used in magnetotelluric sounding (MT), controlled-source audio magnetotelluric sounding (CSAMT), and transient electromagnetic methods (TEM), covering a frequency range of 0.0001Hz-100kHz, making them a core component of geophysical electromagnetic equipment. However, inductive magnetic field sensor technology faces a series of technical challenges, including core development and low-frequency weak signal detection, making it a bottleneck technology hindering the independent development of geophysical electromagnetic exploration equipment. To optimize the design of inductive magnetic field sensors, an equivalent circuit model needs to be established. Through simulation calculations of the model, the system function of the inductive magnetic field sensor, i.e., the sensor's conversion sensitivity (frequency response), can be obtained. Currently, the coil part (including the magnetic core) at the front end of an inductive magnetic field sensor is generally equivalent to a series resonant model of inductance, resistance, and capacitance, which has a single resonant frequency. However, in reality, there is often more than one resonant frequency within the sensor bandwidth, so the current equivalent circuit model of inductive magnetic field sensors is not accurate. Summary of the Invention

[0003] In view of this, in order to at least partially solve at least one of the aforementioned technical problems, this disclosure provides an equivalent circuit model of a multi-resonant point for an inductive magnetic field sensor and a method for establishing it.

[0004] To achieve the above objectives, the technical solution disclosed herein is as follows:

[0005] According to one embodiment of this disclosure, a multi-resonance equivalent circuit model of an inductive magnetic field sensor is provided. The inductive magnetic field sensor includes an electromagnetic induction component, a feedback coil, and an amplification circuit. The multi-resonance equivalent circuit model includes: an output terminal; an RLC equivalent circuit of the electromagnetic induction component, including an equivalent model of the magnetic core and an RLC equivalent circuit coupled to the magnetic core; an equivalent circuit of the amplification circuit, one end of which is connected to the RLC equivalent circuit, and the other end of which is connected to the output terminal; an equivalent circuit of the negative feedback coil, one end of which is connected to the output terminal, and the other end of which is coupled to the RLC equivalent circuit of the electromagnetic induction component; and at least one parallel resonant equivalent circuit connected between the RLC equivalent circuit of the electromagnetic induction component and the equivalent circuit of the amplification circuit, and configured to suppress the resonance peak corresponding to the resonance point within the sensor's operating frequency band.

[0006] According to an embodiment of this disclosure, the electromagnetic induction component includes a magnetic core and an induction coil wound around the magnetic core, and the RLC equivalent circuit of the electromagnetic induction component includes an equivalent capacitance C. sc and connected in parallel to the capacitor C sc The equivalent inductance L at both ends is set in series. pc and equivalent resistance R sc .

[0007] According to an embodiment of this disclosure, a parallel resonant equivalent circuit is introduced based on the resonant point information within the operating frequency band of the magnetic field sensor. The resonant point information includes the number of resonant peaks and the frequency of the resonant point corresponding to each resonant peak.

[0008] According to embodiments of this disclosure, at least one parallel resonant equivalent circuit may be selectively introduced corresponding to the number of resonant peaks.

[0009] According to embodiments of this disclosure, the number of corresponding introduced parallel resonant equivalent circuits is determined based on the number of the resonant peaks.

[0010] According to embodiments of this disclosure, the parallel resonant equivalent circuit includes an equivalent resonant inductor L connected in parallel. m Equivalent resonant resistance R m Equivalent resonant capacitance C m Equivalent inter-turn capacitance C sm The equivalent resonant resistance R m With the equivalent resistance R sc The equivalent resonant inductance L is connected in series. m Derived from equivalent inductance L pc Part of it.

[0011] According to embodiments of this disclosure, the equivalent resonant capacitance The solution formula is:

[0012] ;

[0013] The equivalent resonant resistance R m The solution formula is:

[0014] ;

[0015] in, This is the equivalent resonant inductance value. Let Q be the frequency of the resonant point corresponding to the parallel resonant equivalent circuit, and let Q be the quality factor of the parallel resonant equivalent circuit.

[0016] According to embodiments of this disclosure, the equivalent capacitance C sc One end is grounded, and the other end is connected to the equivalent circuit of the amplifier circuit.

[0017] According to embodiments of this disclosure, the equivalent circuit of the negative feedback coil includes feedback resistors R connected in series. fb The equivalent inductance L of the negative feedback coil s、 and the equivalent resistance R of the negative feedback coil s In this circuit, one end of the equivalent circuit of the negative feedback coil is connected to the output terminal of the equivalent circuit of the amplifier circuit, and the other end of the equivalent circuit of the negative feedback coil is grounded.

[0018] Another aspect of this disclosure provides a method for establishing the above-described multi-resonance point equivalent circuit model, wherein the inductive magnetic field sensor includes an electromagnetic induction component, a feedback coil, and an amplification circuit, and the method includes:

[0019] Establish the RLC equivalent circuit of the electromagnetic induction component;

[0020] Construct the equivalent circuit of the amplifier circuit connected to the RLC equivalent circuit;

[0021] Establish the equivalent circuit of the negative feedback coil to complete the initial establishment of the equivalent circuit model of the magnetic field sensor;

[0022] Based on the initial equivalent circuit model, the resonant point information within the operating frequency band of the magnetic field sensor was confirmed; and

[0023] Based on the resonant point information, a parallel resonant equivalent circuit is introduced to suppress the resonant peak corresponding to the resonant point within the sensor's operating frequency band, thus completing the establishment of the multi-resonant point equivalent circuit model for the inductive magnetic field sensor. Attached Figure Description

[0024] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments of this disclosure with reference to the accompanying drawings, in which:

[0025] Figure 1 This is a schematic diagram of the equivalent circuit model of a single resonant point of a magnetic field sensor.

[0026] Figure 2 This is a schematic diagram showing the sensitivity of the coil and the sensitivity of the magnetic field sensor.

[0027] Figure 3 This is a schematic diagram of an equivalent circuit model of a magnetic field sensor with multiple resonant points according to an embodiment of this disclosure.

[0028] Figure 4 This is a schematic diagram of the impedance test structure of the equivalent circuit model of the multi-resonant point of the magnetic field sensor according to an embodiment of this disclosure.

[0029] Figure 5a This is a schematic diagram of the equivalent circuit model of the multi-resonant point of the magnetic field sensor according to an embodiment of this disclosure.

[0030] Figure 5b This is a schematic flowchart illustrating the method for establishing the equivalent circuit model of a multi-resonant point magnetic field sensor according to an embodiment of this disclosure.

[0031] Figure 6 This is a schematic diagram comparing the simulated results and actual test results of the induced voltage sensitivity of an embodiment of this disclosure.

[0032] Figure 7 This is a schematic diagram comparing the sensitivity simulation and actual test results of the magnetic field sensor according to an embodiment of this disclosure. Detailed Implementation

[0033] This disclosure provides an equivalent circuit model of multiple resonant points for an inductive magnetic field sensor and a method for establishing it. A parallel resonant equivalent circuit is introduced and combined with the sensor front-end amplifier circuit model to obtain the equivalent circuit model of multiple resonant points for the sensor.

[0034] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0035] In this embodiment of the disclosure, combined with Figure 5a and Figure 5b As shown, an equivalent circuit model of a multi-resonant point inductive magnetic field sensor is provided. The inductive magnetic field sensor includes an electromagnetic induction component, a feedback coil, and an amplification circuit. The equivalent circuit model of the multi-resonant point includes:

[0036] Output terminal;

[0037] The RLC equivalent circuit of the electromagnetic induction component includes an equivalent model of the magnetic core and an RLC equivalent circuit coupled to the magnetic core.

[0038] The equivalent circuit of the amplifier circuit is connected to the RLC equivalent circuit at one end and the other end is connected to the output terminal.

[0039] The equivalent circuit of the negative feedback coil has one end connected to the output terminal and the other end coupled to the RLC equivalent circuit of the electromagnetic induction component; and

[0040] At least one parallel resonant equivalent circuit is connected between the RLC equivalent circuit of the electromagnetic induction component and the equivalent circuit of the amplification circuit, and is configured to suppress the resonance peak corresponding to the resonance point within the sensor's operating frequency band.

[0041] According to an embodiment of this disclosure, the electromagnetic induction component includes a magnetic core and an induction coil wound on the magnetic core. The RLC equivalent circuit of the electromagnetic induction component includes: an equivalent capacitance C. sc and connected in parallel to the capacitor C sc The equivalent inductance L at both ends is set in series. pc and equivalent resistance Rsc .

[0042] According to embodiments of this disclosure, parallel resonant equivalent circuits are introduced based on resonant point information within the operating frequency band of the magnetic field sensor. The resonant point information includes the number of resonant peaks and the frequency of each resonant point. The number of parallel resonant equivalent circuits introduced is determined based on the number of resonant peaks. For example, at least one parallel resonant equivalent circuit can be selectively introduced based on the number of resonant peaks. If multiple resonant peaks correspond to multiple resonant points, a parallel resonant equivalent circuit can be introduced based on a second resonant point, or another based on a third resonant point. Alternatively, based on actual needs, more parallel resonant equivalent circuits can be introduced according to the number of resonant points. This allows for better suppression of resonant peaks within the sensor's operating frequency band and provides a better equivalent model describing the sensor over a wider bandwidth.

[0043] According to embodiments of this disclosure, such as Figure 5a As shown, the parallel resonant equivalent circuit ( Figure 5a (As shown in the red box) includes the equivalent resonant inductance L connected in parallel. m Equivalent resonant resistance R m Equivalent resonant capacitance C m Equivalent inter-turn capacitance C sm The equivalent resonant resistance R m With the equivalent resistance R sc Series connection. Equivalent resonant inductance L m The value is selected based on the equivalent inductance L. pc Part of it, namely from the equivalent inductance L pc Extract a small inductor as the equivalent resonant inductance L. m The value of .

[0044] Equivalent resonant capacitance The solution formula is:

[0045] ;

[0046] The equivalent resonant resistance R m The solution formula is:

[0047] ;

[0048] in, This is the equivalent resonant inductance value. Let C be the frequency of the resonant point corresponding to the parallel resonant equivalent circuit, and Q represent the quality factor of the parallel resonant equivalent circuit. The equivalent capacitance C is... sc One end is grounded, and the other end is connected to the equivalent circuit of the amplifier circuit.

[0049] According to embodiments of this disclosure, the equivalent circuit of the negative feedback coil includes feedback resistors R connected in series. fb The equivalent inductance L of the negative feedback coil s、 and the equivalent resistance R of the negative feedback coil s In this circuit, one end of the equivalent circuit of the negative feedback coil is connected to the output terminal of the equivalent circuit of the amplifier circuit, and the other end of the equivalent circuit of the negative feedback coil is grounded.

[0050] According to another embodiment of this disclosure, in conjunction with Figure 5a and Figure 5b As shown, a method for establishing the equivalent circuit model of the multi-resonant point of the above-mentioned inductive magnetic field sensor is provided. The method includes:

[0051] S1: Establish the RLC equivalent circuit of the electromagnetic induction component;

[0052] S2: Construct the equivalent circuit of the amplifier circuit connected to the RLC equivalent circuit;

[0053] S3: Establish the equivalent circuit of the negative feedback coil and complete the initial establishment of the equivalent circuit model of the magnetic field sensor;

[0054] S4: Based on the initial equivalent circuit model, confirm the resonant point information within the operating frequency band of the magnetic field sensor; and

[0055] S5: Based on the resonant point information, a parallel resonant equivalent circuit is introduced to suppress the resonant peak corresponding to the resonant point within the sensor's operating frequency band, thus completing the establishment of the multi-resonant point equivalent circuit model for the inductive magnetic field sensor.

[0056] An inductive magnetic field sensor (magnetic rod) mainly consists of three parts: a magnetic core, a winding coil, and a front-end amplifier circuit. The magnetic core enhances the magnetic flux density passing through the coil, which is highly sensitive to changes in the ambient magnetic field. The amplifier circuit amplifies the minute signal induced in the winding, making it detectable by standard electromagnetic measuring equipment. Generally, the combination of the winding and the magnetic core can be represented as an inductive element with inherent series resistance connected in parallel with a capacitive element. This is the single-resonant-point RLC (resistance-inductance-capacitance) series resonant equivalent circuit model of the magnetic field sensor. This model is fundamental to understanding the sensor's sensitivity to changes in the magnetic field and consists of three key components: resistance (R), inductance (L), and capacitance (C), which together determine the sensor's resonant characteristics.

[0057] The resistance values ​​in this equivalent circuit model correspond to the DC resistance of the coil, which can be easily measured using a multimeter. The inductance value can be measured using an impedance analyzer (such as a 4294A). In practice, as the frequency increases, the coil's impedance changes from inductive reactance to capacitive reactance. Therefore, for accurate measurement of the coil's inductance value, it is best to read the inductance value at low frequencies.

[0058] Determining the capacitance value is a more complex process because it depends on both the measured inductance value and the resonant frequency obtained from an impedance analyzer. The resonant frequency is the frequency at which the sensor impedance is minimum and is a key parameter in the RLC model. By combining the inductance value and the resonant frequency, the capacitance value can be calculated, thus completing the RLC model. This model is crucial for predicting sensor performance and designing circuits capable of accurately detecting and measuring changes in magnetic fields. In summary, the equivalent circuit model of a magnetic field sensor with flux negative feedback is as follows: Figure 1 As shown, where L pc R sc and C sc These represent the equivalent inductance, resistance, and capacitance of the coil, respectively, and e represents the induced voltage, V. i R represents the output voltage of the coil. fb It is the feedback resistor, G represents the amplifier's equivalent gain, and L... s and R s The equivalent inductance and resistance of the negative feedback coil are represented by V, M represents the mutual inductance between the induction coil and the negative feedback coil, and V represents the mutual inductance between the induction coil and the negative feedback coil. out This indicates the output of the magnetic field sensor.

[0059] According to Faraday's law, the induced voltage e in the coil can be expressed as:

[0060] ;

[0061] Where f represents frequency, μ app Let N represent the apparent permeability of the magnetic core, S represent the number of turns of the coil, S represent the cross-sectional area of ​​the magnetic core, and B represent the magnetic flux density. Clearly, the induced voltage is proportional to the frequency.

[0062] According to circuit principles, the output voltage V of the coil i It is represented as:

[0063] (2);

[0064] Where ω represents the angular frequency, ω=2πf.

[0065] Based on the algorithm for solving the transfer function in a negative feedback system, we can obtain:

[0066] (3);

[0067] (4);

[0068] (5);

[0069] Substituting equations (1), (4), and (5) into equation (3), we can obtain the relationship between the output voltage and the input magnetic field:

[0070] (6);

[0071] For example, the sensitivity of the induction coil (via the dashed line V) i (reflected) and the sensitivity of the magnetic field sensor (via the solid line V) out (Embody) such as Figure 2 As shown.

[0072] Clearly, magnetic flux negative feedback can effectively flatten the sensitivity of a magnetic field sensor near a single resonant frequency.

[0073] However, the coils of magnetic field sensors typically have multiple resonant points (or resonant peaks) within their operating bandwidth. To address this complexity, the traditional series resonance model is extended by introducing a parallel resonant equivalent circuit (or parallel resonant equivalent model), such as... Figure 3 As shown in the red box, this parallel resonant equivalent circuit introduces an additional resistance R. m Capacitor C m and inductor L m The introduction of parallel resonant equivalent circuits will allow for a more comprehensive description or simulation of magnetic field sensors.

[0074] In the parallel resonant equivalent circuit, a small inductance is extracted from the total inductance of the induction coil as the equivalent resonant inductance. Equivalent resonant capacitance C m The equivalent resonant resistance R is determined by the second resonant frequency point fm and the equivalent resonant inductance. m The Q factor, determined by measurements at the second resonant point, is typically a large resistance value.

[0075] (7);

[0076] (8);

[0077] In order to estimate Figure 3 The values ​​of each equivalent component in the equivalent circuit model shown require two steps: impedance testing and coil induced voltage testing, in order to estimate all parameters.

[0078] 1. Regarding impedance testing:

[0079] Taking a double resonant coil as an example, the AC impedance test results of the coil obtained using an impedance analyzer (model 4294A) are as follows: Figure 4 As shown, the inductance value measured at 40Hz is denoted as L. testThe red dashed line represents inductance, and the blue line represents resistance. The first resonant peak corresponds to the first resonant frequency f. r1 The second resonant frequency corresponding to the second resonant peak is f. r2 ,but:

[0080] L test =L m +L pc (9);

[0081] (10);

[0082] (11);

[0083] Assume L m Given 10H, the equivalent inductance L can be calculated. pc The value of . Furthermore, the resistance measured by the impedance analyzer includes core losses. Therefore, the coil resistance R in the model . sc The value should be determined by the measured DC resistance of the coil. At this point, the parameter values ​​in the dual-resonance model of the magnetic field sensor can be derived from the impedance test results, as detailed in Table 1 below.

[0084] Table 1 Parameters of Magnetic Field Sensor

[0085]

[0086] Based on circuit theory and the double resonant point model, the induced voltage V i The analytical expression is transformed from formula (2) to formula (12) as follows:

[0087] (12);

[0088] By substituting the values ​​in Table 1, the sensitivity of the induced voltage can be simulated and calculated. The simulation results are compared with the actual results as follows: Figure 6 As shown, Figure 6 The upper middle section of the graph reflects the sensitivity (amplitude) results, and the lower section reflects the sensitivity (phase) results. Sensitivity was measured using a solenoid calibration system. The solenoid's scaling factor was 16.934 nT / mA. The frequency scanner in the system was a dynamic signal analyzer (model 35670A).

[0089] It can be observed that the actual measurement results of the magnetic field sensor are basically consistent with the simulation results, indicating that the dual-resonance point model is effective.

[0090] 2. Regarding the sensitivity test of the magnetic field sensor:

[0091] By deriving the transfer function of the flux negative feedback magnetic field sensor, it can be observed that formula (5) remains unchanged, while formula (4) is revised to formula (13), as shown below:

[0092] (13);

[0093] The expression in formula (13) can be simplified to:

[0094] (14);

[0095] Among them, molecule N A :

[0096] (15);

[0097] Denominator DA:

[0098] (16);

[0099] By substituting formulas (13) and (5) into formula (3) and simplifying the numerator and denominator, the sensitivity of the sensor can be obtained:

[0100] (17);

[0101] Unlike when calculating induced voltage, where the input impedance of the device is considered, here the coil is connected to an amplifier circuit, so the input impedance of the circuit, specifically the input resistance R of the amplifier circuit, needs to be taken into account. c The input capacitance is 4 GOhm, and the input capacitor is C. ca The value is 200 pF. Clearly, due to the isolation provided by the circuit, the input parameters of the test equipment no longer need to be considered in this scenario.

[0102] Furthermore, due to the inclusion of a negative feedback coil, shielding layer, and calibration coil in the sensor assembly, there is an inter-turn capacitance C between these coils. cm The value will be increased to 20 pF. Specific parameters are listed in Table 1. Similarly, a comparison of the simulated results and actual test results of the magnetic field sensor is shown below. Figure 7 As shown, Figure 7 The upper middle section of the graph reflects the sensitivity (amplitude) results, while the lower section reflects the sensitivity (phase) results.

[0103] Considering the differences between the design and actual implementation of the sensor filter, the test results show that the experimental and simulation results are consistent. Notably, by introducing the equivalent parallel resonant circuit model corresponding to the second resonant point, the fluctuation in the sensor's measurement sensitivity at 9kHz is effectively explained.

[0104] The dual-resonant model of the magnetic field sensor, as described above, can have its coil parameters obtained through impedance analysis. By incorporating the parameters of the test equipment, the coil output was directly connected to the equipment to measure the sensitivity of the induced voltage, and the results were consistent with the simulation. Furthermore, by integrating the circuit parameters and connecting the coil to the circuit, the sensor's sensitivity was tested, and the results also matched the simulation. Therefore, the dual-resonant model of the sensor proposed in this scheme has been verified as correct and effective.

[0105] Currently, inductive magnetic field sensors are modeled using a single resonant point, which does not provide a comprehensive description of the sensor. This disclosure presents a multi-resonant point equivalent circuit model and establishment method for inductive magnetic field sensors. It introduces a parallel resonant equivalent circuit of the second resonant point of the coil, a component of the magnetic field sensor, thereby explaining the change in sensor sensitivity and effectively expanding the sensor theory.

[0106] The embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. It should be noted that implementations not illustrated or described in the drawings or the main text of the specification are forms known to those skilled in the art and are not described in detail. Furthermore, the definitions of the various elements and methods described above are not limited to the specific structures, shapes, or methods mentioned in the embodiments, and those skilled in the art can easily modify or substitute them.

[0107] Furthermore, unless otherwise specified, the ordinal numbers such as "first," "second," etc., used herein are merely for distinguishing multiple elements with the same name and do not indicate any hierarchy, order of execution, or process sequence among them. A "first" element and a "second" element may appear together in the same component or separately in different components. The presence of an element with a higher ordinal number does not necessarily indicate the presence of another element with a lower ordinal number.

[0108] In this document, unless otherwise specified, the term "characteristic A" or "and / or" and "characteristic B" means that A exists alone, B exists alone, or A and B exist simultaneously; the term "characteristic A" and "and" or "and" and "and" and "characteristic B" means that A and B exist simultaneously; the terms "including", "containing", "having", and "containing" refer to, but are not limited to, these.

[0109] Furthermore, unless specifically described or required to occur in a specific order, the order of the above steps is not limited to those listed above and can be varied or rearranged according to the desired design. Moreover, the above embodiments can be used in combination with each other or with other embodiments based on design and reliability considerations; that is, technical features from different embodiments can be freely combined to form more embodiments.

[0110] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A multi-resonant equivalent circuit model for an inductive magnetic field sensor, the inductive magnetic field sensor comprising an electromagnetic induction component, a feedback coil, and an amplification circuit, the multi-resonant equivalent circuit model comprising: Output terminal; The RLC equivalent circuit of the electromagnetic induction component includes an equivalent model of the magnetic core and an RLC equivalent circuit coupled to the magnetic core. The equivalent circuit of the amplifier circuit is connected to the RLC equivalent circuit at one end and the other end is connected to the output terminal. The equivalent circuit of the negative feedback coil has one end connected to the output terminal and the other end coupled to the RLC equivalent circuit of the electromagnetic induction component. as well as At least one parallel resonant equivalent circuit is connected between the RLC equivalent circuit of the electromagnetic induction component and the equivalent circuit of the amplification circuit, and is configured to suppress the resonance peak corresponding to the resonance point within the sensor's operating frequency band.

2. According to the multi-resonant equivalent circuit model of claim 1, the electromagnetic induction component includes a magnetic core and an induction coil wound around the magnetic core, and the RLC equivalent circuit of the electromagnetic induction component includes an equivalent capacitance C. sc and connected in parallel to the equivalent capacitance C sc The equivalent inductance L at both ends is set in series. pc and equivalent resistance R sc .

3. According to claim 2, the multi-resonance point equivalent circuit model is based on the resonance point information within the operating frequency band of the magnetic field sensor, and the resonance point information includes the number of resonance peaks and the frequency of the resonance point corresponding to each resonance peak.

4. According to the multi-resonance point equivalent circuit model of claim 3, at least one parallel resonant equivalent circuit may be selectively introduced corresponding to the number of resonance peaks.

5. The multi-resonance point equivalent circuit model according to claim 3, wherein the number of corresponding introduced parallel resonant equivalent circuits is determined based on the number of resonance peaks.

6. The multi-resonant equivalent circuit model according to any one of claims 2-5, wherein the parallel resonant equivalent circuit includes an equivalent resonant inductor L connected in parallel. m Equivalent resonant resistance R m Equivalent resonant capacitance C m and equivalent inter-turn capacitance C sm The equivalent resonant resistance R m With the equivalent resistance R sc The equivalent resonant inductance L is connected in series. m Derived from equivalent inductance L pc Part of it.

7. The multi-resonant point equivalent circuit model according to claim 6, wherein the equivalent resonant capacitance C m The solution formula is: ； The equivalent resonant resistance R m The solution formula is: ； in, L m f is the equivalent resonant inductance value. m Let Q be the frequency of the resonant point corresponding to the parallel resonant equivalent circuit, and let Q be the quality factor of the parallel resonant equivalent circuit.

8. The multi-resonant point equivalent circuit model according to any one of claims 2-5, wherein the equivalent capacitance C sc One end is grounded, and the other end is connected to the equivalent circuit of the amplifier circuit.

9. The multi-resonant equivalent circuit model according to any one of claims 2-5, wherein the equivalent circuit of the negative feedback coil includes feedback resistors R connected in series. fb The equivalent inductance L of the negative feedback coil s and the equivalent resistance R of the negative feedback coil s ,in, One end of the equivalent circuit of the negative feedback coil is connected to the output terminal of the equivalent circuit of the amplifier circuit, and the other end of the equivalent circuit of the negative feedback coil is grounded.

10. A method for establishing a multi-resonant point equivalent circuit model according to any one of claims 1-9, wherein the inductive magnetic field sensor includes an electromagnetic induction component, a feedback coil, and an amplification circuit, and the method includes: Establish the RLC equivalent circuit of the electromagnetic induction component; Construct the equivalent circuit of the amplifier circuit connected to the RLC equivalent circuit; Establish the equivalent circuit of the negative feedback coil to complete the initial establishment of the equivalent circuit model of the magnetic field sensor; Based on the initial equivalent circuit model of the magnetic field sensor, the resonant point information within the operating frequency band of the magnetic field sensor was confirmed. as well as Based on the resonant point information, a parallel resonant equivalent circuit is introduced to suppress the resonant peak corresponding to the resonant point within the sensor's operating frequency band, thus completing the establishment of the multi-resonant point equivalent circuit model for the inductive magnetic field sensor.

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