A flux-weakening detection device

Abstract

The utility model provides a kind of weak magnetic detection equipment.The weak magnetic detection equipment adopts background magnetic field sensor to sense the sensing signal generated by background magnetic field to generate excitation current to drive excitation coil, and the influence of the induced magnetic field generated by excitation coil to weak magnetic sensor is offset, so that weak magnetic sensor works in the environment close to "zero magnetic field" in sensing direction to accurately measure target weak magnetic field. Wherein, the background magnetic field sensor is large dynamic range, low sensitivity magnetic sensor, and the weak magnetic sensor is small dynamic range, high sensitivity low noise magnetic field sensor. The components used by the weak magnetic detection equipment are integrated on a PCB to realize the miniaturization of the equipment, to better adapt to medical detection, internal micro-current detection of electronic equipment and other weak magnetic detection environments.

Description

Technical Field

[0001] This application relates to the field of magnetic field measurement devices or equipment, specifically to a weak magnetic field detection device with high measurement accuracy and small size. Background Technology

[0002] High-precision weak magnetic field detection technology is a modern detection technology that uses high-sensitivity equipment to detect changes in weak magnetic fields. It is mainly used in many fields such as aerial submarine exploration, marine monitoring, and underground ferromagnetic object detection. This technology has the characteristics of high sensitivity and fast response frequency. The theoretical limit of the improved equipment can reach the 0.1pT level [1]. Its application scope has now been expanded to earthquake prediction, medical detection and other livelihood fields.

[0003] The evolution of weak magnetic field detection technology is inseparable from the innovation of weak magnetic field measurement instruments and magnetic sensors. Currently, commonly used instruments and sensors in this field include optically pumped magnetometers, proton magnetometers, fluxgate magnetometers, superconducting quantum interference devices (SQUIDs), and magnetoelectric sensors. Although weak magnetic field sensors can detect minute changes in magnetic fields and show great application potential in fields such as biomagnetic field measurement, they are often accompanied by a reduced dynamic range, requiring operation in a weak background magnetic field environment, or even near-zero magnetic field environment. SQUIDs operate in a zero magnetic environment, pT-level atomic magnetometers typically have a dynamic range lower than or close to the Earth's magnetic field strength, and pT-level GMIs have an operating range of only a few hundred nT. Furthermore, closed-loop schemes can effectively extend the dynamic range of magnetic sensors and improve output linearity, but due to the use of deep negative feedback, they also reduce the transient response capability of the signal. Utility Model Content

[0004] This invention proposes a weak magnetic field detection device. The device utilizes a large dynamic range magnetic sensor to measure the background magnetic field and obtain its intensity. ② Using this background magnetic field, a near-zero magnetic space is obtained through magnetic compensation, allowing the weak magnetic sensor to operate within this near-zero space for accurate measurement of minute magnetic field changes. The large dynamic range magnetic sensor and the high-sensitivity weak magnetic sensor work together to achieve high spatial magnetic field resolution measurement even under strong background magnetic fields, such as measuring minute magnetic field changes in the nT or tens of nT range against a background of several to hundreds of Gauss. Furthermore, this weak magnetic field detection device does not employ closed-loop magnetic field compensation measures, resulting in a fast response speed.

[0005] The weak magnetic field detection device provided by this utility model includes: a PCB board, and a weak magnetic field sensor, a background magnetic field sensor, an excitation coil, a coil driving circuit, a weak magnetic field measurement circuit, and a background magnetic field measurement circuit disposed on the PCB board.

[0006] The sensing directions of the weak magnetic field sensor and the background magnetic field sensor are parallel or antiparallel to the line connecting them. The weak magnetic field sensor and the background magnetic field sensor are respectively positioned at a certain distance from each other on the PCB board so that the influence of the magnetic field generated by the current in the excitation coil on the background magnetic field sensor is negligible. The background magnetic field measurement circuit is connected to both the background magnetic field sensor and the coil drive circuit, generating a control signal input to the coil drive circuit based on the sensing signal from the background magnetic field sensor. The weak magnetic field measurement circuit, in conjunction with the weak magnetic field sensor, detects the target weak magnetic field and outputs a weak magnetic field sensing signal. The excitation coil is fixedly positioned near the weak magnetic field sensor, and the coil drive circuit generates an excitation current flowing through the excitation coil based on the control signal to counteract the background magnetic field at the location of the weak magnetic field sensor, which is parallel or antiparallel to the sensing direction of the weak magnetic field sensor.

[0007] In some embodiments, the control signal is a sensing signal from a background magnetic field sensor, and the coil drive circuit generates the excitation current corresponding to the sensing signal from the background magnetic field sensor according to a predetermined proportionality coefficient. Obviously, the corresponding proportionality coefficient can be experimentally measured in advance and set in the coil drive circuit.

[0008] Preferably, the excitation coil is wound around the weak magnetic sensor, and the winding direction is perpendicular to the sensing direction of the weak magnetic sensor.

[0009] Furthermore, the PCB board is rectangular, with a weak magnetic field sensor and a background magnetic field sensor located at both ends of the PCB, and the line connecting them parallel to the long side of the PCB board. The weak magnetic field sensor is a magnetic field sensor implemented based on an XMR magnetoresistive unit, and the background magnetic field sensor is a Hall sensor or a magnetic field sensor implemented based on an XMR magnetoresistive unit. The XMR includes GMR, TMR, and AMR.

[0010] Furthermore, the magnetic field weakening measurement circuit includes a conditioning circuit for correcting and amplifying the sensing signal of the magnetic field weakening sensor. The magnetic field weakening measurement circuit also includes a quantization output module for quantizing and outputting the output signal of the conditioning circuit.

[0011] The weak magnetic field detection device provided by this invention effectively suppresses background magnetic field interference and ensures measurement accuracy, while exhibiting good response speed and sensitivity (due to the absence of a closed-loop feedback mechanism). Furthermore, all components are integrated onto a single PCB board, achieving miniaturization and enabling better application in weak magnetic field detection scenarios such as medical testing and micro-current detection in electronic equipment. Attached Figure Description

[0012] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the weak magnetic field detection device provided by this utility model.

[0014] Figure 2 This is a schematic diagram illustrating the relative positions of the excitation coil and the weak magnetic sensor of the weak magnetic field detection device in one embodiment. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0016] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0018] The present invention will now be described in further detail with reference to the accompanying drawings.

[0019] like Figure 1 As shown, the weak magnetic field detection device provided by this utility model includes: a PCB board 100, and a weak magnetic field sensor 1, a background magnetic field sensor 2, an excitation coil 3, a coil driving circuit 4, a background magnetic field measurement circuit 5, and a weak magnetic field measurement circuit 6 disposed on the PCB board 100. The weak magnetic field measurement circuit 6 includes a signal conditioning circuit 61 and a quantization output module 62.

[0020] likeFigure 1 As shown, the PCB board 100 is a rectangular PCB board, and the weak magnetic field sensor 1 and the background magnetic field sensor 2 are disposed at both ends of the PCB board, with the line connecting the two parallel to the long side of the PCB board.

[0021] Furthermore, the weak magnetic field sensor 1 is a magnetic field sensor implemented based on an XMR magnetoresistive unit, and the background magnetic field sensor 2 can be a Hall sensor or a magnetic field sensor implemented based on an XMR magnetoresistive unit. The XMR includes GMR, TMR, and AMR.

[0022] like Figure 1 As shown, the sensing directions of the weak magnetic field sensor 1 and the background magnetic field sensor 2 are parallel or antiparallel to the line connecting them (i.e., Figure 1 (Horizontal direction in the middle). The weak magnetic field sensor 1 and the background magnetic field sensor 2 are respectively set at a certain distance from each other on the PCB board 100, so that the influence of the magnetic field generated by the current in the excitation coil 3 on the background magnetic field sensor 2 is negligible. The background magnetic field sensor 2 can be a magnetic sensor with a large dynamic range and low sensitivity, while the weak magnetic field sensor 1 can be a magnetic field sensor with a small dynamic range, high sensitivity, and low noise.

[0023] like Figure 1 As shown, the background magnetic field measurement circuit 5 is connected to the background magnetic field sensor 2 and the coil drive circuit 4, respectively. The background magnetic field measurement circuit 5 generates a control signal input to the coil drive circuit 4 based on the sensing signal of the background magnetic field sensor 2. The control signal can be directly the sensing signal of the background magnetic field sensor 2.

[0024] The magnetic field weakening measurement circuit 6, in conjunction with the magnetic field weakening sensor 1, detects the target weak magnetic field and outputs a magnetic field weakening sensing signal. The excitation coil 3 is fixedly positioned near the magnetic field weakening sensor 1, and the coil driving circuit 4 generates an excitation current flowing through the excitation coil 3 based on the control signal. This excitation current flowing through the excitation coil 3 generates a compensating magnetic field to counteract the background magnetic field at the location of the magnetic field weakening sensor 1, which is parallel or antiparallel to the sensing direction of the sensor 1. Clearly, given a fixed position of the excitation coil 3 and its relative position to the magnetic field weakening sensor 1, the correspondence between the excitation current and the control signal (or the sensing signal from the background magnetic field sensor 2) can be experimentally obtained in advance. The coil driving circuit 4 generates an excitation current of a corresponding magnitude based on this correspondence.

[0025] like Figure 2As shown, in some embodiments, the excitation coil 3 is wound around the weak magnetic field sensor 1, with the winding direction perpendicular to the sensing direction of the weak magnetic field sensor 1. This allows it to maximize the use of the magnetic field generated by the excitation coil 3 (and its excitation current) to counteract the background magnetic field in the sensing direction of the weak magnetic field sensor 1, enabling it to operate in a "near-zero background magnetic field" state and ensuring the accuracy of the measurement of the target weak magnetic field. In some embodiments, the control signal is the sensing signal of the background magnetic field sensor 2, and the coil drive circuit 4 generates the excitation current corresponding to the sensing signal of the background magnetic field sensor 2 according to a predetermined proportional coefficient (or conversion coefficient).

[0026] Furthermore, the magnetic field weakening measurement circuit 6 includes a conditioning circuit 61 for correcting and amplifying the sensing signal of the magnetic field weakening sensor 1. The magnetic field weakening measurement circuit 6 also includes a quantization output module 62 for quantizing and outputting the output signal of the conditioning circuit. Obviously, the quantization output module 62 may include various interfaces for communication with a host computer.

[0027] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A flux-weakening detection device, characterized by, The weak magnetic field detection device includes: a PCB board, and a weak magnetic field sensor, a background magnetic field sensor, an excitation coil, a coil driving circuit, a weak magnetic field measurement circuit, and a background magnetic field measurement circuit disposed on the PCB board. The sensing directions of the weak magnetic field sensor and the background magnetic field sensor are parallel or antiparallel to the line connecting them. The weak magnetic field sensor and the background magnetic field sensor are respectively set on the PCB board at a certain distance apart so that the influence of the magnetic field generated by the current in the excitation coil on the background magnetic field sensor can be ignored. The background magnetic field measurement circuit is connected to the background magnetic field sensor and the coil drive circuit respectively, and generates a control signal input to the coil drive circuit based on the sensing signal of the background magnetic field sensor. The weak magnetic field measurement circuit works with the weak magnetic field sensor to detect the weak magnetic field of the target and outputs a weak magnetic field sensing signal. An excitation coil is fixedly installed near a weak magnetic sensor. The coil drive circuit generates an excitation current flowing through the excitation coil based on the control signal to counteract the background magnetic field at the location of the weak magnetic sensor, which is parallel or antiparallel to the sensing direction of the weak magnetic sensor.

2. The field-weakening detection device of claim 1, wherein The control signal is the sensing signal of the background magnetic field sensor, and the coil drive circuit generates the excitation current corresponding to the sensing signal of the background magnetic field sensor according to a predetermined proportional coefficient.

3. The field-weakening detection device according to claim 1 or 2, wherein The excitation coil is wound around the weak magnetic sensor, and the winding direction is perpendicular to the sensing direction of the weak magnetic sensor.

4. The field-weakening detection device of claim 3, wherein The PCB board is rectangular, and the weak magnetic field sensor and the background magnetic field sensor are located at both ends of the PCB board, with the line connecting the two parallel to the long side of the PCB board.

5. The field-weakening detection device of claim 3, wherein The weak magnetic field measurement circuit includes a conditioning circuit that corrects and amplifies the sensing signal from the weak magnetic field sensor.

6. The field-weakening detection device of claim 5, wherein The weak magnetic field measurement circuit also includes a quantization output module for quantizing and outputting the output signal of the conditioning circuit.

7. The field-weakening detection device of claim 1, wherein The weak magnetic field sensor is a magnetic field sensor based on an XMR magnetoresistive unit, and the background magnetic field sensor is a Hall sensor or a magnetic field sensor based on an XMR magnetoresistive unit; the XMR includes GMR, TMR, and AMR.

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