A method and device for measuring the surface magnetic induction intensity of a permanent magnet

Abstract

This application belongs to the field of magnetic measurement, specifically disclosing a method and apparatus for measuring the magnetic induction intensity of a permanent magnet surface. Under the premise that the magnetic field generated on the surface of the permanent magnet material remains constant during the measurement process, at the start of the measurement, the measuring coil is placed close to the point to be measured on the surface of the permanent magnet. After the measurement begins, the coil is moved at a constant speed in a direction perpendicular to the surface of the permanent magnet, thereby changing the distance between the measuring coil and the point to be measured on the permanent magnet surface, until the coil moves away from the point to be measured and the magnetic field is essentially zero. During this movement, the measuring coil cuts magnetic field lines to generate an induced voltage, which is collected by the collection unit and integrated to obtain the surface magnetic field of the point to be measured on the permanent magnet material. The entire measurement is simple and fast, requiring only the placing of the measuring coil at the point to be measured, automatic upward lifting of the measuring coil while simultaneously collecting signals, digital integration to obtain the magnetic field magnitude, and automatic sweeping across the plane of the permanent magnet material to achieve accurate and rapid measurement of the magnetic induction intensity of the magnetic field on the surface of the permanent magnet material.

Description

Technical Field

[0001] This application belongs to the field of magnetic measurement and relates to a method and device for measuring the magnetic induction intensity on the surface of a permanent magnet. Background Technology

[0002] The magnetic properties of permanent magnet materials (such as neodymium iron boron, samarium cobalt, ferrite, etc.), especially their surface magnetic induction intensity (referred to as "surface magnetism"), are core parameters for evaluating material quality, classifying products, and guiding engineering applications (such as the design and production of motors, sensors, magnetic devices, etc.).

[0003] Currently, the main method for measuring the surface magnetic field of permanent magnet materials is the Hall effect method. This method directly senses the magnetic field using a gaussmeter, i.e., a Hall element. It has the advantages of simple operation and the ability to measure static magnetic fields, making it a commonly used method in industrial settings. However, this method has several inherent limitations in practical applications: First, the sensitivity, linearity, and temperature stability of the Hall element directly affect the measurement accuracy and require periodic calibration to compensate for drift. Second, Hall probes typically have certain physical size and spatial resolution limitations, making it difficult to accurately measure the point magnetic field of tiny magnetic poles or areas with extremely large magnetic field gradients. Furthermore, minute changes in the probe's positioning accuracy, the angle (direction) with the measured surface, and the spacing during measurement can introduce significant measurement errors, requiring high levels of operational skill and sophisticated tooling.

[0004] Existing technology also includes a method for measuring the magnetic flux of the entire magnetic block using a coil, such as... Figure 1 As shown, the detection coil is positioned to surround the magnetic body. When the coil and the magnetic field being measured undergo a relative change (such as relative movement or rotation between the magnet and the detection coil, or a change in the magnetic field itself), an induced electromotive force (EMF) is generated in the coil. By performing specific processing on this EMF (such as integration), the change in magnetic flux linked to the coil can be derived, thereby obtaining information on the magnetic flux density. However, in the entire magnetic flux measurement method based on the coil, the measuring coil is relatively large and is usually placed outside the permanent magnet being measured. Stray magnetic fields around the permanent magnet enter the measuring coil, thus obtaining the magnetic flux of the entire permanent magnet. The magnetic flux density measured by the measuring coil is actually the average magnetic flux density of the space outside the permanent magnet inside the coil, and cannot measure the magnetic flux density on the surface of the permanent magnet. Furthermore, the relative movement between the magnet and the detection coil usually involves keeping the coil position unchanged and having the permanent magnet move within the magnetic field lines of the coil driven by a motor / traction structure, which cannot achieve single-point or multi-magnet surface magnetic field measurement. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this application is to provide a method and device for measuring the magnetic induction intensity of a permanent magnet surface, which aims to solve the problem that the prior art cannot efficiently and accurately measure the magnetic induction intensity of a single point on the surface of a permanent magnet.

[0006] To achieve the above objectives, in a first aspect, this application provides a method for measuring the magnetic induction intensity of a permanent magnet surface, comprising: driving a measuring coil to move at a constant speed along a direction perpendicular to the test point on the surface of the permanent magnet, wherein at the starting point of the constant speed movement the measuring coil is in close contact with the test point on the surface of the permanent magnet, and at the ending point the induced voltage signal is zero; collecting the induced voltage signal generated by the measuring coil cutting magnetic field lines during the constant speed movement; and integrating the collected induced voltage signal to obtain the surface magnetic induction intensity of the permanent magnet material at the test point.

[0007] Preferably, it further includes: the inner diameter of the measuring coil does not exceed the point to be measured, so as to measure the surface magnetic induction intensity of a single point to be measured.

[0008] Preferably, it further includes: the measuring coil covering the surface of the permanent magnet to be measured as much as possible, so as to measure the average surface magnetic intensity of the permanent magnet surface.

[0009] Preferably, it further includes: independently driving multiple measuring coils to simultaneously measure the surface magnetism at different points on the surface of the same permanent magnet material to be tested, so as to obtain the surface magnetism distribution in the corresponding area.

[0010] Preferably, it further includes: independently driving multiple measuring coils to simultaneously measure multiple permanent magnets to confirm the magnetic field consistency among the permanent magnets.

[0011] To achieve the above objectives, in a second aspect, this application provides a device for measuring the surface magnetic flux density of a permanent magnet, comprising: a driving module for receiving a control signal and driving a measuring coil to move at a constant speed along a direction perpendicular to the test point on the surface of the permanent magnet, wherein the measuring coil is in close contact with the test point on the surface of the permanent magnet at the starting point of the constant speed movement, and the induced voltage signal is zero at the ending point; a collection module for collecting the induced voltage signal generated by the measuring coil cutting magnetic field lines during the constant speed movement; and a control module for sending a control signal to the driving module, receiving the induced voltage signal returned by the collection module, integrating it, and obtaining the surface magnetic flux density of the test point on the permanent magnet material.

[0012] Preferably, the drive module includes: a motor in the XY axis guide rail, used to accurately position the measuring coil to the surface of the permanent magnet to be measured under the action of a control signal; and a Z-axis motion system, used to uniformly lift the measuring coil fixing head upward under the action of a control signal, thereby driving the measuring coil to move uniformly in a direction perpendicular to the measuring point on the surface of the permanent magnet to be measured.

[0013] Preferably, the magnetizing coil and the measuring coil are installed on the coil fixing head at the same time to realize the integration of magnetization and detection.

[0014] Preferably, the measuring coil is replaceable.

[0015] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: (1) This application proposes a method and apparatus for measuring the magnetic induction intensity of a permanent magnet surface. Under the premise that the magnetic field generated on the surface of the permanent magnet material remains constant during the measurement process, at the beginning of the measurement, the measuring coil is placed close to the point to be measured on the surface of the permanent magnet. After the measurement begins, the coil is moved at a constant speed in a direction perpendicular to the surface of the permanent magnet to be measured, thereby changing the distance between the measuring coil and the point to be measured on the surface of the permanent magnet until the coil moves away from the point to be measured until the magnetic field is basically zero. During this movement, the measuring coil cuts the magnetic field lines to generate an induced voltage, which is collected by the collection unit and integrated to obtain the magnitude of the surface magnetic field at the point to be measured on the permanent magnet material. The entire measurement is simple and fast. It only requires placing the measuring coil at the point to be measured, automatically pulling the measuring coil upward and simultaneously collecting the signal, digitally integrating to obtain the magnitude of the magnetic field, and automatically sweeping across the plane of the permanent magnet material to be measured, thereby realizing accurate and rapid measurement of the magnetic induction intensity of the magnetic field on the surface of the permanent magnet material.

[0016] (2) This application proposes a method and device for measuring the magnetic induction intensity on the surface of a permanent magnet. Compared with the Hall sensor measurement scheme in a gaussmeter, the measurement results of this application depend only on the geometric dimensions, number of turns and accuracy of the lifting displacement of the coil. Theoretically, there is no device drift and the long-term stability is good.

[0017] (3) This application proposes a method and device for measuring the magnetic induction intensity of a permanent magnet surface. Compared with the gaussmeter, which cannot be completely attached to the surface of the permanent magnet to be measured, resulting in a certain measurement error, the measuring coil in this application only needs an upward movement space and the initial position can be in close contact with the permanent magnet to be measured, thereby minimizing the gap between the measuring point and the surface and reducing the measurement error. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a scheme for measuring the magnetic flux of the entire magnetic block using a coil, provided by existing technology.

[0019] Figure 2 This is a flowchart of a method for measuring the magnetic induction intensity on the surface of a permanent magnet, provided in an embodiment of this application.

[0020] Figure 3 This is one of the structural schematic diagrams of a permanent magnet surface magnetic induction intensity measuring device provided in the embodiments of this application.

[0021] Figure 4 This is the second schematic diagram of a permanent magnet surface magnetic induction intensity measuring device provided in the embodiments of this application. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0023] The embodiments of this application are described below with reference to the accompanying drawings.

[0024] like Figure 1 As shown, this application provides a method for measuring the magnetic induction intensity of a permanent magnet surface, comprising: driving a measuring coil to move at a constant speed along a direction perpendicular to the test point on the surface of the permanent magnet, wherein at the starting point of the constant speed movement the measuring coil is in close contact with the test point on the surface of the permanent magnet, and at the ending point the induced voltage signal is zero; collecting the induced voltage signal generated by the measuring coil cutting magnetic field lines during the constant speed movement; and integrating the collected induced voltage signal to obtain the surface magnetic induction intensity of the permanent magnet material at the test point.

[0025] Preferably, it further includes: the inner diameter of the measuring coil does not exceed the point to be measured, so as to measure the surface magnetic induction intensity of a single point to be measured.

[0026] Preferably, the measuring coil is fabricated using photolithography to integrate a high number of turns on a small scale. A higher number of turns results in a higher induced voltage in the coil, making signal measurement easier. A changing magnetic field generates a changing magnetic flux in the coil, and the rate of change of magnetic flux is positively correlated with the induced voltage in the coil. A smaller inner diameter allows the measurement range to be closer to the point being measured, thus preventing stray magnetic flux from entering the measuring coil. Furthermore, a smaller magnetic flux measurement area leads to a more accurate magnetic field measurement point. In summary, increasing the number of coil turns while reducing the inner diameter improves the measurement accuracy of the measuring coil, enabling precise measurement of point magnetic fields, and is particularly suitable for measuring small-sized magnetic poles or complex magnetic field distributions.

[0027] In one illustrated embodiment, the induced voltage is between 100mV and 500mV, the number of turns of the measuring coil is selected as 100 turns, and the inner diameter is selected according to the type of permanent magnet to be measured.

[0028] Preferably, the method further includes: the measuring coil covering the surface of the permanent magnet to be measured as much as possible to measure the average surface magnetic field strength of the permanent magnet surface. Setting the coil size to be close to the size of the permanent magnet to be measured can also measure the magnetic flux of the entire measured area to obtain the remanent magnetization property of the permanent magnet.

[0029] Preferably, it further includes: independently driving multiple measuring coils to simultaneously measure the surface magnetism at different points on the surface of the same permanent magnet material to be tested, so as to obtain the surface magnetism distribution in the corresponding area.

[0030] In one illustrated embodiment, a measurement coil array is integrated on a polyimide film, with each measurement coil operating independently, enabling cost-effective and efficient simultaneous measurement of the magnetic properties of multiple test points.

[0031] In another illustrated embodiment, multiple measuring coils are arranged in parallel in a multi-layer array coil to measure the three-dimensional magnetic field. By arranging multiple coil arrays in parallel and spaced at equal intervals to form an array group, and simultaneously pulling the measuring coil array group upwards, the three-dimensional magnetic field distribution of the entire space on the surface region of the permanent magnet material under test can be obtained.

[0032] Preferably, it further includes: independently driving multiple measuring coils to simultaneously measure multiple permanent magnets to confirm the magnetic field consistency among the permanent magnets.

[0033] In one illustrated embodiment, a measurement coil array consisting of multiple measurement coils is used to measure the remanence of multiple permanent magnets, thereby obtaining the magnetic field consistency between different permanent magnets and determining whether any permanent magnets exhibit unsaturated magnetization. This method can be used for magnetic steel array platforms or magnetic poles assembled from multiple permanent magnets. By using the array of measurement coils, it can detect whether there is inconsistent magnetization of the permanent magnets in the assembled permanent magnet platform or magnetic poles.

[0034] This application provides a device for measuring the magnetic induction intensity of a permanent magnet surface, comprising: a driving module for receiving a control signal and driving a measuring coil to move at a constant speed along a direction perpendicular to the test point on the surface of the permanent magnet, wherein the measuring coil is in close contact with the test point on the surface of the permanent magnet at the starting point of the constant speed movement, and the induced voltage signal is zero at the ending point; a collection module for collecting the induced voltage signal generated by the measuring coil cutting magnetic field lines during the constant speed movement; and a control module for sending a control signal to the driving module, receiving the induced voltage signal returned by the collection module, integrating it, and obtaining the surface magnetic induction intensity of the permanent magnet material at the test point.

[0035] In one illustrated embodiment, the collection module is a data acquisition card or an oscilloscope.

[0036] Preferably, the drive module includes: a motor in the XY axis guide rail, used to accurately position the measuring coil to the surface of the permanent magnet to be measured under the action of a control signal; and a Z-axis motion system, used to uniformly lift the measuring coil fixing head upward under the action of a control signal, thereby driving the measuring coil to move uniformly in a direction perpendicular to the measuring point on the surface of the permanent magnet to be measured.

[0037] Permanent magnet materials are mostly rare-earth permanent magnets. Normally, permanent magnets are not magnetic when they are manufactured; they need to be magnetized by applying an external magnetic field. The magnetization process is usually accomplished using a magnetizing coil, which generates a magnetic field parallel to the easy magnetization axis within the permanent magnet region, causing the magnetic domains in the permanent magnet to deflect. After magnetization, the permanent magnet needs to be tested to determine if it has reached magnetic saturation. This process is typically measured using a fluxmeter.

[0038] A fluxmeter typically consists of a set of independent Helmholtz coils. When a permanent magnet is placed in the center of the coil, a voltage signal is induced in the coil, thus obtaining the magnetic flux of the permanent magnet and determining whether it is magnetized to saturation. This method usually requires moving the permanent magnet to the fluxmeter for detection after it has been magnetized, which involves many steps and makes real-time detection impossible.

[0039] This application proposes to detect the surface magnetism of the permanent magnet in real time after magnetization is completed, thereby making a preliminary judgment on whether the permanent magnet has reached saturation. Specifically, the magnetization coil and the measuring coil are installed on the coil fixing head simultaneously, realizing the integration of magnetization and detection.

[0040] Preferably, the measuring coil is replaceable.

[0041] Example 1 like Figure 3 As shown in the figure, this embodiment proposes a device for measuring the surface magnetic induction intensity of a permanent magnet. A multi-turn measuring coil, uniformly wound with enameled wire, is used at the very tip of the sample rod. The coil's output end is connected to a data acquisition card, which in turn is connected to a host computer. The coil is placed firmly against the surface of the permanent magnet material to be measured, and then the sample rod is pulled upwards at a uniform speed, moving the coil away from the measurement point until the magnetic field is essentially zero. The data acquisition card collects the voltage signal and integrates it to obtain the magnetic field signal, thus determining the magnitude of the surface magnetic field.

[0042] Example 2 like Figure 4 As shown, this embodiment proposes a device for measuring the magnetic induction intensity of a permanent magnet surface. It adopts a three-dimensional moving guide rail. By controlling the motor in the xy-axis guide rail, the measuring coil is precisely positioned on the surface of the permanent magnet to be measured. By controlling the z-axis, the coil fixing head is pulled upward at a constant speed to drive the measuring coil to move at a constant speed, thereby obtaining the surface magnetic field of the point to be measured.

[0043] In this application, the terms "first" and "second," etc., are used to distinguish different objects, not to describe a specific order of objects. For example, "first response message" and "second response message," etc., are used to distinguish different response messages, not to describe a specific order of response messages.

[0044] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0045] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0046] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0047] Furthermore, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0048] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. "Fixed connection" refers to a connection where the relative positional relationship remains unchanged after connection. "Rotary connection" refers to a connection where the components can rotate relative to each other after connection. "Sliding connection" refers to a connection where the components can slide relative to each other after connection. The directional terms mentioned in the embodiments of this application, such as "top," "bottom," "inner," "outer," "left," and "right," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0049] Furthermore, the mathematical concepts mentioned in the embodiments of this application, such as symmetry, equality, parallelism, and perpendicularity, are limitations specific to the current technological level, rather than absolute and strict mathematical definitions. Slight deviations are permissible; approximations of symmetry, equality, parallelism, and perpendicularity are all acceptable. For example, "A and B are parallel" means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. "A and B are perpendicular" means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0050] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for measuring the magnetic induction intensity on the surface of a permanent magnet, characterized in that, include: The driving measuring coil moves at a constant speed along the direction perpendicular to the test point on the surface of the permanent magnet. At the starting point of the constant speed movement, the measuring coil is in close contact with the test point on the surface of the permanent magnet, and at the end point, the induced voltage signal is zero. Collect the induced voltage signal generated when the measuring coil cuts magnetic field lines during uniform motion; The collected induced voltage signal is integrated to obtain the surface magnetic flux density at the test point of the permanent magnet material.

2. The measurement method as described in claim 1, characterized in that, Also includes: The inner diameter of the measuring coil does not exceed the point to be measured, in order to measure the surface magnetic induction intensity of a single point to be measured.

3. The measurement method as described in claim 1, characterized in that, Also includes: The measuring coil covers the surface of the permanent magnet to be measured as much as possible in order to measure the average surface magnetic intensity of the permanent magnet.

4. The measurement method as described in claim 1, characterized in that, Also includes: Multiple measuring coils are driven independently to simultaneously measure the surface magnetic field at different points on the surface of the same permanent magnet material, so as to obtain the surface magnetic field distribution in the corresponding area.

5. The measurement method as described in claim 1, characterized in that, Also includes: Multiple measuring coils are independently driven to simultaneously measure multiple permanent magnets to confirm the consistency of the magnetic field among the permanent magnets.

6. A device for measuring the magnetic induction intensity on the surface of a permanent magnet, characterized in that, include: The drive module is used to receive control signals and drive the measuring coil to move at a constant speed along the direction perpendicular to the test point on the surface of the permanent magnet. At the starting point of the constant speed movement, the measuring coil is in close contact with the test point on the surface of the permanent magnet, and at the end point, the induced voltage signal is zero. The collection module is used to collect the induced voltage signal generated by the measuring coil cutting magnetic field lines during uniform movement; The control module is used to send control signals to the drive module, receive the induced voltage signal returned by the collection module, integrate it, and obtain the surface magnetic induction intensity of the permanent magnet material at the test point.

7. The measuring device as described in claim 6, characterized in that, The driving module includes: The motor in the XY axis guide rail is used to precisely position the measuring coil onto the surface of the permanent magnet to be measured under the action of the control signal; The Z-axis motion system is used to uniformly lift the measuring coil fixing head upward under the action of the control signal, so as to drive the measuring coil to move uniformly in the direction perpendicular to the measuring point on the surface of the permanent magnet to be measured.

8. The measuring device as described in claim 6, characterized in that, The magnetizing coil and the measuring coil are installed on the coil fixing head at the same time to realize the integration of magnetization and detection.

9. The measuring device as described in claim 6, characterized in that, The measuring coil can be replaced.

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