A method for detecting a permanent magnet of a motor rotor core

Abstract

The application relates to the technical field of rotor detection, and discloses a motor rotor core permanent magnet detection method, which is characterized by comprising the following steps: S1, fixing a magnetic field detection device at a tangent point position of the permanent magnet rotor; placing a detection probe of the magnetic field detection device at a certain position away from the rotor, the magnetic field detection device needs to be aligned with the diameter of the rotor, and the spacing between the detection probe and the rotor can ensure that the magnetic tiles placed later will not contact the detection probe; S2, a speed detection motor detects the rotating speed and rotating position of the rotor while the motor drives the rotor to rotate. The application compares multiple'magnetic field strength-mechanical angle' models, and compares the magnetic field strengths under the four mechanical angles of 0-90 DEG, 90-180 DEG, 180-270 DEG and 270-360 DEG in the same coordinate system, so that whether the four main tiles on the rotor appear the phenomenon of magnetic field deficiency can be intuitively analyzed.

Description

Technical Field

[0001] This invention relates to the field of motor rotor testing technology, specifically a method for testing the permanent magnet of a motor rotor core. Background Technology

[0002] A permanent magnet synchronous motor mainly consists of a stator, rotor, and end covers. The stator is made of laminated laminations to reduce iron losses during motor operation and contains three-phase AC windings called the armature. The rotor can be made solid or made of laminated laminations, and it is fitted with permanent magnet material. Manufacturing process refers to the methods and procedures by which workers use various production tools to process or treat various raw materials and semi-finished products, ultimately transforming them into finished products. During the motor manufacturing process, it is often necessary to analyze the permanent magnet strength and the uniformity of the magnetic field distribution on the rotor.

[0003] Existing testing processes for permanent magnets in motor rotor cores often only test the magnetic field strength of the rotor before it is installed. They lack a more precise testing process for the magnets that have already been installed on the rotor. This results in uneven magnetic field distribution in the rotor after installation due to the combined force between the magnets. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a method for detecting permanent magnets in the rotor core of an electric motor, thus solving the problems mentioned in the background section.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for detecting permanent magnets in the rotor core of an electric motor, characterized by comprising the following steps:

[0008] S1. Fix the magnetic field detection device at the tangent position of the permanent magnet rotor: Place the detection probe of the magnetic field detection device at a certain distance from the rotor. The magnetic field detection device needs to be aligned with the diameter of the rotor. The distance between the detection probe and the rotor can ensure that when the magnetic tiles are placed on the rotor later, the magnetic tiles placed later will not come into contact with the detection probe.

[0009] S2. While the motor drives the rotor to rotate, the speed measuring motor detects the rotor's speed and rotation position: other external motor equipment is used to drive the rotor to rotate, and the rotor's speed and rotational mechanical angle can be recorded or changed after rotation. When it is detected that one or more of the four tiles on the rotor are demagnetized, the demagnetized tile can be decelerated when it turns towards the magnetic field detection device, while the magnetic field detection device increases its power to improve the accuracy of the magnetic detection of the tiles in the area.

[0010] S3. Establish a coordinate system model based on the mechanical angle and magnetic field strength of the rotating magnetic field: While the magnetic field detection device detects the rotor, its external drive device drives the rotor to rotate. During the rotor's movement, the magnetic field strength received by its detection probe will also change periodically. A 'magnetic field strength - mechanical angle' model can be drawn based on the magnetic field strength detected by the detection probe and the mechanical angle of the rotor.

[0011] S4. Repeat the detection process multiple times and compare the magnetic field established each time to reduce the error in a single detection: The position and attitude of the magnetic field detection equipment remain unchanged and the number of rotations of the permanent magnet rotor is increased. For each additional rotation of the rotor, the magnetic field detection equipment completes a detection of the magnetic field strength at each angle of the rotor. After drawing the 'magnetic field strength-mechanical angle' model under the corresponding number of rotations, it is necessary to label it according to the number of rotations.

[0012] S5. Using the superposition principle, magnetic tiles are symmetrically added to the rotor: tiles are installed in the air gap of the rotor, and the installed tiles must ensure the principle of central symmetry.

[0013] S6. Repeat the rotation detection of the rotor: When repeatedly detecting the rotor after adding the additional tiles, apply the same conditions as in the overall magnetic field analysis step above, and apply the same power parameters of the detection equipment in the above analysis step. Compare the time offset of the change in the direction of the magnetic field detected by the detection probe at each time with the time offset of the change in the direction of the magnetic field detected by the detection probe when no additional tiles are added.

[0014] Preferably, in step S2, increasing the power of the magnetic field detection device is achieved by increasing the magnetic field sampling frequency, that is, increasing the number of times the detection probe measures the magnetic flux per unit time. This method of increasing the power of the magnetic field detection device makes the established 'magnetic field strength-mechanical angle' model more accurate in the presence of demagnetized tiles.

[0015] Preferably, in step S4, the 'magnetic field strength-mechanical angle' model drawn for each revolution is averaged, and the averaged model is compared with the randomly selected model parameters. At the same time, the magnetic field strengths under four mechanical angles of 0-90°, 90-180°, 180-270° and 270-360° are placed in the same coordinate system for comparison, and the magnetic field similarity between the four tiles on the rotor is analyzed.

[0016] Preferably, in step S6, adding a tile in the air gap between the four main tiles of the rotor will cause the magnetic field zero point located at the center line of the air gap to shift.

[0017] Preferably, step S1 includes the following specific steps:

[0018] S101. Change the distance between the magnetic field detection device and the permanent magnet rotor: After changing the distance between the magnetic field detection device and the rotor, continue to adjust the orientation of the magnetic field detection device to be the same as the diameter direction of the rotor and then fix it.

[0019] S102. Bring the testing equipment closer to the permanent magnet rotor until the distance is only 0.3mm-1mm: After the testing probe of the testing equipment is brought closer to the rotor to 0.3mm-1mm, the change in the magnetic field after the rotor rotates can be greatly increased.

[0020] S103. Rotate the rotor again and use the magnetic field detection device to analyze the magnetic field of the rotor and establish a model: When the detection device is brought close to the rotor to 0.3mm-1mm and detected, the same conditions as in the above-mentioned overall magnetic field analysis steps are given, and the same power parameters of the detection device are given in the above-mentioned analysis steps.

[0021] S104. Compare the magnetic field strength of the four tiles on the rotor and analyze the existence of tile eccentricity on the rotor.

[0022] S105. After wrapping tape around the rotor surface and using a pressure probe to contact the tape, rotate the rotor.

[0023] Preferably, in step S104, when performing close-range rotor magnetic field analysis, it is necessary to exclude the existence of eccentric rotation of the tile. That is, if the distance between the eccentric tile and the detection probe is larger or smaller, it will directly change the intensity of the magnetic field detected by the detection probe.

[0024] Preferably, in step S105, the rotor surface has tiles and air gaps. After a thin tape is wrapped clockwise around the surface of the tiles and air gaps, the rotor rotates counterclockwise and the pressure probe contacts the tape to detect rotor eccentricity and eliminate the presence of rotor eccentricity.

[0025] (III) Beneficial Effects

[0026] This invention provides a method for detecting permanent magnets in the rotor core of an electric motor, which has the following advantages:

[0027] (1) This invention compares multiple 'magnetic field strength-mechanical angle' models and compares the magnetic field strength under four mechanical angles of 0-90°, 90-180°, 180-270° and 270-360° in the same model in the same coordinate system. This allows for a direct analysis of whether the four main tiles on the rotor are demagnetized.

[0028] (2) By minimizing the distance between the detection probe and the rotor, the present invention can significantly reduce the influence of the external magnetic field on the detection probe. At the same time, tape can be wrapped around the rotor to detect the eccentricity of the rotor, which can avoid the pressure probe being affected by the air gap. Using this method can eliminate the uneven magnetic field distribution caused by the eccentricity of the rotor. Attached Figure Description

[0029] Figure 1 This is a flowchart of the present invention;

[0030] Figure 2 This is a flowchart illustrating the specific steps of step 1 of the present invention;

[0031] Figure 3 This is a schematic diagram of the rotor structure of the present invention. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] like Figure 1-3 The method for detecting permanent magnets in the rotor core of an electric motor, as shown, includes the following steps:

[0035] S1. Fix the magnetic field detection device at the tangent point of the permanent magnet rotor: Place the detection probe of the magnetic field detection device at a certain distance from the rotor. The magnetic field detection device needs to be aligned with the diameter of the rotor. The distance between the detection probe and the rotor should be sufficient to ensure that the magnetic tiles placed later on the rotor will not come into contact with the detection probe.

[0036] S2. While the motor drives the rotor to rotate, the speed measuring motor detects the rotor's speed and rotation position: other external motor equipment is used to drive the rotor to rotate, and the rotor's speed and rotational mechanical angle can be recorded or changed after rotation. When it is detected that one or more of the four tiles on the rotor are demagnetized, the demagnetized tile can be decelerated when it turns towards the magnetic field detection device, while the magnetic field detection device increases its power to improve the accuracy of the magnetic detection of the tiles in that area.

[0037] S3. Establish a coordinate system model based on the mechanical angle and magnetic field strength of the rotating magnetic field: While the magnetic field detection device detects the rotor, its external drive device drives the rotor to rotate. During the rotor's movement, the magnetic field strength received by its detection probe will also change periodically. A 'magnetic field strength - mechanical angle' model can be drawn based on the magnetic field strength detected by the detection probe and the mechanical angle of the rotor.

[0038] S4. Repeat the detection process multiple times and compare the magnetic field established each time to reduce the error in a single detection: The position and attitude of the magnetic field detection equipment remain unchanged and the number of rotations of the permanent magnet rotor is increased. For each additional rotation of the rotor, the magnetic field detection equipment completes a detection of the magnetic field strength at each angle of the rotor. After drawing the 'magnetic field strength - mechanical angle' model under the corresponding number of rotations, the number of rotations needs to be labeled.

[0039] S5. Using the superposition principle, magnetic tiles are symmetrically added to the rotor: tiles are installed in the air gap of the rotor, and the installed tiles must ensure the principle of central symmetry.

[0040] S6. Repeat the rotation detection of the rotor: When repeatedly detecting the rotor after adding the additional tiles, apply the same conditions as in the overall magnetic field analysis step above, and apply the same power parameters of the detection equipment in the above analysis step. Compare the time offset of the change in the direction of the magnetic field detected by the detection probe at each time with the time offset of the change in the direction of the magnetic field detected by the detection probe when no additional tiles are added.

[0041] Specifically, increasing the power of the magnetic field detection equipment involves increasing the magnetic field sampling frequency, i.e., increasing the number of times the detection probe measures magnetic flux per unit time. This method of increasing the power of the magnetic field detection equipment makes the established 'magnetic field strength-mechanical angle' model more accurate in the presence of demagnetized tiles. The 'magnetic field strength-mechanical angle' model drawn for each revolution is averaged, and the averaged model is compared with randomly selected model parameters. Simultaneously, the magnetic field strengths at four mechanical angles (0-90°, 90-180°, 180-270°, and 270-360°) are compared in the same coordinate system, and the similarity of the magnetic fields among the four tiles on the rotor is analyzed. Adding tiles to the air gap between the four main tiles of the rotor causes the magnetic field zero point, originally located at the center line of the air gap, to shift. This zero point shift can be used to determine whether the deviation of the array distribution of the four main tiles is reasonable.

[0042] Example 2

[0043] like Figure 2 As shown, step S1 includes the following specific steps:

[0044] S101. Change the distance between the magnetic field detection device and the permanent magnet rotor: After changing the distance between the magnetic field detection device and the rotor, continue to adjust the orientation of the magnetic field detection device to be the same as the diameter direction of the rotor and then fix it. After each adjustment of the position of the magnetic field detection device, it is necessary to ensure that the orientation of its detection probe is the same as the diameter of the rotor.

[0045] S102. Bring the testing equipment closer to the permanent magnet rotor until the distance is only 0.3mm-1mm: After the testing probe of the testing equipment is brought closer to the rotor to 0.3mm-1mm, the change in the magnetic field after the rotor rotates can be greatly increased. Since the factory error standard of the rotor is no more than 0.1mm, using 0.3mm-1mm can ensure that the testing probe will not be hit while maximizing the testing of the rotor.

[0046] S103. Rotate the rotor again and use the magnetic field detection device to analyze the magnetic field of the rotor and establish a model: When the detection device is brought close to the rotor to 0.3mm-1mm and detected, the same conditions as in the above-mentioned overall magnetic field analysis steps are given, and the same power parameters of the detection device are given as in the above-mentioned analysis steps.

[0047] S104. Compare the magnetic field strength of the four tiles on the rotor and analyze the existence of tile eccentricity on the rotor.

[0048] S105. After wrapping tape around the rotor surface and using a pressure probe to contact the tape, rotate the rotor.

[0049] Specifically: When performing close-range rotor magnetic field analysis, it is necessary to rule out the existence of eccentric rotation of the tiles. That is, if the distance between the eccentric tile and the detection probe is larger or smaller, it will directly change the strength of the magnetic field detected by the detection probe. The rotor surface has tiles and air gaps. After wrapping a thin tape clockwise around the surface of the tiles and air gaps, the rotor rotates counterclockwise and contacts the pressure probe with the tape to detect rotor eccentricity and rule out the existence of rotor eccentricity.

[0050] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover 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 process, method, article, or apparatus.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for detecting permanent magnets in the rotor core of an electric motor, characterized in that... This includes the following steps: S1. Fix the magnetic field detection equipment at the tangent position of the permanent magnet rotor: Place the detection probe of the magnetic field detection equipment at a certain distance from the rotor. The magnetic field detection equipment needs to be aligned with the diameter of the rotor. The distance between the detection probe and the rotor should be sufficient to ensure that the magnetic tiles placed later on the rotor will not come into contact with the detection probe. S2. While the motor drives the rotor to rotate, the speed measuring motor detects the rotor's speed and rotation position: other external motor equipment is used to drive the rotor to rotate, and the rotor's speed and rotational mechanical angle can be recorded or changed after rotation. When it is detected that one or more of the four tiles on the rotor are demagnetized, the demagnetized tile can be decelerated when it turns towards the magnetic field detection device. At the same time, the magnetic field detection device increases its power by increasing the magnetic field sampling frequency, thereby improving the accuracy of the magnetic detection of the tiles in this area. S3. Establish a coordinate system model based on the rotor's mechanical angle and magnetic field strength: While the magnetic field detection device detects the rotor, its external drive device drives the rotor to rotate. During the rotor's movement, the magnetic field strength received by its detection probe will also change periodically. A 'magnetic field strength - mechanical angle' model can be drawn based on the magnetic field strength detected by the detection probe and the rotor's mechanical angle. S4. Repeat the detection process multiple times and compare the magnetic field established each time to reduce the error in a single detection: The position and attitude of the magnetic field detection equipment remain unchanged and the number of rotations of the permanent magnet rotor is increased. For each additional rotation of the rotor, the magnetic field detection equipment completes a detection of the magnetic field strength at each angle of the rotor. After drawing the 'magnetic field strength-mechanical angle' model under the corresponding number of rotations, it is necessary to label it according to the number of rotations. S5. Using the superposition principle, magnetic tiles are symmetrically added to the rotor: tiles are installed in the air gap of the rotor, and the installed tiles must ensure the principle of central symmetry. S6. Repeat the rotation detection of the rotor: When repeatedly detecting the rotor after adding tiles, the same conditions as in steps S1 to S5 above are applied, and the power parameters of the detection equipment in the above steps are the same. The time offset of the change in the direction of the magnetic field detected by the detection probe at each time is compared with the time offset of the change in the direction of the magnetic field detected by the detection probe when no additional tiles are added.

2. The method for detecting permanent magnets in the rotor core of an electric motor according to claim 1, characterized in that: In step S4, the 'magnetic field strength-mechanical angle' model drawn for each revolution is averaged, and the averaged model is compared with the randomly selected model parameters. At the same time, the magnetic field strength under four mechanical angles of 0-90°, 90-180°, 180-270° and 270-360° is placed in the same coordinate system for comparison, and the magnetic field similarity between the four tiles on the rotor is analyzed.

3. The method for detecting permanent magnets in the rotor core of an electric motor according to claim 1, characterized in that: In step S6, adding a tile to the air gap between the four main tiles of the rotor will cause the magnetic field zero point, which is located at the center line of the air gap, to shift.

4. The method for detecting permanent magnets in the rotor core of an electric motor according to claim 1, characterized in that: Step S1 includes the following specific steps: S101. Change the distance between the magnetic field detection device and the permanent magnet rotor: After changing the distance between the magnetic field detection device and the rotor, continue to adjust the orientation of the magnetic field detection device to be the same as the diameter direction of the rotor and then fix it. S102. Bring the testing equipment closer to the permanent magnet rotor until the distance is only 0.3mm-1mm: After the testing probe of the testing equipment is brought closer to the rotor to 0.3mm-1mm, the change in the magnetic field after the rotor rotates can be greatly increased. S103. Rotate the rotor again and use the magnetic field detection device to analyze the magnetic field of the rotor and establish a model: When the detection device is brought close to the rotor to 0.3mm-1mm and the detection is performed, the same conditions and power parameters of the detection device as in steps S101 to S102 above are applied. S104. Compare the magnetic field strength of the four tiles on the rotor and analyze the existence of tile eccentricity on the rotor. S105. After wrapping tape around the rotor surface and using a pressure probe to contact the tape, rotate the rotor.

5. The method for detecting permanent magnets in the rotor core of an electric motor according to claim 4, characterized in that: In step S104, when performing close-range rotor magnetic field analysis, it is necessary to exclude the existence of eccentric rotation of the tiles. That is, if the distance between the eccentric tile and the detection probe is larger or smaller, it will directly change the intensity of the magnetic field detected by the detection probe.

6. The method for detecting permanent magnets in the rotor core of an electric motor according to claim 4, characterized in that: In step S105, the rotor surface has tiles and air gaps. After a thin tape is wrapped clockwise around the surface of the tiles and air gaps, the rotor rotates counterclockwise and the pressure probe contacts the tape to detect rotor eccentricity and eliminate the presence of rotor eccentricity.

Images