A high-temperature demagnetization simulation device for a magnetic steel of a permanent magnet motor
By designing magnetic steel slots and air slots on the magnetic guide block to form a closed magnetic circuit, the problems of high cost and inaccurate test results in the high-temperature irreversible demagnetization rate test of neodymium iron boron magnets are solved, achieving more efficient and accurate test results and meeting the actual needs of motors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GUANGDONG DONGGUAN DIANJI CO LTD
- Filing Date
- 2025-08-08
- Publication Date
- 2026-07-24
AI Technical Summary
In the existing technology, the high-temperature irreversible demagnetization rate detection of neodymium iron boron magnets has problems such as high cost, waste of materials, and difficulty in obtaining user acceptance of the test results. Especially when using the 'semi-open circuit' method, the test temperature is usually set based on experience, which is difficult to meet the actual needs of the motor.
A high-temperature demagnetization simulation device for permanent magnet motor magnets was designed using the 'closed-circuit' method. By setting magnet slots and air slots on the magnetic guide block, a closed magnetic circuit is formed to simulate the magnetic field distribution under extreme operating conditions of the motor, thereby improving the magnetic permeability and ensuring that the detection temperature is consistent with the motor's temperature resistance rating.
This technology achieves increased detection temperature without increasing the coercivity of the magnets, reduces waste of magnetic materials, and provides more accurate detection results that meet the actual needs of the motor, eliminating users' concerns about reducing the detection temperature.
Smart Images
Figure CN224555414U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of high-temperature demagnetization detection of magnets, and specifically discloses a high-temperature demagnetization simulation device for permanent magnet motor magnets. Background Technology
[0002] Rare earth neodymium iron boron (NdFeB) magnets are a crucial component for the high efficiency and energy saving of permanent magnet motors, accounting for approximately 30% of the motor's material cost. The incoming inspection of NdFeB magnets plays a dominant role in the quality control of permanent magnet motors. High-temperature irreversible demagnetization rate is a critical inspection item for magnets, and its inspection standards and quality control determine the performance and quality of permanent magnet motor products.
[0003] Typical demagnetization curves of neodymium iron boron magnets are as follows: Figure 1 As shown, the vertical axis represents the magnetic induction intensity B, and the horizontal axis represents the magnetic field strength H. df is the spontaneous magnetization curve of the magnet when there is no external magnetic field. The intersection of the curve and the horizontal axis is called the intrinsic coercivity Hcj. At the same temperature, when the external magnetic field strength H is 0, the magnetic induction intensity within the magnet is the remanence Br. Since there is no demagnetizing material, any magnetic circuit system has an external magnetic field, i.e., a demagnetizing field opposite to that of the magnet is formed externally, forcing the magnet to operate on the demagnetization curve de. When the demagnetizing field makes B 0, the magnetic field strength is called the coercivity Hcb. Due to the negative temperature coefficient characteristic of neodymium iron boron magnets, the demagnetization curve will show an inflection point after reaching a certain temperature, such as... Figure 1 The gi curve in the figure. Pc is the permeability of the motor under the corresponding load condition, and the intersection of the curve with the corresponding temperature demagnetization curve is the operating point at this time.
[0004] Magnetic permeability is expressed as:
[0005] Pc=Bj / (-Hj) (1).
[0006] In equation (1) above, Bj and Hj are the magnetic induction intensity and magnetic field intensity under motor load conditions, respectively. When the operating point (Bj, Hj) is above the inflection point, the demagnetization of the magnet is reversible (recoverable), and when the operating point is below the inflection point, it is irreversible (unrecoverable). The irreversible demagnetization rate of the magnets in a qualified permanent magnet motor should be controlled within a very small range.
[0007] The testing of the irreversible demagnetization rate of magnets at high temperatures typically involves placing the magnet and a magnetically conductive component in an oven for baking. A "semi-open circuit" method is generally used, where the magnet is placed on a magnetically conductive plate of a certain thickness. Because the magnetic circuit in the "semi-open circuit" method contains more air, the magnet is more prone to irreversible demagnetization in high-temperature testing environments. Therefore, a baking temperature lower than the temperature resistance rating of the magnet or motor is usually used for testing. However, the testing temperature is usually determined based on experience and actual motor testing, resulting in high testing costs and potential waste of permanent magnet materials and increased costs. Lowering the testing temperature and the resulting test results are also difficult to accept by users. Utility Model Content
[0008] A 1 / 4 scale two-dimensional model of the motor is as follows Figure 2 As shown, when the motor is subjected to a 3 times torque overload (extreme operating condition), the magnetic induction intensity of the magnet and the distribution of the motor's magnetic field lines are as follows: Figure 3 As shown, the permeability distribution of the magnet from a to b (one end to the other) is as follows: Figure 4 As shown. By Figures 3-4 It can be seen that the magnetic induction intensity and permeability are lowest at end a of the magnet, with the lowest permeability being 0.78. Taking the standard N42SH magnet as an example, the demagnetization curve is as follows: Figure 5 As shown, the Pc curve for ultimate overload and the demagnetization curve at 150℃ are both above the inflection point.
[0009] A device for testing the irreversible demagnetization rate of "semi-open circuit" magnets at high temperatures, such as... Figure 6 As shown, the device includes a magnet and a steel plate (magnetic plate), with the Y-axis representing the magnetization direction of the magnet. The magnetic induction intensity and magnetic field distribution of this demagnetizing device are shown in the figure. Figure 7 As shown, the permeability distribution of the magnet from left to right is as follows: Figure 8 As shown, by Figures 7-8 It can be seen that the left and right ends of the magnet, close to the steel plate, have relatively high permeability and magnetic induction intensity, while the middle part of the magnet, being far from the steel plate, has very low permeability and magnetic induction intensity. In particular, over 22% of the magnet's position has a permeability below 0.15. The demagnetization curve is below the inflection point at the operating point of 150℃. Baking N42SH magnets at this temperature will cause a large irreversible demagnetization rate. To avoid this situation, methods such as increasing the coercivity of the magnet or decreasing the magnet testing temperature are usually adopted. Since increasing the coercivity increases the cost of the magnet, the method of decreasing the magnet testing temperature is generally preferred. Figure 5 As shown, a magnetic permeability of 0.15 requires the detection temperature to be reduced to at least 130℃. Lowering the detection temperature of the magnet is unlikely to be accepted by users compared to permanent magnet motors with F-class or even higher temperature resistance ratings.
[0010] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a high-temperature demagnetization simulation device for permanent magnet motor magnets. This solution uses a closed-circuit method to detect the high-temperature irreversible demagnetization rate of the magnets. The permeability of the magnets within the device can be simulated equivalent to the permeability of the magnets under extreme motor operating conditions; that is, the minimum Pc value of the internal magnets under extreme motor operating conditions is used as the minimum Pc value of the magnets in this solution's device. Therefore, the detection temperature of the magnets can be increased without increasing the magnet's coercivity.
[0011] This utility model discloses a high-temperature demagnetization simulation device for permanent magnet motor magnets, which adopts the following technical solution:
[0012] A high-temperature demagnetization simulation device for permanent magnet motor magnets includes a magnetic guide block. The magnetic guide block has at least two magnetic slots for inserting magnets, and the extension directions of two adjacent magnetic slots intersect. Air slots are connected to both ends of each magnetic slot. A distance L1 is left between one end of the magnetic slot and the edge of the magnetic guide block, a distance L2 is left between the other end of the magnetic slot and the edge of the magnetic guide block, and a distance L3 is left between the corresponding air slots of two adjacent magnetic slots.
[0013] Preferably, the magnetic guide block is provided with a plurality of magnetic steel simulation groups, each magnetic steel simulation group including at least two magnetic steel slots, and an isolation slot is provided between adjacent magnetic steel simulation groups, the isolation slot serving as the edge of the magnetic guide block of the corresponding magnetic steel simulation group.
[0014] Preferably, the plurality of magnetic steel simulation groups are arranged in a matrix, with longitudinal isolation grooves between adjacent magnetic steel simulation groups on the left and right, and transverse isolation grooves between adjacent magnetic steel simulation groups on the top and bottom.
[0015] Preferably, the magnet slots of different magnet simulation groups have different sizes.
[0016] Preferably, L1 and / or L2 and / or L3 are different for different groups of magnets.
[0017] Preferably, the magnetic block is provided with a fixing member.
[0018] Preferably, the cross-section of the air trough is triangular.
[0019] Preferably, the magnetic conductive block is a plate made by pressing silicon steel sheets together.
[0020] Compared with the prior art, the present invention has at least the following beneficial effects:
[0021] This utility model discloses a high-temperature demagnetization simulation device for permanent magnet motors. By designing a magnetic guide plate, a magnet slot, and an air slot, and leaving magnetic guide plate portions at positions L1, L2, and L3 between the slots of two adjacent magnets, these magnetic guide plate portions play a crucial role in the high-temperature demagnetization simulation device for permanent magnet motors. By forming a closed magnetic circuit, simulating the magnetic field distribution of an actual motor, and enhancing the stability and independence of the magnetic field, they ensure that the device can more accurately simulate the working state of the magnet in actual applications, providing more reliable technical support for the high-temperature demagnetization detection of magnets.
[0022] Unlike traditional "semi-open circuit" demagnetization testing devices, this solution employs a "closed circuit" simulation device, which improves the permeability of the magnets within the device and avoids waste of magnetic materials. Furthermore, the permeability of the magnets within the device is simulated equivalent to the permeability of the magnets under extreme motor operating conditions. This ensures that the minimum Pc value of the internal magnets under extreme motor operating conditions is used as the minimum Pc value of the magnets in the device, thereby significantly increasing the magnet testing temperature. The temperature standard can be the same as the motor's temperature resistance rating, eliminating customer concerns about lowering the magnet testing temperature. Attached Figure Description
[0023] Figure 1 Typical demagnetization curves for rare earth neodymium iron boron steel;
[0024] Figure 2 A two-dimensional model diagram of a standard motor, 1 / 4 the size of the standard motor.
[0025] Figure 3 for Figure 2 The magnetic induction intensity of the magnets and the distribution of magnetic field lines of the motor in the model;
[0026] Figure 4 for Figure 2 The horizontal distribution of the magnetic permeability of the magnet in the model;
[0027] Figure 5 Demagnetization curve of standard N42SH magnet;
[0028] Figure 6 This is a high-temperature irreversible demagnetization testing device for "semi-open circuit" magnets in existing technologies.
[0029] Figure 7 The diagram shows the magnetic induction intensity and magnetic field line distribution using the "semi-open circuit" method.
[0030] Figure 8 The horizontal distribution of magnetic permeability of the magnet in the "semi-open circuit" method;
[0031] Figure 9 This is the high-temperature demagnetization simulation device for permanent magnet motor magnets in Embodiment 1.
[0032] Figure 10 for Figure 9The horizontal distribution of magnetic permeability of the magnet in the simulation device;
[0033] Figure 11 This is the high-temperature demagnetization simulation device for permanent magnet motor magnets in Embodiment 2.
[0034] Explanation of icon numbers:
[0035] 1. Stator core; 2. Winding; 3. Magnet; 4. Rotor core; 5. Magnetic guide plate; 51. Magnet slot; 52. Air slot; 53. Isolation slot; 6. Rivet. Detailed Implementation
[0036] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0037] Example 1
[0038] By Figure 2 Taking a motor model as an example, a simulation device for the irreversible demagnetization of magnets at high temperatures is designed, with a particular focus on the equivalent design of the minimum Pc value of the magnets under extreme operating conditions (3 times overload). Since the motor has a periodically changing structure in the circumferential direction and a similar structure in the axial direction, two magnets, a section of magnets in the axial direction, and the iron core are selected for simulation design.
[0039] Reference Figure 9 This embodiment discloses a high-temperature demagnetization simulation device for permanent magnet motor magnets, which includes a magnetic guide block 5. The magnetic guide block 5 is provided with at least two magnetic steel slots 51 for magnets 3 to be inserted. The extension directions of two adjacent magnetic steel slots 51 intersect, that is, the two magnetic steel slots 51 are relatively inclined. Each magnetic steel slot 51 has an air slot 52 with a triangular cross-section at both ends. One end of the magnetic steel slot 51 is left with a distance L1 from the edge of the magnetic guide block 5, and the other end of the magnetic steel slot 51 is left with a distance L2 from the edge of the magnetic guide block 5. The air slots 52 corresponding to two adjacent magnetic steel slots 51 are left with a distance L3.
[0040] By setting a magnetic groove 51 on the magnetic block 5, it can be used to place the magnet 3 for high-temperature demagnetization simulation. The magnetization direction is perpendicular to the magnet 3. See Figure 9 The air slot 52 generates magnetic reluctance, which can simulate the magnetic force distribution of a real motor. The distances L1, L2, and L3 can be adjusted according to actual needs to optimize the layout of the magnet slots and the magnetic field distribution, better simulating demagnetization under different operating conditions. In this simulation device, the magnet dimensions are consistent with those of the motor magnets. By adjusting the distances L1 and L2 between the magnet slot 51 and the edge of the magnetic guide block 5, and the distance L3 between adjacent magnet slots 51 and corresponding air slots 52, the permeability of the magnet 3 within the device is adjusted. After adjustment, the permeability distribution of the magnet 3 from a to b within the device is as follows: Figure 10As shown, the minimum Pc value is 0.78, which is... Figure 4 The minimum Pc value is consistent under extreme operating conditions of the motor.
[0041] This solution adopts the "closed-circuit" method, which forms a closed magnetic circuit by placing the magnet 3 in the magnetically conductive block 5. This more accurately simulates the working state of the magnet in actual applications. Compared with the "semi-open-circuit" method, it improves the magnetic permeability of the magnet in the device and avoids the waste of magnetic materials. In addition, the "closed-circuit" method of this solution increases the magnet inspection temperature compared with the "semi-open-circuit" method. The temperature standard can be the same as the motor temperature resistance rating, which can eliminate customers' doubts about reducing the magnet inspection temperature.
[0042] As a preferred embodiment, the magnetic conductive block 5 is a plate made by stacking silicon steel sheets. Silicon steel sheets have excellent magnetic permeability and low eddy current loss. By stacking silicon steel sheets into a plate to make the magnetic conductive block, the performance advantages of silicon steel sheets can be fully utilized, the magnetic permeability of the magnetic conductive block can be improved, and the energy loss caused by eddy current loss during high-temperature demagnetization simulation can be reduced, thereby improving the energy efficiency and performance of the entire simulation device, and also helping to extend the service life of the device.
[0043] Example 2
[0044] Unlike Embodiment 1, in this embodiment, to improve the versatility of the permanent magnet motor magnet high-temperature demagnetization simulation device, the magnetic guide block 5 is provided with several magnet simulation groups. Each magnet simulation group includes at least two magnet slots 51, and an isolation slot 53 is provided between adjacent magnet simulation groups. The isolation slot 53 acts as the edge of the magnetic guide block of the corresponding magnet simulation group. As a preferred embodiment, the magnet slot sizes of different magnet simulation groups are different, and L1 and / or L2 and / or L3 of different magnet simulation groups are different.
[0045] By designing multiple magnet simulation groups with different magnet slot sizes (51) and adjusting the L1, L2, and L3 parameters of different magnet simulation groups, it can be applied to different testing objects and working conditions. This allows for precise control of the magnetic field distribution and magnet slot layout of each magnet simulation group, thus better simulating various complex working conditions. The device can more accurately reflect the high-temperature demagnetization characteristics of magnets under different conditions, providing more comprehensive and accurate data support for the design and optimization of permanent magnet motors, and improving the performance and reliability of permanent magnet motors. The high-temperature demagnetization simulation device for permanent magnet motors in this embodiment is applicable to the testing of magnets of different grades and sizes. The device can simulate high-temperature demagnetization of multiple different groups of magnets. Each group can be set with different magnet slot parameters and magnetic field distributions according to different testing needs, greatly improving the versatility and flexibility of the device, meeting diverse testing requirements. It achieves efficient testing of various magnets without frequent device replacements or complex structural adjustments. The isolation slots further enhance the magnetic field isolation effect between groups, ensuring that the simulations of each group do not interfere with each other.
[0046] In this embodiment, the high-temperature demagnetization simulation device for multiple magnet simulation groups is as follows: Figure 11 As shown, and not limited to, four magnet simulation groups, the number of poles can be increased appropriately according to the weight of the device. The four magnet simulation groups are arranged in a matrix, with longitudinal isolation slots 53 between adjacent left and right magnet simulation groups and transverse isolation slots 53 between adjacent top and bottom magnet simulation groups. The matrix distribution of the magnet simulation groups is reasonable and compact, making full use of the space of the magnetic blocks and improving the overall integration and detection efficiency of the device. The setting of longitudinal and transverse isolation slots 53 isolates the magnetic field of the magnet simulation groups from two directions, further optimizing the magnetic field distribution and making the magnetic field within each magnet simulation group more independent and stable. Even in a high-density matrix layout, the accuracy and reliability of the demagnetization simulation results of each magnet simulation group can be guaranteed.
[0047] As a preferred embodiment, the magnetic block is equipped with a fixing component, specifically a rivet. The rivet securely fixes the magnetic block to the relevant equipment or structure, ensuring its stability during the high-temperature demagnetization simulation process and preventing displacement or loosening of the magnetic block due to external factors, thereby guaranteeing the reliability of the simulation device and the accuracy of the test results.
[0048] The technical solution provided by this utility model has been described in detail above. Specific examples have been used to illustrate the principle and implementation of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.
Claims
1. A high-temperature demagnetization simulation device for permanent magnet motor magnets, characterized in that, The device includes a magnetic guide block, which has at least two magnetic slots for inserting magnets, and the extension directions of two adjacent magnetic slots intersect. Each magnetic slot has an air slot connected to both ends. One end of the magnetic slot is at a distance L1 from the edge of the magnetic guide block, the other end of the magnetic slot is at a distance L2 from the edge of the magnetic guide block, and the corresponding air slots of two adjacent magnetic slots are at a distance L3.
2. The high-temperature demagnetization simulation device for permanent magnet motors according to claim 1, characterized in that, The magnetic guide block is provided with a plurality of magnetic steel simulation groups, each magnetic steel simulation group including at least two magnetic steel slots, and an isolation slot is provided between adjacent magnetic steel simulation groups, the isolation slot serving as the edge of the magnetic guide block of the corresponding magnetic steel simulation group.
3. The high-temperature demagnetization simulation device for permanent magnet motors according to claim 2, characterized in that, Several of the magnetic steel simulation groups are arranged in a matrix, with longitudinal isolation slots between adjacent magnetic steel simulation groups on the left and right, and transverse isolation slots between adjacent magnetic steel simulation groups on the top and bottom.
4. The high-temperature demagnetization simulation device for permanent magnet motors according to claim 2, characterized in that, The magnet slots of different magnet simulation groups have different dimensions.
5. The high-temperature demagnetization simulation device for permanent magnet motors according to claim 2, characterized in that, The L1 and / or L2 and / or L3 of the different magnetic steel simulation groups are different.
6. The high-temperature demagnetization simulation device for permanent magnet motor magnets according to claim 1, characterized in that, The magnetic block is equipped with a fixing component.
7. The high-temperature demagnetization simulation device for permanent magnet motors according to claim 1, characterized in that, The air trough has a triangular cross-section.
8. The high-temperature demagnetization simulation device for permanent magnet motors according to claim 1, characterized in that, The magnetic conductive block is a plate made by pressing silicon steel sheets together.