Anti-demagnetization motor rotor

Abstract

The invention relates to an anti-demagnetization motor rotor which comprises a motor stator. Stator iron cores are circumferentially distributed on the inner wall of the motor stator, and a rotor structure is arranged in the middle of the motor stator. According to the anti-demagnetization motor rotor, the permanent magnet structures are additionally arranged, the first magnet grooves and the second permanent magnet grooves are of a V-shaped structure and have the magnetism gathering effect, and the auxiliary grooves are additionally arranged, so that magnetic field distribution is more uniform and reasonable, and the performance of a motor is improved; the magnetic isolation grooves II are additionally arranged, so that the magnetic field distribution of the motor is more reasonable and uniform, the magnetic circuit efficiency is improved, the output performance of the motor is improved, and the bypass magnetic circuit is additionally arranged to improve the trend of magnetic lines, thereby reducing the local demagnetization risk of the permanent magnets and improving the performance and reliability of the motor. The magnetic isolation grooves I are additionally arranged, so that the magnetic field intensity of the permanent magnet with the maximum demagnetization risk is reduced, the probability of the demagnetization risk of the permanent magnet is reduced, and the anti-demagnetization capability of the motor is improved on the premise that the thickness of the permanent magnet is not increased.

Description

Technical Field

[0001] The present invention relates to the technical field of high-efficiency energy-saving motors, and particularly to a motor rotor with anti-demagnetization function. Background Art

[0002] The step-start permanent magnet motor belongs to the high-efficiency energy-saving motor. The characteristic of the step-start permanent magnet motor is that it can be directly started by power frequency power supply without a frequency converter, thereby improving the simplicity of the drive system, reducing costs, improving the performance-price ratio of the motor, and making it easier for users to accept.

[0003] The two main factors causing irreversible demagnetization of the permanent magnet in the permanent magnet motor are the reverse demagnetizing field and high temperature. During the operation of the permanent magnet synchronous motor, it is inevitable that it occasionally operates in the demagnetization condition, which will cause the motor performance to decline, the loss to increase, the temperature rise to be serious, and even the motor to stop rotating. Therefore, it is very important to optimize the anti-demagnetization of the permanent magnet motor.

[0004] The rotor optimization design for anti-demagnetization of the permanent magnet often improves the anti-demagnetization ability of the motor by increasing the thickness of the permanent magnet, which will directly lead to a significant increase in the manufacturing cost of the permanent magnet synchronous motor. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] To solve the above technical problems, the present invention provides a motor rotor with anti-demagnetization function.

[0007] (2) Technical Solutions

[0008] Based on this, the present invention provides the following technical solutions: A motor rotor with anti-demagnetization function, including a motor stator; the inner wall of the motor stator is circumferentially distributed with a stator core, the middle of the motor stator is provided with a rotor structure, and the inner side of the rotor structure is circumferentially distributed with a permanent magnet structure; the permanent magnet structure includes a first permanent magnet slot, a bypass magnetic path, a first magnetic isolation slot, a permanent magnet, a second magnetic isolation slot, and a second permanent magnet slot. The first permanent magnet slot is opened on the inner side of the rotor structure, the bypass magnetic path is arranged on the left side of the first permanent magnet slot, the upper left end of the first permanent magnet slot is provided with the first magnetic isolation slot, the middle of the first permanent magnet slot is embedded with the permanent magnet, the right side of the first permanent magnet slot is provided with the second magnetic isolation slot, and the lower end of the first permanent magnet slot is provided with the second magnetic isolation slot.

[0009] Preferably, the first permanent magnet slot, the bypass magnetic path, the first magnetic isolation slot, and the permanent magnet together form an anti-demagnetization structure. There are two groups of demagnetization structures, which are arranged oppositely along the left and right sides of the second magnetic isolation slot, and the two first permanent magnet slots together form a V-shaped structure.

[0010] Preferably, the structure of the first permanent magnet slot is the same as that of the second permanent magnet slot, and the first permanent magnet slot and the second permanent magnet slot are arranged in parallel. The second permanent magnet slot is provided with a bypass magnetic path, a first magnetic isolation slot, a permanent magnet, and a second magnetic isolation slot.

[0011] Preferably, both the first magnet slot and the second permanent magnet slot are inclined at an angle of 18°.

[0012] Preferably, when the permanent magnet is arranged inside the first permanent magnet slot, auxiliary slots exist on the left and right sides of the first permanent magnet slot, and the depth of the auxiliary slot is 0.5 mm.

[0013] Preferably, the length of the second magnetic isolation slot is 5.5 mm and the width is 2 mm.

[0014] Preferably, the bypass magnetic path is arranged in multiple segments, and multiple groups of inner grooves are arranged on the bypass magnetic path. The thickness and interval of each segment of the inner groove are both 0.5 mm, and the length of the inner groove is 1.5 mm.

[0015] Preferably, the first magnetic isolation slot is arranged at the corner of the outer layer of the permanent magnet, and the width of the first magnetic isolation slot is 0.6 mm.

[0016] Preferably, the thickness of the first permanent magnet slot is the same as that of the second permanent magnet slot. The thickness of the first permanent magnet slot is t b1 , and the thickness of the second permanent magnet slot 46 is t b2 , the inner diameter of the rotor structure is D r , the outer diameter of the rotor structure is D sh , and the expression of the permanent magnet content rate is:

[0017]

[0018] (III) Beneficial effects

[0019] Compared with the prior art, the present invention provides a demagnetization-resistant motor rotor, which has the following beneficial effects:

[0020] For the demagnetization-resistant motor rotor, by adding a permanent magnet structure, firstly, the first magnet slot and the second permanent magnet slot are in a V-shaped structure, which has a magnetic focusing effect, and an auxiliary slot is added, making the magnetic field distribution more uniform and reasonable, thereby improving the performance of the motor; adding the second magnetic isolation slot makes the magnetic field distribution of the motor more reasonable and uniform, improves the magnetic circuit efficiency, and improves the output performance of the motor. Adding the bypass magnetic path improves the direction of the magnetic force lines, thereby reducing the risk of local demagnetization of the permanent magnet and improving the performance and reliability of the motor. Adding the first magnetic isolation slot reduces the magnetic field intensity of the part with the greatest risk of permanent magnet demagnetization, thereby reducing the probability of permanent magnet demagnetization risk and improving the demagnetization resistance of the motor without increasing the thickness of the permanent magnet. Description of the drawings

[0021] Figure 1 Schematic diagram of the overall structure of the present invention;

[0022] Figure 2 Schematic diagram of the partial sectional structure of the present invention;

[0023] Figure 3 Schematic diagram of the sectional structure of the permanent magnet structure of the present invention;

[0024] Figure 4 Schematic diagram of the demagnetization rate of the permanent magnet under different temperatures and currents of the present invention;

[0025] Figure 5 Schematic diagram of the demagnetization rate of the permanent magnet with different lengths of magnetic isolation grooves of the present invention;

[0026] Figure 6 Schematic diagram of the demagnetization rate of the permanent magnet with different lengths of bypass magnetic paths of the present invention;

[0027] Figure 7 Schematic diagram of the demagnetization rate of the permanent magnet with different widths of magnetic isolation grooves of the present invention;

[0028] Figure 8 Schematic diagram of the electromagnetic torque and reluctance torque of the motor of the present invention.

[0029] In the figure: motor stator - 1, stator core - 2, rotor structure - 3, permanent magnet structure - 4, permanent magnet slot 1 - 41, bypass magnetic path - 42, magnetic isolation groove 1 - 43, permanent magnet - 44, magnetic isolation groove 2 - 45, permanent magnet slot 2 - 46. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] Please refer to Figures 1 - 2 , an anti - demagnetization motor rotor, including a motor stator 1; the inner wall of the motor stator 1 is circumferentially distributed with a stator core 2, a rotor structure 3 is arranged in the middle of the motor stator 1, and a permanent magnet structure 4 is circumferentially distributed inside the rotor structure 3.

[0032] Please refer to Figure 3, a demagnetization-resistant motor rotor, the permanent magnet structure 4 includes a first permanent magnet groove 41, a bypass magnetic path 42, a first magnetic isolation groove 43, a permanent magnet 44, a second magnetic isolation groove 45, and a second permanent magnet groove 46. The first permanent magnet groove 41 is opened on the inner side of the rotor structure 3. A bypass magnetic path 42 is provided on the left side of the first permanent magnet groove 41. A first magnetic isolation groove 43 is provided at the upper left end of the first permanent magnet groove 41. A permanent magnet 44 is embedded and installed in the middle of the first permanent magnet groove 41. A second magnetic isolation groove 45 is opened on the right side of the first permanent magnet groove 41. A second magnetic isolation groove 45 is provided at the lower end of the first permanent magnet groove 41. The first permanent magnet groove 41, the bypass magnetic path 42, the first magnetic isolation groove 43, and the permanent magnet 44 together form a demagnetization-resistant structure. There are two sets of demagnetization structures, which are arranged oppositely along the left and right sides of the second magnetic isolation groove 45, and the two first permanent magnet grooves 41 together form a V-shaped structure. The structure of the first permanent magnet groove 41 is the same as that of the second permanent magnet groove 46, and the first permanent magnet groove 41 and the second permanent magnet groove 46 are arranged parallel to each other. The second permanent magnet groove 46 is provided with a bypass magnetic path 42, a first magnetic isolation groove 43, a permanent magnet 44, and a second magnetic isolation groove 45.

[0033] In some embodiments, both the first magnet groove 41 and the second permanent magnet groove 46 are inclined at an angle of 18°, and the V-shaped structure has a magnetic focusing effect.

[0034] In some embodiments, when the permanent magnet 44 is arranged inside the first permanent magnet groove 41, there are auxiliary grooves on the left and right sides of the first permanent magnet groove 41, and the depth of the auxiliary groove is 0.5 mm. Two-dimensional models are respectively established by using finite element software, and the motor model is as Figure 3 shown. The auxiliary groove can effectively improve the demagnetization resistance of the motor. In the motor model, the auxiliary groove makes the magnetic field distribution more uniform and reasonable, thereby improving the performance of the motor. If the auxiliary groove is set too deep, it may cause excessive stress on the rotor structure 3 and affect the service life of the motor. If it is set too shallow, the optimization effect is not obvious and the expected improvement effect cannot be achieved. Therefore, parametric simulation is carried out on the depth of the auxiliary groove, and the motor is placed in an extreme working condition under the combined action of temperature and external magnetic field to analyze the influence of auxiliary grooves with different depths on the demagnetization resistance of the motor, as Figure 4 shown. It can be seen from Figure 4 that when the depth of the auxiliary groove is set to 0.1 mm and 0.3 mm, it is too shallow to reach the best demagnetization resistance, while the depth of 0.7 mm is too deep, which instead increases the demagnetization rate of the permanent magnet. Therefore, setting the rotor auxiliary groove to 0.5 mm is a relatively reasonable choice.

[0035] In some embodiments, the length of the second magnetic isolation groove 45 is 5.5 mm and the width is 2 mm. By adding the second magnetic isolation groove 45, the magnetic leakage problem of the motor can be effectively reduced, thereby improving the performance of the motor. In the motor model, adding the second magnetic isolation groove 45 can make the magnetic field distribution of the motor more reasonable and uniform, improve the magnetic circuit efficiency, and improve the output performance of the motor. However, during the process of adding the middle magnetic isolation groove, the test of the mechanical strength of the rotor needs to be considered, especially the stress condition of the middle magnetic bridge. Therefore, on the basis of retaining a 1 mm thick middle magnetic bridge, the length of the second magnetic isolation groove 45 is parametrically simulated, and the motor is placed under extreme working conditions to analyze the influence of different sizes of the middle magnetic isolation groove on the demagnetization of the motor. As Figure 5 shown. It can be seen from the figure that when the length of the middle magnetic isolation groove is set to 5.5 mm, the demagnetization rate of the permanent magnet is the lowest. Therefore, the width of the middle magnetic isolation groove is selected to be 2 mm, the length is 5.5 mm, and the magnetic bridges on both sides of the middle magnetic isolation groove are 0.5 mm wide each. This can effectively balance the performance and mechanical strength of the motor, ensuring that the motor can maintain a stable and reliable operating state during use.

[0036] In some embodiments, the bypass magnetic path 42 is arranged in multiple segments, and multiple groups of inner grooves are provided on the bypass magnetic path 42. The thickness and interval of each segment of the inner groove are both 0.5 mm, and the length of the inner groove is 1.5 mm. During the operation of the motor, the permanent magnet 44 is prone to demagnetization at the corners near the air gap, which will cause a greater demagnetization risk to the permanent magnet at the corners. To solve this problem, the bypass magnetic path 42 can be added to improve the direction of the magnetic force lines, thereby reducing the local demagnetization risk of the permanent magnet and improving the performance and reliability of the motor. In the motor model, the number of segments, position, thickness, and length of the bypass magnetic path 42 will all have different effects on the demagnetization resistance ability of the permanent magnet 44. If the set position is too close to the permanent magnet 44, the bypass magnetic path will deform due to the high-speed rotation of the rotor and collide with the permanent magnet, thereby affecting the performance and life of the motor, and even having the risk of damaging the motor and endangering personal safety; in addition, the space available for setting the bypass magnetic path 42 is limited, and the number should not be too small. Therefore, it is appropriate to set three segments of the bypass magnetic path in the permanent magnet slot, and the thickness and interval of each segment are both 0.5 mm. In addition, the length of the bypass magnetic path 42 is parametrically analyzed, and the motor is placed under extreme working conditions to analyze the influence of different lengths of the bypass magnetic path on the demagnetization resistance ability of the motor, as Figure 6As shown. It can be seen from the figure that the lengths of 1.0 mm and 1.25 mm do not achieve the best anti-demagnetization effect, while the length of 1.75 mm causes the magnetic field lines guided by it to converge again at the edge of the permanent magnet 44 due to the too long bypass magnetic path 42, thereby causing a relatively large demagnetizing magnetic field and resulting in an increase rather than a decrease in the demagnetization rate. Therefore, the length of the bypass magnetic path 42 is finally set to 1.5 mm, which can maximize the anti-demagnetization ability of the permanent magnet while ensuring the performance and reliability of the motor, and ensure the stable operation of the motor.

[0037] In some embodiments, the magnetic isolation groove 43 is provided at the corner of the outer layer of the permanent magnet 44. The width of the magnetic isolation groove 43 is 0.6 mm, which can effectively reduce the magnetic field strength of the part of the permanent magnet 44 that is most vulnerable to demagnetization risk, thereby reducing the probability of the demagnetization risk of the permanent magnet 44. If the magnetic isolation groove 43 is set too large, the magnetic energy density of the permanent magnet 44 will be reduced, affecting the output performance of the motor. If it is too close to the outside, the permanent magnet 44 at the corner will bear a greater demagnetizing magnetic field, making the local part of the permanent magnet 44 more likely to demagnetize; if it is set too small or close to the inside, the effect of the magnetic isolation groove 43 may not be significant enough. Therefore, the center of the magnetic isolation groove 43 is selected to be set at the highest demagnetization rate and extended to both sides until it is 1.5 mm away from the corner of the outermost layer of the permanent magnet 44. At this time, the length of the magnetic isolation groove 43 is 4 mm. An unreasonable setting of the width of the magnetic isolation groove 43 will also affect the anti-demagnetization performance of the permanent magnet. Therefore, the width of the magnetic isolation groove is parameterized, and the motor is placed under extreme working conditions to analyze the influence of magnetic isolation grooves with different widths on the anti-demagnetization ability of the motor, as Figure 7 shown. It can be seen from the figure that the magnetic isolation grooves 43 with widths of 0.3 mm and 0.4 mm have not achieved the best demagnetization effect. When the width is set to 0.6 mm, a relatively high demagnetizing magnetic field will be formed near the magnetic isolation groove 43, resulting in an increase in the demagnetization rate of the permanent magnet. Therefore, it is finally appropriate to set the width of the magnetic isolation groove 43 to 0.5 mm.

[0038] In some embodiments, the thickness of the permanent magnet groove 41 is the same as the thickness of the permanent magnet groove 46. The thickness of the permanent magnet groove 41 is t b1 , and the thickness of the permanent magnet groove 46 is t b2 , the inner diameter of the rotor structure 3 is D r , and the outer diameter of the rotor structure 3 is D sh , and the permanent magnet content rate expression is: As Figure 8 shown, by simulating and comparing the electromagnetic torque and reluctance torque of the motor under different permanent magnet content rates, that is, different K air values. The electromagnetic torque and reluctance torque increase with the increase of the K air value, and the reluctance torque reaches its maximum value at K airWhen it is 0.35, it reaches the maximum of 188 N·m. With the magnetic barrier width unchanged, K air As the value of K increases, the amount of permanent magnet used increases, resulting in an enhanced air-gap magnetic field and a greater electromagnetic torque output by the motor. At the same time, as K air increases, the width of the magnetic barrier in the direct-axis direction increases, leading to an increase in the direct-axis component of the rotor inductance and a larger reluctance torque. However, when K air exceeds 0.35, the reluctance torque no longer increases. Taking the minimum value as the judgment condition, when K air takes the value of 0.35, the thickness of the permanent magnet slot 41 and the thickness of the permanent magnet slot 46 can be obtained therefrom.

[0039] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An anti-demagnetization motor rotor, characterized in that: including a motor stator (1); The inner wall of the motor stator (1) is circumferentially distributed with a stator core (2), a rotor structure (3) is arranged in the middle of the motor stator (1), and a permanent magnet structure (4) is circumferentially distributed inside the rotor structure (3); The permanent magnet structure (4) includes a first permanent magnet groove (41), a bypass magnetic path (42), a first magnetic isolation groove (43), a permanent magnet (44), a second magnetic isolation groove (45), and a second permanent magnet groove (46). The first permanent magnet groove (41) is opened inside the rotor structure (3). A bypass magnetic path (42) is arranged on the left side of the first permanent magnet groove (41). A first magnetic isolation groove (43) is arranged at the upper left end of the first permanent magnet groove (41). A permanent magnet (44) is embedded and installed in the middle of the first permanent magnet groove (41). A second magnetic isolation groove (45) is opened on the right side of the first permanent magnet groove (41). A second magnetic isolation groove (45) is arranged at the lower end of the first permanent magnet groove (41).

2. The anti-demagnetization motor rotor according to claim 1, characterized in that: The first permanent magnet groove (41), the bypass magnetic path (42), the first magnetic isolation groove (43), and the permanent magnet (44) together form a demagnetization resistance structure. There are two sets of demagnetization resistance structures, which are arranged oppositely along the left and right sides of the second magnetic isolation groove (45), and the two first permanent magnet grooves (41) together form a V-shaped structure.

3. The anti-demagnetization motor rotor according to claim 1, characterized in that: The structure of the first permanent magnet groove (41) is the same as that of the second permanent magnet groove (46), and the first permanent magnet groove (41) and the second permanent magnet groove (46) are arranged parallel to each other. The second permanent magnet groove (46) is provided with a bypass magnetic path (42), a first magnetic isolation groove (43), a permanent magnet (44), and a second magnetic isolation groove (45).

4. A demagnetization-resistant motor rotor according to claim 1, characterized in that: Both the first magnet groove (41) and the second permanent magnet groove (46) are inclined at an angle of 18°.

5. A demagnetization-resistant motor rotor according to claim 1, characterized in that: When the permanent magnet (44) is arranged inside the first permanent magnet groove (41), there are auxiliary grooves on the left and right sides of the first permanent magnet groove (41), and the depth of the auxiliary grooves is 0.5 mm.

6. The anti-demagnetization motor rotor according to claim 1, wherein: The length of the second magnetic isolation groove (45) is 5.5 mm and the width is 2 mm.

7. The anti-demagnetization motor rotor according to claim 1, characterized in that: The bypass magnetic path (42) is arranged in multiple segments, and multiple groups of inner grooves are arranged on the bypass magnetic path (42). The thickness and interval of each inner groove are both 0.5 mm, and the length of the inner groove is 1.5 mm.

8. The anti-demagnetization motor rotor according to claim 1, characterized in that: The first magnetic isolation groove (43) is arranged at the corner of the outer layer of the permanent magnet (44), and the width of the first magnetic isolation groove (43) is 0.6 mm.

9. An anti-demagnetization motor rotor according to claim 1, characterized in that: The thickness of the first permanent magnet slot (41) is the same as that of the second permanent magnet slot (46), and the thickness of the first permanent magnet slot (41) is t b1 , and the thickness of the second permanent magnet slot (46) is t b2 , the inner diameter of the rotor structure (3) is D r , the outer diameter of the rotor structure (3) is D sh , and the expression of the permanent magnet content ratio is as follows:

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