Motor rotor and permanent magnet motor

Abstract

This invention provides a motor rotor and a permanent magnet motor. The motor rotor includes a rotor core with multiple permanent magnet slots. Permanent magnets are disposed within these slots. At one pole, the permanent magnets include a first, second, third, and fourth permanent magnet. The first and third permanent magnets are located on a first side of the d-axis, the second and fourth permanent magnets are located on a second side of the d-axis, the third permanent magnet is located on the side of the first permanent magnet closest to the d-axis, and the fourth permanent magnet is located on the side of the second permanent magnet closest to the d-axis. The magnetic coercivity of the first permanent magnet is less than that of the third permanent magnet, and the magnetic coercivity of the second permanent magnet is less than that of the fourth permanent magnet. The length of the first permanent magnet is greater than that of the third permanent magnet, and the length of the second permanent magnet is greater than that of the fourth permanent magnet. The motor rotor according to this invention improves the demagnetization resistance of the permanent magnet motor and enhances motor performance.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more specifically, to a motor rotor and a permanent magnet motor. Background Technology

[0002] A permanent magnet motor is an electric motor that uses permanent magnets as the magnetic poles in its rotor or stator. It typically features high efficiency, high power density, and good dynamic response characteristics. The selection and configuration of permanent magnets are crucial to the motor's performance. Common permanent magnet materials include neodymium iron boron (NdFeB), samarium cobalt (SCo), and ferrite, among which NdFeB is the preferred choice for high power density permanent magnet motors due to its high coercivity and high remanence.

[0003] During the operation of a permanent magnet motor, the permanent magnets of the motor are often subjected to a certain reverse magnetic field. Especially when the motor is operating under harsh conditions, fails to start, or is subjected to strong mechanical vibration, the controller will generate a large instantaneous current, applying a large instantaneous reverse magnetic field to the permanent magnets. This reverse magnetic field is usually much larger than the demagnetizing component in the stator magnetic field during normal operation, causing the motor to demagnetize, and the motor performance will decrease or even become unusable.

[0004] In recent years, the development of motors has trended towards miniaturization and high power density. This requires motors to be smaller in size under heavy load conditions, resulting in a lower operating point for the rotor permanent magnet. Under heavy load conditions, the risk of demagnetization of the motor increases, leading to poor motor performance and inability to work normally. At the same time, the motor flux decreases, reducing efficiency. Summary of the Invention

[0005] The main objective of this invention is to provide a motor rotor and a permanent magnet motor that can improve the demagnetization resistance of the permanent magnet motor and enhance its performance.

[0006] To achieve the above objectives, according to one aspect of the present invention, an electric motor rotor is provided, comprising a rotor core, a plurality of permanent magnet slots being formed on the rotor core, and permanent magnets being disposed within the permanent magnet slots. At one pole, the permanent magnets include a first permanent magnet, a second permanent magnet, a third permanent magnet, and a fourth permanent magnet. The first and third permanent magnets are located on a first side of the d-axis, the second and fourth permanent magnets are located on a second side of the d-axis, the third permanent magnet is located on the side of the first permanent magnet closer to the d-axis, and the fourth permanent magnet is located on the side of the second permanent magnet closer to the d-axis. The magnetic coercivity of the first permanent magnet is less than that of the third permanent magnet, and the magnetic coercivity of the second permanent magnet is less than that of the fourth permanent magnet. In a cross-section perpendicular to the central axis of the rotor core, the length of the first permanent magnet is greater than the length of the third permanent magnet, and the length of the second permanent magnet is greater than the length of the fourth permanent magnet.

[0007] Furthermore, a magnetic bridge is formed between the first end of the third permanent magnet and the outer circle of the rotor, and a predetermined interval is formed between the second end of the third permanent magnet and the d-axis. A magnetic bridge is formed between the first end of the fourth permanent magnet and the outer circle of the rotor, and a predetermined interval is formed between the second end of the fourth permanent magnet and the d-axis. A magnetic bridge is formed between the first end of the first permanent magnet and the outer circle of the rotor, and a magnetic bridge is formed between the first end of the second permanent magnet and the outer circle of the rotor.

[0008] Furthermore, the first permanent magnet is parallel to the third permanent magnet, and the second permanent magnet is parallel to the fourth permanent magnet; and / or, the first and second permanent magnets are symmetrical about the d-axis, and the third and fourth permanent magnets are symmetrical about the d-axis.

[0009] Furthermore, in a cross-section perpendicular to the central axis of the rotor core, the lengths of the first and second permanent magnets are W1, and the lengths of the third and fourth permanent magnets are W2, where 4mm≤5W2≤W1≤21mm.

[0010] Furthermore, the magnetic coercivity of the first permanent magnet is Hc1, the magnetic coercivity of the second permanent magnet is Hc2, the magnetic coercivity of the third permanent magnet is Hc3, and the magnetic coercivity of the fourth permanent magnet is Hc4, with 2.84Hc1≤Hc3≤4.55Hc1 and 2.84Hc2≤Hc4≤4.55Hc2.

[0011] Furthermore, the first permanent magnet and the second permanent magnet form a V-shaped structure, and the included angle of the V-shaped structure is set as A, where 85°≤A≤100°.

[0012] Furthermore, the third permanent magnet has a first magnetic isolation groove at its second end near the d-axis. The first magnetic isolation groove extends from the second end of the third permanent magnet to the outer circle of the rotor and forms a magnetic isolation bridge with the outer circle of the rotor. The fourth permanent magnet has a third magnetic isolation groove at its second end near the d-axis. The third magnetic isolation groove extends from the second end of the fourth permanent magnet to the outer circle of the rotor and forms a magnetic isolation bridge with the outer circle of the rotor.

[0013] Furthermore, a second magnetic isolation groove is provided on the side of the first magnetic isolation groove away from the d-axis. A magnetic isolation bridge is formed between the first end of the second magnetic isolation groove and the third permanent magnet, and a magnetic isolation bridge is formed between the second end and the outer circle of the rotor. A fourth magnetic isolation groove is provided on the side of the third magnetic isolation groove away from the d-axis. A magnetic isolation bridge is formed between the first end of the fourth magnetic isolation groove and the fourth permanent magnet, and a magnetic isolation bridge is formed between the second end and the outer circle of the rotor.

[0014] Furthermore, in a cross-section perpendicular to the central axis of the rotor core, the distance between the first permanent magnet and the third permanent magnet is L1, and the distance between the second magnetic isolation slot and the third permanent magnet is L2, where 3≤L1 / L2≤4.

[0015] Furthermore, in a cross section perpendicular to the central axis of the rotor core, the angle between the side of the first magnetic isolation groove away from the second magnetic isolation groove and the first permanent magnet is C, and the angle between the side of the first magnetic isolation groove near the second magnetic isolation groove and the third permanent magnet is B, where 0.8≤B / C≤1.

[0016] Furthermore, in the cross section perpendicular to the central axis of the rotor core, both the first and second magnetic isolation slots are rectangular slots. The intersection of the extended center line of the first magnetic isolation slot with the d-axis is the first intersection point, and the intersection of the extended center line of the second magnetic isolation slot with the d-axis is the second intersection point. The distance between the first intersection point and the center of the rotor core is H1, and the distance between the second intersection point and the center of the rotor core is H2, where 40mm≤H1≤H2≤46mm.

[0017] Furthermore, in a cross section perpendicular to the central axis of the rotor core, the width of the first magnetic isolation slot near the outer circle of the rotor along the circumferential direction is S1, and the width of the second end of the second magnetic isolation slot along the circumferential direction is S2, where 1.1mm≤S1≤1.25S2≤1.5mm.

[0018] Furthermore, the width of the magnetic bridge between the first and second magnetic isolation slots on the side near the outer circle of the rotor is K, 0.6σ≤K≤0.8σ, where σ is the air gap width of the motor, 0.8mm≤σ≤1.5mm.

[0019] Furthermore, in a cross section perpendicular to the central axis of the rotor core, the first magnetic isolation groove includes a first groove segment and a second groove segment. The first groove segment is provided at the end of the third permanent magnet, and the second groove segment is located on the side of the third permanent magnet close to the d-axis. The width of the first groove segment is smaller than the width of the second groove segment.

[0020] Furthermore, the length of the first slot is L3, the length of the second slot is L4, 3.4σ≤L4≤3.7σ, 2.3L4<L3<2.5L4, where σ is the air gap width of the motor, 0.8mm<σ<1.5mm.

[0021] Furthermore, the first and third magnetic isolation slots are symmetrical about the d-axis, and the second and fourth magnetic isolation slots are symmetrical about the d-axis.

[0022] Furthermore, the corners of the first, second, third, and fourth magnetic isolation grooves are rounded, with a radius of R1, where 0.2mm≤R1≤0.4mm.

[0023] Furthermore, the first, second, third, and fourth permanent magnets are magnetized in the same direction; and / or, in a section perpendicular to the central axis of the rotor core, the width of the first, second, third, and fourth permanent magnets is t, where 2.3 mm ≤ t ≤ 2.5 mm.

[0024] According to another aspect of the present invention, a permanent magnet motor is provided, comprising a motor rotor and a motor stator, wherein the motor rotor is the aforementioned motor rotor, and the motor stator is located on the outer periphery of the motor rotor.

[0025] According to the technical solution of this invention, the motor rotor includes a rotor core, on which a plurality of permanent magnet slots are formed. Permanent magnets are disposed within the slots. Under one pole, the permanent magnets include a first permanent magnet, a second permanent magnet, a third permanent magnet, and a fourth permanent magnet. The first and third permanent magnets are located on the first side of the d-axis, the second and fourth permanent magnets are located on the second side of the d-axis, the third permanent magnet is located on the side of the first permanent magnet closer to the d-axis, and the fourth permanent magnet is located on the side of the second permanent magnet closer to the d-axis. The magnetic coercivity of the first permanent magnet is less than that of the third permanent magnet, and the magnetic coercivity of the second permanent magnet is less than that of the fourth permanent magnet. In a cross-section perpendicular to the central axis of the rotor core, the length of the first permanent magnet is greater than that of the third permanent magnet, and the length of the second permanent magnet is greater than that of the fourth permanent magnet. This permanent magnet motor optimizes the positional relationship and the relationship between the magnetic coercivity of the first, second, third, and fourth permanent magnets. Because the third and fourth permanent magnets are located near the outer end of the rotor and their coercivity is greater than that of the first and second permanent magnets, it reduces the irreversible demagnetization caused by the demagnetizing magnetic field on the first and second permanent magnets, thus improving their resistance to demagnetization. Furthermore, the lengths of the first and second permanent magnets are greater than the lengths of the third and fourth permanent magnets. This design ensures that the first and second permanent magnets effectively protect the third and fourth permanent magnets, guaranteeing the magnetomotive force output of the magnets and preventing the first and second permanent magnets from demagnetizing due to demagnetizing magnetic fields. It also controls the cost of the magnet materials. Through this structural design, the demagnetizing resistance of the first and second permanent magnets can be increased, the demagnetizing magnetic field component of the armature magnetic field in the magnetization direction of the third and fourth permanent magnets can be reduced, the demagnetizing resistance of the third and fourth permanent magnets can be improved, and the motor efficiency and performance can be enhanced. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 A schematic diagram of the motor rotor according to an embodiment of the present invention is shown;

[0028] Figure 2 A dimensional structural diagram of the motor rotor according to an embodiment of the present invention is shown;

[0029] Figure 3A schematic diagram of the magnetization of a motor rotor according to an embodiment of the present invention is shown;

[0030] Figure 4 A schematic diagram of the structure of a permanent magnet motor according to an embodiment of the present invention is shown;

[0031] Figure 5 A schematic diagram of the demagnetization state of a permanent magnet motor according to an embodiment of the present invention is shown; and

[0032] Figure 6 A schematic diagram showing the current required for demagnetizing a permanent magnet motor according to an embodiment of the present invention is provided.

[0033] The above figures include the following reference numerals:

[0034] 1. Rotor core; 2. Permanent magnet slot; 3. First permanent magnet; 4. Second permanent magnet; 5. Third permanent magnet; 6. Fourth permanent magnet; 7. Magnetic isolation bridge; 8. First magnetic isolation slot; 9. Second magnetic isolation slot; 10. Third magnetic isolation slot; 11. Fourth magnetic isolation slot; 12. First slot segment; 13. Second slot segment; 14. Motor stator. Detailed Implementation

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] See also Figures 1 to 6 As shown, according to an embodiment of the present invention, the motor rotor includes a rotor core 1, on which a plurality of permanent magnet slots 2 are formed. Permanent magnets are disposed in the permanent magnet slots 2. Under one pole, the permanent magnets include a first permanent magnet 3, a second permanent magnet 4, a third permanent magnet 5, and a fourth permanent magnet 6. The first permanent magnet 3 and the third permanent magnet 5 are located on the first side of the d-axis, and the second permanent magnet 4 and the fourth permanent magnet 6 are located on the second side of the d-axis. The third permanent magnet 5 is located on the side of the first permanent magnet 3 closer to the d-axis, and the fourth permanent magnet 6 is located on the side of the second permanent magnet 4 closer to the d-axis. The magnetic coercivity of the first permanent magnet 3 is less than that of the third permanent magnet 5, and the magnetic coercivity of the second permanent magnet 4 is less than that of the fourth permanent magnet 6. In a cross section perpendicular to the central axis of the rotor core 1, the length of the first permanent magnet 3 is greater than that of the third permanent magnet 5, and the length of the second permanent magnet 4 is greater than that of the fourth permanent magnet 6.

[0037] This permanent magnet motor optimizes the positional relationship and the relationship between the magnetic coercivity of the first permanent magnet 3, the second permanent magnet 4, the third permanent magnet 5, and the fourth permanent magnet 6. Because the third permanent magnet 5 and the fourth permanent magnet 6 are located near the outer end of the rotor and their coercivity is greater than that of the first permanent magnet 3 and the second permanent magnet 4, the irreversible demagnetization phenomenon caused by the demagnetizing magnetic field on the first permanent magnet 3 and the second permanent magnet 4 can be reduced, thus improving their anti-demagnetization capability. Furthermore, the lengths of the first permanent magnet 3 and the second permanent magnet 4 are greater than the lengths of the third permanent magnet 5 and the fourth permanent magnet 6. The design ensures that the protective effect of the first permanent magnet 3 and the second permanent magnet 4 on the third permanent magnet 5 and the fourth permanent magnet 6 is effectively implemented, guarantees the magnetomotive force output of the magnets, prevents the first permanent magnet 3 and the second permanent magnet 4 from being demagnetized by the demagnetizing magnetic field, and controls the cost of the magnet material. Through the above structural design, the demagnetizing resistance of the first permanent magnet 3 and the second permanent magnet 4 can be increased, the demagnetizing magnetic field component of the armature magnetic field in the magnetization direction of the third permanent magnet 5 and the fourth permanent magnet 6 can be reduced, the demagnetizing resistance of the third permanent magnet 5 and the fourth permanent magnet 6 can be improved, the motor efficiency can be increased, and the motor performance can be improved.

[0038] In this embodiment, the positional relationship of the first permanent magnet 3, the second permanent magnet 4, the third permanent magnet 5, and the fourth permanent magnet 6, as well as the relationship between their magnetic coercivity, are defined simultaneously. This allows them to interact with each other, which can improve the anti-demagnetization performance of the permanent magnets from the perspective of their coercivity, and also change the strength of the demagnetizing magnetic field by utilizing the relationship between their lengths, thereby improving the anti-demagnetization ability of the permanent magnets. As a result, the anti-demagnetization ability of the permanent magnets is greatly improved in terms of overall performance.

[0039] This design, by using permanent magnets with varying magnetic coercivity, effectively addresses the operational requirements of motors at different temperatures. Particularly in high-temperature environments, it significantly improves the motor's magnetic stability and reduces the risk of permanent magnet demagnetization. It is suitable for applications such as electric vehicles and industrial equipment requiring stable operation at high temperatures. Implementation results demonstrate that this design effectively enhances the motor's magnetic properties and thermal stability, greatly reducing the risk of demagnetization at high temperatures, thereby improving the motor's overall operating efficiency and reliability.

[0040] In response to the market demand for high power density motors, the permanent magnets of this motor rotor operate at a lower point. Under heavy load conditions, motors are at risk of demagnetization. The motor rotor can disperse the demagnetizing effect of the armature magnetic field on the first and second permanent magnets, thereby improving the overall demagnetization resistance of the motor. Without increasing the cost of the motor, it can improve the power factor, increase the output torque, reduce the operating current, reduce copper losses, and improve the efficiency of the motor.

[0041] The application scenarios for this motor rotor include, but are not limited to, drive motors for electric vehicles, high-load motors in industrial production equipment, and special motor devices that need to maintain stable operation in high-temperature environments.

[0042] In one embodiment, a magnetic bridge 7 is formed between the first end of the third permanent magnet 5 and the outer circle of the rotor, and a predetermined interval is formed between the second end of the third permanent magnet 5 and the d-axis. A magnetic bridge 7 is formed between the first end of the fourth permanent magnet 6 and the outer circle of the rotor, and a predetermined interval is formed between the second end of the fourth permanent magnet 6 and the d-axis. A magnetic bridge 7 is formed between the first end of the first permanent magnet 3 and the outer circle of the rotor, and a magnetic bridge 7 is formed between the first end of the second permanent magnet 4 and the outer circle of the rotor.

[0043] The design of the magnetic bridge 7 effectively reduces magnetic flux leakage and optimizes the magnetic field distribution, thereby improving the efficiency and power density of the motor. It is particularly suitable for electric vehicle drive motors that require high efficiency and high power density. In practical applications, the magnetic bridge 7 design not only reduces unnecessary magnetic flux loss but also significantly improves the motor's magnetic efficiency by optimizing the internal magnetic flux path. This reduces motor losses and temperature rise, allowing the motor to maintain a lower temperature under high load operation and extending its service life.

[0044] Furthermore, through the aforementioned limitations, the third permanent magnet 5 is positioned on the side of the region enclosed by the first permanent magnet 3 and the outer circle of the rotor, close to the outer circle of the rotor and far from the d-axis. The fourth permanent magnet 6 is positioned on the side of the region enclosed by the second permanent magnet 4 and the outer circle of the rotor, close to the outer circle of the rotor and far from the d-axis. This allows sufficient magnetic conduction channels to be left between the third permanent magnet 5 and the fourth permanent magnet 6, enabling the magnetic circuits of the first permanent magnet 3 and the second permanent magnet 4 to pass smoothly through the magnetic conduction channels between the third permanent magnet 5 and the fourth permanent magnet 6. This improves the magnetic circuit conduction effect and enhances the magnetic performance of the motor.

[0045] In one embodiment, the first permanent magnet 3 is parallel to the third permanent magnet 5, and the second permanent magnet 4 is parallel to the fourth permanent magnet 6. Along the q-axis to the d-axis, the third permanent magnet 5 is located outside and parallel to the first permanent magnet 3. The first permanent magnet 3 is closer to the stator reverse magnetic field. Therefore, placing the third permanent magnet 5 outside the first permanent magnet 3 can reduce the demagnetization phenomenon of the first permanent magnet 3 near the center surface region of the air gap side. The fourth permanent magnet 6 is located outside and parallel to the second permanent magnet 4. The second permanent magnet 4 is closer to the stator reverse magnetic field. Therefore, placing the fourth permanent magnet 6 outside the second permanent magnet 4 can reduce the demagnetization phenomenon of the second permanent magnet 4 near the center surface region of the air gap side. Through the above arrangement, the demagnetization resistance of the first permanent magnet 3 and the second permanent magnet 4 can be increased, the demagnetization magnetic field component of the armature magnetic field in the magnetization direction of the third permanent magnet 5 and the fourth permanent magnet 6 can be reduced, the demagnetization resistance of the third permanent magnet 5 and the fourth permanent magnet 6 can be improved, and the motor efficiency can be increased.

[0046] The first permanent magnet 3 and the second permanent magnet 4 are symmetrical about the d-axis, as are the third permanent magnet 5 and the fourth permanent magnet 6. This symmetrical design improves the demagnetization consistency of the third permanent magnet 5 and the fourth permanent magnet 6, enhances the motor's resistance to demagnetization, ensures the motor's balance during operation, reduces vibration and noise, and improves the motor's operating quality. It is suitable for precision equipment and household appliances with high requirements for vibration and noise control. Through this symmetrical permanent magnet layout, the motor can maintain good balance characteristics during high-speed rotation, effectively suppressing vibration and noise generation, and improving the motor's comfort and reliability. It is particularly suitable for precision equipment and household appliances, such as high-end washing machines, air conditioner compressors, and precision measuring instruments, which have strict requirements for low vibration and low noise during operation.

[0047] In one embodiment, in a cross section perpendicular to the central axis of the rotor core 1, the lengths of the first permanent magnet 3 and the second permanent magnet 4 are W1, and the lengths of the third permanent magnet 5 and the fourth permanent magnet 6 are W2, where 4mm≤5W2≤W1≤21mm.

[0048] By limiting the length relationship and length range of the first permanent magnet 3, the second permanent magnet 4, the third permanent magnet 5, and the fourth permanent magnet 6, the length settings of the first permanent magnet 3, the second permanent magnet 4, the third permanent magnet 5, and the fourth permanent magnet 6 can be kept within an optimal range. This more effectively ensures that the protective effect of the first permanent magnet 3 and the second permanent magnet 4 on the third permanent magnet 5 and the fourth permanent magnet 6 can be effectively implemented, guarantees the magnetomotive force output of the magnets, prevents the first permanent magnet 3 and the second permanent magnet 4 from being demagnetized by the demagnetizing magnetic field, and controls the cost of the magnetic steel material.

[0049] In one embodiment, the magnetic coercivity of the first permanent magnet 3 is Hc1, the magnetic coercivity of the second permanent magnet 4 is Hc2, the magnetic coercivity of the third permanent magnet 5 is Hc3, and the magnetic coercivity of the fourth permanent magnet 6 is Hc4, where 2.84Hc1≤Hc3≤4.55Hc1 and 2.84Hc2≤Hc4≤4.55Hc2.

[0050] By reasonably defining the relationship between the magnetic induction coercivity of the first permanent magnet 3 and the third permanent magnet 5, as well as the relationship between the second permanent magnet 4 and the fourth permanent magnet 6, the irreversible demagnetization phenomenon caused by the demagnetizing magnetic field on the first permanent magnet 3 and the second permanent magnet 4 can be reduced more effectively, thereby improving the demagnetization resistance of the first permanent magnet 3 and the second permanent magnet 4.

[0051] See also Figure 5As shown, when the ratio of the magnetic coercivity of the third permanent magnet 5 to that of the first permanent magnet 3 and the ratio of the magnetic coercivity of the fourth permanent magnet 6 to that of the second permanent magnet 4 are limited to the above range, the demagnetizing current consumed by the permanent magnets can be larger, and the demagnetizing resistance can be better.

[0052] By rationally distributing the magnetic coercivity of permanent magnets, it is possible to reduce the dependence on permanent magnets with high magnetic coercivity while ensuring the magnetic performance of the motor, thereby reducing the manufacturing cost of the motor. This is particularly suitable for cost-sensitive industrial motors and household appliance motors.

[0053] In one embodiment, the first permanent magnet 3 and the second permanent magnet 4 form a V-shaped structure, and the included angle of the V-shaped structure is set as A, where 85°≤A≤100°.

[0054] This design can reduce the demagnetization problem of the surface areas of the first permanent magnet 3 and the second permanent magnet 4 near the rotor center, making the demagnetization area of ​​the permanent magnet farther away from the reverse magnetic field of the stator, and mitigating the effect of the reverse demagnetization magnetic field on the demagnetization area.

[0055] The V-shaped permanent magnet design optimizes the magnetic field distribution inside the motor, providing a more uniform magnetic field. This results in a more uniform and stable magnetic field during operation, significantly improving the motor's magnetic performance and reducing fluctuations during operation. This design not only enhances motor efficiency but also extends its lifespan, providing strong technical support for the development of precision instruments and high-end electric vehicles.

[0056] In one embodiment, the third permanent magnet 5 has a first magnetic isolation groove 8 at its second end near the d-axis. The first magnetic isolation groove 8 extends from the second end of the third permanent magnet 5 to the outer circle of the rotor, forming a magnetic isolation bridge 7 between it and the outer circle of the rotor. The fourth permanent magnet 6 has a third magnetic isolation groove 10 at its second end near the d-axis. The third magnetic isolation groove 10 extends from the second end of the fourth permanent magnet 6 to the outer circle of the rotor, forming a magnetic isolation bridge 7 between it and the outer circle of the rotor. The permanent magnet motor can guide the direction of the magnetic field through the first magnetic isolation groove 8 connected to the third permanent magnet 5 and the third magnetic isolation groove 10 connected to the fourth permanent magnet 6, thereby reducing the risk of demagnetization of the first permanent magnet 3 and the second permanent magnet 4 by guiding the direction of the magnetic circuit.

[0057] There is a magnetic steel gap between the third permanent magnet 5 and the permanent magnet slot 2. The magnetic steel gap is connected to the first magnetic isolation slot 8 and extends away from the third permanent magnet 5. Through this design, the magnetic field direction can be guided by the first magnetic isolation slot 8, thereby reducing the influence of the third permanent magnet 5 with higher magnetic coercivity on the first permanent magnet 3 with lower magnetic coercivity and optimizing motor noise. The design of the fourth permanent magnet 6 and the third magnetic isolation slot 10 is the same and has the same effect.

[0058] The magnetic isolation slot and magnetic isolation bridge 7 can precisely control the magnetic flux path inside the motor, reduce magnetic flux leakage, improve the magnetic performance and operating efficiency of the motor, effectively prevent unnecessary leakage of magnetic flux, reduce the energy consumption of the motor, and improve the reliability and service life of the motor.

[0059] In one embodiment, a second magnetic isolation groove 9 is provided on the side of the first magnetic isolation groove 8 away from the d-axis. A magnetic isolation bridge 7 is formed between the first end of the second magnetic isolation groove 9 and the third permanent magnet 5, and a magnetic isolation bridge 7 is formed between the second end and the outer circle of the rotor. A fourth magnetic isolation groove 11 is provided on the side of the third magnetic isolation groove 10 away from the d-axis. A magnetic isolation bridge 7 is formed between the first end of the fourth magnetic isolation groove 11 and the fourth permanent magnet 6, and a magnetic isolation bridge 7 is formed between the second end and the outer circle of the rotor.

[0060] The motor rotor can effectively increase the protection of the first permanent magnet 3 and the second permanent magnet 4 through the first magnetic isolation slot 8 and the second magnetic isolation slot 9, and reduce the influence of the first permanent magnet 3 and the second permanent magnet 4 on the third and fourth permanent magnets. The simultaneous setting of the first magnetic isolation slot 8 and the second magnetic isolation slot 9 can improve the direction of the guiding magnetic field, solve the problem of easy demagnetization of permanent magnets near the air gap end, optimize the air gap magnetic field of the motor, make the sinusoidal degree of the air gap magnetic flux density curve higher, reduce the motor operating current, improve the demagnetization resistance of the permanent magnet motor, reduce copper loss, and improve motor efficiency.

[0061] The multi-slot design further optimizes the magnetic field distribution, reduces magnetic flux leakage, and improves the motor's magnetic properties and operating efficiency. Through this multi-slot design, the motor can maintain a more stable and efficient operating state under extreme temperature conditions, effectively reducing magnetic flux leakage, optimizing the magnetic field distribution, significantly improving the motor's magnetic properties and operating efficiency, and ensuring the motor's reliability and performance in harsh environments.

[0062] In one embodiment, in a cross section perpendicular to the central axis of the rotor core 1, the distance between the first permanent magnet 3 and the third permanent magnet 5 is L1, and the distance between the second magnetic isolation groove 9 and the third permanent magnet 5 is L2, where 3≤L1 / L2≤4.

[0063] L1 and L2 are related and can improve the mechanical strength of the rotor laminations, optimize the distribution of the rotor magnetic field, and improve the electromagnetic torque of the motor. If the ratio of L1 to L2 is too small, it will increase eddy current losses. Eddy currents will cause the magnets to heat up, and high temperature will cause the permanent magnets to demagnetize. Eddy current losses will also lead to a deterioration in motor performance. If the ratio is too large, the utilization rate of the permanent magnets will be reduced, making it difficult to meet the motor performance requirements. Setting this size can also ensure that there is a sufficiently large air gap magnetic field in the motor air gap to meet the motor performance indicators, and increase the shunting effect of armature reaction, thereby increasing the overall demagnetization resistance of the motor.

[0064] By controlling the distance between the permanent magnet and the magnetically shielding slot, the magnetic properties of the motor can be optimized, the mechanical strength of the rotor laminations can be improved, the distribution of the rotor magnetic field can be optimized, the electromagnetic torque of the motor can be increased, and the efficiency and power density of the motor can be improved. This is particularly suitable for electric vehicle drive motors and industrial equipment motors that require high efficiency and high power density. In practical applications, by precisely controlling the ratio of L1 to L2, the magnetic properties of the motor can be effectively optimized, and the unnecessary loss of magnetic flux can be reduced, thereby improving the efficiency and power density of the motor.

[0065] In one embodiment, in a cross section perpendicular to the central axis of the rotor core 1, the width of the first magnetic isolation groove 8 near the outer circle of the rotor along the circumferential direction is S1, and the width of the second end of the second magnetic isolation groove 9 along the circumferential direction is S2, where 1.1mm≤S1≤1.25S2≤1.5mm.

[0066] When the motor operates at high speed, the magnetic isolation bridge 7 of the rotor is subjected to large forces. The narrow magnetic isolation bridge 7 is difficult to meet the rotor structural strength requirements at high speed. This design can improve the rotor structural strength while reducing leakage flux.

[0067] By controlling the width of the magnetic isolation slots, the magnetic field distribution can be further optimized, magnetic flux leakage can be reduced, and the magnetic performance and operating efficiency of the motor can be improved. This is particularly suitable for electric vehicles and industrial equipment motors that require high magnetic performance and high efficiency. By controlling the widths of S1 and S2, the magnetic field distribution of the motor can be precisely optimized, reducing unnecessary loss of magnetic flux, thereby significantly improving the magnetic performance and operating efficiency of the motor.

[0068] In one embodiment, in a cross section perpendicular to the central axis of the rotor core 1, both the first magnetic isolation slot 8 and the second magnetic isolation slot 9 are rectangular slots. The intersection of the extended center line of the first magnetic isolation slot 8 with the d-axis is the first intersection point, and the intersection of the extended center line of the second magnetic isolation slot 9 with the d-axis is the second intersection point. The distance between the first intersection point and the center of the rotor core 1 is H1, and the distance between the second intersection point and the center of the rotor core 1 is H2, where 40mm≤H1≤H2≤46mm.

[0069] By limiting the positions of the first magnetic isolation groove 8 and the second magnetic isolation groove 9, the direction of the magnetic field can be effectively guided, the air gap magnetic flux waveform can be improved, magnetic flux leakage can be reduced, and the magnetic performance and operating efficiency of the motor can be improved.

[0070] In one embodiment, the width of the magnetic bridge 7 on the side near the outer circumference of the rotor between the first magnetic isolation slot 8 and the second magnetic isolation slot 9 is K, where 0.6σ≤K≤0.8σ, and σ is the air gap width of the motor, 0.8mm≤σ≤1.5mm. The width design of the magnetic bridge 7 can effectively improve the mechanical strength of the rotor laminations, optimize the rotor magnetic field distribution, and improve the magnetic performance and operating efficiency of the motor.

[0071] In one embodiment, the first magnetic isolation groove 8 includes a first groove segment 12 and a second groove segment 13. The first groove segment 12 is disposed at the end of the third permanent magnet 5, and the second groove segment 13 is located on the side of the third permanent magnet 5 near the d-axis. The width of the first groove segment 12 is smaller than the width of the second groove segment 13. This design can effectively control the magnetic flux path, reduce magnetic flux leakage, improve the magnetic performance and operating efficiency of the motor, and reduce the cost of using permanent magnets.

[0072] In one embodiment, the length of the first slot segment 12 is L3, the length of the second slot segment 13 is L4, 3.4σ≤L4≤3.7σ, 2.3L4<L3<2.5L4, where σ is the air gap width of the motor, 0.8mm<σ<1.5mm. These limitations ensure that the magnetic reluctance of the first magnetic isolation slot 8 is greater than the air gap magnetic reluctance, reducing magnetic leakage and ensuring excellent motor performance.

[0073] In one embodiment, in a cross section perpendicular to the central axis of the rotor core 1, the angle between the side of the first magnetic isolation groove 8 away from the second magnetic isolation groove 9 and the first permanent magnet 3 is C, and the angle between the side of the first magnetic isolation groove 8 near the second magnetic isolation groove 9 and the third permanent magnet 5 is B, where 0.8≤B / C≤1.

[0074] This design can improve the demagnetization and leakage of magnets in motors, reduce leakage between permanent magnets, reduce leakage of permanent magnets themselves, improve magnet utilization, and increase the power factor of the motor.

[0075] In one embodiment, the first magnetic isolation slot 8 and the third magnetic isolation slot 10 are symmetrical about the d-axis, and the second magnetic isolation slot 9 and the fourth magnetic isolation slot 11 are symmetrical about the d-axis. The symmetrical magnetic isolation slot design can ensure the balance of the motor during operation, improve the symmetry of the permanent magnet motor rotor, reduce torque pulsation, reduce back EMF harmonics, reduce motor noise level, and improve the operating quality of the motor.

[0076] In the above embodiments, the first magnetic isolation groove 8 and the third magnetic isolation groove 10 have the same structure and are symmetrical about the d-axis. The second magnetic isolation groove 9 and the fourth magnetic isolation groove 11 have the same structure and are symmetrical about the d-axis. Therefore, in the above embodiments, the structural design of the first magnetic isolation groove 8 can also be applied to the third magnetic isolation groove 10, and the structural design of the second magnetic isolation groove 9 can also be applied to the fourth magnetic isolation groove 11.

[0077] In one embodiment, the corners of the first magnetic isolation groove 8, the second magnetic isolation groove 9, the third magnetic isolation groove 10, and the fourth magnetic isolation groove 11 are rounded, with a radius of R1 of 0.2mm ≤ R1 ≤ 0.4mm. The rounded corner design can reduce stress concentration, reduce the magnetic focusing effect at each corner of the magnetic groove, reduce the harmonic content of the air gap magnetic flux density, and improve the structural stability of the permanent magnet and the magnetic isolation groove.

[0078] In one embodiment, the first permanent magnet 3, the second permanent magnet 4, the third permanent magnet 5, and the fourth permanent magnet 6 are magnetized in the same direction. This consistency in magnetization direction and optimization of the permanent magnet width provide a more uniform magnetic field distribution, improving the motor's magnetic performance and operating efficiency. This structural design further increases the magnetic flux of each pole, enhances the motor's flux linkage, and further improves the motor's output torque and power, which is beneficial for increasing the motor's reluctance torque and field weakening speed range.

[0079] Within a cross-section perpendicular to the central axis of the rotor core 1, the widths of the first permanent magnet 3, the second permanent magnet 4, the third permanent magnet 5, and the fourth permanent magnet 6 are t, where 2.3mm ≤ t ≤ 2.5mm. By limiting the width of each permanent magnet, the processing difficulty of the permanent magnets can be reduced, the processing cost can be reduced, the overall cost of the motor can be reduced, and the magnetic lines of force of the magnets can be fully transmitted through the air gap to reach the stator teeth, forming a linkage with the coil. This is beneficial for increasing the reluctance torque of the motor and improving the power density of the motor.

[0080] By optimizing the magnetization direction and the width of the permanent magnet, the magnetic field distribution inside the motor can be significantly improved, providing a more uniform and stable magnetic field, thereby significantly improving the magnetic performance and operating efficiency of the motor.

[0081] See also Figure 6 The current required for demagnetizing the permanent magnet motor in this embodiment of the invention is increased by 20% compared to the current required for demagnetizing the permanent magnet motor in related technologies, thus significantly improving the anti-demagnetization performance of the permanent magnet motor.

[0082] See also Figure 4 As shown, according to an embodiment of the present invention, the permanent magnet motor includes a motor rotor and a motor stator 14. The motor rotor is the aforementioned motor rotor, and the motor stator 14 is located on the outer periphery of the motor rotor. This motor has the advantages of high anti-demagnetization capability, high motor torque density, and high motor efficiency.

[0083] By employing the aforementioned optimized rotor design, permanent magnet motors can significantly improve their overall performance and reliability. They are particularly suitable for electric vehicle drive systems, precision instruments, and industrial equipment requiring high power density, high efficiency, and high reliability, offering significant economic benefits and application value. This design can meet the future demands of electric vehicles and industrial automation for high-efficiency, high-power-density motors. In practical applications, this optimized permanent magnet motor design can significantly improve the overall performance of electric vehicle drive systems and enhance the operating efficiency and reliability of precision instruments and industrial equipment. It not only reduces energy consumption and improves energy efficiency but also provides strong technical support for future electric vehicles and industrial automation, demonstrating significant economic benefits and broad application prospects. This design can effectively promote technological progress and development in the fields of electric vehicles and industrial automation.

[0084] In summary, the motor rotor and permanent magnet motor of this application, through a series of optimized designs, including the use of permanent magnets with different magnetic coercivity and length, as well as the ingenious design of the magnetic isolation bridge 7 and magnetic isolation slot, not only improve the magnetic performance and operating efficiency of the motor, but also reduce the cost of using permanent magnets, and enhance the stability and reliability of the motor under extreme conditions. This provides a more efficient, stable and reliable power solution for electric vehicles, precision instruments and industrial equipment, with significant economic benefits and broad application prospects, and can effectively promote technological progress and development in related fields.

[0085] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0086] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0087] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A motor rotor, characterized in that, The system includes a rotor core (1), on which multiple permanent magnet slots (2) are formed. Permanent magnets are disposed within the slots (2). At one pole, the permanent magnets include a first permanent magnet (3), a second permanent magnet (4), a third permanent magnet (5), and a fourth permanent magnet (6). The first permanent magnet (3) and the third permanent magnet (5) are located on the first side of the d-axis, the second permanent magnet (4) and the fourth permanent magnet (6) are located on the second side of the d-axis, and the third permanent magnet (5) is located near the first permanent magnet (3) on the d-axis. On the side, the fourth permanent magnet (6) is located on the side of the second permanent magnet (4) close to the d-axis. The magnetic coercivity of the first permanent magnet (3) is less than that of the third permanent magnet (5), and the magnetic coercivity of the second permanent magnet (4) is less than that of the fourth permanent magnet (6). In the cross section perpendicular to the central axis of the rotor core (1), the length of the first permanent magnet (3) is greater than that of the third permanent magnet (5), and the length of the second permanent magnet (4) is greater than that of the fourth permanent magnet (6). The third permanent magnet (5) has a first magnetic isolation groove (8) at its second end near the d-axis. The first magnetic isolation groove (8) extends from the second end of the third permanent magnet (5) to the outer circle of the rotor and forms a magnetic isolation bridge (7) with the outer circle of the rotor. The fourth permanent magnet (6) has a third magnetic isolation groove (10) at its second end near the d-axis. The third magnetic isolation groove (10) extends from the second end of the fourth permanent magnet (6) to the outer circle of the rotor and forms a magnetic isolation bridge (7) with the outer circle of the rotor. A second magnetic isolation groove (9) is provided on the side of the first magnetic isolation groove (8) away from the d-axis. A magnetic isolation bridge (7) is formed between the first end of the second magnetic isolation groove (9) and the third permanent magnet (5), and a magnetic isolation bridge (7) is formed between the second end and the outer circle of the rotor. A fourth magnetic isolation groove (11) is provided on the side of the third magnetic isolation groove (10) away from the d-axis. A magnetic isolation bridge (7) is formed between the first end of the fourth magnetic isolation groove (11) and the fourth permanent magnet (6), and a magnetic isolation bridge (7) is formed between the second end and the outer circle of the rotor.

2. The motor rotor according to claim 1, characterized in that, A magnetic bridge (7) is formed between the first end of the third permanent magnet (5) and the outer circle of the rotor. A preset interval is formed between the second end of the third permanent magnet (5) and the d-axis. A magnetic bridge (7) is formed between the first end of the fourth permanent magnet (6) and the outer circle of the rotor. A preset interval is formed between the second end of the fourth permanent magnet (6) and the d-axis. A magnetic bridge (7) is formed between the first end of the first permanent magnet (3) and the outer circle of the rotor. A magnetic bridge (7) is formed between the first end of the second permanent magnet (4) and the outer circle of the rotor.

3. The motor rotor according to claim 1, characterized in that, The first permanent magnet (3) is parallel to the third permanent magnet (5), and the second permanent magnet (4) is parallel to the fourth permanent magnet (6); and / or, the first permanent magnet (3) and the second permanent magnet (4) are symmetrical about the d-axis, and the third permanent magnet (5) and the fourth permanent magnet (6) are symmetrical about the d-axis.

4. The motor rotor according to any one of claims 1 to 3, characterized in that, In a cross section perpendicular to the central axis of the rotor core (1), the lengths of the first permanent magnet (3) and the second permanent magnet (4) are W1, and the lengths of the third permanent magnet (5) and the fourth permanent magnet (6) are W2, with 4mm≤5W2≤W1≤21mm.

5. The motor rotor according to any one of claims 1 to 3, characterized in that, The magnetic coercivity of the first permanent magnet (3) is Hc1, the magnetic coercivity of the second permanent magnet (4) is Hc2, the magnetic coercivity of the third permanent magnet (5) is Hc3, and the magnetic coercivity of the fourth permanent magnet (6) is Hc4. 2.84Hc1≤Hc3≤4.55Hc1, 2.84Hc2≤Hc4≤4.55Hc2.

6. The motor rotor according to any one of claims 1 to 3, characterized in that, The first permanent magnet (3) and the second permanent magnet (4) form a V-shaped structure, and the included angle of the V-shaped structure is set as A, where 85°≤A≤100°.

7. The motor rotor according to claim 1, characterized in that, In a cross section perpendicular to the central axis of the rotor core (1), the distance between the first permanent magnet (3) and the third permanent magnet (5) is L1, and the distance between the second magnetic isolation groove (9) and the third permanent magnet (5) is L2, 3≤L1 / L2≤4.

8. The motor rotor according to claim 1, characterized in that, In a cross section perpendicular to the central axis of the rotor core (1), the angle between the side of the first magnetic isolation groove (8) away from the second magnetic isolation groove (9) and the first permanent magnet (3) is C, and the angle between the side of the first magnetic isolation groove (8) near the second magnetic isolation groove (9) and the third permanent magnet (5) is B, 0.8≤B / C≤1.

9. The motor rotor according to claim 1, characterized in that, In a cross section perpendicular to the central axis of the rotor core (1), both the first magnetic isolation groove (8) and the second magnetic isolation groove (9) are rectangular grooves. The intersection of the extension of the center line of the first magnetic isolation groove (8) with the d-axis is the first intersection point, and the intersection of the extension of the center line of the second magnetic isolation groove (9) with the d-axis is the second intersection point. The distance between the first intersection point and the center of the rotor core (1) is H1, and the distance between the second intersection point and the center of the rotor core (1) is H2. 40mm≤H1≤H2≤46mm.

10. The motor rotor according to claim 1, characterized in that, In a cross section perpendicular to the central axis of the rotor core (1), the width of the first magnetic isolation groove (8) near the outer circle of the rotor along the circumferential direction is S1, and the width of the second end of the second magnetic isolation groove (9) along the circumferential direction is S2, 1.1mm≤S1≤1.25S2≤1.5mm.

11. The motor rotor according to claim 1, characterized in that, The width of the magnetic bridge (7) of the first magnetic isolation groove (8) and the second magnetic isolation groove (9) on the side near the outer circle of the rotor is K, 0.6σ≤K≤0.8σ, where σ is the air gap width of the motor, 0.8mm≤σ≤1.5mm.

12. The motor rotor according to claim 1, characterized in that, In a cross section perpendicular to the central axis of the rotor core (1), the first magnetic isolation groove (8) includes a first groove segment (12) and a second groove segment (13). The first groove segment (12) is disposed at the end of the third permanent magnet (5), and the second groove segment (13) is located on the side of the third permanent magnet (5) near the d-axis. The width of the first groove segment (12) is smaller than the width of the second groove segment (13).

13. The motor rotor according to claim 12, characterized in that, The length of the first slot segment (12) is L3, and the length of the second slot segment (13) is L4. 3.4σ≤L4≤3.7σ, 2.3L4<L3<2.5L4, where σ is the air gap width of the motor, 0.8mm<σ<1.5mm.

14. The motor rotor according to any one of claims 8 to 11, characterized in that, The first magnetic isolation groove (8) and the third magnetic isolation groove (10) are symmetrical about the d-axis, and the second magnetic isolation groove (9) and the fourth magnetic isolation groove (11) are symmetrical about the d-axis.

15. The motor rotor according to claim 8, characterized in that, The corners of the first magnetic isolation groove (8), the second magnetic isolation groove (9), the third magnetic isolation groove (10) and the fourth magnetic isolation groove (11) are rounded with a radius of R1, 0.2mm≤R1≤0.4mm.

16. The motor rotor according to any one of claims 1 to 3, characterized in that, The first permanent magnet (3), the second permanent magnet (4), the third permanent magnet (5) and the fourth permanent magnet (6) are magnetized in the same direction; and / or, in a cross section perpendicular to the central axis of the rotor core (1), the width of the first permanent magnet (3), the second permanent magnet (4), the third permanent magnet (5) and the fourth permanent magnet (6) is t, 2.3mm≤t≤2.5mm.

17. A permanent magnet motor, comprising a motor rotor and a motor stator (14), characterized in that, The motor rotor is the motor rotor according to any one of claims 1 to 16, and the motor stator (14) is located on the outer periphery of the motor rotor.

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