Rotor of permanent magnet motor

Abstract

The invention provides a rotor of a permanent magnet motor, which comprises at least one first section (10) and at least one second section (20) which are stacked in the axial direction, the first section (10) comprises a first iron core (11) and a plurality of radial flux permanent magnet groups (12), an equivalent magnetic field formed by each radial flux permanent magnet group (12) faces the radial inner side or the radial outer side in the first iron core (11), and the equivalent magnetic field formed by each radial flux permanent magnet group (12) faces the radial outer side in the first iron core (11). The second section (20) comprises a second iron core (21) and a plurality of tangential magnetic flux permanent magnets (22). The magnetizing directions of the tangential magnetic flux permanent magnets (22) are in the second iron core (21), and the N pole of the first section (10) and the N pole and the S pole of the second section (20) which are adjacent in the tangential direction and the axial direction are respectively aligned in the circumferential direction. According to the rotor, the usage amount of the rare earth permanent magnet material is small, the NVH performance is good, and the efficiency is high.

Description

Technical Field

[0001] The present invention relates to the field of motors, and more particularly to a rotor of a permanent magnet motor. Background Art

[0002] Taking permanent magnet motors used in electric vehicles as an example, with the increasing demand for various vehicle performance, the role of permanent magnet motors has become increasingly prominent. Among them, how to reduce the amount of rare earth in permanent magnets in motors and improve the NVH indicators of motors have become the current research hotspots. Summary of the invention

[0003] The purpose of the present invention is to overcome or at least alleviate the deficiencies of the above-mentioned prior art and to provide a rotor for a permanent magnet motor with a small amount of rare earth permanent magnet material, good NVH performance and high efficiency.

[0004] The present invention provides a rotor of a permanent magnet motor, comprising at least one first section and at least one second section stacked in the axial direction. The first section includes a first iron core and a plurality of radial flux permanent magnet groups, wherein the equivalent magnetic field formed by each radial flux permanent magnet group is directed radially inward or radially outward in the first iron core, and the equivalent magnetic fields of two circumferentially adjacent radial flux permanent magnet groups are directed in opposite directions. The second section includes a second core and a plurality of tangential flux permanent magnets, the number of the tangential flux permanent magnets is equal to the number of the radial flux permanent magnet groups, the magnetization direction of the tangential flux permanent magnets is tangential in the second core, and the magnetization directions of two tangential flux permanent magnets adjacent to each other in the circumferential direction are opposite, The N poles of the first segments adjacent to each other in the axial direction are aligned with the N poles of the second segments in the circumferential direction, and the S poles of the first segments adjacent to each other in the axial direction are aligned with the S poles of the second segments in the circumferential direction.

[0005] In at least one embodiment, there are at least two second sections, the first section is disposed at an axial middle position of the rotor, and the two second sections are respectively disposed on two axial sides of an integral component formed by the first section.

[0006] In at least one embodiment, the rotor further comprises a pin, The second core is formed with a plurality of second pin holes, and the second pin holes are distributed between adjacent radial flux permanent magnet groups. The pin passes through the second pin hole.

[0007] In at least one embodiment, the first core is formed with a plurality of first pin holes, and each of the pins passes through at least one of the first pin holes and at least one of the second pin holes.

[0008] In at least one embodiment, the rotor further comprises two end plates, which are respectively arranged at two axial ends of the rotor. The end plate is formed with a plurality of third pin holes, and each of the pins passes through at least one of the third pin holes and at least one of the second pin holes.

[0009] In at least one embodiment, the rotor further comprises a first end plate and a second end plate, wherein the first end plate and the second end plate are respectively disposed at two axial ends of the rotor. The first end plate is formed with a plurality of third pin holes, and the pins are formed integrally with the second end plate. Each of the pins passes through at least one of the third pin holes and at least one of the second pin holes.

[0010] In at least one embodiment, each radial flux permanent magnet group includes at least one permanent magnet sub-group, and each permanent magnet sub-group includes two permanent magnets symmetrically arranged in a V-shape.

[0011] In at least one embodiment, each radial flux permanent magnet group includes a plurality of permanent magnet sub-groups, and the plurality of permanent magnet sub-groups are layered in a radial direction of the rotor.

[0012] In at least one embodiment, each radial flux permanent magnet group includes two permanent magnet subgroups, The first core is formed with a plurality of first pin holes, and the first pin holes are located in the radial middle of the two permanent magnet subgroups of each group of the radial flux permanent magnet group. The rotor further includes pins, each of which passes through at least one of the first pin holes.

[0013] In at least one embodiment, the second core is further formed with a plurality of magnetic isolation holes, and each magnetic isolation hole is provided on the radial inner side and the radial outer side of the receiving slot of each tangential flux permanent magnet.

[0014] Compared with conventional full radial flux rotors and full tangential flux rotors, the rotor of the permanent magnet motor according to the present invention uses less rare earth permanent magnet material, has good NVH performance and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of a rotor of a permanent magnet motor according to an embodiment of the present application.

[0016] Figure 2 is a schematic diagram of a first section of a rotor of a permanent magnet motor according to one embodiment of the present application.

[0017] Figure 3 is a schematic diagram of a second section of a rotor of a permanent magnet motor according to an embodiment of the present application.

[0018] Figure 4 yes Figure 2 Schematic diagram of the corresponding magnetic circuit direction of the first section.

[0019] Figure 5 yes Figure 3 Schematic diagram of the corresponding magnetic circuit direction of the second section.

[0020] Figure 6 It is a schematic diagram of an end plate of a rotor of a permanent magnet motor according to an embodiment of the present application.

[0021] Figure 7 Schematic diagram of a pin of a rotor of a permanent magnet motor according to an embodiment of the present application.

[0022] Figure 8 It is a simulation of the electromagnetic force density of a full radial flux rotor with the same specifications as the embodiment of the present application.

[0023] Fig. 9 It is a simulation of the electromagnetic force density of a full tangential flux rotor with the same specifications as the embodiment of the present application.

[0024] Fig.10 The present invention is a simulation of electromagnetic force density of a rotor of a permanent magnet motor according to an embodiment of the present application.

[0025] Fig.11 It is a simulation of the electromagnetic force density of the rotor of a permanent magnet motor for a hypothetical comparison scheme.

[0026] Description of reference numerals: 10 first section; 11 first iron core; 110 first pin hole; 12 radial flux permanent magnet group; 120 permanent magnet subgroup; 20 second section; 21 second iron core; 210 second pin hole; 211 magnetic isolation hole; 22 tangential flux permanent magnet; 30 end plate; 31 third pin hole; 40 pin. DETAILED DESCRIPTION

[0027] The exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present invention, and are not intended to exhaust all possible modes of the present invention, nor to limit the scope of the present invention.

[0028] Reference Figures 1 to 11 , introduces a rotor of a permanent magnet motor according to an embodiment of the present application, hereinafter referred to as a rotor. Unless otherwise specified, the radial, circumferential and axial directions referred to below are all based on the radial, circumferential and axial directions of the rotor.

[0029] The rotor in this embodiment includes two first sections 10, two second sections 20 and two end plates 30. The two first sections 10 are stacked together in the axial direction to form an integral component; the two second sections 20 are respectively arranged on both axial sides of the integral component of the first section 10; the end plate 30 is arranged at the axial end of the second section 20 away from the first section 10, that is, the two end plates 30 are respectively arranged at the axial ends of the rotor.

[0030] The first section 10 is used to form a radial magnetic field. The first section 10 includes a first core 11 and a plurality of (six in this embodiment) radial flux permanent magnet groups 12. Figure 2 Each radial flux permanent magnet group 12 includes two permanent magnet subgroups 120, and the two permanent magnet subgroups 120 are layered in the radial direction. Each permanent magnet subgroup 120 includes two permanent magnets arranged in a substantially V-shape and symmetrical in the radial direction. It should be understood that in other possible embodiments, each radial flux permanent magnet group 12 may also include other numbers of permanent magnet subgroups, for example, one or three permanent magnet subgroups 120.

[0031] The present application does not impose any restriction on the angle between two V-shaped permanent magnets in the permanent magnet subgroup 120 , and it can be adjusted according to specific design target parameters, and ensures that permanent magnets of adjacent poles do not form position interference.

[0032] Figure 4 The magnetization direction of each permanent magnet in the radial flux permanent magnet group 12 is shown. For a single permanent magnet in the radial flux permanent magnet group 12, its magnetization direction is perpendicular to the thickness direction of the permanent magnet. Since the two permanent magnets of the permanent magnet subgroup 120 are symmetrical in the radial direction, the equivalent magnetic field formed by the two permanent magnets in the first core 11 is radial. In addition, the equivalent magnetic fields of the circumferentially adjacent permanent magnet subgroups 120 are opposite in the radial direction, thereby forming magnetic poles spaced between N poles and S poles in the circumferential direction of the first core 11.

[0033] The second section 20 is used to form a tangential magnetic field and includes a second core 21 and a plurality of (six in this embodiment) tangential flux permanent magnets 22 , the number of which is equal to the number of the radial flux permanent magnet group 12 . Figure 5 The magnetization direction of each of the tangential flux permanent magnets 22 is shown. The magnetization directions of the tangential flux permanent magnets 22 adjacent to each other in the circumferential direction are opposite in the tangential direction, so that magnetic poles with N poles and S poles spaced apart are formed in the circumferential direction of the second core 21 .

[0034] A plurality of magnetic isolation holes 211 are further formed on the second core 21 . The magnetic isolation holes 211 are formed on the radial inner side and the radial outer side of the receiving slot of each tangential flux permanent magnet 22 .

[0035] When the first segment 10 and the second segment 20 are overlapped, the N pole of the first segment 10 is aligned with the N pole of the second segment 20 in the circumferential direction, and the S pole of the first segment 10 is aligned with the S pole of the second segment 20 in the circumferential direction.

[0036] The magnetic field of a pure radial flux rotor is relatively saturated at the magnetic bridge position, and the magnetic field saturation is low at the non-magnetic bridge position. Its surface magnetic field will change dramatically, so the electromagnetic force density component is large and the amplitude is large. The magnetic lines of force of a tangential flux rotor pass through a longer magnetic path to reach the outer diameter of the rotor, and the surface magnetic field is smoother, so the electromagnetic force density component is small and the amplitude is small. In addition, by combining tangential flux permanent magnets and radial flux permanent magnets, the amount of permanent magnet material used can be saved.

[0037] In order to facilitate the alignment of the magnetic poles of the first segment 10 and the second segment 20 , the present embodiment further provides an end plate 30 and a pin 40 .

[0038] The end plate 30 is formed with a plurality of (six in this embodiment) third pin holes 31 penetrating in the axial direction.

[0039] The first core 11 is formed with a plurality of (six in this embodiment) first pin holes 110 , and a first pin hole 110 is distributed in the radial space between the receiving slots of the two permanent magnet sub-groups 120 of each radial flux permanent magnet group 12 .

[0040] The second core 21 is formed with a plurality of (six in this embodiment) second pin holes 210 , and one second pin hole 210 is provided between circumferentially adjacent tangential flux permanent magnets 22 .

[0041] The pin 40 penetrates the third pin hole 31 , the second pin hole 210 and the first pin hole 110 in the axial direction, so that the first section 10 and the second section 20 can be accurately positioned in the circumferential direction.

[0042] In addition, the pin 40 also serves to increase the structural strength of the first iron core 11 and the second iron core 21 , so that when the rotor rotates at a high speed, the first iron core 11 and the second iron core 21 can resist a large centrifugal force.

[0043] Furthermore, due to the existence of the first pin hole 110 , the magnetic bridge of the first core 11 becomes relatively thinner, which also improves the torque and power provided by the first section 10 to a certain extent.

[0044] It is worth noting that, since the magnetic bridge of the first core 11 can provide structural strength for resisting the centrifugal force exerted on the permanent magnet, it can be considered that the second core 21 is more in need of strengthening the structural strength than the first core 11 and the second core 21. Therefore, in other possible implementations, the pin 40 may also only partially extend into the first core 11 in the axial direction to mainly provide a positioning function; or, without considering the positioning function, the pin 40 may not extend into the first core 11, but only penetrate the end plate 30 and the second core 21.

[0045] It is understood that in other possible embodiments, the pin 40 may also be integrated into one of the end plates. For example, the two end plates are divided into a first end plate and a second end plate, the first end plate is formed with a plurality of third pin holes, and the pin is fixed to the second end plate.

[0046] The electromagnetic force density of the rotor provided by this embodiment at different spatial and temporal orders is simulated and compared with the electromagnetic force density of a complete radial flux rotor (it can be assumed that all the second sections of the rotor of this embodiment are replaced by the first section) and a complete tangential flux rotor (it can be assumed that all the first sections of the rotor of this embodiment are replaced by the second section) of the same specification. The simulation results are shown in Figure 2. Figures 8 to 10 As shown in Table 1, Figure 8 For a fully radial flux rotor, Fig. 9 For a fully tangential flux rotor, Fig.10 Corresponding to the rotor of this embodiment.

[0047] Table 1 Electromagnetic force density simulation

[0048] It can be found that with the increase of the time order, the electromagnetic force density of the rotor of this embodiment is significantly less than (that is, better than) the fully radial flux rotor or the fully tangential flux rotor of the same specification, showing excellent performance. This is because the combination of the two different directions of flux, the first section 10 and the second section 20, couples the two magnetic circuits of the motor, and through different harmonic phases, it plays a role in adjusting the electromagnetic force of the main harmonics of the motor. In addition, it can be foreseen that when the rotor according to this embodiment runs at high speed, the weak magnetic current of the motor is also small, so the efficiency of the motor will be improved.

[0049] In addition, the applicant also hypothesized a scheme in which radial flux permanent magnets and tangential flux permanent magnets are integrated on the same rotor section (different from the two different sections in the axial direction in the present application). For this hypothetical scheme, the structure close to the outer surface of the rotor will be a structure in which magnetic steel and non-magnetic magnetic isolation bridges are alternately arranged. The surface magnetic field of this structure will still change dramatically, and it does not have the function of weakening the electromagnetic force density; and the rotor magnetic bridge is a cantilever-like structure, which does not have the property requirements of high speed.

[0050] The applicant Fig.11 The electromagnetic force density of this hypothetical scheme is simulated in . When the spatial order and time order are 0 and 18 respectively, the electromagnetic force density of the hypothetical scheme is 3083N / m 2 ; When the spatial order and time order are 0 and 54 respectively, the electromagnetic force density of the hypothetical scheme is 3120N / m 2 , are inferior to the solutions of this implementation.

[0051] It should be understood that the above-mentioned embodiments and some aspects or features thereof may be appropriately combined.

[0052] The present invention has at least one of the following advantages: (i) The present application stacks a rotor first section with radial magnetic flux and a rotor second section with tangential magnetic flux, and the amount of tangential magnetic flux permanent magnets used is reduced compared to the amount of radial magnetic flux permanent magnets, thereby saving the amount of rare earth permanent magnet materials used.

[0053] (ii) The stacking combination of the first rotor section with radial magnetic flux and the second rotor section with tangential magnetic flux couples the magnetic circuit characteristics of the two rotor sections. By utilizing the different phases of their main harmonics, the electromagnetic force of the main harmonics of the motor can be adjusted, thereby achieving the purpose of improving NVH.

[0054] (iii) By coordinating the two rotor sections with magnetic circuits in different directions, the weak magnetic current of the motor is low when running at high speed, thereby improving the efficiency of the motor.

[0055] Of course, the present invention is not limited to the above-mentioned embodiments, and those skilled in the art can make various modifications to the above-mentioned embodiments of the present invention under the guidance of the present invention without departing from the scope of the present invention. For example: The number of the first section and the second section can be set as needed. And the stacking position is not limited to the situation where the second section clamps the first section at the two axial ends. For example, the first section and the second section can also be spaced apart in the axial direction. Of course, it can be understood that since the heat dissipation capacity of the axial middle area of ​​the core is worse, and since the eddy current loss of the rotor stack structure magnetic steel with tangential magnetic flux is smaller (the harmonics of the stator act on the permanent magnets in the rotor, causing the permanent magnets to generate eddy current losses, wherein the harmonics close to the outer surface of the rotor penetrate more, and the harmonics away from the outer surface of the rotor penetrate less, so compared with the radial structure, the tangential structure magnetic steel loss is smaller), the heat generation is low, and it is less likely to demagnetize when placed in the middle section. Therefore, it is beneficial to set the second section in the middle axial direction from the perspective of heat dissipation.

Claims

1. A rotor of a permanent magnet motor, characterized in that: The invention comprises at least one first section (10) and at least one second section (20) which are stacked in the axial direction. The first section (10) comprises a first iron core (11) and a plurality of radial flux permanent magnet groups (12), wherein the equivalent magnetic field formed by each radial flux permanent magnet group (12) is directed radially inward or radially outward within the first iron core (11), and the equivalent magnetic fields of two radial flux permanent magnet groups (12) adjacent to each other in the circumferential direction are in opposite directions. The second section (20) comprises a second iron core (21) and a plurality of tangential flux permanent magnets (22), the number of the tangential flux permanent magnets (22) being equal to the number of the radial flux permanent magnet group (12), the magnetization directions of the tangential flux permanent magnets (22) being tangentially in the second iron core (21), and the magnetization directions of two tangential flux permanent magnets (22) adjacent to each other in the circumferential direction being opposite, The N pole of the first segment (10) adjacent to each other in the axial direction is aligned with the N pole of the second segment (20) in the circumferential direction, and the S pole of the first segment (10) adjacent to each other in the axial direction is aligned with the S pole of the second segment (20) in the circumferential direction.

2. The rotor of the permanent magnet motor according to claim 1, characterized in that: There are at least two second sections (20), the first section (10) is arranged at an axial middle position of the rotor, and the two second sections (20) are respectively arranged on two axial sides of an integral component formed by the first section (10).

3. The rotor of the permanent magnet motor according to claim 1, characterized in that: The rotor further comprises a pin (40), The second iron core (21) is formed with a plurality of second pin holes (210), wherein the second pin holes (210) are distributed between adjacent radial flux permanent magnet groups (12). The pin (40) passes through the second pin hole (210).

4. The rotor of the permanent magnet motor according to claim 3, characterized in that: The first iron core (11) is formed with a plurality of first pin holes (110), and each of the pins (40) passes through at least one of the first pin holes (110) and at least one of the second pin holes (210).

5. The rotor of the permanent magnet motor according to claim 3, characterized in that: The rotor further comprises two end plates (30), wherein the end plates (30) are respectively arranged at two axial ends of the rotor. The end plate (30) is formed with a plurality of third pin holes (31), and each of the pins (40) passes through at least one of the third pin holes (31) and at least one of the second pin holes (210).

6. The rotor of the permanent magnet motor according to claim 3, characterized in that: The rotor further comprises a first end plate and a second end plate, wherein the first end plate and the second end plate are respectively arranged at two axial ends of the rotor. The first end plate is formed with a plurality of third pin holes (31), and the pin (40) is formed integrally with the second end plate. Each of the pins (40) passes through at least one of the third pin holes (31) and at least one of the second pin holes (210).

7. The rotor of the permanent magnet motor according to claim 1, characterized in that: Each radial flux permanent magnet group (12) comprises at least one permanent magnet subgroup (120), and each permanent magnet subgroup (120) comprises two permanent magnets symmetrically arranged in a V shape.

8. The rotor of the permanent magnet motor according to claim 7, characterized in that: Each radial flux permanent magnet group (12) comprises a plurality of permanent magnet subgroups (120), and the plurality of permanent magnet subgroups (120) are arranged in layers in the radial direction of the rotor.

9. The rotor of the permanent magnet motor according to claim 8, characterized in that: Each radial flux permanent magnet group (12) includes two permanent magnet subgroups (120), The first iron core (11) is formed with a plurality of first pin holes (110), wherein the first pin holes (110) are located in the radial middle of the two permanent magnet sub-groups (120) of each group of the radial flux permanent magnet groups (12). The rotor further comprises pins (40), each of the pins (40) passing through at least one of the first pin holes (110).

10. The rotor of the permanent magnet motor according to claim 1, characterized in that: The second iron core (21) is further formed with a plurality of magnetic isolation holes (211), and each magnetic isolation hole (211) is provided on the radial inner side and the radial outer side of the receiving slot of each tangential flux permanent magnet (22).

Images