Alternating Spoke Parallel Magnetic Circuit Rare Earth Permanent Magnet Motor

Abstract

The present invention discloses an alternating-spoke parallel magnetic circuit low-rare-earth permanent magnet motor, comprising a rotating shaft, an alternating-spoke parallel permanent magnet rotor, and a stator, which are coaxially sleeved from the inside out or from the outside in. The alternating-spoke parallel permanent magnet rotor comprises a rotor core, a first-spoke magnet group, and a second-spoke magnet group. The first-spoke magnet group includes p high-energy-density permanent magnets with the same magnetization direction and arranged radially. The second-spoke magnet group includes p low-energy-density permanent magnets with the same magnetization direction and arranged radially. The high- and low-energy-density permanent magnets have opposite magnetization directions and are arranged alternately and cyclically along the circumference of the rotor core to form p pairs of magnetic poles. The present invention not only reduces the amount of rare earth material required but also improves the utilization rate of permanent magnet material, thereby effectively reducing the cost of the motor. Furthermore, the present invention can eliminate even harmonics in the back electromotive force and odd harmonics in the cogging torque, thereby effectively suppressing torque pulsation.

Description

Technical Field

[0001] The invention relates to the field of motor design and manufacturing, in particular to an alternating spoke parallel magnetic circuit low rare earth permanent magnet motor. Background Art

[0002] Permanent magnet motors (PMMs), with their advantages of high torque / power density, high efficiency, and high power factor, have been adopted in a variety of fields, including home appliances, electric vehicles, and aerospace. Currently, high-performance PMMs generally utilize high-energy-density rare earth permanent magnet materials, such as neodymium iron boron and samarium cobalt. However, rare earths are a non-renewable, important natural resource, and their long-term and stable supply faces significant challenges. Furthermore, with the rapid development of various industries, the price of rare earth permanent magnet materials has risen rapidly. Therefore, the efficient utilization of rare earth permanent magnet materials is of great practical significance for reducing motor development costs and alleviating the rare earth resource crisis. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide an alternating spoke parallel magnetic circuit less rare earth permanent magnet motor. The alternating spoke parallel magnetic circuit less rare earth permanent magnet motor can reduce the required amount of rare earth materials and improve the utilization rate of permanent magnet materials, thereby effectively reducing the cost of the motor.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] An alternating spoke parallel magnetic circuit low rare earth permanent magnet motor comprises a rotating shaft, an alternating spoke parallel magnetic circuit rotor and a stator which are coaxially sleeved in sequence from the inside to the outside or from the outside to the inside.

[0006] The alternating-spoke permanent magnet parallel magnetic circuit rotor includes a rotor core, a first-spoke magnetic steel group, and a second-spoke magnetic steel group.

[0007] The first Spoke magnet group includes p high-energy-density permanent magnets with the same magnetization direction and arranged radially.

[0008] The second Spoke magnet group includes p low-energy-density permanent magnets with the same magnetization direction and arranged radially.

[0009] The energy density of each high-energy-density permanent magnet is greater than the energy density of the low-energy-density permanent magnet.

[0010] The magnetization directions of the p high-energy-density permanent magnets and the p low-energy-density permanent magnets are opposite, and they are alternately arranged in a circumferential direction of the rotor core to form p pairs of magnetic poles.

[0011] The alternating-spoke permanent magnet parallel magnetic circuit rotor comprises 2n rotor segments which are coaxially and equidistantly arranged in sequence along the axial direction, wherein n≥1.

[0012] Each rotor segment has the same axial length, and each rotor segment comprises a rotor core, a first Spoke magnetic steel group, and a second Spoke magnetic steel group.

[0013] The magnetic circuits of two adjacent rotor segments are complementary.

[0014] The center lines of the first Spoke magnetic steel groups of the n rotor segments and the center lines of the second Spoke magnetic steel groups of the remaining n rotor segments are located at the same circumferential position, and the magnetization directions of the first Spoke magnetic steel groups of the n rotor segments and the second Spoke magnetic steel groups of the remaining n rotor segments are the same.

[0015] Each high energy density permanent magnet and each low energy density permanent magnet are tangentially magnetized.

[0016] Each high energy density permanent magnet contains rare earth permanent magnet material.

[0017] Rare earth permanent magnet materials are neodymium iron boron or samarium cobalt.

[0018] The low energy density permanent magnet is ferrite.

[0019] There is an air gap between the rotor and the stator of the alternating spoke permanent magnet parallel magnetic circuit; an auxiliary high energy density permanent magnet is provided on the side of each low energy density permanent magnet facing the air gap, and the auxiliary high energy density permanent magnet is made of the same material as the high energy density permanent magnet.

[0020] A mechanical connection bridge is provided at the junction of each high energy density permanent magnet and the adjacent low energy density permanent magnet on the side away from the air gap and on the side of each high energy density permanent magnet facing the air gap.

[0021] When each low-energy-density permanent magnet is provided with an auxiliary high-energy-density permanent magnet on the side facing the air gap, a mechanical connection bridge is provided on the side facing the air gap of the auxiliary high-energy-density permanent magnet; when each low-energy-density permanent magnet is not provided with an auxiliary high-energy-density permanent magnet on the side facing the air gap, a mechanical connection bridge is provided on the side facing the air gap of each low-energy-density permanent magnet.

[0022] The present invention has the following beneficial effects:

[0023] 1. The alternating spoke parallel magnetic circuit rare earth permanent magnet motor of the present invention not only reduces the required amount of rare earth materials, but also improves the utilization rate of permanent magnet materials, thereby effectively reducing the cost of the motor.

[0024] 2. The alternating spoke permanent magnet parallel magnetic circuit rotor arrangement of the present invention satisfies the "magnetic circuit complementary condition", which can eliminate the even harmonics in the back electromotive force and the odd harmonics in the cogging torque, thereby effectively suppressing torque pulsation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a structural diagram of an alternating spoke parallel magnetic circuit rare earth permanent magnet motor in Example 1 of the present invention.

[0026] Figure 2 A schematic diagram showing the layout position of the mechanical connection bridge in Example 1 of the present invention is shown.

[0027] Figure 3a It shows a schematic diagram of the planar structure of adjacent rotor segments in embodiment 2 of the present invention.

[0028] Figure 3b A schematic diagram of the axial assembly of the rotor segments in Example 2 of the present invention is shown.

[0029] Figure 3c A schematic diagram showing the magnets in the Spoke magnet group when being pulled out in Example 2 of the present invention is shown.

[0030] Figure 4 The diagram shows the structure of Example 3 of the present invention when an auxiliary high-energy-density permanent magnet is provided.

[0031] Figure 5 A schematic diagram showing embodiment 3 of the present invention in which an auxiliary high-energy-density permanent magnet and a mechanical connection bridge are provided is shown.

[0032] Figure 6 A schematic diagram showing the magnetic lines of force generated by the first Spoke magnet group is shown.

[0033] Figure 7 A schematic diagram showing the magnetic lines of force generated by the second Spoke magnet group is shown.

[0034] Among them are:

[0035] 1. Rotating shaft;

[0036] 2. Alternating Spoke permanent magnet parallel magnetic circuit rotor;

[0037] 21. Rotor core;

[0038] 22. First Spoke magnet group; 221. High energy density permanent magnet;

[0039] 23. Second Spoke magnet group; 231. Low energy density permanent magnet;

[0040] 24. Mechanical connection bridge;

[0041] 25. Auxiliary high energy density permanent magnet;

[0042] 3. Stator; 31. Stator core; 32. Armature winding. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below with reference to the accompanying drawings and specific preferred embodiments.

[0044] In the description of the present invention, it should be understood that the terms "left side," "right side," "upper," "lower," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Terms such as "first" and "second" do not indicate the importance of components and therefore should not be construed as limitations on the present invention. The specific dimensions used in this embodiment are intended only to illustrate the technical solution and do not limit the scope of protection of the present invention.

[0045] The present invention uses three-phase armature winding m=3, stator slot number Ns=12, rotor pole pair number p =5 inner rotor as an example to explain the present invention in detail.

[0046] Example 1

[0047] like Figure 1 As shown, an alternating spoke parallel magnetic circuit low rare earth permanent magnet motor includes a rotating shaft 1, an alternating spoke parallel magnetic circuit permanent magnet rotor 2 and a stator 3 which are coaxially sleeved from the inside to the outside.

[0048] Alternatively, when the present invention is used as an outer rotor, the rotating shaft, the alternating spoke permanent magnet parallel magnetic circuit rotor and the stator are coaxially sleeved in sequence from the outside to the inside.

[0049] The stator comprises a stator core 31 and an armature winding 32. The stator core is made of magnetic conductive material, and the armature winding comprises A, B,

[0050] C three-phase winding, where phase A can be composed of coils A1, A2, A3, and A4 connected in series, or A1-A2 and A3-A4 connected in series and then in parallel; the same applies to phases B and C.

[0051] The alternating-spoke permanent magnet parallel magnetic circuit rotor includes a rotor core 21 , a first-spoke magnetic steel group 22 and a second-spoke magnetic steel group 23 .

[0052] The rotor core is preferably made of magnetic conductive material, such as Figure 2 As shown, the rotor core includes p radial thin slots and p radial wide slots alternately arranged along the radial direction. Furthermore, each radial thin slot is preferably provided with an apple-shaped slot on the side facing away from the air gap, and each radial wide slot is preferably provided with a wedge-shaped slot on the side facing away from the air gap. Both the apple-shaped slots and the wedge-shaped slots act as magnetic isolation slots, suppressing leakage flux generated by the permanent magnets on the inner side of the rotor (the yoke).

[0053] The first Spoke magnet group includes p high-energy-density permanent magnets with the same magnetization direction and arranged radially. The p high-energy-density permanent magnets are located in p radial slots and are preferably all tangentially magnetized.

[0054] The second Spoke magnet group includes p low-energy-density permanent magnets with the same magnetization direction and arranged radially. The p low-energy-density permanent magnets are located in p radially wide slots and are preferably all tangentially magnetized.

[0055] The energy density of each high-energy-density permanent magnet is greater than the energy density of the low-energy-density permanent magnet.

[0056] Each high energy density permanent magnet contains rare earth permanent magnet material, wherein the rare earth permanent magnet material is preferably neodymium iron boron or samarium cobalt, etc. Each low energy density permanent magnet is preferably ferrite, etc.

[0057] The magnetization directions of the p high-energy-density permanent magnets and the p low-energy-density permanent magnets are opposite, and they are alternately arranged in a circumferential direction of the rotor core to form p pairs of magnetic poles.

[0058] The air gap magnetic flux of each pole is jointly generated by the two adjacent Spoke magnets, and the main magnetic fluxes of the first Spoke magnet group and the second Spoke magnet group are in a parallel magnetic circuit relationship (that is, the main magnetic flux generated by the first Spoke magnet group does not pass through the second Spoke magnet group, and the main magnetic flux generated by the second Spoke magnet group does not pass through the first Spoke magnet group, respectively). Figure 6 and 7 As shown in the figure) (Note: the magnetic resistance of the magnetic steel is much greater than the magnetic resistance of the iron core and the air gap), the magnetic resistance of the main magnetic flux path is small, and the utilization rate of the permanent magnet material is high.

[0059] Furthermore, a mechanical connection bridge is provided in the rotor core, and the mechanical connection bridge can be specifically designed according to the actual operation conditions or process level, and can meet the mechanical safety requirements. Figure 2 As shown, a mechanical connection bridge 24 is preferably provided at the junction of each high energy density permanent magnet and the adjacent low energy density permanent magnet on the side facing away from the air gap and on the side of each high energy density permanent magnet facing the air gap.

[0060] Example 2

[0061] The alternating-spoke permanent magnet parallel magnetic circuit rotor includes 2n rotor segments 20 coaxially and equidistantly arranged in sequence along the axial direction, wherein n≥1. In this embodiment 2, preferably n=1.

[0062] The axial length of each rotor segment is equal, and the structure of each rotor segment is the same as that of the single alternating-Spoke permanent magnet parallel magnetic circuit rotor in Example 1, that is, each has a rotor core, a first-Spoke magnetic steel group, and a second-Spoke magnetic steel group.

[0063] like Figure 3a 、 3b As shown in Figure 3c, the centerlines of the first-spoke magnetic steel groups of n rotor segments and the centerlines of the second-spoke magnetic steel groups of the remaining n rotor segments are located at the same circumferential position (i.e., axially aligned), and the magnetization directions of the first-spoke magnetic steel groups of these n rotor segments and the second-spoke magnetic steel groups of the remaining n rotor segments are the same. Therefore, the odd-order harmonics of the cogging torque generated by these n-segment rotor and the remaining n-segment rotor have equal amplitudes and opposite directions (i.e., they cancel each other out); and the even-order harmonics of the back-electromotive force generated by these n-segment rotor and the remaining n-segment rotor have equal amplitudes and opposite directions (i.e., they cancel each other out).

[0064] Therefore, the above 2n rotor segments meet the “magnetic circuit complementary condition”, which can eliminate the even harmonics in the back electromotive force and the odd harmonics in the cogging torque, thereby effectively suppressing torque pulsation.

[0065] Example 3

[0066] like Figure 4 As shown, this is essentially the same as the above-mentioned Example 1 or Example 2, with the difference that, since low-energy-density permanent magnet material requires a thicker design to generate a sufficient air-gap magnetic field, thicker Spoke magnets increase the air-gap reluctance per pole. Therefore, the second Spoke magnet group of the present invention can use auxiliary high-energy-density permanent magnets in the portion near the air-gap (this portion uses only a small amount of high-energy-density permanent magnet material to increase the cross-sectional area of ​​the air-gap per pole), thereby reducing the air-gap reluctance per pole and further improving the utilization rate of the permanent magnet material (Note: the air-gap reluctance per pole is inversely proportional to the cross-sectional area of ​​the air-gap per pole, i.e., the larger the cross-sectional area, the lower the reluctance).

[0067] Further, when each low-energy-density permanent magnet is provided with an auxiliary high-energy-density permanent magnet on the side facing the air gap, the auxiliary high-energy-density permanent magnet is preferably provided with a mechanical connection bridge on the side facing the air gap; when each low-energy-density permanent magnet is not provided with an auxiliary high-energy-density permanent magnet on the side facing the air gap, the mechanical connection bridge is preferably provided on the side facing the air gap.

[0068] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the scope of protection of the present invention.

Claims

1. An alternating spoke parallel magnetic circuit rare earth permanent magnet motor, characterized by: It includes a rotating shaft, an alternating-Spoke permanent magnet parallel magnetic circuit rotor and a stator which are coaxially sleeved from the inside to the outside or from the outside to the inside; The alternating-spoke permanent magnet parallel magnetic circuit rotor includes a rotor core, a first-spoke magnetic steel group, and a second-spoke magnetic steel group; The first Spoke magnet group includes p high energy density permanent magnets with the same magnetization direction and arranged radially; The second Spoke magnet group includes p low energy density permanent magnets with the same magnetization direction and arranged radially; The energy density of each high-energy-density permanent magnet is greater than the energy density of the low-energy-density permanent magnet; The magnetization directions of p high-energy-density permanent magnets and p low-energy-density permanent magnets are opposite, and they are alternately arranged along the circumference of the rotor core to form p pairs of magnetic poles. There is an air gap between the rotor and stator of the alternating spoke permanent magnet parallel magnetic circuit; A mechanical connection bridge is provided at the junction of each high energy density permanent magnet and the adjacent low energy density permanent magnet on the side facing away from the air gap and on the side of each high energy density permanent magnet facing the air gap; When each low energy density permanent magnet is provided with an auxiliary high energy density permanent magnet on the side facing the air gap, a mechanical connection bridge is provided on the side facing the air gap of the auxiliary high energy density permanent magnet; When no auxiliary high-energy-density permanent magnet is provided on the side of each low-energy-density permanent magnet facing the air gap, a mechanical connection bridge is provided on the side of each low-energy-density permanent magnet facing the air gap; Each high-energy-density permanent magnet is provided with an apple-shaped slot on the side facing away from the air gap, and each low-energy-density permanent magnet is provided with a wedge-shaped slot on the side facing away from the air gap. Both the apple-shaped slot and the wedge-shaped slot are magnetic isolation slots that can suppress the leakage magnetic flux formed by the permanent magnets on the inner side of the rotor.

2. The alternating spoke parallel magnetic circuit low rare earth permanent magnet motor according to claim 1, characterized in that: The alternating spoke permanent magnet parallel magnetic circuit rotor comprises 2n rotor segments coaxially and equidistantly arranged in sequence along the axial direction, wherein n≥1; Each rotor segment has an equal axial length, and each rotor segment comprises a rotor core, a first Spoke magnetic steel group, and a second Spoke magnetic steel group; The magnetic circuits of two adjacent rotor segments are complementary.

3. The alternating spoke parallel magnetic circuit low rare earth permanent magnet motor according to claim 2, characterized in that: The center lines of the first Spoke magnetic steel groups of the n rotor segments and the center lines of the second Spoke magnetic steel groups of the remaining n rotor segments are located at the same circumferential position, and the magnetization directions of the first Spoke magnetic steel groups of the n rotor segments and the second Spoke magnetic steel groups of the remaining n rotor segments are the same.

4. The alternating spoke parallel magnetic circuit low rare earth permanent magnet motor according to claim 1, characterized in that: Each high energy density permanent magnet and each low energy density permanent magnet are tangentially magnetized.

5. The alternating spoke parallel magnetic circuit low rare earth permanent magnet motor according to claim 1, characterized in that: Each high energy density permanent magnet contains rare earth permanent magnet material.

6. The alternating spoke parallel magnetic circuit low rare earth permanent magnet motor according to claim 5, characterized in that: Rare earth permanent magnet materials are neodymium iron boron or samarium cobalt.

7. The alternating spoke parallel magnetic circuit low rare earth permanent magnet motor according to claim 1, characterized in that: The low energy density permanent magnet is ferrite.

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