CN107124053B - An alternating pole permanent magnet motor rotor using hybrid permanent magnets - Google Patents

Abstract

The invention discloses a kind of Consequent pole permanent magnet motor rotor using hybrid permanent-magnet, including rotor core section, magnetic guiding loop, high-energy density permanent magnet and low energy densities permanent magnet, a magnetic guiding loop is coaxially disposed between two neighboring rotor core section；Consequent pole permanent magnet motor rotor can be used as internal rotor, can also be used as outer rotor.The outer surface of each rotor core section or the inner surface circumferentially uniformly distributed outer salient pole for having p arc, wherein p is motor number of pole-pairs；An outer arcuate slot is formed between two neighboring outer salient pole, lays a high-energy density permanent magnet in each outer arcuate slot；It is circumferentially uniformly distributed on the inner or outer side anchor ring of each rotor core section to have n inner arc slot, and n >=p；A low energy densities permanent magnet is laid in each inner arc slot.The present invention can further increase the torque output capability of alternately pole surface formula magneto while saving motor cost and weakening alternately pole surface formula magneto shaft leakage field.

Description

An alternating pole permanent magnet motor rotor using hybrid permanent magnets

technical field

The invention relates to the field of motor design, in particular to an alternating pole permanent magnet motor rotor using mixed permanent magnets.

Background technique

Permanent magnet motors have high torque density and high efficiency, and have been widely used in medical equipment, household appliances, electric vehicles, wind power generation and aerospace. Different permanent magnet motor rotor structures make the magnetic circuit different, which makes the motor performance, control system, manufacturing process and applicable occasions different. According to the coordinate transformation theory of permanent magnet synchronous motor, the direct axis magnetic circuit and quadrature axis magnetic circuit of surface permanent magnet motor. Straight-axis magnetic circuit: permanent magnet → air gap → stator core → air gap → adjacent permanent magnet → rotor core → back to the permanent magnet. (The stator core and air gap are not shown in the figure, but they are known in the industry). Quadrature-axis magnetic circuit: at the boundary of two permanent magnets → air gap → stator core → air gap → at the boundary of two adjacent permanent magnets → rotor core → back to the boundary of the two permanent magnets.

It can be seen that the reluctance of the direct-axis magnetic circuit is equal to that of the quadrature-axis magnetic circuit, so the direct-axis inductance is equal to the quadrature-axis inductance.

The electromagnetic torque _Te expression of the permanent magnet synchronous motor is shown in formula (a).

In formula (a), p is the number of pole pairs of the motor, ψ _pm is the permanent magnet flux linkage, L _d and L _q are the direct-axis inductance and quadrature-axis inductance, respectively, and _id and i _q are the direct axis of the armature winding, respectively. current and quadrature current. I _a is the peak value of the sinusoidal phase current and β is the current phase angle. T _pm and _Tr are the permanent magnet torque component and the reluctance torque component, respectively.

Since the direct-axis inductance of the surface-type permanent magnet motor is equal to the quadrature-axis inductance, its reluctance torque component is zero. It only contains the permanent magnet torque component, that is, the electromagnetic torque _Te expression of the surface permanent magnet motor, which can be shown by formula (b).

The manufacturing process of the surface type permanent magnet motor rotor is simple, and its output torque does not contain a reluctance torque component, so the control method is simple, and it is widely used in servo transmission occasions such as machine tools, robots and medical equipment. The traditional surface-type permanent magnet motor uses a large amount of high-priced rare earth permanent magnet materials, which is the main reason for its high production cost. In order to reduce its cost, the invention patent with the application number of 200710010915.0 provides a surface-type permanent magnet servo motor rotor. The permanent magnets and "dummy poles" are alternately arranged, and the number of permanent magnets is only half of the traditional surface-type permanent magnet motor. Permanent magnet material is saved, thereby reducing the overall cost of the motor.

However, as pointed out in an article published in the Journal of the IEEE Magnetic Society: Comparative Analysis of End Effect in Partitioned Stator Flux Reversal Machines Having Surface-Mounted and Consequent Pole Permanent Magnets, the permanent magnet motor with alternating pole structure has serious magnetic leakage at the end.

In addition, the end of the rotating shaft of the alternating-pole surface permanent magnet motor will have unipolar magnetic leakage, which will make the end of the rotating shaft of the motor magnetized, which will affect the reliability and safety of the entire motor system. The invention patent 201611011019.1 proposes a method of rotor segmentation to provide a magnetic leakage path inside the rotor and the rotating shaft, which weakens the magnetization of the end of the rotating shaft. However, the flux leakage at the junction of the two rotors will reduce the torque output capability and the utilization of permanent magnets is low.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is aimed at the deficiencies of the above-mentioned prior art, and provides an alternating pole permanent magnet motor rotor using mixed permanent magnets. The alternating pole permanent magnet motor rotor using mixed permanent magnets can save motor costs and reduce costs. While weakening the magnetic leakage of the rotating shaft of the alternating pole surface type permanent magnet motor, the torque output capability of the alternating pole surface type permanent magnet motor is further improved.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

An alternating pole permanent magnet motor rotor using mixed permanent magnets includes a rotor core segment, a magnetic conducting ring, a high energy density permanent magnet and a low energy density permanent magnet.

There are at least two rotor core segments, and they are all coaxially arranged; a magnetic conducting ring is coaxially arranged between two adjacent rotor core segments.

The alternating pole permanent magnet motor rotor can be used as an inner rotor as well as an outer rotor.

When the alternating pole permanent magnet motor rotor is used as the inner rotor, the layout includes.

1) Both the rotor core segment and the magnetic conductive ring are coaxially sleeved on the rotating shaft.

2) The outer surface of each rotor core segment is evenly distributed with p arc-shaped outer salient poles along the circumferential direction, where p is the number of motor pole pairs; an outer arc-shaped slot is formed between two adjacent outer salient poles, An outer tile-type permanent magnet is arranged in each outer arc-shaped slot, and each outer tile-type permanent magnet is a permanent magnet with high energy density.

3) On the inner annular surface of each rotor core segment, n inner arc-shaped grooves are uniformly distributed in the circumferential direction, and n≥p; the inner diameter of each inner arc-shaped groove is larger than the inner diameter of the rotor core segment, and two adjacent The rotor core segments between the inner arc-shaped slots constitute inner reinforcing ribs; an inner-tile-type permanent magnet is arranged in each inner-arc-shaped slot, and each inner tile-type permanent magnet is a low-energy density permanent magnet.

When the alternating pole permanent magnet motor rotor is used as the outer rotor, the layout includes.

(1) There are n outer arc grooves uniformly distributed on the outer annular surface of each rotor core segment along the circumferential direction, and n≥p; the outer diameter of each outer arc groove is smaller than the outer diameter of the rotor core segment, The rotor core segment between two adjacent outer arc-shaped slots constitutes an outer reinforcing rib; an outer tile-type permanent magnet is arranged in each outer arc-shaped slot, and each outer tile-type permanent magnet is a low-energy density permanent magnet ;

(2) p arc-shaped inner salient poles are evenly distributed on the inner surface of each rotor core segment along the circumferential direction, and an inner arc-shaped slot is formed between two adjacent inner salient poles, and each inner arc-shaped slot is An inner tile type permanent magnet is arranged, and each inner tile type permanent magnet is a high energy density permanent magnet.

The alternating pole permanent magnet motor rotor also has the following arrangement, whether it is used as an inner rotor or an outer rotor.

The electrical period angle of the high-energy-density permanent magnets on the two adjacent rotor core segments offset in the circumferential direction is 360°/2p.

The magnetization directions of all the outer tile permanent magnets located on the same rotor core segment are the same, and the magnetization directions of all inner tile permanent magnets located on the same rotor core segment are the same. The magnetization directions of the outer tiled permanent magnets and the inner tiled permanent magnets are opposite.

The magnetization directions of the outer tile-type permanent magnets on the two adjacent rotor core segments are opposite; the magnetization directions of the inner tile-type permanent magnets on the two adjacent rotor core segments are opposite.

Magnetic isolation slots are provided on both sides of each outer tile-type permanent magnet and each inner tile-type permanent magnet.

Coefficient of magnetic isolation slots on both sides of high energy density permanent magnets Wherein θ _b1 is the central angle of the magnetic isolation slot on both sides of the high energy density permanent magnet, θ _m1 is the central angle of the high energy density permanent magnet; the value range of k _c1 is 0-0.2.

Coefficient of magnetic isolation slots on both sides of low energy density permanent magnets Wherein θ _b2 is the central angle of the magnetic isolation slot on both sides of the low energy density permanent magnet, and the value of k _c2 ranges from 0 to 0.2.

The outer or inner circumference of the magnetic conducting ring is coaxially sleeved with an axially magnetized permanent magnet; it is assumed that the outer diameter of the axially magnetized permanent magnet is r1, the outer diameter of the high-energy density permanent magnet is r3, and the outer diameter of the high-energy density permanent magnet is r3. The inner diameter is r4, then r3≤r1≤r4.

The magnetization directions of the two axially magnetized permanent magnets located on both sides of the same rotor core segment are opposite.

Axial Length Factor of Magnetic Ring Wherein L _a is the axial length of the magnetic permeable ring, L _ef is the effective axial length of the motor as a whole; the value range of _ka is 0-0.1.

The pole arc coefficient α _p1 =θ _m1 p/(2π) of the high energy density permanent magnet, where θ _m1 is the central angle of the high energy density permanent magnet, and the value of α _p1 ranges from 0.35 to 0.75.

The pole arc coefficient α _p2 = θ _m2 n/(2π) of the low energy density permanent magnet, where n is the number of low energy density permanent magnet slots, θ _m2 is the central angle of the low energy density permanent magnet, and the value range of α _p2 is 0.7-0.99.

The high energy density permanent magnet is NdFeB, and the low energy density permanent magnet is ferrite.

After adopting the above structure, the present invention can further improve the torque output capability of the alternating pole surface type permanent magnet motor while saving the motor cost and weakening the magnetic leakage of the rotating shaft of the alternating pole surface type permanent magnet motor.

Description of drawings

Fig. 1 shows a schematic diagram of the two-dimensional structure of the rotor core segment when the present invention is used as an inner rotor.

FIG. 2 shows a two-dimensional schematic diagram of the magnetization direction of permanent magnets in two adjacent rotor core segments when the present invention is used as an inner rotor.

FIG. 3 shows a schematic diagram of the three-dimensional structure of the present invention when it is used as an inner rotor and does not contain an axially magnetized permanent magnet.

FIG. 4 shows the path diagram of the leakage magnetic flux at the end of the rotating shaft when the present invention is used as an inner rotor.

Figure 5 shows the main magnetic flux path diagram of the low energy density permanent magnet of the present invention as an inner rotor.

FIG. 6 shows a schematic diagram of the three-dimensional structure of the present invention when it is used as an inner rotor and contains axially magnetized permanent magnets.

FIG. 7 shows a two-dimensional schematic diagram of the magnetization direction of permanent magnets in two adjacent rotor core segments when the present invention is used as an outer rotor.

Fig. 8 shows a schematic diagram of the three-dimensional structure of the present invention as an outer rotor.

Figure 9 shows the electromagnetic torque comparison (half electrical cycle) of the present invention and a prior art machine.

Including:

10. Rotor core segment; 11. Outer salient pole; 12. Outer arc groove; 13. Inner reinforcing rib; 14. Inner arc groove; 15. Magnetic isolation slot; 16. Inner salient pole; 17. Outer reinforcing rib;

21. High energy density permanent magnet; 22. Low energy density permanent magnet;

30. Magnetic ring; 31. Axial magnetized permanent magnet;

40. The rotating shaft; 50. The leakage magnetic flux path at the end of the rotating shaft; 60. The main magnetic flux path.

Detailed ways

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

The present invention takes a 10-pole motor (5 pairs of poles, that is, p=5) as an example, and is separately described as an inner rotor and an outer rotor.

1. The rotor of alternating pole permanent magnet motor is used as the inner rotor

As shown in FIGS. 1 to 6 , an alternating pole permanent magnet motor rotor using hybrid permanent magnets includes a rotor core segment 10 , a magnetic permeable ring 30 , high energy density permanent magnets 21 and low energy density permanent magnets 22 .

The high energy density permanent magnet is preferably NdFeB, and the low energy density permanent magnet is preferably ferrite.

There are at least two rotor core segments, and a magnetic conducting ring is coaxially arranged between two adjacent rotor core segments.

In the present invention, two rotor core segments will be taken as an example for detailed description, and there will be one magnetic conducting ring. Two rotor core segments and a magnetic conducting ring are coaxially sleeved on the rotating shaft.

The outer surface of each rotor core segment is uniformly distributed with p arc-shaped outer salient poles along the circumferential direction, where p is the number of motor pole pairs, and p=5 in the present invention.

An outer arc-shaped slot is formed between two adjacent outer salient poles, and an outer tile-type permanent magnet is arranged in each outer arc-shaped slot, and each outer tile-type permanent magnet is a high-energy density permanent magnet.

On the inner annular surface of each rotor core segment, n inner arc-shaped grooves are uniformly distributed along the circumferential direction, and n≥p, in the present invention, preferably n=5.

The inner diameter of each inner arc groove is larger than the inner diameter of the rotor core segment.

The rotor core segment between the two adjacent inner arc slots constitutes the inner reinforcing rib 13; an inner tile permanent magnet is arranged in each inner arc slot, and each inner tile permanent magnet is a permanent magnet with low energy density. magnet.

The electrical period angle at which the outer tile-type permanent magnets (ie high-energy density permanent magnets) on two adjacent rotor core segments are offset in the circumferential direction is 360°/2p, which is preferably 36° in the present invention.

As shown in Figure 2, the magnetization directions of all outer tile-type permanent magnets located on the same rotor core segment are the same, and the magnetization directions of all inner tile-type permanent magnets located on the same rotor core segment are the same. The magnetization directions of the outer shingled permanent magnets and the inner shingled permanent magnets on one rotor core segment are opposite.

The magnetization directions of the outer tile-type permanent magnets on the two adjacent rotor core segments are opposite; the magnetization directions of the inner tile-type permanent magnets on the two adjacent rotor core segments are opposite.

Magnetic isolation slots 15 are provided on both sides of each outer tile-type permanent magnet and each inner tile-type permanent magnet.

Coefficient of magnetic isolation slots on both sides of outer tile permanent magnets Wherein θ _b1 is the central angle of the magnetic isolation slots on both sides of the outer tile type permanent magnet, θ _m1 is the central angle of the outer tile type permanent magnet; the value range of k _c1 is 0-0.2.

Coefficient of magnetic isolation slot on both sides of inner tile permanent magnet Wherein θ _b2 is the central angle of the magnetic isolation slot on both sides of the inner tile-type permanent magnet, and the value of k _c2 ranges from 0 to 0.2.

The outer circumference of the magnetic conducting ring is coaxially sleeved with an axially magnetized permanent magnet 31. The axially magnetized permanent magnet 31 can be either a high-energy density permanent magnet or a low-energy density permanent magnet. In the present invention, a high-energy permanent magnet is preferred. Density permanent magnets.

As shown in FIG. 9 , the arrangement of the axially magnetized permanent magnets 31 can greatly improve the torque output capability of the alternating pole permanent magnet motor.

Assuming that the outer diameter of the axially magnetized permanent magnet is r1, the outer diameter of the high energy density permanent magnet is r3, and the inner diameter of the high energy density permanent magnet is r4, then r3≤r1≤r4.

The magnetization directions of the two axially magnetized permanent magnets located on both sides of the same rotor core segment are opposite.

Axial Length Factor of Magnetic Ring Among them, L _a is the axial length of the magnetic permeable ring, and L _ef is the effective axial length of the motor, that is, the shaft length of all rotor cores plus the axial length of the magnetic permeable ring; the value range of _ka is 0-0.1.

The pole arc coefficient α _p1 =θ _m1 p/(2π) of the outer tile permanent magnet, where θ _m1 is the central angle of the outer tile permanent magnet, and the value range of α _p1 is 0.35-0.75.

The pole arc coefficient α _p2 =θ _m2 n/(2π) of the inner tile permanent magnet, where n is the number of inner tile permanent magnet slots, θ _m2 is the central angle of the inner tile permanent magnet, α _p2 The value range is 0.7-0.99.

An inner arc-shaped slot is provided on the inner side of the alternating pole permanent magnet motor for placing low energy density permanent magnets. Due to the existence of the inner arc-shaped slot, the magnetic resistance in the magnetic flux path of the outer tile-type permanent magnet through the magnetic flux leakage at the end of the rotating shaft increases, so the magnetic leakage at the end of the rotating shaft generated by the outer tile-type permanent magnet is reduced. Now, the leakage magnetic flux path 50 at the end of the rotating shaft is shown in FIG. 4 . Since the inner tile-type permanent magnet also adopts unipolar magnetization, the magnetization directions of the two adjacent low-energy density permanent magnets are opposite, so that the magnetic circuit can be closed by the stator core, the two-stage rotor core and the magnetic conducting ring. The loop: one segment of inner tile permanent magnets→outer salient poles→air gap→stator core→air gap→another segment of outer salient poles→another segment of inner tiled permanent magnets→magnetic conductive ring→return to the inner tile at the beginning type permanent magnet, such as the main magnetic flux path 60 of the inner tile type permanent magnet as shown in FIG. 5 . It is precisely because the main magnetic flux path of the inner tile-type permanent magnet is closed by the magnetic conducting ring, the magnetic flux leakage at the end of the rotating shaft is very small. In addition, the inner tile type permanent magnet can further increase the main magnetic flux of the motor, thereby improving the torque output capability of the alternating pole permanent magnet motor. As shown in FIG. 9 , the electromagnetic torque of the present invention is much higher than that of the background art 201611011019.1.

2. The rotor of alternating pole permanent magnet motor is used as the outer rotor

As shown in FIGS. 7 and 8 , an alternating pole permanent magnet motor rotor using hybrid permanent magnets also includes a rotor core segment 10 , a magnetic permeable ring 30 , high energy density permanent magnets 21 and low energy density permanent magnets 22 .

There are at least two rotor core segments, and a magnetic conducting ring is coaxially arranged between two adjacent rotor core segments.

In the present invention, two rotor core segments will be taken as an example for detailed description, and there will be one magnetic conducting ring.

The stator is coaxially fixed and sleeved on the outer circumference of the fixed shaft, and the two form an integrated structure; two ends of the fixed shaft respectively protrude from both ends of the stator, and each of the two extended ends of the fixed shaft is sleeved with a bearing.

Two rotor core segments and a magnetic conducting ring are coaxially sleeved on the outer circumference of the stator, and are coaxially mounted on the bearing through the support body.

P arc-shaped inner salient poles are uniformly distributed on the inner surface of each rotor core segment along the circumferential direction, and preferably p=5 in the present invention.

An inner arc slot is formed between two adjacent inner salient poles, and an inner tile type permanent magnet is arranged in each inner arc slot, and each inner tile type permanent magnet is a permanent magnet with high energy density.

On the outer annular surface of each rotor core segment, n outer arc grooves are uniformly distributed along the circumferential direction, and n≥p, preferably n=5 in the present invention.

The outer diameter of each outer arc-shaped slot is smaller than the outer diameter of the rotor core segment, and the rotor core segment between two adjacent outer arc-shaped slots constitutes an outer reinforcing rib 17 .

An outer tile-type permanent magnet is arranged in each outer arc-shaped slot, and each outer tile-type permanent magnet is a low-energy density permanent magnet.

The electrical period angle at which the inner tile-type permanent magnets (ie high-energy density permanent magnets) on two adjacent rotor core segments are offset in the circumferential direction is 360°/2p, which is preferably 36° in the present invention.

As shown in Figure 7, the magnetization directions of all the outer tile-type permanent magnets located on the same rotor core segment are the same, and the magnetization directions of all the inner tile-type permanent magnets located on the same rotor core segment are the same. The magnetization directions of the outer shingled permanent magnets and the inner shingled permanent magnets on one rotor core segment are opposite.

The magnetization directions of the outer tile-type permanent magnets on the two adjacent rotor core segments are opposite; the magnetization directions of the inner tile-type permanent magnets on the two adjacent rotor core segments are opposite.

Magnetic isolation slots 15 are provided on both sides of each outer tile-type permanent magnet and each inner tile-type permanent magnet.

Coefficient of magnetic isolation slots on both sides of high energy density permanent magnets Wherein θ _b1 is the central angle of the magnetic isolation slot on both sides of the high energy density permanent magnet, θ _m1 is the central angle of the high energy density permanent magnet; the value range of k _c1 is 0-0.2.

Coefficient of magnetic isolation slots on both sides of low energy density permanent magnets Wherein θ _b2 is the central angle of the magnetic isolation slot on both sides of the low energy density permanent magnet, and the value of k _c2 ranges from 0 to 0.2.

The inner circumference of the magnetic conducting ring is coaxially sleeved with an axially magnetized permanent magnet. The axially magnetized permanent magnet can be either a high-energy density permanent magnet or a low-energy density permanent magnet. In the present invention, a high-energy density permanent magnet is preferred. Permanent magnets.

As shown in FIG. 9 , the arrangement of the axially magnetized permanent magnets 31 can greatly improve the torque output capability of the alternating pole permanent magnet motor.

Assuming that the outer diameter of the axially magnetized permanent magnet is r1, the outer diameter of the high energy density permanent magnet is r3, and the inner diameter of the high energy density permanent magnet is r4, then r3≤r1≤r4.

The magnetization directions of the two axially magnetized permanent magnets located on both sides of the same rotor core segment are opposite.

Axial Length Factor of Magnetic Ring Wherein L _a is the axial length of the magnetic permeable ring, L _ef is the effective axial length of the whole motor; the value range of _ka is 0-0.1.

The pole arc coefficient α _p1 =θ _m1 p/(2π) of the high energy density permanent magnet, where θ _m1 is the central angle of the high energy density permanent magnet, and the value of α _p1 ranges from 0.35 to 0.75.

The pole arc coefficient α _p2 = θ _m2 n/(2π) of the low energy density permanent magnet, where n is the number of low energy density permanent magnet slots, θ _m2 is the central angle of the low energy density permanent magnet, and the value range of α _p2 is 0.7-0.99.

When used as an outer rotor, an outer arc-shaped slot is arranged on the outer side of the alternating pole permanent magnet motor for placing low energy density permanent magnets. Due to the existence of the outer arc-shaped slot, the magnetic resistance in the magnetic flux path of the inner tile-type permanent magnet through the leakage flux at the end of the fixed shaft becomes larger, so the leakage of the inner tile-type permanent magnet at the end of the fixed shaft is generated. Magnetism decreased. Since the outer tile-type permanent magnet also adopts unipolar magnetization, the magnetization directions of the two adjacent low-energy density permanent magnets are opposite, and the main magnetic flux path of the outer tile-type permanent magnet is closed by the magnetic conducting ring. The resulting magnetic flux leakage at the end of the fixed shaft is very small. In addition, the outer tile type permanent magnet can further increase the main magnetic flux of the motor, thereby improving the torque output capability of the alternating pole permanent magnet motor.

The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above-mentioned embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention. These equivalent transformations All belong to the protection scope of the present invention.

Claims (10)

1. a kind of alternating pole permanent magnet motor rotor adopting hybrid permanent magnet, it is characterized in that: comprise rotor core segment, magnetic permeable ring, high energy density permanent magnet and low energy density permanent magnet; There are at least two rotor core segments, and they are all coaxially arranged; a magnetic conducting ring is coaxially arranged between two adjacent rotor core segments; The rotor of the alternating pole permanent magnet motor can be used as an inner rotor or an outer rotor; When the alternating pole permanent magnet motor rotor is used as the inner rotor, the layout methods include: 1) The rotor core segment and the magnetic conductive ring are coaxially sleeved on the rotating shaft; 2) The outer surface of each rotor core segment is evenly distributed with p arc-shaped outer salient poles along the circumferential direction, where p is the number of motor pole pairs; an outer arc-shaped slot is formed between two adjacent outer salient poles, An outer tile-type permanent magnet is arranged in each outer arc-shaped slot, and each outer tile-type permanent magnet is a high-energy density permanent magnet; 3) On the inner annular surface of each rotor core segment, n inner arc-shaped grooves are uniformly distributed in the circumferential direction, and n≥p; the inner diameter of each inner arc-shaped groove is larger than the inner diameter of the rotor core segment, and two adjacent The rotor core segment between the inner arc slots constitutes an inner reinforcing rib; an inner tile permanent magnet is arranged in each inner arc slot, and each inner tile permanent magnet is a low energy density permanent magnet; When the alternating pole permanent magnet motor rotor is used as the outer rotor, the layout includes: (1) There are n outer arc grooves uniformly distributed on the outer annular surface of each rotor core segment along the circumferential direction, and n≥p; the outer diameter of each outer arc groove is smaller than the outer diameter of the rotor core segment, The rotor core segment between two adjacent outer arc-shaped slots constitutes an outer reinforcing rib; an outer tile-type permanent magnet is arranged in each outer arc-shaped slot, and each outer tile-type permanent magnet is a low-energy density permanent magnet ; (2) p arc-shaped inner salient poles are evenly distributed on the inner surface of each rotor core segment along the circumferential direction, and an inner arc-shaped slot is formed between two adjacent inner salient poles, and each inner arc-shaped slot is An inner tile-type permanent magnet is arranged, and each inner tile-type permanent magnet is a permanent magnet with high energy density; The alternating pole permanent magnet motor rotor also has the following layouts, whether it is used as an inner rotor or an outer rotor: The electrical period angle at which the outer tile-type permanent magnets or the inner tile-type permanent magnets on the two adjacent rotor core segments are offset in the circumferential direction is 360°/2p; The magnetization directions of all the outer tile permanent magnets located on the same rotor core segment are the same, and the magnetization directions of all inner tile permanent magnets located on the same rotor core segment are the same. The magnetization directions of the outer tile-type permanent magnet and the inner tile-type permanent magnet are opposite; The magnetization directions of the outer tile-type permanent magnets on the two adjacent rotor core segments are opposite; the magnetization directions of the inner tile-type permanent magnets on the two adjacent rotor core segments are opposite. 2. The alternating pole permanent magnet motor rotor adopting hybrid permanent magnets according to claim 1, is characterized in that: both sides of each outer tile type permanent magnet and each inner tile type permanent magnet are provided with magnetic isolation groove. 3. The alternating pole permanent magnet motor rotor adopting the hybrid permanent magnet according to claim 2, is characterized in that: the coefficient of the magnetic isolation slot on both sides of the high energy density permanent magnet Wherein θ _b1 is the central angle of the magnetic isolation slot on both sides of the high energy density permanent magnet, θ _m1 is the central angle of the high energy density permanent magnet; the value range of k _c1 is 0-0.2. 4. The alternating pole permanent magnet motor rotor using hybrid permanent magnets according to claim 2 is characterized in that: the coefficient of the magnetic isolation slots on both sides of the low energy density permanent magnets Wherein θ _b2 is the central angle of the magnetic isolation slot on both sides of the low energy density permanent magnet, θ _m2 is the central angle of the low energy density permanent magnet, and k _c2 ranges from 0 to 0.2. 5. The alternating pole permanent magnet motor rotor adopting hybrid permanent magnets according to claim 1, is characterized in that: the outer circumference or inner circumference of the magnetic conducting ring is coaxially sleeved with axially magnetized permanent magnets; The outer diameter of the permanent magnet is r1, the outer diameter of the high energy density permanent magnet is r3, and the inner diameter of the high energy density permanent magnet is r4, then r3≤r1≤r4. 6 . The alternating-pole permanent magnet motor rotor using hybrid permanent magnets according to claim 5 , wherein the magnetization directions of the two axially magnetized permanent magnets located on both sides of the same rotor core segment are opposite. 7 . 7. The alternating-pole permanent magnet motor rotor using hybrid permanent magnets according to claim 1, characterized in that: the axial length coefficient of the magnetically permeable ring Wherein L _a is the axial length of the magnetic permeable ring, L _ef is the effective axial length of the whole motor; the value range of _ka is 0-0.1. 8. The alternating pole permanent magnet motor rotor using hybrid permanent magnets according to claim 1, characterized in that: the pole arc coefficient α _p1 =θ _m1 p/(2π) of the high energy density permanent magnets, wherein θ _m1 is high The central angle of the energy density permanent magnet, α _p1 ranges from 0.35 to 0.75. 9 . The alternating pole permanent magnet motor rotor using hybrid permanent magnets according to claim 1 , wherein: the pole arc coefficient α _p2 =θ _m2 n/(2π) of the low energy density permanent magnets, wherein n is low energy The number of density permanent magnet slots, θ _m2 is the central angle of the low energy density permanent magnet, and the value range of α _p2 is 0.7-0.99. 10 . The alternating pole permanent magnet motor rotor using hybrid permanent magnets according to claim 1 , wherein the high energy density permanent magnets are NdFeB and the low energy density permanent magnets are ferrites. 11 .