CN107425629A - A kind of permanent magnet machine rotor - Google Patents

Abstract

The invention discloses a permanent magnet motor rotor, which comprises an alternating pole permanent magnet motor rotor core, two conventional permanent magnet motor rotor cores and tile-type permanent magnets. The axial length of one conventional permanent magnet motor rotor core is 0.1-0.3 times the axial length of the entire rotor core, and is coaxially arranged on both sides of the alternating pole permanent magnet motor rotor core. The outer or inner circumferential surface of the rotor core of the alternating pole permanent magnet motor is uniformly arranged with p salient poles along the circumferential direction, and permanent magnet slots are formed between two adjacent salient poles; where p is the number of pole pairs of the motor; conventional permanent magnet 2p permanent magnet slots 1 are evenly distributed along the circumferential direction on the outer or inner peripheral surface of the rotor core of the motor; each permanent magnet slot 1 and each permanent magnet slot 2 are nested with a tile-type permanent magnet. The invention adopts the method of combining the traditional surface type permanent magnet motor rotor and the alternating pole surface type permanent magnet motor rotor to reduce the cost of the motor and ensure the torque output capability, and at the same time weaken the magnetic flux leakage and magnetization at the end of the rotating shaft.

Description

A permanent magnet motor rotor

technical field

The invention relates to the field of motor design, in particular to a permanent magnet motor rotor.

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, aerospace and other fields. Different permanent magnet motor rotor structures make the magnetic circuit different, which makes the motor performance, control system, manufacturing process and applicable occasions also different. According to the coordinate transformation theory of the permanent magnet synchronous motor, the direct-axis magnetic circuit and the quadrature-axis magnetic circuit of the surface permanent magnet motor are shown in Figure 1. Direct axis magnetic circuit 12: permanent magnet→air gap→stator core→air gap→adjacent permanent magnet→rotor core→back to 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 13: the boundary of two permanent magnets→air gap→stator core→air gap→the boundary of two adjacent permanent magnets→rotor core→back to the boundary of the first 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 its direct-axis inductance is equal to the quadrature-axis inductance.

The expression of the electromagnetic torque T _e 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 i _d and i _q are the direct axis of the armature winding 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 T _r are the permanent magnet torque component and the reluctance torque component, respectively.

Since the direct-axis inductance of the surface permanent magnet motor is equal to the quadrature-axis inductance, its reluctance torque component is zero. Contains only the permanent magnet torque component, that is, the expression of the electromagnetic torque T _e of the surface permanent magnet motor, which can be expressed by formula (b).

The manufacturing process of the surface permanent magnet motor rotor is simple, and its output torque does not contain the 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. Traditional surface permanent magnet motors use a large amount of expensive rare earth permanent magnet materials, which is the main reason for their high production costs. In order to reduce its cost, the invention patent with application number 200710010915.0 provides a surface type permanent magnet servo motor rotor, permanent magnets and "false poles" are arranged alternately, and the number of permanent magnets is only half of the traditional surface type permanent magnet motor. The permanent magnet material is saved, thereby reducing the overall cost of the motor.

However, as pointed out in the article published in IEEE Magnetics Society: Comparative Analysis of End Effect in Partitioned Stator Flux Reversal Machines Having Surface-Mounted and Consequent Pole Permanent Magnets, permanent magnet motors with alternating pole structures have serious magnetic flux leakage at the end.

In addition, there will be unipolar flux leakage at the end of the rotating shaft of the alternating pole surface permanent magnet motor, which will cause the end of the rotating shaft of the motor to be magnetized, which will affect the reliability and safety of the entire motor system. Invention patent 201611011019.1 proposes the method of segmenting the rotor to provide a magnetic flux leakage path inside the rotor and the shaft, which weakens the magnetization at the end of the shaft. However, there is an axial flux leakage at the junction of the two rotors, and its flux leakage path is shown in Figure 15: permanent magnets of one rotor → air gap → permanent magnets on the adjacent rotor → rotor core → back to the original Permanent magnets. Although the invention patent 201611011019.1 can reduce the magnetic flux leakage at the end of the rotating shaft and avoid its magnetization, the magnetic flux leakage at the junction of the two rotors will reduce the torque output capability and the utilization rate of the permanent magnets is low.

Contents of the invention

The technical problem to be solved in the present invention is to provide a permanent magnet motor rotor for the above-mentioned deficiencies in the prior art. The permanent magnet motor rotor adopts a combination of a traditional surface permanent magnet motor rotor and an alternating pole surface permanent magnet motor rotor. The method, while reducing the cost of the motor and ensuring the torque output capability, weakens the magnetic flux leakage and the magnetization at the end of the rotating shaft.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

A permanent magnet motor rotor includes a rotor iron core, a rotating shaft and tile-type permanent magnets, and the rotor iron core is coaxially arranged on the rotating shaft.

The rotor core includes an alternating pole permanent magnet motor rotor core and a conventional permanent magnet motor rotor core arranged side by side on both sides of the alternating pole permanent magnet motor rotor core.

The axial length of each conventional permanent magnet motor rotor core is 0.1-0.3 times the axial length of the entire rotor core.

On the outer or inner circumferential surface of the rotor core of the alternating pole permanent magnet motor, p salient poles are evenly distributed along the circumferential direction, and a permanent magnet slot 2 is formed between two adjacent salient poles; where p is the number of pole pairs of the motor.

2p permanent magnet slots 1 are evenly distributed along the circumferential direction on the outer or inner circumferential surface of the rotor core of a conventional permanent magnet motor.

A tile-type permanent magnet is embedded in each permanent magnet slot 1 and each permanent magnet slot 2; wherein, the tile-type permanent magnet nested in the permanent magnet slot 1 is tile-type permanent magnet 1, and the nesting The tile type permanent magnet in the permanent magnet slot two is the tile type permanent magnet two.

The magnetization directions of two adjacent tile-type permanent magnets are opposite, and form a pair of magnetic poles.

There is a magnetic separation groove between the second tile-type permanent magnet and the adjacent salient poles; the magnetization direction of all the second tile-type permanent magnets is the same, and the second tile-type permanent magnet forms a pair with one of the adjacent salient poles. magnetic pole.

The axial length of the second tile-type permanent magnet is less than or equal to the axial length of the rotor core of the alternating pole permanent magnet motor.

The axial length of each conventional permanent magnet motor rotor core is 0.2-0.3 times the axial length of the entire rotor core.

The first tile-type permanent magnet and the second tile-type permanent magnet adopt radial magnetization or parallel magnetization.

The axial lengths of the two conventional permanent magnet motor rotor cores are equal.

After adopting the above structure, the present invention uses the method of combining the traditional surface permanent magnet motor rotor and the alternating pole surface permanent magnet motor rotor to reduce the cost of the motor and ensure the torque output capability while weakening the magnetic flux leakage at the end of the rotating shaft and its magnetization. In addition, the motor can run electrically or generate electricity. Further, the present invention can be used for both inner rotor motors and outer rotor motors. After being used as an outer rotor motor, the torque output capability can be further improved.

Description of drawings

FIG. 1 shows a schematic structural view of a rotor core of a conventional permanent magnet motor in Embodiment 1.

Fig. 2 shows a schematic structural view of the rotor core of the alternating pole permanent magnet motor in Embodiment 1.

FIG. 3 shows a schematic structural view of a permanent magnet motor rotor without axial magnetic isolation slots in Embodiment 1. FIG.

FIG. 4 shows a schematic structural view of a permanent magnet motor rotor in Embodiment 1 when there are axial magnetic isolation slots.

FIG. 5 shows a schematic diagram of the magnetic flux path of the end magnetic flux leakage of a permanent magnet motor rotor in Embodiment 1. FIG.

FIG. 6 shows a schematic structural view of the rotor core of a conventional permanent magnet motor in Embodiment 2.

Fig. 7 shows a schematic structural view of the rotor core of the alternating pole permanent magnet motor in Embodiment 2.

Fig. 8 shows a schematic structural view of a permanent magnet motor rotor without axial magnetic isolation slots in Embodiment 2.

FIG. 9 shows a schematic structural view of a rotor of a permanent magnet motor in Embodiment 2 when there are axial magnetic isolation slots.

Fig. 10 shows a comparison diagram of electromagnetic torque between a permanent magnet motor rotor in Embodiment 1 and a motor rotor in the prior art.

FIG. 11 shows the relationship diagram of ΔT _avg changing with k _l in Example 1.

Fig. 12 shows the relationship diagram of the variation of ΔB _e with k _l in Example 1.

Fig. 13 shows the relationship diagram of the variation of ΔV _m with k _l in Example 1.

Fig. 14 shows the magnetic density comparison diagram of the present invention (when k _l =0.3) and the alternating pole permanent magnet motor in the embodiment 1 at the 40mm end of the rotating shaft.

Fig. 15 shows a schematic diagram of the flux leakage path at the junction of two rotors in the background technology 201611011019.1.

Fig. 16 shows the magnetic flux leakage analysis diagram at the junction of the conventional permanent magnet motor rotor core and the alternating pole permanent magnet motor rotor core according to the present invention.

Figure 17 shows a schematic diagram of the magnetic flux paths of the present invention.

Including:

1. Conventional permanent magnet motor rotor core; 11. Permanent magnet slot 1; 12. Direct axis magnetic circuit; 13. Quadrature axis magnetic circuit;

2. Alternating pole permanent magnet motor rotor core; 21. Salient pole; 22. Permanent magnet slot two; 23. Magnetic isolation slot;

3. Rotating shaft; 4. Tile-type permanent magnet; 5. Axial magnetic isolation groove; 6. Magnetic flux leakage path; 7. Axial magnetic flux leakage path;

8. Flux paths in the rotor of an alternating pole permanent magnet motor.

detailed description

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

Embodiment 1 The permanent magnet motor rotor is an inner rotor

As shown in FIG. 3 , FIG. 4 and FIG. 5 , a permanent magnet motor rotor includes a rotor core, a rotating shaft 3 and tile-type permanent magnets 4 , and the rotor core is coaxially arranged on the rotating shaft.

The rotor core includes an alternating pole permanent magnet motor rotor core 1 and a conventional permanent magnet motor rotor core 2 arranged side by side and coaxially on both sides of the alternating pole permanent magnet motor rotor core.

As shown in FIG. 1 , 2p permanent magnet slots 11 are evenly distributed along the circumferential direction on the outer circumferential surface of the rotor core of a conventional permanent magnet motor. Among them, p is the number of motor pole pairs.

The present invention takes a 10-pole inner-rotor motor as an example to describe in detail, that is, p=5.

A tile-type permanent magnet 4 is nested in each permanent magnet slot 1; wherein, the tile-type permanent magnet nested in the permanent magnet slot 1 is a tile-type permanent magnet 1, that is, a conventional permanent magnet motor rotor 10 tile-type permanent magnets are nested on the outer peripheral surface of the iron core.

The magnetization directions of two adjacent tile-type permanent magnets are opposite, and form a pair of magnetic poles.

The axial lengths of the two conventional permanent magnet motor rotor cores are preferably equal.

The polar arc coefficient of tile-type permanent magnet 1 in the rotor core of a conventional permanent magnet motor α _p2 =θ _m p/π, where θ _m is the central angle of the tile-type permanent magnet in Figure 1, and the value range of α _p2 is 0.7- 1.0.

As shown in FIG. 2 , p salient poles 21 are uniformly arranged on the outer circumferential surface of the rotor core of the alternating pole permanent magnet motor along the circumferential direction, and a permanent magnet slot 22 is formed between two adjacent salient poles.

A tile-type permanent magnet 4 is nested in each permanent magnet slot 2, and the tile-type permanent magnet nested in the permanent magnet slot 2 is assumed to be tile-type permanent magnet 2.

Between the second tile-type permanent magnet and the adjacent salient poles, a magnetic separation groove 23 is arranged, that is, the central angle of the second tile-type permanent magnet is smaller than or equal to the central angle of the second permanent magnet groove.

The magnetization directions of all tile-type permanent magnets 2 are the same, and the tile-type permanent magnet 2 forms a pair of magnetic poles with one of the adjacent salient poles.

Pole arc coefficient α _p1 = θ _m p/(2π) of tile permanent magnet 2 in the rotor of alternating pole permanent magnet motor, where θ _m is the central angle of tile permanent magnet 2 in Fig. 2 . The value range of α _p1 is 0.35-0.75.

The coefficient of the magnetic isolation slot (that is, the circumferential magnetic isolation slot) of the second tile permanent magnet in the rotor of the alternating pole permanent magnet motor Where θ _b is the central angle of the circumferential magnetic isolation slot. The value range of k _c is 0-0.2.

Axial length coefficients of tile permanent magnet 2 and axial isolation slots in alternating pole permanent magnet motor rotors Among them, L _b is the axial length of the axial magnetic separation slot, and L _m is the axial length of the rotor core in the alternating pole permanent magnet motor. Wherein, the value range of k _a is 0-0.1.

Further, the axial length of the second tile-type permanent magnet is less than or equal to the axial length of the rotor core of the alternating pole permanent magnet motor.

Further, the above-mentioned tile-type permanent magnet 1 and tile-type permanent magnet 2 are preferably magnetized radially or parallelly, but other known magnetization methods are also used, which are within the protection scope of the present invention.

Further, as shown in FIG. 4 , axial magnetic isolation slots 5 are provided between the rotor cores of the alternating pole permanent magnet motor and the rotor cores of the two conventional permanent magnet motors.

The axial length of each conventional permanent magnet motor rotor core is 0.1-0.3 times, more preferably 0.2-0.3 times, the axial length of the entire rotor core. In the present invention, the axial lengths of the two conventional permanent magnet motor rotor cores are both 0.3 times the axial length of the entire rotor core.

It is assumed that the ratio of the axial length of the rotor core of a conventional permanent magnet motor to the axial length of the entire rotor core is k _l .

Next, for the average electromagnetic torque, the magnetic density at the end of the rotating shaft and the amount of permanent magnets, the incremental parameters are respectively established, as shown in formula (1) - formula (3).

In the formula, ΔT _avg is the average electromagnetic torque increment; ΔB _e is the magnetic density increment at the end of the rotating shaft; ΔV _m is the permanent magnet volume increment; T _{avg_0} is the average motor torque of the alternating pole permanent magnet motor; B _{e_0} is The flux density of the shaft end of the alternating pole permanent magnet motor; V _{m_0} is the permanent magnet volume of the conventional permanent magnet motor; T _{avg_x} is the average motor torque of the permanent magnet motor of the present invention; _{Be_x} is the shaft end of the permanent magnet motor of the present invention Magnetic density; V _{m_x} is the permanent magnet volume of the permanent magnet motor of the present invention.

The relationship of ΔT _avg , ΔB _e and ΔV _m with k _l is shown in Figure 11 , Figure 12 and Figure 13 . As k _l becomes larger, ΔT _avg and ΔB _e become larger gradually, and ΔV _m becomes smaller gradually.

As shown in Figure 10, when k _l reaches 0.3, its torque output capability is not only equivalent to that of conventional permanent magnet motors, but also saves 20% of permanent magnets. Therefore, in the case of ensuring the torque output capability, the permanent magnets should be saved as much as possible, and the magnetic flux leakage at the end of the rotating shaft should be weakened as much as possible; the preferred range of k _l is 0.2-0.3.

The structural design of the above permanent magnet motor rotor increases the reluctance of the unipolar leakage flux path 6 of the alternating pole permanent magnet motor, as shown in Figure 5, resulting in most of its leakage flux not passing through the end of the shaft , which weakens the unipolar flux leakage at the end of the shaft.

According to the "principle of least reluctance", magnetic flux always forms a loop through the path with less reluctance. The magnetic flux path of the permanent magnet on the rotor of the alternating pole permanent magnet motor of the present invention: permanent magnet→rotor core→air gap→stator core→air gap→back to the original permanent magnet. Since the conventional permanent magnet motor rotor is located on both sides, the axial flux leakage path 7 of the permanent magnet on the conventional permanent magnet motor rotor: permanent magnet → air gap → stator core → air gap → rotor core → back to the permanent magnet. However, since the direction of the magnetic flux path 8 of the rotor of the alternating pole permanent magnet motor is opposite to the direction of the axial leakage flux of the permanent magnets on the rotor of the conventional permanent magnet motor, it is opposite on the salient pole core of the alternating pole rotor, as shown in FIG. 16 . Moreover, the axial leakage flux of the permanent magnets on the rotor of the conventional permanent magnet motor is much smaller than that of the permanent magnets on the rotor of the alternating pole permanent magnet motor. The flux of the magnets is forced back to the main flux path of the conventional permanent magnet motor rotor, as shown in Figure 17. Therefore, the axial flux leakage of the present invention is very small.

The present invention (when k _l =0.3) and the magnetic density at the end of the rotating shaft of the alternating pole permanent magnet motor at 40mm are shown in Figure 14, as can be seen from the figure, the present invention can effectively weaken the unipolarity at the end of the rotating shaft Flux leakage.

Embodiment 2 The rotor of the permanent magnet motor is an outer rotor

The structure and principle of embodiment 2 and embodiment 1 are basically the same, and the differences are as follows:

As shown in Figures 6-9, 2p permanent magnet slots-11 are evenly arranged along the circumferential direction of the inner circumferential surface of the rotor core of a conventional permanent magnet motor, and each permanent magnet slot-11 is nested with a tile-type permanent magnet- .

The p salient poles 21 are evenly arranged along the circumferential direction of the inner circumferential surface of the rotor core of the alternating pole permanent magnet motor, a permanent magnet slot 22 is formed between two adjacent salient poles, and a permanent magnet slot 22 is nested in each permanent magnet slot 22 Tile type permanent magnet two.

After the rotor of the permanent magnet motor of the present invention is used as an outer rotor, the utilization ratio of the space of the stator and the rotor can be improved, and the torque output capability can be further improved.

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

Claims (5)

1. A kind of 1. permanent magnet machine rotor, it is characterised in that：It is same including rotor core, rotating shaft and tile type permanent magnet, rotor core Axle is arranged in rotating shaft；

   Rotor core includes Consequent pole permanent magnet motor rotor core and is disposed in parallel in Consequent pole permanent magnet motor rotor core both sides Conventional permanent magnet electric machine rotor iron core；

   The axial length of each Conventional permanent magnet electric machine rotor iron core is 0.1-0.3 times of whole rotor core axial length；

   The excircle or inner circumferential surface of Consequent pole permanent magnet motor rotor core are circumferentially uniformly laid with p salient pole, and adjacent two A permanent magnet trough two is formed between individual salient pole；Wherein, p is motor number of pole-pairs；

   The excircle or inner circumferential surface of Conventional permanent magnet electric machine rotor iron core are circumferentially uniformly laid with 2p permanent magnet trough one；

   Each permanent magnet trough one and each nested tile type permanent magnet in each permanent magnet trough two；Wherein, it is nested in permanent magnet Tile type permanent magnet in groove one is tile type permanent magnet one, and the tile type permanent magnet being nested in permanent magnet trough two is tile type Permanent magnet two；

   The magnetizing direction of two neighboring tile type permanent magnet one is on the contrary, and a pair of magnetic poles of formation；

   Magnet isolation tank is provided between tile type permanent magnet two and Adjacent salient poles；The magnetizing direction of all tile type permanent magnets two is equal Identical, tile type permanent magnet two forms a pair of magnetic poles with one of Adjacent salient poles.
2. 2. permanent magnet machine rotor according to claim 1, it is characterised in that：The axial length of tile type permanent magnet two is less than Or the axial length equal to Consequent pole permanent magnet motor rotor core.
3. 3. permanent magnet machine rotor according to claim 1, it is characterised in that：The axial direction of Conventional permanent magnet electric machine rotor iron core is long Spend for 0.2-0.3 times of whole rotor core axial length.
4. 4. permanent magnet machine rotor according to claim 1, it is characterised in that：Tile type permanent magnet one and tile type permanent magnet Two use radial magnetizing or parallel magnetization.
5. 5. permanent magnet machine rotor according to claim 1, it is characterised in that：The axle of two Conventional permanent magnet electric machine rotor iron cores To equal length.