A double-stator double-salient-pole permanent magnet motor

Abstract

The present invention relates to the technical field of stator permanent magnet motors, and in particular to a dual-stator double-salient pole permanent magnet motor, comprising an outer stator, a rotor and an inner stator which are arranged coaxially in sequence from the outside to the inside, and is characterized in that the outer stator comprises an outer stator core and an armature winding, the inner surface of the outer stator core is provided with a plurality of outer stator core teeth protruding in the axial direction, outer stator slots are provided between adjacent outer stator core teeth, and the armature winding is wound on the outer stator core teeth; the inner stator comprises a permanent magnet and an annular inner stator core, the permanent magnet is radially embedded in the inner stator core; the rotor is arranged between the outer stator and the inner stator, and comprises a rotor iron block and a non-magnetic conductive connection device; the number of outer stator slots N is os =6k, number of rotor iron blocks N r =4k, 8k or 4k-1, number of permanent magnets N pm =3k. This motor can effectively solve the problem of large torque pulsation existing in traditional motor structures while dissipating heat well and not increasing the loss of the rotor core and permanent magnets.

Description

Technical field

[0001] The present invention belongs to the technical field of motors, and in particular relates to a double-stator double-salient-pole permanent magnet motor. [Background Technology]

[0002] A dual-stator doubly salient permanent magnet motor (DSPMM) is a type of stator-type permanent magnet motor with two stators. Compared to traditional DSPMMs, DSPMMs offer advantages such as high efficiency and power density due to the placement of permanent magnets and armature windings on two stators, resulting in better space utilization. This has garnered widespread attention in the electrical engineering community due to its advantages.

[0003] However, when the number of outer stator slots N of the three-phase double-stator doubly salient permanent magnet motor is os 、Number of rotor iron blocks r and the number of permanent magnets N pm Continue to use the traditional ratio (ie N os :N r :N pm =6k:6k±2k:2k, k is a positive integer), the torque pulsation is very large, which limits the further promotion and application of this motor in industrial production.

[0004] For example, Chinese patent publication CN105978270A discloses a stator-partitioned double-salient-pole permanent-magnet brushless motor. This improved motor comprises, from outside to inside, a coaxial outer stator, an intermediate rotor, and an inner stator. The outer stator consists of an annular stator core and multiple permanent magnets, which are embedded in the stator core at intervals along the circumference, with each pair of permanent magnets forming a pole pair. The intermediate rotor consists of a rotor core and a non-magnetic connecting structure, which is evenly embedded in the rotor core along the circumference and divides the rotor core into multiple rotor core blocks. The inner stator has a salient-pole structure, with armature windings wound around the salient-pole teeth. The windings and permanent magnets are placed separately, with the permanent magnets placed on the outer stator. This allows heat generated by the permanent magnets to be dissipated through the housing, making them easier to cool and effectively preventing irreversible demagnetization. The split rotor structure effectively reduces rotor core losses and improves motor efficiency.

[0005] Disadvantage analysis:

[0006] 1) In the above-mentioned improved motor, the number of permanent magnets is increased to be equal to the number of stator slots. This does fundamentally eliminate the problems of magnetic circuit asymmetry and three-phase flux imbalance, but this is accompanied by a significant increase in the amount of permanent magnets used and a deterioration in the utilization rate of permanent magnets.

[0007] 2) According to the traditional quantitative ratio, when the number of salient pole stator slots is 6, the number of rotor blocks is 4 or 8, and the number of permanent magnets is 2. However, in the above-mentioned improved motor, the number of rotor blocks is increased to 10 and the number of permanent magnets is increased to 6. The permanent magnet loss increases with the increase in the number of permanent magnets and rotor blocks.

[0008] 3) The heat sources of a stator-partitioned doubly salient permanent magnet motor include stator core loss, rotor core loss, permanent magnet eddy current loss, and armature winding copper loss. Typically, the armature winding copper loss is greater than the losses in the other three components, generating more heat. In the improved motor described above, placing the armature winding, which represents a greater heat source, in the inner stator slots makes heat dissipation through the inner stator shaft more difficult. The permanent magnets, which represent a smaller heat source, are placed on the outer stator and dissipate heat through the housing, failing to fully utilize the housing's excellent heat dissipation capabilities.

[0009] 4) The rotor of the motor described in the above-mentioned existing patent adopts a split structure. Although it can reduce rotor loss, the number of rotor core blocks increases, and the amount of core used and the frequency will increase, which will aggravate the loss. [Summary of the invention]

[0010] Based on the deficiencies in the prior art, the present invention provides a dual-stator double-salient pole permanent magnet motor, which can effectively solve the problem of large torque pulsation in traditional motor structures while achieving good heat dissipation and without increasing the loss of the rotor core and permanent magnets.

[0011] To achieve the above-mentioned object, the present invention provides the following technical solution: a double-stator double-salient-pole permanent magnet motor, comprising an outer stator, a rotor and an inner stator arranged coaxially from the outside to the inside, the outer stator comprising an outer stator core and an armature winding, a plurality of outer stator core teeth protruding in the axial direction are provided on the inner surface of the outer stator core, outer stator slots are provided between adjacent outer stator core teeth, the armature winding is wound on the outer stator core teeth; the inner stator comprises a permanent magnet and an annular inner stator core. The core, the permanent magnet is radially embedded in the inner stator core; the rotor is annular and is arranged between the outer stator and the inner stator, including a plurality of arc-shaped rotor iron blocks and non-magnetic connecting devices filled between adjacent rotor iron blocks; the rotor is formed by alternately combining the rotor iron blocks and the non-magnetic connecting devices, the inner diameter of the rotor iron block is equal to the inner diameter of the non-magnetic connecting device, and the outer diameter of the rotor iron block is equal to the outer diameter of the non-magnetic connecting device; wherein, the number of outer stator slots N os =6k, number of rotor iron blocks N r =4k, 8k or 4k-1, number of permanent magnets N pm =3k, and since permanent magnets need to exist in pairs, k is a positive even number, so the number of outer stator slots N os 、Number of rotor iron blocks r ,Number of permanent magnets pmThe ratio relationship can be expressed as N os :N r :N pm =6k:4k:3k, N os :N r :N pm =6k:8k:3k or N os :N r :N pm =6k:(4k-1):3k.

[0012] The present invention improves the ratio of the number of outer stator slots, the number of rotor iron blocks and the number of permanent magnets, and improves the position of the armature winding and the permanent magnets on the stator. The number of permanent magnets and the number of rotor iron blocks in the motor are relatively small, which is beneficial to reducing torque pulsation, improving the quality of the three-way back electromotive force waveform, reducing the loss of the rotor iron blocks and permanent magnets, and improving heat dissipation.

[0013] As a preference, the number N of rotor iron blocks r =4k-1, the new number of outer stator slots N os 、Number of rotor iron blocks r ,Number of permanent magnets pm The ratio relationship is N os :N r :N pm =i*(6k:(4k-1):3k), where i is a positive integer, indicating doubling the initial ratio. This reduces the number of rotor iron blocks, thereby reducing losses in the permanent magnets and core. Furthermore, optimizing the number of rotor iron blocks eliminates even harmonics of the three-way back EMF, reduces permanent magnet torque harmonics, and ultimately reduces torque ripple.

[0014] Preferably, the annular inner stator core is provided with a heat sink. The heat sink may be an air-cooling structure, a liquid-cooling structure, or a combination thereof. Specifically, the air-cooling structure may be a fan disposed at the end of the inner stator core, and the liquid-cooling structure may be a water-cooling channel axially extending through the center of the inner stator. The heat sink is used to enhance the heat dissipation capability of the permanent magnets. The permanent magnets are connected to the heat sink so that heat generated by the permanent magnets can be quickly dissipated through the heat sink.

[0015] Preferably, the outer stator core and the outer stator core teeth are integrally formed to make the structure more solid.

[0016] Preferably, the outer stator has a circular, rectangular or polygonal outline. The motor's mechanical structure can be rotary, linear or a combination of the two.

[0017] Compared with the prior art, the beneficial effects of the present invention include at least:

[0018] In the present invention, the ratio of the number of outer stator slots to the number of permanent magnets is 2. Compared with the existing technical solutions, the number of permanent magnets is significantly reduced, thereby improving the utilization rate of permanent magnets. At the same time, the symmetry of the permanent magnet magnetic circuit is not changed, and the symmetry of the three-way back electromotive force is still guaranteed.

[0019] In the proposed ratio of outer stator slots, rotor iron blocks, and permanent magnets, the number of rotor iron blocks and permanent magnets is reduced. The electrical frequency of this motor is proportional to the number of rotor iron blocks, so reducing the number of rotor iron blocks can effectively reduce losses in the rotor core and permanent magnets. Furthermore, each permanent magnet experiences stator outer magnetic flux leakage and end magnetic flux leakage. Reducing the number of permanent magnet blocks can reduce magnetic flux leakage to a certain extent. Furthermore, compared to existing motors, a larger number of rotor iron blocks makes it easier for leakage flux to be closed. In the motor of the present invention, the reduced number of rotor iron blocks suppresses magnetic flux leakage to a certain extent.

[0020] In the present invention, the armature winding with a larger heat source is wound on the outer stator core teeth, making full use of the good thermal conductivity of the casing and achieving better heat dissipation effect; and the permanent magnet is placed on the inner stator core, and its loss is relatively small, so it can be quickly discharged through the heat dissipation device.

Brief Description of the Drawings

[0021] Figure 1 Schematic diagram of the structure of the motor of the present invention;

[0022] Figure 2 A schematic diagram of the motor structure with a heat dissipation device according to the present invention;

[0023] Figure 3 Schematic diagram of the motor structure when the number of rotor iron blocks is 7 in the present invention;

[0024] Figure 4 The motor of the present invention (N os :N pm =2) and the existing motor (N os :N pm =3) electromagnetic torque waveform comparison diagram;

[0025] Among them, 1-external stator, 11-external stator core, 111-external stator core teeth, 112-external stator slots, 12-armature winding, 2-rotor, 21-rotor iron block, 22-non-magnetic connection device, 3-inner stator, 31-permanent magnet, 32-inner stator core, 33-heat dissipation device. [Specific implementation method]

[0026] The present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings, but the present invention is not limited to the following specific embodiments.

[0027] A double-stator double-salient permanent magnet motor, such as Figure 1As shown, the outer stator 1, the rotor 2 and the inner stator 3 are sequentially arranged coaxially from the outside to the inside. The outer stator 1 includes an outer stator core 11 and an armature winding 12. The inner surface of the outer stator core 11 is provided with a plurality of outer stator core teeth 111 protruding toward the axis direction. An outer stator slot 112 is provided between adjacent outer stator core teeth 111. The armature winding 12 is wound on the outer stator core teeth 111; the inner stator 3 includes a permanent magnet 31 and an annular inner stator core 32. The permanent magnet 31 has a diameter of 1 / 4. The rotor 2 is annular and is arranged between the outer stator 1 and the inner stator 3, and includes a plurality of arc-shaped rotor iron blocks 21 and non-magnetic connecting devices 22 filled between adjacent rotor iron blocks 21; the rotor 2 is composed of the rotor iron blocks 21 and the non-magnetic connecting devices 22 alternately, the inner diameter of the rotor iron block 21 is equal to the inner diameter of the non-magnetic connecting device 22, and the outer diameter of the rotor iron block 21 is equal to the outer diameter of the non-magnetic connecting device 22; wherein, the number of outer stator slots N is os =6k, number of rotor iron blocks N r =4k, 8k or (4k-1), number of permanent magnets N pm =3k, and k is a positive even number. In this embodiment, when k=2, the number of permanent magnets and rotor iron blocks in the motor is relatively small. The present invention improves the ratio of the number of outer stator slots, the number of rotor iron blocks, and the number of permanent magnets, and improves the position of the armature winding 12 and the permanent magnets 31 on the inner and outer stators, which is beneficial for reducing torque ripple, improving the quality of the three-way back EMF waveform, reducing losses in the rotor iron blocks and permanent magnets, and improving heat dissipation.

[0028] Furthermore, the number of rotor iron blocks N r =8k, the number of outer stator slots N os 、Number of rotor iron blocks r ,Number of permanent magnets pm The ratio relationship is N os :N r :N pm =6k:8k:3k, specifically, when k=2, the number of outer stator slots N os It can be 12, the number of rotor iron blocks N r is 16, the number of permanent magnets N pm is 6.

[0029] Furthermore, in this embodiment, the number of rotor iron blocks N r =4k-1, number of outer stator slots N os 、Number of rotor iron blocks r ,Number of permanent magnets pm The ratio relationship is N os :N r :N pm =i*(6k:(4k-1):3k), where i is a positive integer. Specifically, Figure 3As shown, it is preferred that k = 2, at which time the number of outer stator slots N os It can be 12, the number of rotor iron blocks N r is 7, the number of permanent magnets N pm The torque pulsation of the motor in this patented technology is smaller.

[0030] Further, if Figure 2 As shown, in this embodiment, a heat dissipation device 33 is provided in the annular inner stator core 32. The heat dissipation device 33 can be a water cooling channel axially opened in the center of the inner stator, or the heat dissipation device can also be a fan provided at the end of the inner stator core 32.

[0031] Furthermore, the outline shape of the outer stator 1 is circular, rectangular or polygonal, and the mechanical structure of the motor can be rotary, linear or a combination of the two.

[0032] Furthermore, the outer stator core 11 and the outer stator core teeth 111 are integrally formed.

[0033] The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be included in the scope of protection of the present invention. In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention. Therefore, the scope of protection of the present invention shall be based on the scope of protection of the claims.

Claims

1. A double-stator double-salient-pole permanent magnet motor, comprising an outer stator (1), a rotor (2) and an inner stator (3) arranged coaxially from the outside to the inside, characterized in that: The outer stator (1) comprises an outer stator core (11) and an armature winding (12); a plurality of outer stator core teeth (111) protruding toward the axial direction are provided on the inner surface of the outer stator core (11); outer stator slots (112) are provided between adjacent outer stator core teeth (111); and the armature winding (12) is wound on the outer stator core teeth (111); The inner stator (3) comprises a permanent magnet (31) and an annular inner stator core (32), wherein the permanent magnet (31) is radially embedded in the inner stator core (32); The rotor (2) is annular and is arranged between the outer stator (1) and the inner stator (3), and includes a plurality of arc-shaped rotor iron blocks (21) and non-magnetic connection devices (22) filled between adjacent rotor iron blocks (21); the rotor (2) is formed by alternately combining the rotor iron blocks (21) and the non-magnetic connection devices (22); Among them, the number of outer stator slots N os =6k, number of rotor iron blocks N r =4k, 8k or (4k-1), number of permanent magnets N pm =3k, and k is a positive even number.

2. The dual-stator double-salient-pole permanent magnet motor according to claim 1, characterized in that: The number N of rotor iron blocks r =4k-1, the number of outer stator slots N os 、Number of rotor iron blocks r ,Number of permanent magnets pm The ratio relationship is N os :N r :N pm =i*(6k:(4k-1):3k), where i is a positive integer.

3. The dual-stator doubly salient permanent magnet motor according to claim 1, characterized in that: A heat dissipation device (33) is provided in the annular inner stator core (32).

4. The dual-stator doubly salient permanent magnet motor according to claim 1, characterized in that: The outline shape of the outer stator (1) is circular or polygonal.

5. The dual-stator doubly salient permanent magnet motor according to claim 1, characterized in that: The mechanical structure of the motor is in the form of rotation, linear or a combination of the two.

6. The dual-stator doubly salient permanent magnet motor according to claim 1, characterized in that: The outer stator core (11) and the outer stator core teeth (111) are integrally formed.

Images