Motor rotor, Permanent magnet assisted synchronous reluctance motor, Air conditioner

Abstract

This invention provides a motor rotor, a permanent magnet assisted synchronous reluctance motor, and an air conditioner. The motor rotor includes a rotor core with 2p magnetic poles. Under each magnetic pole, there are first magnetic slots for accommodating a first permanent magnet, second magnetic slots for accommodating a second permanent magnet, third magnetic slots for accommodating a third permanent magnet, and fourth magnetic slots for accommodating a fourth permanent magnet. The second magnetic slot is located in a region away from the second end of the first magnetic slot, while the third and fourth magnetic slots are located in regions away from the first end of the first magnetic slot. All three magnetic slots are situated between the radially inner wall of the first magnetic slot and the outer circular wall of the rotor core, with the third magnetic slot located between the second and fourth magnetic slots. p is the number of pole pairs, and p > 1. This invention can increase the permanent magnet torque content in the output torque, improve the utilization rate of permanent magnet torque, and increase the motor's output torque.

Description

Technical Field

[0001] This invention belongs to the field of motor design technology, specifically relating to a motor rotor, a permanent magnet assisted synchronous reluctance motor, and an air conditioner. Background Technology

[0002] In the field of motor technology, permanent magnet motors have the advantages of high efficiency, high power density and good torque characteristics, and are widely used in industrial, transportation and home appliance fields. Traditional permanent magnet motors have limitations in improving torque density, mainly due to the saturation effect of the motor and the space limitation of the rotor. The limited space of the rotor cannot increase the amount of permanent magnets, or the stator and rotor cores of the motor reach saturation when the amount of permanent magnets reaches a certain level, and the torque cannot be further increased.

[0003] The traditional solution is to use a rotor magnetic barrier structure to further increase the motor's torque density by increasing the reluctance torque. However, the traditional permanent magnet assisted synchronous reluctance motor structure cannot achieve the superposition of the peak reluctance torque and the peak permanent magnet torque, resulting in low utilization of permanent magnet torque and low motor output torque capability. Summary of the Invention

[0004] Therefore, the present invention provides a motor rotor, a permanent magnet assisted synchronous reluctance motor, and an air conditioner, which can overcome the shortcomings of the related technology that the permanent magnet assisted synchronous reluctance motor cannot achieve the superposition of the reluctance torque peak and the permanent magnet torque peak, the low utilization rate of permanent magnet torque, and the low output torque capability of the motor.

[0005] To address the aforementioned problems, the present invention provides a motor rotor, comprising a rotor core having 2p magnetic poles evenly spaced along its circumference, with adjacent magnetic poles having opposite polarities. Each magnetic pole includes a first magnetic slot for accommodating a first permanent magnet, a second magnetic slot for accommodating a second permanent magnet, a third magnetic slot for accommodating a third permanent magnet, and a fourth magnetic slot for accommodating a fourth permanent magnet. The second magnetic slot is located in a region where the first end of the first magnetic slot is far from its second end. The third and fourth magnetic slots are located in regions where the second end of the first magnetic slot is far from its first end. The second, third, and fourth magnetic slots are all located between the radially inner wall of the first magnetic slot and the outer circular wall of the rotor core, with the third magnetic slot located between the second and fourth magnetic slots. p is the number of pole pairs and p > 1.

[0006] In some embodiments, the distance between the second, third, and fourth magnet slots and the d-axis below the magnetic pole increases from the inside out along the radial direction of the rotor core.

[0007] In some embodiments, the central angle formed between the second magnetic groove wall furthest from the d-axis under the magnetic pole and the d-axis is β, the central angle formed between the third magnetic groove wall furthest from the d-axis under the magnetic pole and the d-axis is α, and the central angle formed between the fourth magnetic groove wall furthest from the d-axis under the magnetic pole and the d-axis is γ, where γ > β and β < α.

[0008] In some implementations, 1.05 ≤ (α+γ) / (2β) ≤ 1.8.

[0009] In some embodiments, below each of the magnetic poles, there is also a fifth magnetic steel groove for accommodating a fifth permanent magnet, the fifth magnetic steel groove being located on the side of the fourth magnetic steel groove away from the third magnetic steel groove.

[0010] In some embodiments, the central angle formed between the fifth magnet slot wall furthest from the d-axis under the magnetic pole and the d-axis is g, α < γ < g, g > β, and / or (γ + g) / 2 > β.

[0011] In some embodiments, the thickness of the second permanent magnet is w2, the thickness of the third permanent magnet is w3, the thickness of the fourth permanent magnet is w4, and the thickness of the fifth permanent magnet is w5, where w4 ≥ w3, w4 ≥ w2, and w5. <w2。

[0012] In some embodiments, the second magnet groove is connected to the first end of the first magnet groove, and the third, fourth, and fifth magnet grooves are connected to the second end of the first magnet groove; and / or, the second, third, fourth, and fifth magnet grooves are all closed grooves.

[0013] In some embodiments, the first magnet slot and / or the first permanent magnet is asymmetrical about the d-axis of the magnetic pole in which it is located; and / or, the first magnet slot and / or the first permanent magnet and the d-axis of the magnetic pole in which they are located form an angle c on the side closer to the third magnet slot, where 45°≤c<90°.

[0014] The present invention also provides a permanent magnet assisted synchronous reluctance motor, including the motor rotor described above.

[0015] The present invention also provides an air conditioner, including the aforementioned permanent magnet assisted synchronous reluctance motor.

[0016] The electric motor rotor, permanent magnet assisted synchronous reluctance motor, and air conditioner provided by this invention have the following beneficial effects: The magnetic slots (i.e., the second, third, and fourth magnetic slots) at both ends of the first magnetic slot have different structures, and each magnetic slot is fitted with a permanent magnet. This makes the permanent magnet magnetic field under the same magnetic pole no longer symmetrical about the d-axis of the magnetic pole, that is, no longer with the d-axis as the center of symmetry of the magnetic field, but deviating to one side of the d-axis. The peak current angle of the permanent magnet torque is shifted accordingly. As a result, when superimposed with the reluctance torque, the permanent magnet torque content in the output torque can be increased, the utilization rate of permanent magnet torque can be improved, and the output torque of the motor can be increased. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the axial projection of the motor rotor in an embodiment of the present invention; Figure 2 yes Figure 1 A partial structural diagram of the motor rotor; Figure 3 This is a schematic diagram of the axial projection of the motor rotor in another embodiment of the present invention; Figure 4 This is an axial projection schematic diagram of the motor rotor in another embodiment of the present invention; Figure 5 This is an axial projection schematic diagram of the motor rotor and motor stator after assembly in an embodiment of the present invention; Figure 6 This is a schematic diagram of the output torque of the motor rotor corresponding to different (α+γ) / (2β) values ​​in the technical solution of this invention. The horizontal axis is dimensionless and the vertical axis is in Nm. Figure 7 This is a curve comparison of the motor output torque of the technical solution of the present invention (dashed line in the figure, i.e., the technical solution of the present invention) and the prior art (solid line in the figure, i.e., the U-shaped magnetic steel groove structure). It can be clearly seen from the figure that the motor output torque of the technical solution of the present invention is obviously higher than that of the motor output torque in the prior art. The unit of the horizontal axis in the figure is °, and the unit of the vertical axis is Nm.

[0019] The attached figures are labeled as follows: 1. Rotor core; 21. First permanent magnet; 22. Second permanent magnet; 23. Third permanent magnet; 24. Fourth permanent magnet; 25. Fifth permanent magnet; 31. First magnet slot; 32. Second magnet slot; 33. Third magnet slot; 34. Fourth magnet slot; 35. Fifth magnet slot; 4. Magnet bridge; 5. Shaft hole; 100. Motor stator. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0022] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90° or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0023] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0024] See also Figures 1 to 7 As shown, according to an embodiment of the present invention, a motor rotor is provided, including a rotor core 1. The rotor core 1 has 2p magnetic poles evenly spaced along its circumference, with adjacent magnetic poles having opposite polarities. Each magnetic pole has a d-axis, and a q-axis is located 360 / (2*p) degrees away from each d-axis. In traditional permanent magnet motors, the d-axis is the center line of the magnetic field. However, in some rotor structures, the magnetic barrier structure causes the magnetic field to be non-symmetrical about the d-axis. In this invention, the location of the d-axis is described only as a reference position. Below each magnetic pole, there is a first magnetic groove 31 for accommodating a first permanent magnet 21 and a groove for accommodating a second permanent magnet 22. The second magnet slot 32, the third magnet slot 33 accommodating the third permanent magnet 23, and the fourth magnet slot 34 accommodating the fourth permanent magnet 24 are all located in the region where the first end of the first magnet slot 31 is far from its second end. The third magnet slot 33 and the fourth magnet slot 34 are located in the region where the second end of the first magnet slot 31 is far from its first end. The second magnet slot 32, the third magnet slot 33, and the fourth magnet slot 34 are all located between the radial inner wall of the first magnet slot 31 and the outer circular wall of the rotor core 1. The third magnet slot 33 is located between the second magnet slot 32 and the fourth magnet slot 34. p is the number of pole pairs and p > 1.

[0025] In this technical solution, the magnetic slots (i.e., the second magnetic slot 32, the third magnetic slot 33, and the fourth magnetic slot 34) set at both ends of the first magnetic slot 31 have different structures, and each permanent magnet is embedded in each magnetic slot. This makes the permanent magnetic field under the same magnetic pole no longer symmetrical about the d-axis of the magnetic pole, that is, no longer with the d-axis as the center line of symmetry of the magnetic field, but biased to one side of the d-axis. The peak current angle of the permanent magnet torque is shifted accordingly. As a result, when superimposed with the reluctance torque, the permanent magnet torque content in the output torque can be increased, the utilization rate of permanent magnet torque can be improved, and the output torque of the motor can be increased.

[0026] In some embodiments, along the radial direction of the rotor core 1 from the inside out, the distance between the second magnet slot 32, the third magnet slot 33, and the fourth magnet slot 34 and the d-axis below the magnetic pole increases, thereby forming a trumpet-shaped structure that gradually expands radially from the inside out, which is beneficial to improving the magnetizing effect of each magnetic pole. It should be noted that within the same magnetic pole, the magnetic poles of each permanent magnet facing the d-axis below the magnetic pole are the same. However, within two adjacent magnetic poles, if the magnetic poles of each permanent magnet facing the d-axis in one magnetic pole are N poles, then the magnetic poles of each permanent magnet facing the d-axis in the other magnetic pole are S poles.

[0027] In some embodiments, the central angle formed between the second magnetic slot 32 and the d-axis at the furthest point from the magnetic pole is β; the central angle formed between the third magnetic slot 33 and the d-axis at the furthest point from the magnetic pole is α; and the central angle formed between the fourth magnetic slot 34 and the d-axis at the furthest point from the magnetic pole is γ, where γ > β and β < α. This biases the permanent magnet magnetic field, altering the current angle relationship between the permanent magnet torque and the reluctance torque, thereby increasing the output torque. In a preferred embodiment, 1.05 ≤ (α + γ) / (2β) ≤ 1.8. See details below. Figure 6 As shown, when (α+γ) / (2β) is between 1.05 and 1.8, the motor output torque is at a relatively high level.

[0028] In some embodiments, below each of the magnetic poles, there is also a fifth magnetic groove 35 for accommodating the fifth permanent magnet 25, the fifth magnetic groove 35 being located on the side of the fourth magnetic groove 34 away from the third magnetic groove 33.

[0029] In this technical solution, a fifth permanent magnet 25 located on one side of the third permanent magnet 23 and a fifth magnetic steel groove 35 for embedding it are further provided under each magnetic pole, which can further enhance the asymmetry of the permanent magnet magnetic field. This can further enhance the superposition degree of reluctance torque and permanent magnet torque, that is, increase the permanent magnet torque content in the output torque and improve the utilization rate of the permanent magnet.

[0030] In some embodiments, the central angle formed between the fifth magnet slot 35, the slot wall furthest from the d-axis under the magnetic pole, and the d-axis is g, α<γ<g, g>β, and / or (γ+g) / 2>β, which can further improve the degree of magnetic field bias and further increase the output torque of the motor.

[0031] In some embodiments, the thickness (i.e., its width in the magnetization direction) of the first permanent magnet 21 is w1, the thickness of the second permanent magnet 22 is w2, the thickness of the third permanent magnet 23 is w3, the thickness of the fourth permanent magnet 24 is w4, and the thickness of the fifth permanent magnet 25 is w5, where w4 ≥ w3, w4 ≥ w2, and w5 ≥ w5. <w2。

[0032] In this technical solution, the closer the permanent magnet is to the air gap between the stator and the rotor, the stronger the effective magnetic field generated by it. Limiting that the width of the fourth permanent magnet 24 in the magnetization direction is greater than the width of the third permanent magnet 23 in the magnetization direction can increase the air gap magnetic field strength and increase the output torque of the motor; limiting w4<w2 can increase the effective magnetic flux of the motor and also increase the output torque of the motor; the fifth magnetic steel groove 35 mainly functions to offset the magnetic field of the magnetic pole, and limiting that the thickness of the permanent magnet with a larger offset degree, that is, the thickness of the fifth permanent magnet 25, is smaller than the thickness of the second permanent magnet 22, can help increase the effective magnetic flux of the magnetic pole, thereby increasing the output torque of the motor.

[0033] In some embodiments, the second magnetic steel groove 32 communicates with the first end of the first magnetic steel groove 31, and the third magnetic steel groove 33, the fourth magnetic steel groove 34, and the fifth magnetic steel groove 35 communicate with the second end of the first magnetic steel groove 31, which can reduce the number of grooves formed on the rotor core 1 and improve the mechanical strength of the rotor core 1.

[0034] In some embodiments, the second magnetic steel groove 32, the third magnetic steel groove 33, the fourth magnetic steel groove 34, and the fifth magnetic steel groove 35 are all closed grooves, that is, corresponding magnetic bridges 4 are formed between the radially outer groove walls of the second magnetic steel groove 32, the third magnetic steel groove 33, the fourth magnetic steel groove 34, and the fifth magnetic steel groove 35 and the outer circular wall surface of the rotor core 1, which can reduce torque ripple and improve the mechanical strength of the rotor core 1 at the same time.

[0035] In some embodiments, the first magnetic steel groove 31 and / or the first permanent magnet 21 are asymmetric with respect to the d-axis of the magnetic pole where they are located, that is, the length portions of the first permanent magnet 21 and the first magnetic steel groove 31 on both sides of the d-axis under the magnetic pole where they are located are not equal. This structure can make the magnetic fields on both sides of the d-axis asymmetric, realize that the magnetic field is biased close to the current angle where the reluctance torque peak is located, thereby achieving an increase in the output torque of the motor.

[0036] In some embodiments, an included angle c is formed between the first magnetic steel groove 31 and / or the first permanent magnet 21 and the d-axis of the magnetic pole where it is located on a side close to the third magnetic steel groove 33, where 45°≤c<90°.

[0037] In this technical solution, forming an included angle of 45° to 90° between the first magnetic steel groove 31 and the first permanent magnet 21 and their corresponding d-axis on the side close to the third magnetic steel groove 33 can further promote the offset of the permanent magnetic field and increase the output torque of the motor.

[0038] According to an embodiment of the present invention, a permanent magnet assisted synchronous reluctance motor is also provided, including the motor rotor described above and a motor stator 100 mounted radially outside the motor rotor. In the motor rotor, the magnetic slots (i.e., the second magnetic slot 32, the third magnetic slot 33, and the fourth magnetic slot 34) respectively provided at both ends of the first magnetic slot 31 have different structures, and each permanent magnet is embedded in each magnetic slot. This makes the permanent magnet magnetic field under the same magnetic pole no longer symmetrical about the d-axis of the magnetic pole, that is, no longer with the d-axis as the center line of symmetry of the magnetic field, but biased to one side of the d-axis. The peak current angle of the permanent magnet torque is shifted accordingly, thereby increasing the permanent magnet torque content in the output torque when superimposed with the reluctance torque, improving the utilization rate of permanent magnet torque and increasing the output torque of the motor.

[0039] According to an embodiment of the present invention, an air conditioner is also provided, including the aforementioned permanent magnet assisted synchronous reluctance motor.

[0040] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. An electric motor rotor, comprising a rotor core (1), said rotor core (1) having 2p magnetic poles evenly spaced along its circumference, wherein adjacent magnetic poles have opposite polarities, characterized in that, Below each of the magnetic poles, there are a first magnetic steel groove (31) for accommodating a first permanent magnet (21), a second magnetic steel groove (32) for accommodating a second permanent magnet (22), a third magnetic steel groove (33) for accommodating a third permanent magnet (23), and a fourth magnetic steel groove (34) for accommodating a fourth permanent magnet (24). The second magnetic steel groove (32) is located in the region of the first magnetic steel groove (31) away from its second end. The third magnetic steel groove (33) and the fourth magnetic steel groove (34) are located in the region of the second end of the first magnetic steel groove (31) away from its first end. The second magnetic steel groove (32), the third magnetic steel groove (33), and the fourth magnetic steel groove (34) are all located between the radially inner groove wall of the first magnetic steel groove (31) and the outer circular wall of the rotor core (1). The third magnetic steel groove (33) is located between the second magnetic steel groove (32) and the fourth magnetic steel groove (34). , p is the pole pair number and p>1; the second magnet slot (32) is connected to the first end of the first magnet slot (31), and the third magnet slot (33), the fourth magnet slot (34), and the fifth magnet slot (35) are connected to the second end of the first magnet slot (31); along the radial direction of the rotor core (1) from the inside to the outside, the distance between the second magnet slot (32), the third magnet slot (33), and the fourth magnet slot (34) and the d-axis under the magnetic pole becomes farther and farther; the central angle formed between the groove wall of the second magnet slot (32) farthest from the d-axis under the magnetic pole and the d-axis is β, the central angle formed between the groove wall of the third magnet slot (33) farthest from the d-axis under the magnetic pole and the d-axis is α, the central angle formed between the groove wall of the fourth magnet slot (34) farthest from the d-axis under the magnetic pole and the d-axis is γ, 1.05≤(α+γ) / (2β)≤1.

8.

2. The motor rotor according to claim 1, characterized in that, γ > β, β < α.

3. The motor rotor according to claim 1, characterized in that, Below each of the magnetic poles, there is also a fifth magnetic steel groove (35) for accommodating the fifth permanent magnet (25), the fifth magnetic steel groove (35) being located on the side of the fourth magnetic steel groove (34) away from the third magnetic steel groove (33).

4. The motor rotor according to claim 3, characterized in that, The central angle formed between the fifth magnetic steel groove (35) and the d-axis at the groove wall furthest from the magnetic pole is g, α<γ<g, g>β, and / or, (γ+g) / 2>β.

5. The motor rotor according to claim 3, characterized in that, The thickness of the second permanent magnet (22) is w2, the thickness of the third permanent magnet (23) is w3, the thickness of the fourth permanent magnet (24) is w4, and the thickness of the fifth permanent magnet (25) is w5, where w4 ≥ w3, w4 ≥ w2, and w5 ≥ w5. <w2。 6. The motor rotor according to claim 3, characterized in that, The second magnet groove (32) is connected to the first end of the first magnet groove (31), and the third magnet groove (33), the fourth magnet groove (34), and the fifth magnet groove (35) are connected to the second end of the first magnet groove (31); and / or, the second magnet groove (32), the third magnet groove (33), the fourth magnet groove (34), and the fifth magnet groove (35) are all closed grooves.

7. The motor rotor according to claim 1, characterized in that, The first magnet groove (31) and / or the first permanent magnet (21) are asymmetrical about the d-axis of the magnetic pole in which they are located; and / or, the first magnet groove (31) and / or the first permanent magnet (21) form an angle c with the d-axis of the magnetic pole in which they are located on the side closer to the third magnet groove (33), where 45°≤c<90°.

8. A permanent magnet assisted synchronous reluctance motor, characterized in that, The motor rotor includes any one of claims 1 to 7.

9. An air conditioner, characterized in that, Including the permanent magnet assisted synchronous reluctance motor as described in claim 8.

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