Motor Rotor, Motor, Centrifugal Compressor and Air Conditioner

Abstract

The present disclosure relates to an electric motor rotor, an electric motor, a centrifugal compressor, and an air conditioner. The electric motor rotor includes: a rotor core having a plurality of magnetic poles arranged at intervals in the circumferential direction centered on an axis, each magnetic pole having an embedded permanent magnet and a magnetic isolation hole group located on the side of the embedded permanent magnet away from the axis. Among them, the magnetic isolation hole group includes a plurality of magnetic isolation holes. The reference connection line from the center of each magnetic isolation hole to the center of the rotor core is a first reference connection line. The minimum value of the two included angles between the magnetic pole separation reference lines of the magnetic pole where the magnetic isolation hole is located and the two adjacent magnetic poles and the first reference connection line is a reference included angle α. For every two adjacent magnetic isolation holes, the magnetic isolation hole closer to the magnetic pole separation reference line is a first magnetic isolation hole, and the other magnetic isolation hole is a second magnetic isolation hole. The cross-sectional area of the first magnetic isolation hole is sin(2*α) times the cross-sectional area of the second magnetic isolation hole. Embodiments of the present disclosure can achieve lower vibration while increasing the reluctance torque of the electric motor rotor.

Description

Technical Field

[0001] The present disclosure relates to the field of motors, and particularly to a motor rotor, a motor, a centrifugal compressor, and an air conditioner. Background Art

[0002] With the development of industrialization, water chillers have been widely used in large central air-conditioning systems. At present, the two important indicators for evaluating the energy efficiency characteristics of water chillers are the coefficient of performance (COP) under nominal conditions and the integrated part load value (IPLV), which can effectively promote water chiller manufacturers to improve product performance.

[0003] In engineering applications, the annual energy consumption of water chillers is crucial, but it is even more urgent to fundamentally understand how to improve COP and IPLV. From the perspective of energy consumption, the use of permanent magnet variable frequency direct drive motors is the current main development trend. This is because permanent magnet motors generate a rotating magnetic field by permanent magnet excitation without the need for excitation current, thus improving the motor efficiency. From the system perspective, it mainly improves the system conversion energy efficiency. In order to respond to policies such as carbon neutrality and energy conservation, compressors need to have a high IPLV index in order to achieve efficient and stable operation under all working conditions.

[0004] Due to the relatively high motor speed of centrifugal compressors, limited by the maximum switching frequency and current that the frequency conversion device can reach, the selection of the number of motor poles cannot be too large. In addition, under the limitation of the outer dimension of the motor, the effective length of the iron core is also correspondingly limited. Therefore, the balance between the selection of the motor heat load and the motor efficiency is the key. In order to pursue higher efficiency and increase the power density, the selection of the rotor magnetic circuit structure is crucial.

[0005] In the related art, the design method of high-speed motors for centrifugal compressors usually adopts a straight-line magnetic circuit structure to reduce the vibration impact during high-speed operation. Summary of the Invention

[0006] The inventors have found through research that the straight-line magnetic circuit structure in the related art will cause limitations on the high-speed speed increase range of the motor, and the energy efficiency advantage cannot be reflected under high-speed working conditions, nor can the salient pole effect of the motor be utilized to increase the torque under low-speed working conditions.

[0007] In view of this, the embodiments of the present disclosure provide a motor rotor, a motor, a centrifugal compressor, and an air conditioner, which can achieve lower vibration while increasing the reluctance torque of the motor rotor.

[0008] In one aspect of the present disclosure, a motor rotor is provided, including:

[0009] The rotor core has a plurality of magnetic poles arranged at intervals in the circumferential direction centered on the axis. Each magnetic pole has a built-in permanent magnet and a magnetic isolation hole group located on the side of the built-in permanent magnet away from the axis.

[0010] Among them, the magnetic isolation hole group includes a plurality of magnetic isolation holes. The reference connection line from the center of each magnetic isolation hole to the center of the rotor core is the first reference connection line. The minimum value of the two included angles between the magnetic pole separation reference lines of the magnetic pole where the magnetic isolation hole is located and the two adjacent magnetic poles and the first reference connection line is the reference included angle α. Among every two adjacent magnetic isolation holes, the magnetic isolation hole closer to the magnetic pole separation reference line is the first magnetic isolation hole, and the other magnetic isolation hole is the second magnetic isolation hole. The cross-sectional area of the first magnetic isolation hole is sin(2*α) times that of the second magnetic isolation hole.

[0011] In some embodiments, the plurality of magnetic isolation holes are arranged at intervals in the circumferential direction and are symmetric with respect to the central reference line of the magnetic poles where the plurality of magnetic isolation holes are located.

[0012] In some embodiments, the number of the plurality of magnetic isolation holes is an odd number, and the center of the magnetic isolation hole located in the middle position among the plurality of magnetic isolation holes is located on the central reference line.

[0013] In some embodiments, the number of the plurality of magnetic poles is 4, and the included angles of the magnetic pole separation reference lines of each magnetic pole are all 90°.

[0014] In some embodiments, the minimum value of the cross-sectional areas of the plurality of magnetic isolation holes is greater than or equal to 3 mm 2 .

[0015] In some embodiments, the number of the plurality of magnetic isolation holes is N - c, where N is the number of stator slots per pole of the motor stator that works in cooperation with the motor rotor, and c is a positive integer with a value of 2 to 6.

[0016] In some embodiments, the value of c is 4.

[0017] In some embodiments, the cross-sectional shape of some or all of the plurality of magnetic isolation holes is circular.

[0018] In some embodiments, each magnetic pole has a plurality of built-in permanent magnets with a rectangular cross-section. The plurality of built-in permanent magnets are all tangent to the same reference circle, and the center of the reference circle is located on the side of the plurality of built-in permanent magnets away from the axis of the rotor core.

[0019] In some embodiments, the number of the plurality of built-in permanent magnets is an odd number, the number of the plurality of magnetic isolation holes is an odd number, and the center of the magnetic isolation hole located in the middle position among the plurality of magnetic isolation holes and the center of the built-in permanent magnet located in the middle position among the plurality of built-in permanent magnets are both located on the central reference line of the magnetic poles where the plurality of magnetic isolation holes are located.

[0020] In some embodiments, the distance from the center of the reference circle to any one of the plurality of built-in permanent magnets is equal to the distance from the center of the magnetic isolation hole located at the central position to the axis of the rotor core.

[0021] In some embodiments, the lengths L1 of the plurality of built-in permanent magnets in the tangential direction of the reference circle are all equal.

[0022] In some embodiments, one of each adjacent two of the plurality of magnetic poles is a first magnetic pole and the other is a second magnetic pole. The shortest distance L2 between the built-in permanent magnet closest to the magnetic pole separation reference line among the first magnetic poles and the built-in permanent magnet closest to the magnetic pole separation reference line among the second magnetic poles is greater than 5 mm.

[0023] In some embodiments, the rotor core further has a shaft hole, and the shortest distance L3 between the inner wall of the shaft hole and the built-in permanent magnet located at the central position is greater than 10 mm.

[0024] In one aspect of the present disclosure, there is provided a motor, including: the aforementioned motor rotor.

[0025] In one aspect of the present disclosure, there is provided a centrifugal compressor, including: the aforementioned motor.

[0026] In one aspect of the present disclosure, there is provided an air conditioner, including: the aforementioned centrifugal compressor, or the aforementioned motor.

[0027] Therefore, according to the embodiments of the present disclosure, by setting the cross-sectional areas of adjacent magnetic isolation holes in a sine ratio form, while increasing the reluctance torque, the air-gap magnetic density of each magnetic pole presents a state of being separated by magnetic isolation holes similar to a sine ratio, avoiding large changes in the air-gap magnetic density and resulting in strong vibrations during high-speed rotation, thereby reducing the cogging torque ripple of the motor and further reducing vibrations at higher speeds. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings forming a part of the specification depict embodiments of the present disclosure and, together with the specification, are used to explain the principles of the present disclosure.

[0029] Referring to the drawings, the present disclosure can be more clearly understood from the following detailed description, wherein:

[0030] Figure 1 is a schematic structural diagram of some embodiments of the motor rotor according to the present disclosure;

[0031] Figure 2 is Figure 1 a diagram showing the dimensional marking relationship of

[0032] It should be understood that the dimensions of the various parts shown in the drawings are not drawn in accordance with actual proportional relationships. In addition, the same or similar reference numerals represent the same or similar components. Detailed Description of the Invention

[0033] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and in no way limits the present disclosure or its application or use. The present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present disclosure thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, the compositions of materials, numerical expressions and values set forth in these embodiments should be construed as merely exemplary and not as limitations.

[0034] The terms "first", "second" and similar terms used in the present disclosure do not denote any order, quantity or importance, but are only used to distinguish different parts. Words such as "comprising" or "including" mean that the elements before the word cover the elements listed after the word, and do not exclude the possibility of also covering other elements. Terms such as "upper", "lower", "left", "right" are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0035] In the present disclosure, when it is described that a specific device is located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device. When it is described that a specific device is connected to other devices, the specific device may be directly connected to the other devices without an intermediate device, or may not be directly connected to the other devices and have an intermediate device.

[0036] All terms used in the present disclosure (including technical terms or scientific terms) have the same meaning as understood by those of ordinary skill in the art to which the present disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in a general dictionary, such as those, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense, unless specifically defined as such herein.

[0037] Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods and devices should be regarded as part of the specification.

[0038] Figure 1 is a schematic structural diagram of some embodiments of the motor rotor according to the present disclosure. Figure 2 is Figure 1Dimension marking relationship diagram. Refer to Figure 1 and Figure 2 , in some embodiments, the motor rotor includes: a rotor core 10. The rotor core 10 has a plurality of magnetic poles arranged at intervals in the circumferential direction centered on the axis O, such as Figure 1 the magnetic poles P1, P2, P3, and P4 in. Each magnetic pole has an embedded permanent magnet 12 and a magnetic isolation hole group 13 located on the side of the embedded permanent magnet 12 away from the axis O.

[0039] The rotor core 10 can be formed by stacking a plurality of silicon steel sheets. The embedded permanent magnet 12 can be a magnetic steel embedded in a permanent magnet groove opened on the rotor core 10, such as a ferrite magnetic steel, a neodymium iron boron magnetic steel, etc.

[0040] The magnetic isolation hole group 13 includes a plurality of magnetic isolation holes, such as Figure 2 the magnetic isolation holes 13a, 13b, and 13c in. The reference connection line from the center of each magnetic isolation hole to the center of the rotor core 10 (i.e., the axis O) is the first reference connection line, such as Figure 2 the first reference connection lines CL1, CL2, and CL3 corresponding to the magnetic isolation holes 13a, 13b, and 13c in.

[0041] In Figure 1 , the number of the plurality of magnetic poles is 4. The included angles between the magnetic pole separation reference lines of each magnetic pole are all 90°, that is, the magnetic pole separation reference lines DL1, DL2, DL3, and DL3 are successively separated by 90°. The magnetic pole where the magnetic isolation hole is located and its two adjacent magnetic poles (such as the adjacent magnetic poles upstream and downstream of the magnetic pole in the clockwise direction in the figure) are separated by two magnetic pole separation reference lines (such as the magnetic pole separation reference lines DL1, DL2, DL3, and DL4) respectively.

[0042] The minimum value of the two included angles between the two magnetic pole separation reference lines and the first reference connection line respectively is the reference angle α. For example, the included angle between the first reference connection line CL2 corresponding to the magnetic isolation hole 13b in the magnetic pole P1 and the magnetic pole separation reference line DL2 is smaller than the included angle with the magnetic pole separation reference line DL1, so the included angle between the first reference connection line CL2 and the magnetic pole separation reference line DL2 is used as the reference angle α.

[0043] For every two adjacent magnetic isolation holes, the magnetic isolation hole closer to the magnetic pole separation reference line is the first magnetic isolation hole, and the other magnetic isolation hole is the second magnetic isolation hole. The cross-sectional area of the first magnetic isolation hole is sin(2*α) times the cross-sectional area of the second magnetic isolation hole.

[0044] For example: the angle a between the first reference line CL2 corresponding to the magnetic isolation hole 13b and the magnetic pole separation reference line DL2 is used as the reference angle corresponding to the magnetic isolation hole 13b, the angle b between the first reference line CL3 corresponding to the magnetic isolation hole 13c and the magnetic pole separation reference line DL2 is used as the reference angle corresponding to the magnetic isolation hole 13c, the cross-sectional area S3 of the magnetic isolation hole 13c is sin(2*b) of the cross-sectional area S2 of the magnetic isolation hole 13b, and the cross-sectional area S2 of the magnetic isolation hole 13b is sin(2*a) of the cross-sectional area S1 of the magnetic isolation hole 13a.

[0045] Considering that the output torque of the permanent magnet synchronous motor has two components, including the permanent magnet torque Tm and the reluctance torque Tr of the motor, the permanent magnet torque Tm represents the torque generated by the excitation flux of the permanent magnet of the motor, and the reluctance torque Tr represents the torque generated by the asymmetric structure of the AC and DC axis magnetic circuit of the motor. On the basis of meeting the output torque requirements of the motor, by changing the proportion of the reluctance torque of the motor, the proportion of the permanent magnet torque can be reduced accordingly, thereby reducing the amount of permanent magnets used in the motor and improving the power factor through the convex effect.

[0046] This embodiment realizes the uneven distribution effect of air gap flux density by setting magnetic isolation holes, and by setting the cross-sectional area of ​​adjacent magnetic isolation holes in a sinusoidal ratio, the air gap flux density of each magnetic pole can present a state similar to a sinusoidal distribution, while improving the convexity effect, avoiding large changes in air gap flux density and causing strong vibration during high-speed rotation, thereby reducing the motor tooth torque pulsation, and then reducing vibration at higher speeds. The state similar to the sinusoidal distribution here means that the air gap flux density distribution is high in the middle and low on both sides in the circumferential direction, and the change from the middle to the two sides is smooth, avoiding overly sharp peaks.

[0047] refer to Figure 1 and Figure 2 In some embodiments, the plurality of magnetic isolation holes are arranged at intervals in the circumferential direction and are symmetrical with respect to the central reference line ML of the magnetic pole where the plurality of magnetic isolation holes are located. In this way, the air gap magnetic flux on both sides of the central reference line ML can be evenly distributed. Here, evenly distributed means that the air gap magnetic flux is basically symmetrical with respect to the air gap magnetic flux on both sides of the middle peak in the circumferential direction.

[0048] refer to Figure 2 In some embodiments, the number of the plurality of magnetic isolation holes is an odd number. The center of the magnetic isolation hole located in the middle of the plurality of magnetic isolation holes is located on the central reference line ML. Compared with an even number of magnetic isolation holes, an odd number of magnetic isolation holes can reduce the possibility of resonance when the motor rotor rotates.

[0049] When processing the magnetic isolation holes, a magnetic isolation hole that is too small will not be able to effectively separate the magnetic flux and will increase the cost. Therefore, it is preferred that the minimum cross-sectional area of ​​the multiple magnetic isolation holes is greater than or equal to 3mm. 2 .

[0050] The number of magnetic isolation holes can be determined according to the number of stator slots per pole. Too many magnetic isolation holes will increase the magnetic resistance of the magnetic circuit, while too few magnetic isolation holes will not significantly reduce the cogging torque ripple. Therefore, the number of multiple magnetic isolation holes can be N - c, where N is the number of stator slots per pole of the motor stator that works in matching with the motor rotor, and c is a positive integer with a value of 2 to 6. Further preferably, the value of c is 4. This can ensure that the magnetic density distribution formed by the non-uniform distribution effect of the magnetic isolation holes is not coupled with the number of stator teeth, thereby reducing the possibility of stator-rotor tooth-slot resonance.

[0051] In some embodiments, the cross-sectional shape of some or all of the multiple magnetic isolation holes is circular. This shape can avoid the magnetic density concentration caused by local sharp corners, thereby solving the problem of uneven air-gap magnetic density distribution.

[0052] Reference Figure 1 and Figure 2 , in some embodiments, each magnetic pole has a plurality of built-in permanent magnets 12 with a rectangular cross-section. The plurality of built-in permanent magnets 12 are all tangent to the same reference circle 30. The center O' of the reference circle 30 is located on the side of the plurality of built-in permanent magnets 12 away from the axis O of the rotor core 10. That is to say, the built-in permanent magnets 12 of each magnetic pole as a whole present a curved or broken-line shape that bulges towards the axis O in the middle and is far from the axis O at both ends. This shape can make the built-in permanent magnets at both ends closer to the air gap to achieve a better magnetic flux cutting effect.

[0053] Reference Figure 1 , the number of the plurality of built-in permanent magnets 12 is an odd number, and the number of the plurality of magnetic isolation holes is an odd number. For example, each magnetic pole includes 3 built-in permanent magnets 12 and 5 magnetic isolation holes. The center of the magnetic isolation hole located in the middle position among the plurality of magnetic isolation holes and the center of the built-in permanent magnet 12 located in the middle position among the plurality of built-in permanent magnets 12 are both located on the central reference line ML of the magnetic pole where the plurality of magnetic isolation holes are located. The built-in permanent magnet 12 in the middle position and the built-in permanent magnets 12 on both sides can be symmetric with respect to the central reference line ML, so that the air-gap magnetic density distribution of the magnetic pole is also symmetric with respect to the central reference line ML.

[0054] Reference Figure 2 , in some embodiments, the distance R' from the center O' of the reference circle 30 to any one of the plurality of built-in permanent magnets 12 is equal to the distance R from the center of the magnetic isolation hole located in the middle position to the axis O of the rotor core 10. In other words, R' is equal to R. This can make the air-gap magnetic density distribution achieved by the magnetic isolation holes closer to a sine distribution.

[0055] In Figure 2Among them, the number of multiple built-in permanent magnets 12 is three. The built-in permanent magnet 12 located at the center position is the middle permanent magnet 12a, and the two built-in permanent magnets 12 located on both sides of the middle permanent magnet 12a are two flanged permanent magnets 12b. The permanent magnet slots provided on the rotor core 10 can be provided with parts for pouring fixing glue at the ends to fix the built-in permanent magnets 12 in the permanent magnet slots.

[0056] In addition, in Figure 2 Among them, the lengths L1 of the multiple built-in permanent magnets 12 in the tangential direction of the reference circle 30 can be made equal. In this way, built-in permanent magnets of a unified specification can be adopted, which is not only convenient for processing, but also can reduce the mold cost.

[0057] Taking one of the two adjacent magnetic poles among multiple magnetic poles as the first magnetic pole and the other as the second magnetic pole. Correspondingly, the shortest distance L2 between the built-in permanent magnet 12 closest to the magnetic pole separation reference line among the first magnetic poles and the built-in permanent magnet 12 closest to the magnetic pole separation reference line among the second magnetic poles can be set to 2-3 mm. In this way, the magnetic leakage rate can be reduced and the performance of the motor can be improved.

[0058] In some embodiments, the rotor core 10 further has a shaft hole 11, through which a rotating shaft can pass and be fixedly connected to the rotating shaft. The shortest distance L3 between the inner wall of the shaft hole 11 and the built-in permanent magnet 12 located at the center position can be greater than 10 mm. In this way, the area between the shaft hole 11 and the built-in permanent magnet 12 can be wider and the magnetic density can be smaller, thereby reducing the magnetic resistance of this area.

[0059] Each of the above embodiments of the motor rotor of the present disclosure can be applied to various motors. Therefore, the embodiments of the present disclosure also provide a motor, including any one of the above embodiments of the motor rotor. The motor may further include other components such as a motor stator that cooperates with the motor rotor, which will not be elaborated here.

[0060] The embodiments of the present disclosure also provide a centrifugal compressor, including the above-mentioned motor embodiments. The embodiments of the present disclosure also provide an air conditioner, including: the above-mentioned centrifugal compressor embodiments, or the above-mentioned motor embodiments.

[0061] So far, the embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details well known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed here based on the above description.

[0062] Although some specific embodiments of the present disclosure have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and not for limiting the scope of the present disclosure. Those skilled in the art should understand that the above embodiments can be modified or equivalent substitutions can be made for some technical features without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A motor rotor, characterized in that, Comprising: A rotor core (10) having a plurality of magnetic poles (P1; P2; P3; P4) arranged at intervals in the circumferential direction centered on an axis (O), each magnetic pole (P1; P2; P3; P4) having a built-in permanent magnet (12) and a magnetic isolation hole group (13) on the side of the built-in permanent magnet (12) away from the axis (O). Wherein, the magnetic isolation hole group (13) includes a plurality of magnetic isolation holes (13a; 13b; 13c), and a reference connection line from the center of each magnetic isolation hole (13a; 13b; 13c) to the center of the rotor core (10) is a first reference connection line (CL1; CL2; CL3). The minimum value of the two included angles between the magnetic pole (P1; P2; P3; P4) where the magnetic isolation hole (13a; 13b; 13c) is located and the two magnetic pole separation reference lines (DL1; DL2; DL3; DL4) of two adjacent magnetic poles (P1; P2; P3; P4) and the first reference connection line (CL1; CL2; CL3) is a reference included angle α. Among every two adjacent magnetic isolation holes (13a; 13b; 13c), the magnetic isolation hole (13a; 13b; 13c) closer to the magnetic pole separation reference line (DL1; DL2; DL3; DL4) is a first magnetic isolation hole, and the other magnetic isolation hole (13a; 13b; 13c) is a second magnetic isolation hole. The cross-sectional area of the first magnetic isolation hole is sin(2*α) times that of the second magnetic isolation hole.

2. The motor rotor according to claim 1, characterized in that, The plurality of magnetic isolation holes (13a; 13b; 13c) are arranged at intervals in the circumferential direction and are symmetric with respect to the center reference line (ML) of the magnetic pole (P1; P2; P3; P4) where the plurality of magnetic isolation holes (13a; 13b; 13c) are located.

3. The motor rotor according to claim 2, characterized in that The number of the plurality of magnetic isolation holes (13a; 13b; 13c) is an odd number, and the center of the magnetic isolation hole (13a; 13b; 13c) located at the middle position among the plurality of magnetic isolation holes (13a; 13b; 13c) is located on the center reference line (ML).

4. The motor rotor according to claim 3, wherein The number of the plurality of magnetic poles (P1; P2; P3; P4) is 4, and the included angles of the magnetic pole separation reference lines of each magnetic pole (P1; P2; P3; P4) are all 90°.

5. The motor rotor according to claim 1, characterized in that, The minimum value of the cross-sectional areas of the plurality of magnetic isolation holes (13a; 13b; 13c) is greater than or equal to 3 mm 2 .

6. The motor rotor according to claim 1, characterized in that, The number of the plurality of magnetic isolation holes (13a; 13b; 13c) is N - c, where N is the number of stator slots per pole of the motor stator that works in matching with the motor rotor, and c is a positive integer with a value of 2 to 6.

7. The motor rotor according to claim 6, wherein The value of c is 4.

8. The motor rotor according to claim 1, characterized in that, The cross-sectional shape of some or all of the plurality of magnetic isolation holes (13a; 13b; 13c) is circular.

9. The motor rotor according to claim 1, characterized in that Each magnetic pole (P1; P2; P3; P4) has a plurality of built-in permanent magnets (12) with a rectangular cross-section. The plurality of built-in permanent magnets (12) are all tangent to the same reference circle (30), and the center (O') of the reference circle (30) is located on the side of the plurality of built-in permanent magnets (12) away from the axis (O) of the rotor core (10).

10. The motor rotor according to claim 9, characterized in that, The number of the plurality of built-in permanent magnets (12) is an odd number, the number of the plurality of magnetic isolation holes (13a; 13b; 13c) is an odd number, and the centers of the magnetic isolation holes (13a; 13b; 13c) located at the central position among the plurality of magnetic isolation holes (13a; 13b; 13c) and the centers of the built-in permanent magnets (12) located at the central position among the plurality of built-in permanent magnets (12) are both located on the central reference line (ML) of the magnetic poles (P1; P2; P3; P4) where the plurality of magnetic isolation holes (13a; 13b; 13c) are located.

11. The motor rotor according to claim 10, wherein, The distance (R') from the center (O') of the reference circle (30) to any one of the plurality of built-in permanent magnets (12) is equal to the distance (R) from the center of the magnetic isolation hole (13a; 13b; 13c) located at the central position to the axis (O) of the rotor core (10).

12. The motor rotor according to claim 9, characterized in that, The lengths L1 of the plurality of built-in permanent magnets (12) in the tangential direction of the reference circle (30) are all equal.

13. The motor rotor according to claim 9, characterized in that, Among the plurality of magnetic poles (P1; P2; P3; P4), one magnetic pole (P1; P2; P3; P4) of each adjacent pair of magnetic poles (P1; P2; P3; P4) is a first magnetic pole, and the other is a second magnetic pole. The shortest distance L2 between the built-in permanent magnet (12) closest to the magnetic pole separation reference line (DL1; DL2; DL3; DL4) among the first magnetic poles and the built-in permanent magnet (12) closest to the magnetic pole separation reference line (DL1; DL2; DL3; DL4) among the second magnetic poles is greater than 5 mm.

14. The motor rotor according to claim 10, characterized in that, The rotor core (10) further has a shaft hole (11), and the shortest distance L3 between the inner wall of the shaft hole (11) and the built-in permanent magnet (12) located at the central position is greater than 10 mm.

15. A motor, characterized in that, Comprising: The motor rotor according to any one of claims 1 to 14.

16. A centrifugal compressor, characterized in that, Comprising: The motor according to claim 15.

17. An air conditioner, characterized in that, Comprising: The centrifugal compressor according to claim 16, or the motor according to claim 15.

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