CN116191724A

CN116191724A - Permanent magnet motor and compressor

Info

Publication number: CN116191724A
Application number: CN202211270235.3A
Authority: CN
Inventors: 邱小华; 杨向宇; 朱晓光; 李宏涛
Original assignee: South China University of Technology SCUT; Guangdong Meizhi Compressor Co Ltd
Current assignee: South China University of Technology SCUT; Guangdong Meizhi Compressor Co Ltd
Priority date: 2022-10-14
Filing date: 2022-10-14
Publication date: 2023-05-30

Abstract

The invention discloses a permanent magnet motor and a compressor, wherein the permanent magnet motor comprises a stator and a rotor; the stator comprises a stator core, a central hole and a plurality of stator teeth distributed along the circumferential direction of the central hole are formed on the stator core, the stator teeth are convexly arranged towards the central hole, two adjacent stator teeth form a stator groove, the width of a stator notch is D1, and the width of a stator tooth end is D2; the rotor is rotatably inserted into the central hole and comprises a rotor core and a plurality of permanent magnets, a plurality of magnetic steel grooves extending along the axial direction of the rotor core are formed in the circumferential direction of the rotor core, the permanent magnets are correspondingly arranged in the magnetic steel grooves one by one, and two ends of the magnetic steel grooves are close to the outer side of the rotor core and have the width L1; then L1 is greater than or equal to 0.8 (D2+D1). The technical scheme of the invention aims to weaken the cogging torque of the permanent magnet motor so as to improve the control precision and stability of the motor.

Description

Permanent magnet motor and compressor

Technical Field

The invention relates to the technical field of compressors, in particular to a permanent magnet motor and a compressor.

Background

The permanent magnet auxiliary synchronous reluctance motor is used as a motor utilizing permanent magnet torque and reluctance torque and generally comprises a rotor, a permanent magnet and a stator, and the permanent magnet auxiliary synchronous reluctance motor has higher efficiency and power factor, so that the permanent magnet auxiliary synchronous reluctance motor is more and more emphasized, however, due to the cogging torque generated by the interaction between the permanent magnet and a stator slot on a stator core, the motor generates vibration and noise, and the rotation speed fluctuates, so that the motor cannot stably run, and the control precision and stability of the permanent magnet motor are affected.

Disclosure of Invention

The invention mainly aims to provide a permanent magnet motor, aiming at weakening cogging torque of the permanent magnet motor so as to improve control precision and stability of the motor.

In order to achieve the above object, the present invention provides a permanent magnet motor, which includes a stator and a rotor; the stator comprises a stator core, a central hole and a plurality of stator teeth are formed on the stator core, the plurality of stator teeth are distributed along the circumferential direction of the central hole and are convexly arranged towards the central hole, a stator groove is formed between two adjacent stator teeth, the width of the stator groove is D1 on one side of the stator teeth towards the center of the central hole, and the width of the stator teeth is D2; the rotor is rotatably inserted into the central hole, the rotor comprises a rotor core and a plurality of permanent magnets, a plurality of magnetic steel grooves extending along the axial direction of the rotor core are arranged in the circumferential direction of the rotor core, the permanent magnets are correspondingly arranged in the magnetic steel grooves, on the cross section of the rotor cut by a plane perpendicular to the axial direction of the rotor, two ends of the magnetic steel grooves are arranged close to the outer side of the rotor core, and the width of the end parts of the magnetic steel grooves is L1; then L1 is greater than or equal to 0.8 (D2+D1).

Optionally, in the cross section, when one end of the magnetic steel groove is opposite to the stator tooth, the other end is opposite to the stator groove.

Optionally, the rotor core is further provided with a plurality of magnetic barrier hole groups extending along the axial direction of the rotor core, a magnetic area is formed between the magnetic steel groove and the outer side of the rotor core, the magnetic barrier hole groups are provided with a first edge and a second edge which are close to and far away from the magnetic steel groove, the first edge and the second edge are oppositely arranged, and the distance from the first edge to the second edge is L2, wherein the L2 is more than or equal to D1.

Optionally, the magnetic barrier hole group includes a plurality of magnetic barrier holes, and a plurality of the magnetic barrier holes establish ties, in the cross section, the magnetic barrier hole group has and is adjacent respectively the outside of rotor core sets up both ends, when the one end of magnetic barrier hole group with the stator tooth is relative, the other end with the stator slot is relative.

Optionally, in the cross section, a plurality of the magnetic barrier holes are distributed at intervals along the extending direction of the magnetic steel groove so as to form a straight-axis magnetic circuit and a quadrature-axis magnetic circuit between the magnetic steel groove and the magnetic barrier hole group.

Optionally, in the distribution direction of the magnetic steel groove and the magnetic barrier hole group, the thickness of the permanent magnet is R1, and R1 is more than or equal to L2.

Optionally, in the cross section, the thickness of the middle part of the permanent magnet is greater than or equal to the thickness of the end part of the permanent magnet.

Optionally, the length of the rotor is greater than or equal to the length of the stator in the axial direction of the permanent magnet motor.

Optionally, in the cross section, the magnetic steel groove is in a U shape or a V shape which is opened towards the outer side of the rotor core.

Optionally, the permanent magnet motor further comprises at least two baffles, wherein the baffles are correspondingly fixed at the end parts of the rotor core and are used for fixing the permanent magnet in the magnetic steel groove.

The invention also provides a compressor comprising the permanent magnet motor.

The technical proposal of the invention is that the axial direction of a rotor core is provided with magnetic steel grooves, each magnetic steel groove is correspondingly provided with a permanent magnet, on the cross section obtained by cutting the rotor in a plane vertical to the axial direction of the rotor, the magnetic steel grooves are provided with two end parts which are arranged near the periphery of the rotor core, correspondingly, on the inner peripheral side of a stator facing the rotor, the notch of a stator groove and the end parts of stator teeth alternately appear, without losing generality, on the plane vertical to the axial direction of the rotor, the permanent magnet basically fills the magnetic steel grooves, and the permanent magnet motor is easy to generate cogging torque due to the interaction between the permanent magnet and the stator groove, thereby influencing the normal operation of the motor, in the prior art, when the width of the end part of the magnetic steel groove is equal to the width of the stator groove, the torque pulsation of the permanent magnet motor is overlarge due to the cogging torque at the moment, so, the proportion of the width L1 of the end part of the magnetic steel groove to the width D1 of the notch of the stator groove is adjusted, and then the width D2 of the end part of the stator tooth is combined, as shown in fig. 5, experiments and simulations show, the width L1 of the end part of the magnetic steel groove at the rotor core is adjusted on the cross section of the rotor, and the sum of the width D1 of the notch and the width D2 of the tooth end is adjusted, so that the L1 is more than or equal to 0.8 (D2+D1), the cogging torque generated by the permanent magnet motor can be ensured to be in a lower state, the fluctuation of the rotating speed of the motor is reduced, the motor tends to be in a stable running state, and the control precision and the stability of the permanent magnet motor are improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a permanent magnet motor according to an embodiment of the present invention;

FIG. 2 is an enlarged view of a portion of FIG. 1 at A;

FIG. 3 is a schematic structural view of the rotor core of FIG. 1;

fig. 4 is a schematic structural view of another embodiment of the permanent magnet motor of the present invention;

fig. 5 is a schematic structural view of a permanent magnet motor according to another embodiment of the present invention;

FIG. 6 is a schematic diagram of the relationship between L1 and (D2+D1) of the permanent magnet motor according to the present invention;

fig. 7 is a schematic diagram of the relationship between the length ratio of the rotor and the stator of the permanent magnet motor according to the present invention.

Reference numerals illustrate:

reference numerals	Name of the name	Reference numerals	Name of the name
				100	Rotor	110	Rotor core
111	Magnetic steel groove	112	Magnetic barrier hole
				120	Permanent magnet	200	Stator
210	Stator core	211	Stator teeth
				212	Stator groove

The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present invention are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.

In addition, if there is a description of "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and/or" as it appears throughout includes three parallel schemes, for example "A and/or B", including the A scheme, or the B scheme, or the scheme where A and B are satisfied simultaneously. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present invention.

The invention provides a permanent magnet motor.

In an embodiment of the present invention, referring to fig. 1 to 7, the permanent magnet motor includes a stator 200 and a rotor 100; the stator 200 includes a stator core 210, a central hole and a plurality of stator teeth 211 are formed on the stator core 210, the plurality of stator teeth 211 are distributed along the circumferential direction of the central hole and are protruded towards the central hole, a stator slot 212 is formed between two adjacent stator teeth 211, the slot opening width of the stator slot 212 is D1 at one side of the stator teeth 211 towards the central hole, and the tooth end width of the stator teeth 211 is D2; the rotor 100 is rotatably inserted into the central hole, the rotor 100 comprises a rotor core 110 and a plurality of permanent magnets 120, a plurality of magnetic steel grooves 111 extending along the axial direction of the rotor core 110 are arranged on the circumference of the rotor core 110, the permanent magnets 120 are correspondingly arranged on the magnetic steel grooves 111, on the cross section obtained by cutting the rotor 100 on a plane perpendicular to the axial direction of the rotor 100, two ends of the magnetic steel grooves 111 are arranged close to the outer side of the rotor core 110, and the width of the end part of the magnetic steel groove 111 is L1; then L1 is greater than or equal to 0.8 (D2+D1).

According to the technical scheme, the magnetic steel grooves 111 are formed in the axial direction of the rotor core 110, the permanent magnets 120 are correspondingly arranged in each magnetic steel groove 111, and it is required to say that the magnetic steel grooves 111 are provided with two ends which are adjacent to the periphery of the rotor core 110 on the cross section of the rotor 100, correspondingly, on the inner peripheral side of the stator 200 facing the rotor 100, the notch of the stator groove 212 and the end of the stator tooth 211 alternately appear, and the permanent magnets 120 basically fill the magnetic steel grooves 111 on the cross section of the rotor 100, due to the interaction between the permanent magnets 120 and the stator groove 212, the permanent magnet motor is easy to generate cogging torque, the normal operation of the motor is influenced, the cogging torque at the moment causes the torque pulsation of the permanent magnet motor to be overlarge when the end width of the magnetic steel grooves 111 is equal to the width of the stator groove 212, and the end width L1 of the magnetic steel grooves 212 are adjusted, and the end width D2 of the notch of the stator groove 212 are combined, as shown in the experiment and simulation shows that on the cross section of the rotor 100, the end width L1 of the rotor core 110 is adjusted, the width L1 of the end width D1 of the permanent magnet motor is adjusted, the end width D1 of the end of the permanent magnet motor is adjusted, and the end width D2 of the end D1 of the permanent magnet motor is adjusted to be equal to the width of the end of the stator groove 212 is equal to the end of the stator tooth 2, and the torque is equal to the end of the torque, and the torque is stable, and the torque is in the state of the torque, and the torque is stable is in the state, and the speed is stable is in the state and is stable and is in the speed and is stable and is stable.

It should be noted that, in the present embodiment, since L1 is greater than or equal to 0.8 (d2+d1), the number of slots of the stator 200 needs to be greater than the number of poles of the rotor 100, that is, the number of slots of the stator slots 212 is increased, so that the frequency of the cogging torque fundamental wave is increased, and the cogging torque fluctuation is reduced, thereby reducing the rotational speed fluctuation of the permanent magnet motor and ensuring the stable operation of the permanent magnet motor.

In an embodiment, referring to fig. 1 to 5, when one end of the magnetic steel groove 111 is opposite to the stator teeth 211, the other end is opposite to the stator groove 212 in the cross section of the rotor 100. Without loss of generality, in the present embodiment, the width of the end portion of the permanent magnet 120 is approximately equal to the width of the magnetic steel groove 111 in the cross section of the rotor 100, so that one end of the permanent magnet 120 in the magnetic steel groove 111 is opposite to the stator teeth 211, the other end is opposite to the stator groove 212, and tangential components of interaction forces between the two ends of each pole in the rotor 100 and the stator groove 212 and the stator teeth 211 respectively tend to be opposite, so that cogging torque of the rotor 100 is weakened, and control accuracy and running stability of the permanent magnet motor are improved. Of course, in other embodiments, both ends of the magnetic steel groove 111 may be aligned with the stator teeth 211 or the stator grooves 212, respectively, in the cross section of the rotor 100.

In an embodiment, please refer to fig. 1 to 6, the rotor core 110 is further provided with a plurality of magnetic barrier hole groups extending along the axial direction of the rotor core 110, a magnetic region is formed between the magnetic steel groove 111 and the outer side of the rotor core 110, the magnetic barrier hole groups are located in the magnetic region, the magnetic barrier hole groups have a first edge and a second edge which are close to and far away from the magnetic steel groove 111, the first edge and the second edge are opposite, and the distance from the first edge to the second edge is L2, wherein L2 is greater than or equal to D1. It will be appreciated that the width of the magnetic barrier hole 112 should be smaller than the width of the permanent magnet 120, without losing generality, in this embodiment, the end width D2 of the stator teeth 211 is larger than the width D1 of the stator slots 212, so that L1 is approximately equal to L2 and larger than L2, so as to ensure that the permanent magnet torque of the permanent magnet motor can meet the power requirement of the permanent magnet motor, that is, L1 is greater than or equal to L2, L2 is greater than or equal to D1, and it is obtained that L1 needs to be greater than or equal to D1 on the cross section of the rotor, and on the premise that the width of the permanent magnet 120 is constant, the cogging torque of the permanent magnet motor is weakened by reducing the width D1 of the stator slots 212, so that the control accuracy of the permanent magnet motor is improved. Of course, in other embodiments, auxiliary slots may be provided at the ends of the stator teeth 211 facing the rotor 100 to alter the air gap flux density harmonics of the motor, which may reduce the amplitude of the air gap flux density lower harmonics, and thus reduce the amplitude of the lower order radial force harmonics and cogging torque.

Further, in the present embodiment, please continue to refer to fig. 1 to 5, the magnetic barrier hole set includes a plurality of magnetic barrier holes 112, the plurality of magnetic barrier holes 112 are arranged in series, and in the cross section of the rotor 100, the magnetic barrier hole set has two ends respectively arranged adjacent to the outer side of the rotor core 110, when one end of the magnetic barrier hole set is opposite to the stator teeth 211, the other end is opposite to the stator slots 212. It will be appreciated that the groups of barrier holes are in one-to-one correspondence with the magnetic steel slots 111 and are located within the range of action of the permanent magnets 120 and the stator 200, and the tangential components of the interaction forces of the stator teeth 211 and the stator slots 212 at the two ends of the groups of barrier holes tend to be opposite, so that when the rotor 100 rotates around the axis, the forces between the stator teeth 211 and the stator slots 212 in each pole of the permanent magnet motor tend to cancel each other, thereby weakening cogging torque ripple and reducing permanent magnet motor speed ripple. Of course, in other embodiments, the two ends of the set of barrier holes may be aligned with the stator teeth 211 or stator slots 212, respectively, in the cross-section of the rotor 100.

Specifically, in the present embodiment, please continue to refer to fig. 1 to 5, on the cross section of the rotor 100, a plurality of magnetic barrier holes 112 are distributed at intervals along the extending direction of the magnetic steel groove 111, so as to form a straight-axis magnetic circuit and a quadrature-axis magnetic circuit between the magnetic steel groove 111 and the magnetic barrier hole set. It will be appreciated that the magnetic barrier hole sets are distributed in series, and on the straight-axis magnetic circuit and the quadrature-axis magnetic circuit, the magnetic barrier hole sets can adjust the magnetic flux distribution of the permanent magnet 120, specifically, promote the magnetic resistance of the straight-axis magnetic circuit through the action of the magnetic barrier holes 112, so that the magnetic flux tends to be distributed along the quadrature-axis magnetic circuit, thereby increasing the magnetic resistance difference between the straight-axis magnetic circuit and the quadrature-axis magnetic circuit, that is, increasing the magnetic resistance difference between the q-axis and the d-axis, and promoting the magnetic resistance torque. Of course, in other embodiments, a low permeability medium may be placed in the magnetic barrier 112 to achieve the effect of the magnetic barrier 112 to promote reluctance of the direct axis magnetic circuit.

In an embodiment, referring to fig. 1 to 5, in the distribution direction of the magnetic steel groove 111 and the magnetic barrier hole set, the thickness of the permanent magnet 120 is R1, and R1 is equal to or greater than L2. It should be noted that, in this embodiment, R1 needs to be greater than or equal to the maximum value of the distance L2 from the first edge to the second edge in the magnetic barrier hole set, it can be understood that the magnetic barrier hole 112 is used to increase the magnetic resistance of the direct-axis magnetic circuit, and on the premise that the volume of the permanent magnet 120 is constant, the magnetic resistance of the direct-axis magnetic circuit is too large to affect the magnetic flux of the permanent magnet 120 on the d axis, so setting R1 to be greater than or equal to the maximum value of L2 can avoid that the width of the magnetic barrier hole 112 is too large to cause the magnetic resistance of the direct-axis magnetic circuit to be too large to affect the permanent magnet torque of the permanent magnet motor, thereby achieving the purpose of guaranteeing the output of the permanent magnet torque and achieving the optimal motor output effect. Of course, in other embodiments, the maximum width of the set of magnetic barrier holes may be set to be suitably larger than the thickness of the permanent magnet 120, provided that the permanent magnet torque is effectively output.

In the operation process of the permanent magnet motor, heat energy is easily generated due to electromagnetic action, so that the permanent magnet motor heats, and the permanent magnet 120 is easily demagnetized in an environment with overhigh temperature, so that the reliability of the permanent magnet motor is reduced. Thus, in an embodiment, referring to fig. 1 to 5, the thickness of the middle portion of the permanent magnet 120 is greater than or equal to the thickness of the end portion of the permanent magnet 120 in the cross section of the rotor 100. When the temperature of the permanent magnet motor increases, the permanent magnet 120 with fewer corners has stronger anti-demagnetization capability than the permanent magnet 120 with more corners, so that the permanent magnet 120 is configured to have a structure with thick middle and thin two ends, so that the local demagnetization of the permanent magnet 120 can be relieved, thereby improving the reliability of the permanent magnet motor, and in addition, the permanent magnet 120 with different thicknesses can prevent the permanent magnet 120 from sliding in the mounting groove to generate vibration demagnetization. Of course, in other embodiments, the width of the middle portion of the permanent magnet 120 may be smaller than the width of the end portions of the permanent magnet 120 in the cross section of the rotor 100 while securing the anti-demagnetization capability of the permanent magnet 120.

It will be appreciated that adjusting the ratio of the length to the span of the permanent magnet 120 in the cross section of the rotor 100 can effectively increase the air gap density of the permanent magnet 120, and in one embodiment, referring to fig. 1 to 5, the magnetic steel slots 111 are U-shaped or V-shaped opening toward the outer side of the rotor core 110 in the cross section of the rotor 100. In this embodiment, the permanent magnets 120 are fully installed in the magnetic steel grooves 111, so that the magnetic steel grooves 111 are provided in a U shape or V shape that is open toward the outer side of the rotor core 110, which improves the width of the permanent magnets 120 in the radial direction of the rotor 100 and reduces the span of the permanent magnets 120, effectively increasing the air gap density of the permanent magnets 120 of each pole of the rotor 100, that is, effectively increasing the permanent magnetic flux in the d-axis and q-axis directions of the rotor 100, thereby improving the utilization rate of the permanent magnets 120 and the performance of the rotor 100 without increasing the amount of the permanent magnets 120. Of course, in other embodiments, the magnetic steel grooves 111 may be provided in a serpentine or other shape on the premise of increasing the width of the permanent magnets 120 in the radial direction of the rotor 100 and decreasing the span of the permanent magnets 120 in the cross section of the rotor 100. Without loss of generality, in an embodiment, on the premise of meeting the permanent magnet torque requirement of the permanent magnet motor, the permanent magnets 120 in each magnetic steel groove 111 may be formed by splicing a plurality of permanent magnets 120, or the plurality of permanent magnets 120 are arranged at intervals and keep the same magnetic pole facing the same side of the magnetic steel groove 111.

In an embodiment, referring to fig. 7, the length of the rotor 100 is greater than or equal to the length of the stator 200 in the axial direction of the permanent magnet motor. Thus, on the premise of a certain motor power, increasing the length of the rotor 100 can raise the volume of the permanent magnet 120, so that the magnetic flux generated by the rotor 100 is increased, and stronger flux linkage is generated, thereby reducing the working current of the stator 200, or reducing the copper wire consumption in the stator 200, and reducing the cost of the permanent magnet motor. On the other hand, increasing the length of the rotor 100 can increase the magnetic flux of the rotor 100 to increase the permanent magnet torque and reluctance torque of the permanent magnet motor, thereby increasing the output capacity of the motor. Of course, in other embodiments, the length of the rotor 100 may be less than the length of the stator 200 when the magnetic flux of the rotor 100 meets the permanent magnet torque requirements of the motor.

In an embodiment, referring to fig. 1 to 5, the permanent magnet motor further includes at least two baffles, which are correspondingly fixed to the ends of the rotor core 110, for fixing the permanent magnets 120 in the magnetic steel slots 111. In this way, the permanent magnet 120 can be fixed inside the rotor 100, so as to avoid the permanent magnet 120 sliding out of the rotor 100 or vibrating during the operation or transportation of the permanent magnet motor, resulting in demagnetization of the permanent magnet 120, thereby improving the reliability of the permanent magnet motor.

The invention also provides a compressor comprising a permanent magnet motor, wherein the specific structure of the permanent magnet motor refers to the embodiment, and as the compressor adopts all the technical schemes of all the embodiments, the compressor at least has all the beneficial effects brought by the technical schemes of the embodiments, and the description is omitted herein.

The foregoing description is only of the optional embodiments of the present invention, and is not intended to limit the scope of the invention, and all the equivalent structural changes made by the description of the present invention and the accompanying drawings or the direct/indirect application in other related technical fields are included in the scope of the invention.

Claims

1. A permanent magnet motor, comprising:

the stator comprises a stator core, wherein a central hole and a plurality of stator teeth are formed on the stator core, the plurality of stator teeth are distributed along the circumferential direction of the central hole and are convexly arranged towards the central hole, stator grooves are formed between two adjacent stator teeth, the width of each stator groove is D1 on one side of each stator tooth towards the center of the central hole, and the width of each stator tooth is D2; and

the rotor is rotatably inserted into the central hole and comprises a rotor iron core and a plurality of permanent magnets, a plurality of magnetic steel grooves extending along the axial direction of the rotor iron core are formed in the circumferential direction of the rotor iron core, the permanent magnets are correspondingly arranged in the magnetic steel grooves, on a cross section obtained by cutting the rotor in a plane perpendicular to the axial direction of the rotor, two ends of the magnetic steel grooves are arranged adjacent to the outer side of the rotor iron core, and the width of the end parts of the magnetic steel grooves is L1; l1 is more than or equal to 0.8 (D2+D1).

2. The permanent magnet machine of claim 1 wherein, in said cross section, one end of said magnetic steel slot is opposite said stator teeth and the other end is opposite said stator slots.

3. The permanent magnet motor of claim 1 wherein the rotor core is further provided with a plurality of groups of magnetic barrier holes extending in an axial direction of the rotor core, wherein a magnetic area is formed between the magnetic steel grooves and an outer side of the rotor core, wherein the groups of magnetic barrier holes are located in the magnetic area, the groups of magnetic barrier holes have a first edge and a second edge which are close to and far from the magnetic steel grooves, the first edge and the second edge are arranged opposite to each other, and a distance from the first edge to the second edge is L2, and L2 is equal to or greater than D1.

4. A permanent magnet machine according to claim 3 wherein said set of barrier holes comprises a plurality of barrier holes, a plurality of said barrier holes being arranged in series, said set of barrier holes having two ends disposed adjacent to the outer side of said rotor core, respectively, in said cross section, the other end being opposite said stator slot when one end of said set of barrier holes is opposite said stator teeth.

5. The permanent magnet machine of claim 4 wherein in said cross section, a plurality of said barrier holes are spaced apart along the extension of said magnet steel slots to form a straight axis magnetic circuit and a quadrature axis magnetic circuit between said magnet steel slots and said set of barrier holes.

6. The permanent magnet motor of claim 3 wherein the permanent magnet has a thickness R1, R1 being greater than or equal to L2 in the direction of distribution of the magnet steel grooves and the groups of barrier holes.

7. The permanent magnet machine of claim 1 wherein, in said cross section, a thickness of a central portion of said permanent magnet is greater than or equal to a thickness of an end portion of said permanent magnet.

8. The permanent magnet machine of claim 1 wherein the length of the rotor is greater than or equal to the length of the stator in the axial direction of the permanent magnet machine.

9. The permanent magnet machine of claim 1 wherein said magnetic steel slots are U-shaped or V-shaped in cross section opening to the outside of said rotor core.

10. The permanent magnet motor according to any one of claims 1 to 9, further comprising at least two baffles correspondingly secured to ends of the rotor core for securing the permanent magnets in the magnetic steel slots.

11. A compressor comprising the permanent magnet motor according to any one of claims 1 to 10.