A permanent magnet synchronous motor and variable frequency compressor

Abstract

The present invention provides a permanent magnet synchronous motor and a variable frequency compressor, which relate to the technical field of compressor design and manufacturing. The permanent magnet synchronous motor includes a stator core and a rotor core arranged inside the stator core; the stator core includes stator teeth uniformly distributed in the circumferential direction, a stator yoke is arranged between two adjacent stator teeth, two adjacent stator teeth and the stator yoke between the two stator teeth form a stator slot, and a winding is embedded in the stator slot; a plurality of uniformly distributed eccentric arcs and straight line segments are arranged in the circumferential direction of the outer edge of the rotor core, uniformly distributed magnetic steel plug holes are arranged inside the rotor core, and a groove is arranged between two adjacent magnetic steel plug holes; a permanent magnet with alternating NS poles is arranged in the magnetic steel plug hole. In the present invention, by limiting the inner diameter Rsi of the stator core, the maximum outer diameter Rro of the rotor core and the axial length Les of the stator core to satisfy: 0.455≤Les / (Rsi+Rro)≤1.264, the torque density of the synchronous motor can be increased and the cost can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of compressor design and manufacturing, and in particular to a permanent magnet synchronous motor and a variable frequency compressor. Background Art

[0002] The high energy efficiency rating of permanent magnet synchronous motors gives them a significant advantage in energy utilization, which can effectively reduce energy consumption and is in line with the current global development trend of energy conservation and emission reduction. Its wide operating range and high overload capacity allow the compressor to operate stably and efficiently under different working conditions.

[0003] However, it cannot be ignored that compared with asynchronous motors, permanent magnet synchronous motors have a low torque density, which means that at the same volume or weight, their output torque is relatively small, which may be limited in some special application scenarios with high torque requirements; the high cost also makes some companies hesitate when choosing, increasing the overall manufacturing cost and selling price of the product, and affecting the speed of market promotion. In addition, the back EMF of permanent magnet synchronous motors has poor sinusoidality, and the presence of a large number of harmonics not only causes the compressor to vibrate and make noise, but may also affect the service life and operating stability of the motor, posing a higher challenge to the design optimization of the motor, and further in-depth research and technological breakthroughs are needed to overcome these defects.

[0004] The present invention provides a permanent magnet synchronous motor and a variable frequency compressor, aiming to improve torque density, reduce cost, improve the sinusoidality of the motor back electromotive force waveform and thus reduce the vibration noise of the variable frequency compressor. Summary of the invention

[0005] According to the above technical problems of low torque density and poor sinusoidal degree of back electromotive force in existing permanent magnet synchronous motors, a permanent magnet synchronous motor and variable frequency compressor are provided. The present invention can improve the back electromotive force waveform, weaken the back electromotive force harmonics, and reduce the vibration noise during the operation of the variable frequency compressor by changing the angle of the eccentric arc and the straight line segment of the outer edge of the rotor core and the center of the eccentric arc.

[0006] The technical means adopted by the present invention are as follows:

[0007] A permanent magnet synchronous motor comprises a stator core and a rotor core arranged inside the stator core;

[0008] The stator core comprises stator teeth uniformly distributed in the circumferential direction, a stator yoke is arranged between two adjacent stator teeth, two adjacent stator teeth and the stator yoke between the two stator teeth form a stator slot, and a winding is embedded in the stator slot;

[0009] The outer edge of the rotor core is provided with a plurality of evenly distributed eccentric arcs and straight line segments in the circumferential direction, and the rotor core is provided with evenly distributed magnetic steel plug holes, and a groove is provided between two adjacent magnetic steel plug holes; the magnetic steel plug holes are provided with permanent magnets with alternating NS poles;

[0010] The inner diameter of the stator core is Rsi, the maximum outer diameter of the rotor core is Rro, the outer diameter of the stator core is Rso, the axial length of the stator core is Les, and the axial length of the rotor core is Ler;

[0011] Among them, Rsi, Rro and Les satisfy: 0.455≤Les / (Rsi+Rro)≤1.264;

[0012] Between Rso, Rsi and Les: 36992mm 3 ≤(Rso-Rsi) 2 ×Les≤187704.3mm 3 ;

[0013] Rsi and Rro satisfy 0.5+Rro≤Rsi≤1.2+Rro;

[0014] Les and Ler satisfy 1≤Ler / Les≤1.2;

[0015] The value range of Les is: 50mm≤Les≤120mm.

[0016] Furthermore, the number of stator slots is Q, the number of winding phases of the stator core is m, and the number of magnetic steel sockets distributed on the rotor core is p, wherein Q, m and p satisfy: Q / (m*p)=0.5.

[0017] Furthermore, the stator tooth width is wt, wherein the value range of wt is: 17mm≤wt≤21.8mm; the stator yoke thickness is hi, wherein the value range of hi is: 8.6mm≤hi≤14.5mm.

[0018] Further, θ =360° / 2p, the central angle of the eccentric arc between the d-axis and the q-axis is α , the central angle of the straight line segment between the d-axis and the q-axis is β， The angle between the d-axis and the q-axis is θ, in α、β as well as θ Satisfaction between α + β = θ , and 0< β < α < θ; wherein the d-axis is the center line of the permanent magnet along the radial direction, and the q-axis is the center line between two adjacent permanent magnets.

[0019] Furthermore, a vertical distance Rro2 from the straight line segment to the center of the rotor core satisfies the following relationship: 0mm<Rro-Rro2≤2.5mm.

[0020] Furthermore, the value range of the first magnetic isolation bridge width w1 is: 0.5mm≤w1≤1mm, and the value range of the second magnetic isolation bridge width w2 is: 0.6mm≤w2≤1.2mm;

[0021] The value range of the groove width w3 between two adjacent magnetic steel plug holes is: 1mm≤w3≤3mm; the value range of the groove depth d3 between two adjacent magnetic steel plug holes is: Rro-w2≤d3≤Rro-Rrp;

[0022] Rrp is the minimum distance from the center of the rotor core to the line connecting the bottom corners of the two permanent magnets in the groove.

[0023] Furthermore, the width of the permanent magnet is hm, the thickness of the permanent magnet is bm, wherein hm and bm satisfy 8.12≤hm / bm≤16.3.

[0024] Furthermore, the rotor core is provided with an axial hole which is concentric with its rotation center, and rivet holes are evenly arranged around the periphery of the axial hole.

[0025] The present invention also provides a variable frequency compressor, comprising the permanent magnet synchronous motor.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. By limiting the inner diameter Rsi of the stator core, the maximum outer diameter Rro of the rotor core, and the axial length Les of the stator core to satisfy: 0.455≤Les / (Rsi+Rro)≤1.264, the torque density of the synchronous motor can be increased and the cost can be reduced.

[0028] 2. By limiting the number of stator slots Q, the number of winding phases m of the stator core and the magnetic steel jack p of the rotor core to satisfy: Q / (m*p)=0.5, centralized winding can be achieved, the length of the winding end can be reduced, thereby reducing copper loss and increasing motor efficiency.

[0029] 3. By limiting the axial length Les of the stator core and the axial length Ler of the rotor core to satisfy: 1≤Ler / Les≤1.2, the end magnetic leakage can be reduced and the material can be fully utilized under the premise of considering the feasibility of the manufacturing process.

[0030] 4. By changing the angle of the eccentric arc and the straight line segment on the outer edge of the rotor core and the center of the eccentric arc, the back-EMF waveform can be improved, the back-EMF harmonics can be weakened, and the vibration noise during the operation of the variable frequency compressor can be reduced.

[0031] 5. By limiting the groove width w3 between two adjacent magnetic steel holes to satisfy 1mm≤w3≤3mm, and the groove depth d3 between two adjacent magnetic steel holes to satisfy Rro-w2≤d3≤Rro-Rrp, the inter-pole leakage flux can be reduced while ensuring the sinusoidality of the back-electromotive force waveform, thereby improving the torque density and reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0033] Figure 1 It is a structural schematic diagram of the permanent magnet synchronous motor of the present invention.

[0034] Figure 2 It is a schematic diagram of the stator core structure in the present invention.

[0035] Figure 3 It is a schematic diagram of the rotor core structure in the present invention.

[0036] Figure 4 The figure is a cost comparison diagram of the permanent magnet synchronous motor of the present invention and the prior art.

[0037] Figure 5 The figure is a comparison diagram of the no-load back EMF waveforms of the permanent magnet synchronous motor of the present invention and the prior art.

[0038] Figure 6 The figure is a comparison diagram of the no-load back electromotive force harmonics of the permanent magnet synchronous motor of the present invention and the prior art.

[0039] Figure 7 The figure is a comparison chart of the no-load back-EMF harmonic distortion rate of the permanent magnet synchronous motor of the present invention and the prior art.

[0040] In the figure: 1. permanent magnet synchronous motor; 2. stator core; 4. stator teeth; 5. stator yoke; 6. stator slots; 7. stator winding; 3. rotor core; 8. eccentric arc; 9. straight line segment; 10. magnetic steel jack; 11. first magnetic isolation bridge; 12. second magnetic isolation bridge; 13. groove; 14. permanent magnet; 15. shaft hole; 16. rivet hole. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0044] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps described in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0045] like Figure 1-3As shown, the present invention provides a permanent magnet synchronous motor, comprising: a stator core 2 and a rotor core 3 rotatably sleeved inside the stator core 2, the stator core 2 comprising stator teeth 4 uniformly distributed in the circumferential direction, a stator yoke 5 is arranged between two adjacent stator teeth 4, two adjacent stator teeth 4 and the stator yoke 5 therebetween define stator slots 6 equal in number to the stator teeth 4, and windings 7 are embedded in the stator slots 6; a plurality of uniformly distributed eccentric arcs 8 and straight line segments 9 are arranged in the circumferential direction of the outer edge of the rotor core 3, uniformly distributed magnetic steel plug holes 10 are arranged inside the rotor core 3, and a groove 13 is arranged between two adjacent magnetic steel plug holes 10; wherein, the inner diameter Rsi of the stator core 2, the maximum outer diameter Rro of the rotor core 3, and the axial length Les of the stator core 2 satisfy 0.45≤Les / (Rsi+Rro)≤1.264, while reducing the cost of the motor, the torque density is improved, the back electromotive force harmonics are reduced, and the vibration and noise of the variable frequency compressor are reduced;

[0046] The rotor core 3 is provided with an axial hole 15 which is concentric with its rotation center, and rivet holes 16 are evenly arranged on the periphery of the axial hole 15;

[0047] A permanent magnet 14 with alternating N and S poles is disposed in the magnetic steel socket 10 .

[0048] After the rotor punching sheets punched and sheared in the present invention are axially stacked to the required length and riveted through the rivet holes 16, the permanent magnets 14 are inserted into the magnetic steel sockets 10. In order to ensure the power or torque required by the motor output, the residual magnetic flux density Br of the permanent magnets 14 needs to satisfy 12.2kGs≤Br≤15.3kGs.

[0049] The permanent magnets 14 can be further reinforced at both end surfaces of the rotor core 3 by using non-magnetic pressure plates.

[0050] Considering the process of the variable frequency compressor, the cross-section of the permanent magnet 14 is "I"-shaped. The permanent magnet 14 is inserted into the magnetic steel socket 10 and then magnetized. During magnetization, it is necessary to ensure that the magnetic field direction of the permanent magnet 14 is parallel to the d-axis, and the magnetic flux directions are arranged alternately.

[0051] Preferably, the width hm of the permanent magnet 14 and the thickness bm of the permanent magnet 14 satisfy 8.12≤hm / bm≤16.3 to ensure:

[0052] (1) Reasonable pole arc coefficient to make the magnetic field distribution reasonable and obtain good electromagnetic performance;

[0053] (2) The maximum demagnetization working point is within the safe range to avoid the permanent magnet 14 from being unable to be demagnetized;

[0054] (3) Reasonable rotor magnetomotive force, matched with the stator magnetomotive force to ensure the required output torque;

[0055] (4) The permanent magnet 14 can be smoothly inserted into the magnetic steel insertion hole 10 within the limited internal space of the rotor core 3.

[0056] Preferably, the inner diameter Rsi of the stator core 2, the maximum outer diameter Rro of the rotor core 3, and the axial length Les of the stator core 2 satisfy 0.45≤Les / (Rsi+Rro)≤1.264, which can increase the torque density of the motor and reduce the cost of the motor.

[0057] Preferably, the number of stator slots 6 is Q, the number of phases of winding 7 of stator core 2 is m, and the number of magnetic steel jacks 10, p of rotor core 3 satisfy Q / (m*p)=0.5, so that the span of winding 7 is 1, the length of the end of winding 7 is reduced, thereby reducing the copper loss of winding 7 and increasing the efficiency of the motor. In this embodiment, the number of stator slots 6 is Q is 9, the number of magnetic steel jacks 10 is p is 6, and the number of phases of motor winding 7 is m is 3, which satisfies Q / (m*p)=0.5.

[0058] Preferably, the outer diameter Rso of the stator core 2, the inner diameter Rsi of the stator core 2, and the axial length Les of the stator core 2 satisfy 36992 mm. 3 ≤(Rso-Rsi) 2 ×Les≤187704.3mm 3 , which can satisfy the motor's requirement of outputting higher torque within a certain volume and reduce the motor's cost.

[0059] Preferably, the inner diameter Rsi of the stator core 2 and the maximum outer diameter Rro of the rotor core 3 satisfy 0.5+Rro≤Rsi≤1.2+Rro, thereby ensuring the feasibility of the manufacturing process while meeting the cost and electromagnetic performance requirements of the motor.

[0060] The stator core 2 and the rotor core 3 are formed by punching out electromagnetic steel sheets having a specific shape.

[0061] The thickness of the electromagnetic steel sheet is within the range of 0.2 mm to 0.5 mm.

[0062] Preferably, the axial length Les of the stator core 2 and the axial length Ler of the rotor core 3 satisfy 1≤Ler / Les≤1.2, which can reduce end magnetic leakage and fully utilize materials while considering the feasibility of the manufacturing process.

[0063] Preferably, the axial length Les of the stator core 2 satisfies 50 mm ≤ Les ≤ 120 mm, so as to realize a series design of different output torques according to load requirements, cost requirements, etc.

[0064] Preferably, if Figure 2As shown, the width wt of the stator tooth 4 satisfies 17mm≤wt≤21.8mm; the thickness hi of the stator yoke 5 satisfies 8.6mm≤hi≤14.5mm, so as to ensure a certain slot area and achieve a certain line load; fully consider the motor overload condition and the saturation degree of the electromagnetic steel plate to ensure that the tooth magnetic density and the yoke magnetic density are within a reasonable range; achieve a certain stiffness, so that the stator assembly mode is within a reasonable range, thereby reducing the electromagnetic vibration noise.

[0065] Preferably, if Figure 3 As shown, =360° / 2p, the eccentric arc 8 between the d-axis and the q-axis is at the center angle , the straight line segment between the d-axis and the q-axis is 9, the central angle , the angle between the d-axis and the q-axis Satisfaction between + = , and 0< < < , improving the sinusoidality of the back EMF waveform on the basis of less loss of torque density, reducing harmonics, and thus reducing vibration noise.

[0066] The d-axis is the center line of the permanent magnet 14 along the radial direction, and the q-axis is the center line between two adjacent permanent magnets 14. is the angle between the d-axis and the q-axis.

[0067] Preferably, the vertical distance Rro2 from the straight section 9 to the center of the rotor core 3 and the maximum outer diameter Rro of the rotor core 3 satisfy 0mm<Rro-Rro2≤2.5mm, so as to make the air gap non-uniform and improve the air gap magnetic flux density and no-load back EMF waveform.

[0068] Preferably, the width w1 of the first magnetic isolation bridge 11 and the width w2 of the second magnetic isolation bridge 12 satisfy 0.5 mm≤w1≤1 mm and 0.6 mm≤w2≤1.2 mm, respectively, so as to reduce magnetic leakage and improve the back electromotive force waveform.

[0069] While ensuring the mechanical strength, the width w1 of the first magnetic isolation bridge 11 and the width w2 of the second magnetic isolation bridge 12 can be as small as possible.

[0070] Preferably, the width w3 of the groove 13 between two adjacent magnetic steel plug holes 10 satisfies 1mm≤w3≤3mm, and the depth d3 of the groove 13 between two adjacent magnetic steel plug holes 10 satisfies Rro-w2≤d3≤Rro-Rrp, so as to further reduce magnetic leakage, make full use of materials and reduce costs;

[0071] Rrp is the minimum distance between the line connecting the bottom corners of the two permanent magnets 14 close to the groove 13 and the center of the rotor core 3.

[0072] The magnetic leakage coefficient can be between 1.12 and 1.20 to ensure full utilization of the material while having better speed regulation performance.

[0073] It should be noted that the “prior art” mentioned below specifically refers to the fact that the inner diameter Rsi of the stator core 2, the maximum outer diameter Rro of the rotor core 3, and the axial length Les of the stator core 2 do not satisfy 0.45≤Les / (Rsi+Rro)≤1.264, the air gap between the stator and the rotor is not treated for non-uniformity, that is, the outer edge of the rotor core 3 is not treated, and the groove 13 is not set between the poles of the rotor core 3.

[0074] like Figure 4 As shown, it is a cost comparison chart of the permanent magnet synchronous motor 1 of the embodiment of the present invention and the prior art. Among them, Les / (Rsi+Rro) of the prior art is 1.3905, which is outside the scope of the present invention; Les / (Rsi+Rro) of the present invention is 1.0173, which is within the scope of the present invention.

[0075] from Figure 4 It can be seen that the permanent magnet synchronous motor 1 of the present invention saves 15.98% of the cost compared with the permanent magnet synchronous motor 1 of the prior art, and the cost is reduced to a large extent, thereby improving the product competitiveness.

[0076] like Figure 5-7 Shown are a comparison diagram of the no-load back-EMF waveform of the permanent magnet synchronous motor 1 using the embodiment of the present invention and the prior art at a motor speed of 1000 rpm, a comparison diagram of the no-load back-EMF harmonics of the permanent magnet synchronous motor 1 using the embodiment of the present invention and the prior art, and a comparison diagram of the no-load back-EMF harmonic distortion rate of the permanent magnet synchronous motor 1 using the embodiment of the present invention and the prior art.

[0077] The no-load back EMF of the permanent magnet synchronous motor 1 is an important indicator. The effective value of the no-load back EMF determines the efficiency, power factor, weak magnetic field speed expansion capability, etc. of the motor. The sinusoidality of the waveform of the no-load back EMF can be measured by the harmonic distortion rate, which will affect the output torque quality, electromagnetic vibration noise, etc. of the motor.

[0078] from Figure 5 It can be seen that the no-load back EMF waveform of the present invention has better sinusoidality than that of the prior art, which shows that the improvement measures of the present invention have brought about significant improvement.

[0079] from Figure 6 It can be seen that although the amplitude of the fundamental wave of the present invention is slightly lower than that of the prior art, it is still within a reasonable range, and the remaining subharmonics of the present invention are reduced to varying degrees.

[0080] from Figure 7It can be seen that the no-load back EMF harmonic distortion rate of the present invention is significantly lower than that of the prior art, which further proves that based on the above specific implementation method, the no-load back EMF waveform can be effectively improved, thereby weakening harmonics and reducing vibration noise.

[0081] Depend on Figure 2-Figure 7 It can be seen that after adopting the present invention, not only the cost of the prior art is reduced, but also the electromagnetic performance of the motor is significantly improved, so that the competitiveness of the product is enhanced.

[0082] The present invention further proposes a variable frequency compressor, which adopts the above permanent magnet synchronous motor 1. The other structures and operations of the variable frequency compressor are known to those skilled in the art and will not be described in detail.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A permanent magnet synchronous motor, characterized in that: The invention comprises a stator core and a rotor core arranged inside the stator core, wherein the stator core comprises stator teeth uniformly distributed in the circumferential direction, a stator yoke is arranged between two adjacent stator teeth, two adjacent stator teeth and the stator yoke between the two stator teeth form a stator slot, and a winding is embedded in the stator slot; The outer edge of the rotor core is provided with a plurality of evenly distributed eccentric arcs and straight line segments in the circumferential direction, and the rotor core is provided with evenly distributed magnetic steel plug holes, and a groove is provided between two adjacent magnetic steel plug holes; the magnetic steel plug holes are provided with permanent magnets with alternating NS poles; The inner diameter of the stator core is Rsi, the maximum outer diameter of the rotor core is Rro, the outer diameter of the stator core is Rso, the axial length of the stator core is Les, and the axial length of the rotor core is Ler; Among them, Rsi, Rro and Les satisfy: 0.455≤Les / (Rsi+Rro)≤1.264; Between Rso, Rsi and Les: 36992mm 3 ≤(Rso-Rsi) 2 ×Les≤187704.3mm 3 ; Rsi and Rro satisfy 0.5+Rro≤Rsi≤1.2+Rro; Les and Ler satisfy 1≤Ler / Les≤1.2; The value range of Les is: 50mm≤Les≤120mm.

2. The permanent magnet synchronous motor according to claim 1, characterized in that: The number of stator slots is Q, the number of winding phases of the stator core is m, and the number of magnetic steel holes distributed on the rotor core is p, wherein Q, m and p satisfy: Q / (m*p)=0.

5.

3. The permanent magnet synchronous motor according to claim 1, characterized in that: The stator tooth width is wt, where the value range of wt is: 17mm≤wt≤21.8mm; the stator yoke thickness is hi, where the value range of hi is: 8.6mm≤hi≤14.5mm.

4. The permanent magnet synchronous motor according to claim 1, characterized in that: =360° / 2p, the center angle of the eccentric arc between the d-axis and the q-axis is α, the center angle of the straight line segment between the d-axis and the q-axis is β, and the angle between the d-axis and the q-axis is ， where α 、 β and Satisfy α+β= , and 0<β<α< ; The d-axis is the center line of the permanent magnet along the radial direction, and the q-axis is the center line between two adjacent permanent magnets.

5. The permanent magnet synchronous motor according to claim 1, characterized in that: The vertical distance from the straight line segment to the center of the rotor core is Rro2, wherein Rro2 and Rro satisfy the following: 0mm<Rro-Rro2≤2.5mm.

6. The permanent magnet synchronous motor according to claim 1, characterized in that: The value range of the first magnetic isolation bridge width w1 is: 0.5mm≤w1≤1mm, and the value range of the second magnetic isolation bridge width w2 is: 0.6mm≤w2≤1.2mm; The value range of the groove width w3 between two adjacent magnetic steel plug holes is: 1mm≤w3≤3mm; the value range of the groove depth d3 between two adjacent magnetic steel plug holes is: Rro-w2≤d3≤Rro-Rrp; Rrp is the minimum distance from the center of the rotor core to the line connecting the bottom corners of the two permanent magnets in the groove.

7. The permanent magnet synchronous motor according to claim 1, characterized in that: The width of the permanent magnet is hm, and the thickness of the permanent magnet is bm, wherein hm and bm satisfy 8.12≤hm / bm≤16.

3.

8. The permanent magnet synchronous motor according to claim 1, characterized in that: The rotor core is provided with an axial hole which is concentric with the rotation center thereof, and rivet holes are evenly arranged on the periphery of the axial hole.

9. A variable frequency compressor, characterized in that: It comprises a permanent magnet synchronous motor as claimed in any one of claims 1 to 8.

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