A rare earth permanent magnet motor and a variable frequency scroll compressor
By designing rotor and stator cores with specific structures in rare-earth permanent magnet motors, the air gap magnetic flux density harmonics are reduced, solving the problems of non-sinusoidal no-load back EMF waveform, large torque pulsation, high noise, and low efficiency of rare-earth permanent magnet motors in variable frequency scroll compressors, thus achieving better performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DALIAN SANYO COMPRESSOR
- Filing Date
- 2026-06-01
- Publication Date
- 2026-07-31
AI Technical Summary
Rare earth permanent magnet motors used in variable frequency scroll compressors suffer from problems such as high air gap magnetic flux density harmonic content, resulting in poor sinusoidal waveform of no-load back EMF, large cogging torque, large torque pulsation, high noise, and low efficiency.
A rare-earth permanent magnet motor is designed by setting uniformly distributed air slots on the rotor core and loading rare-earth permanent magnets with alternating polarities into the air slots. The outer edge of the rotor core is composed of straight line segments and eccentric circular arcs to satisfy specific geometric relationships to reduce air gap magnetic flux density harmonics.
It effectively reduces air gap magnetic flux density harmonics, improves no-load back EMF waveform, reduces torque pulsation and noise, and improves efficiency.
Smart Images
Figure CN122315960B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of compressor design and manufacturing technology, and more particularly to a rare earth permanent magnet motor and a variable frequency scroll compressor. Background Technology
[0002] The trend of variable frequency scroll compressors is gradually emerging, and rare earth permanent magnet motors play an important role as the power source for variable frequency scroll compressors.
[0003] However, rare-earth permanent magnet motors often have a high content of harmonics in the air gap magnetic flux density, leading to problems such as poor sinusoidal waveform of no-load back EMF, cogging torque, large torque pulsation, high noise, and low efficiency, which severely impact the performance of the compressor. Existing technologies, such as using skewed poles or skewed slots, can only improve some of the above problems, and also lead to a decrease in motor power density and an increase in cost.
[0004] The present invention aims to provide a rare earth permanent magnet motor to improve the poor sinusoidality of the no-load back EMF waveform, large cogging torque, large torque pulsation, high noise, and low efficiency of rare earth permanent magnet motors. Summary of the Invention
[0005] The rare-earth permanent magnet motor that drives the variable frequency scroll compressor has a high air gap magnetic flux density harmonic content, which leads to problems such as poor sinusoidal waveform of no-load back EMF, large torque pulsation, high noise and low efficiency. Therefore, a rare-earth permanent magnet motor is provided.
[0006] The technical means employed in this invention are as follows:
[0007] A rare-earth permanent magnet motor includes a stator core and a rotor core; The outer radius of the stator core is R1, and the inner radius of the stator core is R2; The rotor core has uniformly distributed air slots inside, the number of which is p. Each air slot is filled with rare earth permanent magnets with alternating polarities. The width of the rare earth permanent magnet is defined as w, the thickness of the rare earth permanent magnet is defined as h, the center line of the rare earth permanent magnet in the radial direction is defined as the d-axis, and the axis of symmetry between two adjacent rare earth permanent magnets is defined as the q-axis. The center of the rotor core is O1, and the outer edge of the rotor core is composed of multiple evenly distributed straight line segments and multiple evenly distributed eccentric circular arcs; the number of straight line segments is the same as the number of air slots, and the axis of symmetry of the straight line segments is located on the q-axis; the number of eccentric circular arcs is the same as the number of air slots, and the axis of symmetry of the eccentric circular arcs is located on the d-axis; and the straight line segments intersect with the eccentric circular arcs. The center of the eccentric arc is O2, the maximum distance from the outer edge of the rotor core to the center O1 of the rotor core is R3, and the radius of the eccentric arc is R4. make , , , , , , , , , , , , , , , , , , ,satisfy .
[0008] Furthermore, the number p of the air slots satisfies p=6 or p=8.
[0009] Furthermore, the outer radius R1 of the stator core satisfies: 92.5mm≤R1≤97.5mm.
[0010] Furthermore, the radius R2 of the inner side of the stator core and the maximum distance R3 from the outer edge of the rotor core to the center O1 of the rotor core satisfy the following condition: 0.5mm≤R2-R3≤1mm.
[0011] Furthermore, the maximum distance R3 between the outer edge of the rotor core and the center O1 of the rotor core satisfies: 0.61×R1<R3<0.66×R1.
[0012] Furthermore, the maximum distance R3 from the outer edge of the rotor core to the center O1 of the rotor core and the radius R4 of the eccentric arc satisfy: 5.2mm≤L1<R3-R4≤15.3mm.
[0013] Furthermore, the width w of the rare-earth permanent magnet satisfies: Where ks is the adjustment coefficient, 0.6≤ks<0.9; The thickness h of the rare earth permanent magnet satisfies: 2.5mm ≤ h < L1; The thickness h and width w of the rare earth permanent magnet also satisfy the following conditions with respect to A1 and An: .
[0014] Furthermore, the minimum distance hr between two adjacent air slots satisfies: R2-R3≤hr≤4×(R2-R3).
[0015] Furthermore, the minimum distance wb between the air slot and the outer edge of the rotor core satisfies: 0.45mm≤wb≤1.2mm.
[0016] The present invention also provides a variable frequency scroll compressor, including the aforementioned rare earth permanent magnet motor.
[0017] Compared with the prior art, the present invention has the following advantages: 1. Ensure that the number of straight segments on the outer edge of the rotor core is the same as the number of air slots, and that the axis of symmetry of each straight segment is located on the q-axis. Also ensure that the number of eccentric arcs is the same as the number of air slots, and that the axis of symmetry of each eccentric arc is located on the d-axis. The intersection of each straight segment and each eccentric arc can reduce air gap magnetic flux density harmonics.
[0018] 2. Ensure that the structural parameters of the stator core and rotor core meet the requirements. This can further reduce air gap magnetic flux density harmonics, thereby improving the no-load back EMF waveform, reducing cogging torque, reducing torque pulsation, reducing noise, and improving efficiency. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the structure of the rare earth permanent magnet motor of the present invention.
[0021] Figure 2 This is a schematic diagram of the rotor core structure of the present invention.
[0022] Figure 3 for Figure 2 A magnified view of part A in the image.
[0023] Figure 4 This is a comparison chart of the peak-to-peak value of the cogging torque of the rare-earth permanent magnet motor of this invention and that of existing technologies.
[0024] Figure 5 This is a comparison chart of the harmonic distortion rate of the no-load back EMF of the rare-earth permanent magnet motor of this invention and that of existing technologies.
[0025] Figure 6 This is a comparison diagram of the output electromagnetic torque waveforms of the rare-earth permanent magnet motor of this invention and existing technologies.
[0026] Figure 7 This is a comparison chart of torque pulsation between the rare-earth permanent magnet motor of this invention and existing technologies.
[0027] Figure 8 This is a comparison chart of the radiated acoustic power of the rare-earth permanent magnet motor of this invention and existing technologies at multiple speeds.
[0028] Figure 9 This is a comparison chart of the efficiency of the rare-earth permanent magnet motor of this invention and existing technologies under typical operating conditions.
[0029] In the diagram: 11. Stator core; 12. Rotor core; 121. Air slot; 122. Rare earth permanent magnet; 123. Straight line segment; 124. Eccentric arc. Detailed Implementation
[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.
[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0033] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.
[0034] like Figure 1 , Figure 2 , Figure 3 As shown, this invention provides a rare-earth permanent magnet motor, including a stator core 11 and a rotor core 12. The outer radius of the stator core 11 is R1, and the inner radius is R2. The rotor core 12 has uniformly distributed air slots 121, the number of which is p. Each air slot 121 contains alternating polarity rare-earth permanent magnets 122. The width of each rare-earth permanent magnet 122 is defined as w, the thickness as h, the radial centerline of each rare-earth permanent magnet 122 is defined as the d-axis, and the axis of symmetry between two adjacent rare-earth permanent magnets 122 is defined as the q-axis. The center of the rotor core 12 is O1, and the outer edge of the rotor core 12 consists of multiple uniformly distributed straight segments 123 and multiple uniformly distributed eccentric arcs 124. The number of straight segments 123 is the same as the number of air slots 121, and the axis of symmetry of each straight segment 123 is located at the q-axis. The number of eccentric arcs 124 is the same as the number of air slots 121. The axis of symmetry of each eccentric arc 124 is located on the d-axis, and the straight line segment 123 intersects with the eccentric arc 124. The center of the eccentric arc 124 is O2, the maximum distance from the outer edge of the rotor core 12 to the center O1 of the rotor core 12 is R3, and the radius of the eccentric arc 124 is R4.
[0035] make , , , , , , , , , , , , , , , , , , ,satisfy .
[0036] By implementing the above limitations, the air gap magnetic flux density harmonics can be weakened, the waveform of the no-load back EMF can be improved, and the torque pulsation can be reduced.
[0037] Preferably, under the limitations of the actual operating speed range of the compressor and the variable frequency range of the frequency converter, the number p of the air slots 121 satisfies p=6 or p=8.
[0038] Preferably, under the constraint of the inner diameter of the compressor housing, the outer radius R1 of the stator core 11 satisfies: 92.5mm≤R1≤97.5mm.
[0039] Preferably, the inner radius R2 of the stator core 11 and the maximum distance R3 from the outer edge of the rotor core 12 to the center O1 of the rotor core 12 satisfy the following condition: 0.5mm ≤ R2 - R3 ≤ 1mm. This ensures that the magnetic flux density of the core is reasonable and that assembly is convenient.
[0040] Preferably, in order to select a reasonable pole arc coefficient, make the magnetic circuit distribution more reasonable, reduce the risk of irreversible demagnetization of the rare earth permanent magnet 122, and minimize costs while ensuring performance, the width w of the rare earth permanent magnet 122 satisfies: Where ks is the adjustment coefficient, 0.6≤ks<0.9, the thickness h of rare earth permanent magnet 122 satisfies: 2.5mm≤h<L1. In addition, the thickness h and width w of rare earth permanent magnet 122, along with A1 and An, also satisfy: .
[0041] Preferably, the minimum distance hr between two adjacent air slots 121 satisfies: R2-R3≤hr≤4×(R2-R3). This ensures a certain saliency ratio and magnetic weakening propagation capability.
[0042] Preferably, in order to reduce magnetic leakage, make full use of rare earth permanent magnets 122, and ensure a certain strength, the minimum distance wb between the air slot 121 and the outer edge of the rotor core 12 satisfies: 0.45mm≤wb≤1.2mm.
[0043] Some parameters in this embodiment are shown in the table below: Table: Specific values for each parameter
[0044] It should be noted that "prior art" as used below refers to technology that does not meet any one or more of the limitations in the table above.
[0045] The following explanation will be based on a scroll compressor with R32 refrigerant, a displacement of 160cc, and internal low pressure.
[0046] like Figure 4 The figure shown is a comparison of the peak-to-peak value of the cogging torque between the rare-earth permanent magnet motor of the present invention and the prior art.
[0047] Depend on Figure 4 It can be seen that the peak-to-peak value of the cogging torque of the rare earth permanent magnet motor using the present invention is significantly reduced, thus improving the vibration of the motor and compressor.
[0048] like Figure 5 The figure shown is a comparison of the no-load back EMF harmonic distortion rate between the rare-earth permanent magnet motor of this invention and the existing technology.
[0049] Depend on Figure 5 It can be seen that by using the rare earth permanent magnet motor of the present invention, the harmonic content is reduced, the harmonic distortion rate of the no-load back EMF is smaller, and the waveform is closer to a sine wave.
[0050] like Figure 6 and Figure 7 The figures show a comparison of the output electromagnetic torque waveforms of the rare-earth permanent magnet motor of this invention and existing technologies, and a comparison of the torque pulsation of the rare-earth permanent magnet motor of this invention and existing technologies.
[0051] As can be seen from the figure, the output electromagnetic torque waveform of the rare earth permanent magnet motor using the present invention has a smaller peak value and lower torque pulsation, which can achieve the purpose of improving vibration and noise.
[0052] like Figure 8 The figure shown is a comparison of the radiated sound power of the rare earth permanent magnet motor of the present invention with that of the prior art at multiple speeds.
[0053] Depend on Figure 8 It can be seen that the radiated sound power of the rare earth permanent magnet motor using the present invention is lower than that of the prior art at all speeds, proving that the present invention can effectively reduce noise.
[0054] like Figure 9 The figure shown is a comparison of the efficiency of the rare-earth permanent magnet motor of the present invention with that of the prior art under typical operating conditions.
[0055] Depend on Figure 9 It can be seen that the rare earth permanent magnet motor of this invention has improved efficiency under various typical operating conditions compared with the existing technology.
[0056] In addition, the present invention also provides a variable frequency scroll compressor that uses the above-mentioned rare earth permanent magnet motor. Other structures and operations of the rare earth permanent magnet motor and the variable frequency scroll compressor are known to those skilled in the art and will not be described in detail here.
[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions 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 rare earth permanent magnet electric machine characterized by, Including stator core and rotor core; The outer radius of the stator core is R1, and the inner radius of the stator core is R2; The rotor core has uniformly distributed air slots inside, the number of which is p. Each air slot is filled with rare earth permanent magnets with alternating polarities. The width of the rare earth permanent magnet is defined as w, the thickness of the rare earth permanent magnet is defined as h, the center line of the rare earth permanent magnet in the radial direction is defined as the d-axis, and the axis of symmetry between two adjacent rare earth permanent magnets is defined as the q-axis. The center of the rotor core is O1, and the outer edge of the rotor core is composed of multiple evenly distributed straight line segments and multiple evenly distributed eccentric circular arcs; the number of straight line segments is the same as the number of air slots, and the axis of symmetry of the straight line segments is located on the q-axis; the number of eccentric circular arcs is the same as the number of air slots, and the axis of symmetry of the eccentric circular arcs is located on the d-axis; and the straight line segments intersect with the eccentric circular arcs. The center of the eccentric arc is O2, the maximum distance from the outer edge of the rotor core to the center O1 of the rotor core is R3, and the radius of the eccentric arc is R4. Let , , , , , , , , , , , , , , , , , , , satisfy .
2. The rare-earth permanent magnet motor according to claim 1, characterized in that, The number p of the air slots satisfies p=6 or p=8.
3. The rare-earth permanent magnet motor according to claim 1, characterized in that, The outer radius R1 of the stator core satisfies: 92.5mm≤R1≤97.5mm.
4. The rare-earth permanent magnet motor according to claim 1, characterized in that, The inner radius R2 of the stator core and the maximum distance R3 from the outer edge of the rotor core to the center O1 of the rotor core satisfy the following condition: 0.5mm≤R2-R3≤1mm.
5. The rare-earth permanent magnet motor according to claim 1, characterized in that, The maximum distance R3 from the outer edge of the rotor core to the center O1 of the rotor core satisfies: 0.61×R1<R3<0.66×R1.
6. The rare-earth permanent magnet motor according to claim 1, characterized in that, The maximum distance R3 from the outer edge of the rotor core to the center O1 of the rotor core and the radius R4 of the eccentric arc satisfy: 5.2mm≤L1<R3-R4≤15.3mm.
7. The rare-earth permanent magnet motor according to claim 1, characterized in that, The width w of the rare earth permanent magnet satisfies: Where ks is the adjustment coefficient, 0.6≤ks<0.9; The thickness h of the rare earth permanent magnet satisfies: 2.5mm ≤ h < L1; The thickness h and width w of the rare earth permanent magnet also satisfy the following conditions with respect to A1 and An: .
8. The rare-earth permanent magnet motor according to claim 1, characterized in that, The minimum distance hr between two adjacent air slots satisfies: R2-R3≤hr≤4×(R2-R3).
9. The rare-earth permanent magnet motor according to claim 1, characterized in that, The minimum distance wb between the air slot and the outer edge of the rotor core satisfies: 0.45mm≤wb≤1.2mm.
10. A variable frequency scroll compressor, characterized in that, Includes the rare-earth permanent magnet motor as described in any one of claims 1-9.