A rare earth permanent magnet synchronous motor and scroll type variable frequency compressor

Abstract

The application provides a rare earth permanent magnet synchronous motor and a scroll variable frequency compressor, and relates to the field of scroll compressor design and manufacturing. The rare earth permanent magnet synchronous motor comprises a stator core and a rotor core, the stator core is composed of a stator yoke, a stator tooth and a stator slot, the stator slot is provided with a slot opening and embedded with a winding, the slot opening has a central angle of theta 1, the outer diameter D1 of the stator core and the inner diameter D2 satisfy 0.529 < D2 / D1 < 0.623, and 165 mm <= D1 <= 175 mm. The rotor core is provided with P rare earth permanent magnet placing slots which are uniformly distributed along the circumference, the outer side of the slot is composed of a first circular arc in the middle and two second circular arcs which are symmetrical about the d-axis, the center of the first circular arc is at the center of the rotor, and the diameter D3 satisfies 1 mm <= D2-D3 <= 1.6 mm. The key structure size and the magnetic circuit of the stator and the rotor are optimized, so that the air gap magnetic flux waveform can be effectively improved, the tooth slot torque can be weakened, and the torque ripple can be reduced.

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 synchronous motor and a scroll-type variable frequency compressor. Background Technology

[0002] Scroll compressors, with their advantages of high efficiency, low noise, and stable operation, are widely used in household and commercial refrigeration and heating equipment. The performance of their drive motor directly determines the overall efficiency, operational stability, and service life of the compressor. Rare-earth permanent magnet synchronous motors, due to their high power density, excellent efficiency, and good control performance, are the core component of scroll compressors.

[0003] However, existing rare-earth permanent magnet synchronous motors used in scroll compressors have significant shortcomings in electromagnetic design, making it difficult to meet the requirements of high-end equipment for high efficiency, low noise, and low torque ripple. Currently, key structural parameters such as the inner and outer diameter ratio of the stator core, slot size, and tooth-yoke ratio in conventional motors lack refined design. Simultaneously, the structural parameters of existing motors, such as the outer edge of the rotor core, the size of the rare-earth permanent magnets, the magnetic bridge, and the magnetic ribs, lack systematic optimization. This easily leads to distortion of the air gap magnetic flux density waveform, resulting in high harmonic content and consequently, large cogging torque and significant torque ripple. Excessive cogging torque and torque ripple can cause increased compressor vibration and noise, accelerate wear of moving parts, and reduce the overall reliability and service life of the machine.

[0004] As the refrigeration industry continues to demand higher levels of quietness and reliability from compressors, existing motors can no longer meet the needs of high-performance applications. Therefore, it is necessary to optimize the key dimensions, slot structure, and magnetic circuit system of the stator and rotor to improve the air gap magnetic flux density waveform, reduce cogging torque, decrease torque pulsation, and enhance the overall performance of rare-earth permanent magnet synchronous motors, thereby promoting the technological upgrade of scroll compressors.

[0005] The present invention aims to provide a rare earth permanent magnet synchronous motor to improve the air gap magnetic flux density waveform, reduce cogging torque, and reduce torque pulsation. Summary of the Invention

[0006] To address the technical problems of existing rare-earth permanent magnet synchronous motors used in scroll-type variable frequency compressors, such as poor sinusoidal amplitude of air gap magnetic flux density waveform, large cogging torque, and high torque pulsation, this paper proposes a rare-earth permanent magnet synchronous motor and a scroll-type variable frequency compressor. Through the coordinated limitation and design of key dimensions of the stator and rotor cores, air gap magnetic flux density optimization, torque characteristics improvement, and operational reliability enhancement are achieved.

[0007] The technical means employed in this invention are as follows:

[0008] A rare-earth permanent magnet synchronous motor includes a stator core and a rotor core; The stator core includes a stator yoke, stator teeth, and stator slots. The number of stator teeth and stator slots is S. The stator slots have openings with a central angle of θ1. A winding is embedded in the stator slot. The winding is composed of a conductor and an insulator. The conductor is made of copper, aluminum, or a copper-aluminum mixture. The maximum outer diameter of the stator core is D1, and the inner diameter of the stator core is D2. D1 and D2 satisfy: 0.529 < D2 / D1 < 0.623, where D1 satisfies: 165mm ≤ D1 ≤ 175mm. The rotor core includes rare earth permanent magnet placement slots evenly distributed along the circumference. The axis of symmetry of the rare earth permanent magnet placement slots is the d-axis, and the axis of symmetry of two adjacent rare earth permanent magnet placement slots is the q-axis. Rare earth permanent magnets are installed in the rare earth permanent magnet placement slots, and the number of rare earth permanent magnet placement slots and rare earth permanent magnets is P. Each of the rare earth permanent magnet placement slots includes a first arc located in the middle and second arcs located on both sides. The two second arcs are symmetrical about the d-axis. The center O1 of the first arc is located at the center of the rotor core. The diameter of the first arc is D3, which satisfies: 1mm≤D2-D3≤1.6mm. The central angle of the first arc is θ2, which satisfies: 0.535<θ2 / θ1<1.428. The center O2 of the second arc is located on the line segment from the intersection of the first arc and the second arc to O1.

[0009] Furthermore, the distance from the center O2 of the second arc to the center O1 of the first arc is Lo, satisfying... .

[0010] Furthermore, the number S of stator teeth and stator slots and the number P of rare earth permanent magnet placement slots and rare earth permanent magnets satisfy: S / P=1.5, and 3≤SP≤5, where S and P are both integers.

[0011] Furthermore, the two sides of the stator teeth are parallel, the width of the stator teeth is defined as Lt, and the minimum thickness of the stator yoke is Ly, satisfying: 1.02≤Lt / Ly≤1.38.

[0012] Furthermore, the cross-sectional shape of the rare earth permanent magnet is rectangular, and the width of the rare earth permanent magnet is Lw, satisfying 0.98×(Lt+Ly)<Lw<1.23×(Lt+Ly); The thickness of the rare earth permanent magnet is Lp, which satisfies: 1.7mm≤Lp≤3.2mm.

[0013] Furthermore, the rare earth permanent magnet placement slot is provided with a third arc near the outer side of the rotor core, and the third arc is concentric with the second arc.

[0014] Furthermore, the third arc and the second arc form a magnetically blocked bridge, and the width of the magnetically blocked bridge is Lb, which satisfies: 0.5mm≤Lb≤1.1mm.

[0015] Furthermore, a parallel magnetic rib is formed between two adjacent rare earth permanent magnet placement slots, and the width of the parallel magnetic rib is Lr, which satisfies: Lb≤Lr≤4.5mm.

[0016] Furthermore, the intersection of two adjacent second arcs is chamfered with a chamfer radius of R, satisfying 0.2mm≤R≤4.5mm.

[0017] The present invention also provides a scroll inverter compressor, including the aforementioned rare-earth permanent magnet synchronous motor.

[0018] Compared with the prior art, the present invention has the following advantages: By defining the ratio of the stator core's inner and outer diameters, the central angle of the slot opening, and the rotor's arc angle, combined with the three-section rotor core outer contour and pole-slot fit, the air gap magnetic flux density waveform is made to approximate a sinusoidal distribution, reducing the harmonic content of the air gap magnetic flux density. Compared to traditional methods such as skewed poles and skewed slots, which only provide localized improvement and reduce power density and increase processing costs, this invention can significantly reduce cogging torque and torque pulsation without additional processes, resulting in smoother motor operation. 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 synchronous motor of the present invention.

[0021] Figure 2 This is a schematic diagram of the stator core structure of the present invention.

[0022] Figure 3 This is a schematic diagram of the rotor core structure of the present invention.

[0023] Figure 4 for Figure 3 A magnified view of part A in the image.

[0024] Figure 5 This is a comparison diagram of the air gap magnetic flux density harmonic distribution between the rare earth permanent magnet synchronous motor of this invention and the existing technology.

[0025] Figure 6This is a comparison chart of the peak-to-peak value of the cogging torque of the rare-earth permanent magnet synchronous motor of this invention and the prior art.

[0026] Figure 7 This is a comparison diagram of the electromagnetic torque waveforms of the rare-earth permanent magnet synchronous motor using the present invention and existing technologies.

[0027] Figure 8 This is a comparison chart of torque pulsation between the rare-earth permanent magnet synchronous motor of this invention and existing technologies.

[0028] In the diagram: 1. Rare-earth permanent magnet synchronous motor; 11. Stator core; 111. Stator yoke; 112. Stator teeth; 113. Stator slot; 1131. Slot opening; 1132. Winding; 12. Rotor core; 121. Rare-earth permanent magnet placement slot; 1211. Third arc; 122. Rare-earth permanent magnet; 123. First arc; 124. Second arc; 125. Magnetic bridge; 126. Parallel magnetic ribs. Detailed Implementation

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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 drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0033] like Figure 1-4 As shown, the present invention provides a rare-earth permanent magnet synchronous motor, including a stator core 11 and a rotor core 12; the stator core 11 includes a stator yoke 111, stator teeth 112 and stator slots 113, the number of stator teeth 112 and stator slots 113 is S, the stator slots 113 have slot openings 1131, the central angle of the slot openings 1131 is θ1, and windings 1132 are embedded in the stator slots 113. The windings 1132 are composed of conductors and insulators, the conductor material is copper or aluminum or copper-aluminum mixture, the maximum outer diameter of the stator core 11 is D1, the inner diameter of the stator core 11 is D2, D1 and D2 satisfy: 0.529<D2 / D1<0.623, where D1 satisfies: 165mm≤D1≤175mm.

[0034] The rotor core 12 includes rare earth permanent magnet placement slots 121 evenly distributed along the circumference. The axis of symmetry of the rare earth permanent magnet placement slots 121 is the d-axis, and the axis of symmetry of two adjacent rare earth permanent magnet placement slots 121 is the q-axis. Rare earth permanent magnets 122 are installed in the rare earth permanent magnet placement slots 121. The number of rare earth permanent magnet placement slots 121 and rare earth permanent magnets 122 is P. The outer side of each rare earth permanent magnet placement slot 121 is composed of a first circular arc 123 in the middle and second circular arcs 124 symmetrical about the d-axis on both sides. The center O1 of the first circular arc 123 is located at the center of the rotor core 12. The diameter of the first circular arc 123 is D3, which satisfies: 1mm≤D2-D3≤1.6mm. The central angle of the first circular arc 123 is θ2, which satisfies: 0.535<θ2 / θ1<1.428. The center O2 of the second circular arc 124 is located on the line segment from the intersection of the first circular arc 123 and the second circular arc 124 to O1.

[0035] Preferably, the distance from the center O2 of the second arc 124 to the center O1 of the first arc 123 is Lo, satisfying: .

[0036] By implementing the above limitations, the air gap magnetic flux density waveform can be effectively improved, the cogging torque can be reduced, the torque pulsation can be decreased, and the smoothness of motor and compressor operation can be enhanced.

[0037] Preferably, the number S of stator teeth 112 and stator slots 113 satisfies the following condition with respect to the number P of rare earth permanent magnet placement slots 121 and rare earth permanent magnets 122: S / P = 1.5, and 3 ≤ SP ≤ 5, where S and P are both integers. By selecting a reasonable pole-slot combination, the cogging torque period can be increased, thereby reducing the peak-to-peak value of the cogging torque.

[0038] Preferably, the two sides of the stator tooth 112 are parallel, the width of the stator tooth 112 is Lt, and the minimum thickness of the stator yoke 111 is Ly, satisfying: 1.02≤Lt / Ly≤1.38. This can make the magnetic circuit distribution uniform and reduce the influence of armature reaction on the distortion of the air gap magnetic flux density waveform.

[0039] Preferably, in order to make full use of the rare earth permanent magnet 122, the cross-sectional shape of the rare earth permanent magnet 122 is rectangular, the width of the rare earth permanent magnet 122 is Lw, which satisfies 0.98×(Lt+Ly)<Lw<1.23×(Lt+Ly); the thickness of the rare earth permanent magnet 122 is Lp, which satisfies: 1.7mm≤Lp≤3.2mm.

[0040] Preferably, the rare earth permanent magnet placement slot 121 is provided with a third arc 1211 near the outer side of the rotor core 12, and the third arc 1211 is concentric with the second arc 124.

[0041] Preferably, a magnetic blocking bridge 125 is formed between the third arc 1211 and the second arc 124, and the width of the magnetic blocking bridge 125 is Lb, satisfying: 0.5mm≤Lb≤1.1mm. This is to comprehensively balance factors such as leakage flux, structural strength, and magnetic flux density harmonics.

[0042] Preferably, to ensure a certain saliency ratio and enhance the magnetic weakening propagation capability, parallel magnetic ribs 126 are formed between two adjacent rare-earth permanent magnet placement slots 121. The width of the parallel magnetic ribs 126 is Lr, satisfying: Lb≤Lr≤4.5mm. Preferably, the intersection of two adjacent second arcs 124 is chamfered, with a chamfer radius of R, satisfying 0.2mm≤R≤4.5mm. This ensures the mechanical strength of the magnetic blocking bridge 125.

[0043] Some parameters in this embodiment are shown in the table below:

[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 commercial scroll inverter compressor with R32 refrigerant and a displacement of 120cc.

[0046] like Figure 5 The image shows a comparison of the air gap magnetic flux density harmonic distribution between the rare-earth permanent magnet synchronous motor of this invention and existing technologies. Figure 5 It can be seen that the amplitude of each harmonic of the rare earth permanent magnet synchronous motor 1 of the present invention is significantly reduced, indicating that the air gap magnetic flux density waveform is closer to a sine wave and the magnetic flux density harmonics are effectively suppressed.

[0047] like Figure 6 The image shows a comparison of the peak-to-peak cogging torque of the rare-earth permanent magnet synchronous motor of this invention with that of existing technologies. Figure 6 As can be seen, the rare-earth permanent magnet synchronous motor 1 with the optimized parameters of this invention reduces the peak-to-peak value of the cogging torque from 3.089 Nm to 1.063 Nm, a significant reduction. This significant decrease effectively improves the vibration characteristics of the compressor during start-up, low-speed operation, and steady-state operation, thereby significantly enhancing the overall operational stability and reliability of the scroll inverter compressor, reducing the risk of mechanical wear and structural fatigue caused by excessive vibration, and extending the overall service life of the compressor.

[0048] like Figure 7 The image shows a comparison of the output electromagnetic torque waveforms of the rare-earth permanent magnet synchronous motor of this invention and existing technologies. Figure 7 It can be seen that the output electromagnetic torque waveform of the rare earth permanent magnet synchronous motor 1 using the present invention is smoother, the peak-to-peak value is smaller, and the operation stability is higher.

[0049] like Figure 8 The image shows a comparison of torque ripple between the rare-earth permanent magnet synchronous motor of this invention and existing technologies. Figure 8 It can be seen that the rare earth permanent magnet synchronous motor 1 of the present invention has lower torque pulsation, which can effectively improve the vibration and noise problems during compressor operation.

[0050] In addition, the present invention also provides a scroll inverter compressor that uses the above-mentioned rare earth permanent magnet synchronous motor 1. The other structures and operations of the rare earth permanent magnet synchronous motor 1 and the scroll inverter compressor are known to those skilled in the art and will not be described in detail here.

[0051] 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; and these 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 synchronous motor, characterized in that, Including stator core and rotor core; The stator core includes a stator yoke, stator teeth, and stator slots. The number of stator teeth and stator slots is S. The stator slots have openings with a central angle of θ1. A winding is embedded in the stator slot. The winding is composed of a conductor and an insulator. The conductor is made of copper, aluminum, or a copper-aluminum mixture. The maximum outer diameter of the stator core is D1, and the inner diameter of the stator core is D2. D1 and D2 satisfy: 0.529 < D2 / D1 < 0.623, where D1 satisfies: 165mm ≤ D1 ≤ 175mm. The rotor core includes rare earth permanent magnet placement slots evenly distributed along the circumference. The axis of symmetry of the rare earth permanent magnet placement slots is the d-axis, and the axis of symmetry of two adjacent rare earth permanent magnet placement slots is the q-axis. Rare earth permanent magnets are installed in the rare earth permanent magnet placement slots, and the number of rare earth permanent magnet placement slots and rare earth permanent magnets is P. Each of the rare earth permanent magnet placement slots includes a first arc located in the middle and second arcs located on both sides. The two second arcs are symmetrical about the d-axis. The center O1 of the first arc is located at the center of the rotor core. The diameter of the first arc is D3, which satisfies: 1mm≤D2-D3≤1.6mm. The central angle of the first arc is θ2, which satisfies: 0.535<θ2 / θ1<1.

428. The center O2 of the second arc is located on the line segment from the intersection of the first arc and the second arc to O1.

2. The rare-earth permanent magnet synchronous motor according to claim 1, characterized in that, The distance Lo from the center O2 of the second arc to the center O1 of the first arc satisfies: .

3. The rare-earth permanent magnet synchronous motor according to claim 1, characterized in that, The number S of stator teeth and stator slots and the number P of rare earth permanent magnet placement slots and rare earth permanent magnets satisfy: S / P=1.5, and 3≤SP≤5, where S and P are both integers.

4. The rare-earth permanent magnet synchronous motor according to claim 1, characterized in that, The two sides of the stator teeth are parallel, the width of the stator teeth is defined as Lt, and the minimum thickness of the stator yoke is Ly, satisfying: 1.02≤Lt / Ly≤1.

38.

5. The rare-earth permanent magnet synchronous motor according to claim 4, characterized in that, The cross-sectional shape of the rare earth permanent magnet is rectangular, and the width of the rare earth permanent magnet is Lw, satisfying 0.98×(Lt+Ly)<Lw<1.23×(Lt+Ly); The thickness of the rare earth permanent magnet is Lp, which satisfies: 1.7mm≤Lp≤3.2mm.

6. The rare-earth permanent magnet synchronous motor according to claim 1, characterized in that, The rare earth permanent magnet placement slot is provided with a third arc near the outer side of the rotor core, and the third arc is concentric with the second arc.

7. The rare-earth permanent magnet synchronous motor according to claim 6, characterized in that, The third arc and the second arc form a magnetically blocked bridge, and the width of the magnetically blocked bridge is Lb, which satisfies: 0.5mm≤Lb≤1.1mm.

8. The rare-earth permanent magnet synchronous motor according to claim 7, characterized in that, The adjacent rare earth permanent magnet placement slots form parallel magnetic ribs, and the width of the parallel magnetic ribs is Lr, which satisfies: Lb≤Lr≤4.5mm.

9. The rare-earth permanent magnet synchronous motor according to claim 1, characterized in that, The intersection of two adjacent second arcs is chamfered with a chamfer radius of R, satisfying 0.2mm≤R≤4.5mm.

10. A scroll-type variable frequency compressor, characterized in that, Includes the rare-earth permanent magnet synchronous motor as described in any one of claims 1-9.

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