Rotor core, permanent magnet motor and inverter compressor

Abstract

The invention provides a rotor iron core, a permanent magnet motor and an inverter compressor, and relates to the technical field of motor and compressor design and manufacture, the rotor iron core comprises uniformly distributed permanent magnet grooves, a groove is arranged between two adjacent permanent magnet grooves, each groove extends inwards along the radial direction of the rotor iron core, parallel magnetic bridges are arranged between the grooves and the permanent magnet grooves, and the permanent magnet grooves are connected with the parallel magnetic bridges. A first magnetic barrier groove, a second magnetic barrier groove and a third magnetic barrier groove which are symmetrically distributed are formed in the two sides of the top of each permanent magnet groove respectively, a first arc and a second arc are arranged on the outer side of the rotor core above the magnetic barrier grooves, the second arc intersects with the side edge of the groove, and permanent magnets with alternating magnetism are embedded in the permanent magnet grooves. The radius Rr of the outer side of the rotor iron core, the distance ho from the middle point of the bottom of the permanent magnet groove to the center point of the rotor iron core and the thickness hm of the permanent magnet meet the condition that (Rr-ho) / hm is larger than 2 and smaller than or equal to 3.4. By reasonably arranging the position and the size of the magnetic barrier groove, magnetic circuit distribution can be changed, magnetic flux leakage can be reduced, the power density of the motor can be increased, and electromagnetic vibration noise of the motor and the compressor can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of compressor design and manufacturing, in particular, especially relates to a rotor core, a permanent magnet motor and a variable frequency compressor. BACKGROUND

[0002] The variable frequency compressor is configured with a frequency converter and a rare earth permanent magnet motor, which can dynamically and steplessly adjust the operating speed, can operate at a speed higher than the rated speed in the initial start-up period after temperature setting, realizes rapid refrigeration or heating, and operates at low frequency, low power consumption, low power, low noise when reaching the set temperature, is high in energy efficiency, and is far higher in comprehensive energy efficiency ratio than the fixed frequency compressor. At present, the variable frequency compressor has become the mainstream of household or commercial refrigeration and heating equipment due to its advantages of comfort, energy saving and reliability.

[0003] The motor as the driving power source of the compressor is an important component of the compressor product, and the performance of the motor directly affects the overall performance of the compressor and the customer experience. In recent years, with the development of power electronic devices and control strategy control algorithm, the variable frequency rare earth permanent magnet motor gradually replaces the fixed frequency product using an induction motor. Compared with the induction motor and the electrically excited synchronous motor, the permanent magnet motor can maintain high efficiency and power factor under different loads, is low in energy consumption, small in size and light in weight under the same power, and can realize rapid response and precise control by matching the frequency converter.

[0004] The rare earth permanent magnet motor is often high in cost, and related technical means need to be adopted to increase the power density while ensuring excellent performance and reduce the cost. The permanent magnet motor using fractional slot concentrated winding is widely applied because it can reduce the end length, reduce the copper loss, and can be mass-produced with high manufacturing efficiency. However, a large number of useless harmonics exist in the motor, which brings about large motor torque ripple, obvious vibration and noise and other problems.

[0005] The present application provides a rotor core, a permanent magnet motor and a variable frequency compressor to increase the power density, reduce the cost, and reduce the vibration and noise of the motor and the compressor. SUMMARY

[0006] The rare earth permanent magnet motor is high in cost, and a large number of useless harmonics exist in the motor after using fractional slot concentrated winding, which brings about large motor torque ripple, obvious vibration and noise and other technical problems, and the present application provides a rotor core, a permanent magnet motor and a variable frequency compressor. The present application reasonably sets the positions and sizes of the first magnetic barrier slot, the second magnetic barrier slot and the third magnetic barrier slot on the basis of limiting the maximum vertical distance from the top of the permanent magnet slot to the outside of the rotor core, and sets the grooves between the first arc, the second arc outside the rotor core and the permanent magnet slot, so as to reduce the magnetic flux leakage, improve the magnetic field distribution and reduce the vibration and noise.

[0007] The technical means adopted by the present application are as follows: A rotor core with an outer radius Rr, the rotor core comprising uniformly distributed permanent magnet grooves, the distance from the bottom midpoint of the permanent magnet groove to the center point of the rotor core being ho, and a magnetically alternating permanent magnet being embedded in each of the permanent magnet grooves, the thickness of the permanent magnet being hm, the outer radius Rr of the rotor core, the distance ho from the bottom midpoint of the permanent magnet groove to the center point of the rotor core, and the thickness hm of the permanent magnet satisfying 2 < (Rr-ho) / hm ≤ 3.4. The top of each of the permanent magnet grooves is provided with symmetrically distributed first, second, and third magnetic barrier grooves. The first magnetic barrier groove is at a distance h1 from the top of the permanent magnet groove and at a distance L1 from the side of the permanent magnet groove, and the width of the first magnetic barrier groove is w1; the second magnetic barrier groove is at a distance h2 from the top of the permanent magnet groove and at a distance L2 from the first magnetic barrier groove, and the width of the second magnetic barrier groove is w2; the third magnetic barrier groove is at a distance h3 from the top of the permanent magnet groove and at a distance L3 from the second magnetic barrier groove, and the width of the third magnetic barrier groove is w3. The top of each of the first, second, and third magnetic barrier grooves is a circular arc, and the radius of the circular arc is Rk. Each of the size relationships satisfies 0.45mm ≤ h1 < h2 < h3 ≤ 1.3mm; 2mm ≤ L1 < L2 < L3 ≤ 5mm; 2.55h1 ≤ w1 ≤ 3.5h1; w3 = w2 < L1, h1 < Rr-Rk ≤ h3.

[0008] Further, each edge intersection of all the magnetic barrier grooves is chamfered by 0.2mm.

[0009] Further, the outer side of the rotor core above the magnetic barrier grooves comprises a first circular arc and a second circular arc. The center O1 of the first circular arc is at the center of the rotor core, and the central angle δ thereof satisfies 20° ≤ δ ≤ 30°. The center O2 of the second circular arc is offset from the center O1 of the first circular arc, and the radius Rc of the second circular arc satisfies Rr-25.7mm ≤ Rc ≤ Rr-22.6mm with respect to the outer radius Rr of the rotor core.

[0010] Further, the number of the permanent magnets is p, the number of the stator slots outside the rotor core is Z, and the number of the symmetric windings embedded in the stator core is m, wherein p, m, and Z satisfy p = (2 Z) / m.

[0011] Further, a groove is provided between two adjacent permanent magnet grooves, and each of the grooves extends inward along the radial direction of the rotor core. The intersection of the second circular arc and the side of the groove forms a first chamfer, and the intersection of the side of the groove and the bottom of the groove forms a second chamfer. The angle between the bottom edge of the groove and the bottom edge of the permanent magnet slot is θ, and θ satisfies the relationship between θ and the number of permanent magnet slots p: θ = 180° (1-1 / p).

[0012] Furthermore, the groove and the side of the permanent magnet groove form a parallel magnetic bridge, the width of the parallel magnetic bridge is wb, and wb, Rr and Rk satisfy the following relationship: wb=Rr-Rk.

[0013] Furthermore, the magnetic field directions of adjacent permanent magnets are the same as and opposite to the radial direction of the rotor core, respectively; The permanent magnet is rectangular in shape; The thickness of the permanent magnet is hm, and hm and w1 satisfy the following condition: w1<hm≤3mm; The width of the permanent magnet is wm, and the width of the permanent magnet slot is wc. The relationship between the dimensions of wm, wc and the magnetic barrier slot satisfies: L1+L2+L3+w1+w2+w3<2 / (wc-0.1mm)=wm / 2.

[0014] The present invention also includes a permanent magnet motor, comprising the rotor core described above.

[0015] The present invention also includes a variable frequency compressor, comprising the aforementioned permanent magnet motor.

[0016] Compared with the prior art, the present invention has the following advantages: 1. Based on the relationship between the distance ho from the bottom midpoint of the permanent magnet slot to the center point of the rotor core, the thickness hm of the permanent magnet, the outer radius Rr of the rotor core, and the distance ho from the bottom midpoint of the permanent magnet slot to the center point of the rotor core, the magnetic circuit direction can be changed by limiting the position and size of the first, second, and third magnetic barrier slots symmetrically distributed on both sides of the top of the permanent magnet slot, thereby improving the magnetic field distribution, increasing the effective value of the no-load back EMF, reducing the power density, improving the efficiency of the motor and compressor system, reducing harmonics, and reducing vibration and noise.

[0017] 2. By setting a first arc with its center at the center of the rotor core, a second arc with its center offset from the center of the rotor core, and a groove between the permanent magnet slots on the outer circle of the rotor and defining them accordingly, the back EMF waveform can be improved, leakage flux can be reduced, and power density can be further increased.

[0018] 3. By limiting the width, thickness, shape, and magnetization direction of the permanent magnet, the cost of the motor can be reduced while ensuring electromagnetic performance.

[0019] 4. Based on the original stator refrigerant flow channel, the first magnetic barrier channel, second magnetic barrier channel, third magnetic barrier channel, and groove opened by this invention can further increase the refrigerant flow area inside the compressor, improve temperature rise, reduce losses, and increase efficiency. Attached Figure Description

[0020] 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.

[0021] Figure 1 This is a schematic diagram of the rotor core structure of the present invention.

[0022] Figure 2 for Figure 1 Enlarged view of point A in the middle.

[0023] Figure 3 for Figure 1 Enlarged view of section B in the middle.

[0024] Figure 4 for Figure 1 Enlarged view of point C.

[0025] Figure 5 This is a schematic diagram of the permanent magnet motor in this invention.

[0026] Figure 6 This is a comparison chart of the effective values ​​of the no-load back EMF of the rotor core using the present invention and that of the prior art.

[0027] Figure 7 This is a comparison chart of the efficiency of the rotor core using the present invention and the prior art at the rated point.

[0028] Figure 8 This is a comparison chart of the radiated acoustic power of the rotor core using the present invention and that of the prior art.

[0029] Figure 9 This is a comparison chart of the radiated acoustic power at 24th harmonic frequency between the rotor core of this invention and the prior art.

[0030] In the diagram: 1. Permanent magnet motor; 11. Stator core; 111. Stator slot; 12. Rotor core; 121. Permanent magnet slot; 122. Permanent magnet; 123. First magnetic barrier slot; 124. Second magnetic barrier slot; 125. Third magnetic barrier slot; 126. Groove; 127. Parallel magnetic bridge; 128. First arc; 129. Second arc; 130. First chamfer; 131. Second chamfer. Detailed Implementation

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] like Figures 1-5As shown in the figure, the present invention provides a rotor core and a permanent magnet motor. The permanent magnet motor 1 includes a stator core 11, a stator slot 111 inside the stator core, a rotor core 12. The outer radius of the rotor core 12 is Rr, which includes evenly distributed permanent magnet slots 121. The distance from the midpoint of the bottom of the permanent magnet slot 121 to the center point of the rotor core 12 is ho. Each permanent magnet slot 121 is embedded with permanent magnets 122 with alternating magnetism. The thickness of the permanent magnet 122 is hm, and the relationship is satisfied: 2 < (Rr - ho) / hm ≤ 3.4; on both sides of the top of the permanent magnet slot 121, there are symmetrically distributed first magnetic barrier slots 123, second magnetic barrier slots 124 and third magnetic barrier slots 125. The distance from the first magnetic barrier slot 123 to the top of the permanent magnet slot 121 is h1, and the distance from the first magnetic barrier slot 123 to the side of the permanent magnet slot 121 is L1. The width of the first magnetic barrier slot 123 is w1. The distance from the second magnetic barrier slot 124 to the top of the permanent magnet slot 121 is h2, and the distance from the second magnetic barrier slot 124 to the first magnetic barrier slot 123 is L2. The width of the second magnetic barrier slot 124 is w2; the distance from the third magnetic barrier slot 125 to the top of the permanent magnet slot 121 is h3, and the distance from the third magnetic barrier slot 125 to the second magnetic barrier slot 124 is L3. The width of the third magnetic barrier slot 125 is w3; the tops of the first magnetic barrier slot 123, the second magnetic barrier slot 124 and the third magnetic barrier slot 125 are all arcs, and the radius of the top arc is Rk. Each dimension relationship satisfies: 0.45mm ≤ h1 < h2 < h3 ≤ 1.3mm and 2mm ≤ L1 < L2 < L3 ≤ 5mm and 2.55h1 ≤ w1 ≤ 3.5h1 and w3 = w2 < L1 and h1 < Rr - Rk ≤ h3. On the premise of ensuring the mechanical strength of the rotor core 12, the magnetic circuit direction can be changed, the magnetic field distribution can be improved, the effective value of the no-load back electromotive force can be increased, the power density can be reduced, the harmonics can be reduced, and the electromagnetic vibration noise can be reduced. In this embodiment, Rr = 42.8mm, ho = 34.6mm, hm = 2.5mm, (Rr - ho) / hm = 3.28, which satisfies the relationship of 2 < (Rr - ho) / hm ≤ 3.4; in this embodiment, h1 = 0.5mm, h2 = 0.8mm, h3 = 1.2mm, which satisfies: 0.45mm ≤ h1 < h2 < h3 ≤ 1.3mm; in this embodiment, L1 = 2.7mm, L2 = 3.7mm, L3 = 4.3mm, which satisfies the relationship limit of 2mm ≤ L1 < L2 < L3 ≤ 5mm; in this embodiment, w1 = 1.4mm, which satisfies 2.55h1 = 1.275mm ≤ w1 = 1.4mm ≤ 3.5h1 = 1.75mm; in this embodiment, w2 = w3 = 1mm, which satisfies the limit of w3 = w2 < L1; in this embodiment, Rk = 42.2mm, then h1 = 0.5mm < Rr - Rk = 0.6mm ≤ h3 = 1.2mm.

[0036] Preferably, within the limited space of the rotor core, in order to reduce the mold cost and further improve the magnetic field direction, chamfers of 0.2mm are made at the intersections of the sides of all magnetic barrier slots.

[0037] Preferably, the outer side of the rotor core 12 above each magnetic barrier slot includes a first arc 128 and a second arc 129. The center O1 of the first arc 128 is located at the center of the rotor core 12, and the central angle δ it occupies satisfies: 20°≤δ≤30°. The center O2 of the second arc 129 is offset from the center O1 of the first arc 128, and the radius Rc of the second arc 129 and the outer radius Rr of the rotor core 12 satisfy: Rr-25.7mm≤Rc≤Rr-22.6mm. By setting segmented arcs, the air gap between the rotor core 12 and the stator core 11 can be made non-uniform, improving the magnetic permeability distribution, thereby weakening certain unfavorable harmonics and improving motor performance.

[0038] Preferably, to ensure that the stator core 11 has concentrated windings embedded in the stator slots 111 to reduce end length, lower copper loss, achieve high mass production efficiency, and improve manufacturing efficiency, the number of permanent magnets 122, p, the number of stator slots 111 outside the rotor core 12, Z, and the number of symmetrical winding phases m embedded in the stator core 11 must satisfy: p = (2 Z) / m. In this embodiment, if the number of permanent magnets 122 is p=6, the number of stator slots 111 is Z=9, and the number of symmetrical winding phases is m=3, then p=(2) / m. Z) / m.

[0039] Preferably, to reduce magnetic leakage between permanent magnets 122, a groove 126 is provided between two adjacent permanent magnet slots 121, and each groove 126 extends inward along the radial direction of the rotor core 12; to avoid magnetic field distortion and further improve the magnetic field, the second arc 129 intersects with the side of the groove 126 to form a first chamfer 130, and the side of the groove 126 intersects with the bottom edge of the groove 126 to form a second chamfer 131; to achieve a reasonable cross-axis inductance, increase the refrigerant flow area to improve temperature rise and efficiency, and improve the demagnetization resistance of the permanent magnets 122, the angle θ between the bottom edge of the groove 126 and the bottom edge of the permanent magnet slot 121 and the number p of the permanent magnet slots 121 must satisfy: θ = 180° (1-1 / p). In this embodiment, θ=180° (1-1 / 6)=150°.

[0040] Preferably, to further reduce magnetic leakage, the groove 126 and the side of the permanent magnet groove 121 form a parallel magnetic bridge 127. In order to enhance the effect of reducing magnetic leakage, the magnetic field of the parallel magnetic bridge 127 needs to be highly saturated and ensure that it is not affected by interference and centrifugal force during the rotational speed operation. The width wb of the parallel magnetic bridge 127 needs to satisfy: wb=Rr-Rk.

[0041] Preferably, the magnetic field directions of adjacent permanent magnets 122 are the same as and opposite to the radial direction of the rotor core 12, respectively. To facilitate installation and reduce processing costs, the permanent magnets 122 are rectangular in shape. The thickness hm of the permanent magnets 122 and the width w1 of the first magnetic barrier slot 123 satisfy: w1<hm≤3mm. The width wm of the permanent magnets 122, the width wc of the permanent magnet slot 121, and the dimensions of the first magnetic barrier slot 123, the second magnetic barrier slot 124, and the third magnetic barrier slot 125 satisfy: L1+L2+L3+w1+w2+w3<2 / (wc-0.1mm)=wm / 2. By limiting the width, thickness, shape, and magnetization direction of the permanent magnets 122, a reasonable pole arc coefficient can be ensured. While ensuring electromagnetic performance, the amount of permanent magnets 122 used can be reduced, thus lowering the cost of the motor.

[0042] It should be noted that the term "prior art" as used below specifically refers to a situation where the outer radius of the rotor core 12 is Rr, the distance from the midpoint of the bottom of the permanent magnet slot 121 to the center point of the rotor core 12 is ho, and the thickness of the permanent magnet 122 is hm, satisfying 2 < (Rr - ho) / hm ≤ 3.4, and where the first magnetic barrier slot 123, the second magnetic barrier slot 124, and the third magnetic barrier slot 125 are not provided. The permanent magnet dimensions, remanence, magnetization method, coercivity, etc., of the "prior art" are consistent with those of this invention.

[0043] like Figure 6 The diagram shows a comparison of the effective values ​​of the no-load back electromotive force (EMF) at 1000 rpm between the rotor core of this invention and existing technologies. Using the rotor core of this invention, through the rational design of the magnetic barrier slots, grooves 126, and parallel magnetic bridges 127, the no-load back EMF is increased by 2.35% compared to existing technologies. This means that when the motor is not in a weak magnetic field and the magnetic circuit is not saturated, the current is reduced by the same amount, thus reducing copper losses at low speeds. This achieves the goal of reducing leakage flux between the permanent magnets 122 and increasing power density.

[0044] like Figure 7 The figure shows a comparison of the efficiency of the compressor at rated operating point (load torque 29.1 Nm, speed 3600 rpm) using the rotor core of this invention and existing technology. Figure 7 As can be seen, the rotor core of the present invention improves efficiency.

[0045] like Figures 8-9 The figures shown are a comparison of the radiated acoustic power of the rotor core of the present invention with that of the prior art at high speed and a load torque of 17.43 Nm, and a comparison of the radiated acoustic power of the rotor core of the present invention with that of the prior art at 24th harmonic.

[0046] During high-speed operation of the compressor, the requirements for vibration and noise are relatively high. Figure 8As can be seen, during the high-speed operation of the compressor, the radiated sound power of the rotor core of this invention is reduced to varying degrees compared with the prior art at different speeds, with a more significant reduction at higher speeds. At the three speeds, the radiated sound power is reduced by 2.40%, 7.34%, and 9.07%, respectively, demonstrating the effectiveness of the rotor core of this invention.

[0047] Regarding the 24 times mechanical frequency noise, which is of particular concern to the human ear, from Figure 9 It can be seen that the radiated sound power of the rotor core using the embodiment of the present invention is reduced to varying degrees at different speeds compared with the prior art, further confirming the noise reduction effect of the rotor core using the present invention.

[0048] This invention proposes a permanent magnet motor using the rotor core 12.

[0049] The present invention also proposes a variable frequency compressor that uses the permanent magnet motor 1. The other structures and operations of the permanent magnet motor and the variable frequency compressor are known to those skilled in the art and will not be described in detail here.

[0050] 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 rotor core, characterized in that, The outer radius is Rr, the rotor core includes uniformly distributed permanent magnet slots, the distance from the midpoint of the bottom of the permanent magnet slot to the center point of the rotor core is ho, each permanent magnet slot is embedded with alternating magnetic permanent magnets, the thickness of the permanent magnet is hm, the outer radius Rr of the rotor core, the distance ho from the midpoint of the bottom of the permanent magnet slot to the center point of the rotor core, and the thickness hm of the permanent magnet satisfy 2<(Rr-ho) / hm≤3.4; The top two sides of the permanent magnet slot are provided with a first magnetic barrier slot, a second magnetic barrier slot and a third magnetic barrier slot symmetrically distributed. The first magnetic barrier groove is h1 from the top of the permanent magnet groove and L1 from the side of the permanent magnet groove, and its width is w1; the second magnetic barrier groove is h2 from the top of the permanent magnet groove and L2 from the first magnetic barrier groove, and its width is w2; the third magnetic barrier groove is h3 from the top of the permanent magnet groove and L3 from the second magnetic barrier groove, and its width is w3. The tops of the first magnetic barrier groove, the second magnetic barrier groove, and the third magnetic barrier groove are all arcs, and the radius of the arc is Rk. The dimensional relationships satisfy: 0.45mm≤h1<h2<h3≤1.3mm; 2mm≤L1<L2<L3≤5mm; 2.55h1≤w1≤3.5h1; w3=w2<L1, h1<Rr-Rk≤h3.

2. The rotor core according to claim 1, characterized in that, All intersections of the magnetic barrier slots are chamfered by 0.2mm.

3. The rotor core according to claim 1, characterized in that, The outer side of the rotor core above the magnetic barrier slot includes a first arc and a second arc; The center O1 of the first arc is located at the center of the rotor core, and the central angle δ it occupies satisfies: 20°≤δ≤30°; The center O2 of the second arc deviates from the center O1 of the first arc, and the radius Rc of the second arc satisfies the following relationship with the outer radius Rr of the rotor core: Rr-25.7mm≤Rc≤Rr-22.6mm.

4. The rotor core according to claim 3, characterized in that, The number of permanent magnets is p, the number of stator slots outside the rotor core is Z, and the number of phases of the symmetrical windings embedded in the stator core is m, where p, m, and Z satisfy the following relationship: p = (2... Z) / m.

5. The rotor core according to claim 4, characterized in that, A groove is provided between two adjacent permanent magnet slots, and each groove extends inward along the radial direction of the rotor core. The second arc intersects with the side edge of the groove to form a first chamfer, and the side edge of the groove intersects with the bottom edge of the groove to form a second chamfer; The angle between the bottom edge of the groove and the bottom edge of the permanent magnet slot is θ, and θ satisfies the relationship between θ and the number of permanent magnet slots p: θ = 180° (1-1 / p).

6. The rotor core according to claim 5, characterized in that, The groove and the side of the permanent magnet groove form a parallel magnetic bridge. The width of the parallel magnetic bridge is wb, and wb, Rr and Rk satisfy the following relationship: wb=Rr-Rk.

7. The rotor core according to claim 1, characterized in that, The magnetic field directions of adjacent permanent magnets are the same as and opposite to the radial direction of the rotor core, respectively. The permanent magnet is rectangular in shape; The thickness of the permanent magnet is hm, and hm and w1 satisfy the following condition: w1<hm≤3mm; The width of the permanent magnet is wm, and the width of the permanent magnet slot is wc. The relationship between the dimensions of wm, wc and the magnetic barrier slot satisfies: L1+L2+L3+w1+w2+w3<2 / (wc-0.1mm)=wm / 2.

8. A permanent magnet motor, characterized in that, Includes the rotor core as described in any one of claims 1-7.

9. A variable frequency compressor, characterized in that, The permanent magnet motor described in claim 8 is used.

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