Stator lamination, stator core and single-phase permanent magnet motor for single-phase permanent magnet motor

Abstract

This invention relates to the field of compressor motor technology, and particularly to a stator lamination, stator core, and single-phase permanent magnet motor for use in a single-phase permanent magnet motor. The stator lamination has a stator inner circle at its center, and a plurality of stator teeth are arranged on the inner wall of the stator inner circle. These stator teeth are evenly distributed circumferentially along the stator inner circle, and stator slots are formed between adjacent stator teeth. The number of stator slots is 4k, where k ≥ 1. The stator lamination has four structural corners. In all stator slots, four stator slots form a corner slot. The four corner slots and the four structural corners are arranged radially along the stator inner circle. Furthermore, each corner slot has an expansion groove at its bottom that is recessed away from the center of the stator lamination. This allows for an increase in the conductor cross-sectional area of ​​the winding within the slot, or a reduction in current density, thereby reducing copper losses in the winding to a certain extent and controlling the temperature rise of the stator, ensuring the motor's efficiency and service life.

Description

Technical Field

[0001] This invention relates to the field of compressor motor technology, and in particular to a stator lamination, stator core, and single-phase permanent magnet motor for use in a single-phase permanent magnet motor. Background Technology

[0002] For single-phase permanent magnet motors in refrigerator compressors, the stator core is typically formed by stacking several stator laminations. These laminations are generally square or nearly square, with four structural corners formed on their outer periphery. These corners are used to create positioning holes for mounting the compressor motor. Furthermore, an inner stator circle is formed on the inner side of the stator laminations, and several stator teeth are evenly distributed along the circumferential edge of this inner circle. Stator slots are formed between adjacent stator teeth to accommodate the motor's main and auxiliary windings.

[0003] In related technologies, single-phase permanent magnet motors typically use 4k (a multiple of 4, such as 4, 8, or 12 slots) sector-shaped stator slots. This type of motor has limited slot area formed by the stator laminations, which restricts the cross-sectional area of ​​the winding conductors within the slots. This makes it difficult to reduce the current density in the windings, resulting in higher copper losses at rated current, leading to higher stator temperature rise and impacting motor efficiency and lifespan. Furthermore, when using sector-shaped slots, the core at the four corners is not fully utilized, resulting in low overall stator core utilization. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the existing single-phase permanent magnet motor coil winding copper loss, which affects the efficiency and service life of the motor, and the low overall utilization rate of the stator core. The present invention provides a stator lamination, stator core and single-phase permanent magnet motor for a single-phase permanent magnet motor.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution:

[0006] In a first aspect, the present invention provides a stator lamination for a single-phase permanent magnet motor. A stator inner circle is formed at the center of the stator lamination. A plurality of stator teeth are provided on the inner wall of the stator inner circle, and these teeth are evenly distributed circumferentially along the inner circle. A stator slot is formed between two adjacent stator teeth, and the number of stator slots is 4k, where k ≥ 1. The stator lamination has four structural corners. Four of the stator slots are respectively formed as a corner slot. The four corner slots and the four structural corners are arranged radially along the inner circle of the stator. Furthermore, an expansion groove is formed at the bottom of each corner slot, concave towards the center of the stator lamination.

[0007] The stator lamination for a single-phase permanent magnet motor provided by this invention further improves the four corner slots corresponding to the four structural corners. Specifically, an expansion slot is formed at the bottom of each corner slot, concave towards the center away from the stator lamination, thereby increasing the area inside the slot. This allows for the placement of more windings within the slot, or a reduction in winding density. This increases the conductor cross-sectional area of ​​the windings within the slot, or reduces the current density. As a result, the copper loss of the windings can be reduced to a certain extent, and the temperature rise of the stator can be controlled, thus ensuring the efficiency and service life of the motor.

[0008] Preferably, the chamfered contours of all the structural corners are on the same circular contour, and positioning holes are provided at the positions of each structural corner;

[0009] Along the radial direction of the inner circle of the stator, the groove depth h of the expansion groove satisfies:

[0010] ,

[0011] Where R1 is the radius of the circular profile of the chamfered contour at the structural corner, R2 is the radius of the circular profile of the bottom of the stator slot, D is the diameter of the positioning hole, and B... r B is the remanence of the permanent magnet in a single-phase permanent magnet motor. K To determine the magnetic flux density (R) of the stator core material of a single-phase permanent magnet motor, 转 H is the outer diameter of the rotor of a single-phase permanent magnet motor. 磁 This represents the thickness of the permanent magnet in a single-phase permanent magnet motor along the rotor radial direction.

[0012] This design allows for sufficient lamination thickness between the bottom of the groove and the positioning hole after the groove is deepened by the expansion groove, thus avoiding excessive local magnetic flux density or excessive core loss at that location.

[0013] Preferably, along the circumferential direction of the inner circle of the stator, the extension shape of the bottom surface of the expansion groove is a perfect circular arc.

[0014] This configuration allows for the formation of a regular slot shape inside the corner slot, facilitating subsequent winding setup.

[0015] Preferably, the radius R of the circular arc containing the bottom surface of the expansion groove is... 扩 satisfy:

[0016] ,

[0017] Wherein, θ1 is the angle between the radial direction of the stator lamination where the centerline of the corner groove is located and the radial direction of the stator lamination where the edge of the corner groove is located.

[0018] This setup allows the corresponding dimensions of the expansion groove to be determined based on the magnetic properties of different motor specifications and core materials.

[0019] Preferably, the groove area ΔS of each expansion groove satisfies:

[0020] ,

[0021] Wherein, θ2 is the angle between the radial direction of the expansion groove at the edge of the corner groove and the radial direction of the stator lamination where the centerline of the corner groove is located.

[0022] Preferably, the relative reduction ΔP in winding copper loss satisfies:

[0023] ,

[0024] Where S is the area of ​​each corner groove.

[0025] With this setup, the slot area increment and copper loss improvement of motors with different slot numbers can be designed and calibrated using uniform parameters through a unified ΔS / (kS) relationship.

[0026] Preferably, along the circumferential direction of the inner circle of the stator, the extension shape of the bottom surface of the expansion groove is an elliptical arc; or, the extension shape of the bottom surface of the expansion groove is a broken line.

[0027] Secondly, the present invention also provides a stator core for a single-phase permanent magnet motor, comprising a plurality of stator laminations as described above, wherein all the stator laminations are stacked sequentially along the axial direction of the inner circle of the stator.

[0028] The stator core described in this invention has the same beneficial effects as the stator laminations mentioned above, and will not be repeated here.

[0029] Thirdly, the present invention also provides a single-phase permanent magnet motor, which includes a rotor and a stator core as described above, wherein the rotor is disposed at a position on the inner circle of the stator core.

[0030] The single-phase permanent magnet motor described in this invention has the same beneficial effects as the stator laminations and stator cores mentioned above, and will not be repeated here.

[0031] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the stator lamination provided in Embodiment 1 of the present invention.

[0033] Figure 2 This is a partial structural schematic diagram of the stator lamination provided in Embodiment 1 of the present invention.

[0034] Figure 3 This is a schematic diagram of the stator lamination provided in Embodiment 2 of the present invention.

[0035] Figure 4 This is a partial structural schematic diagram of the stator lamination provided in Embodiment 2 of the present invention.

[0036] Figure 5 The graph shows the variation of the magnetic flux density of the stator core material with the magnetic field strength of the stator core, as provided in the embodiments of the present invention.

[0037] Figure 6 The graph shows the variation of loss and efficiency of a single-phase permanent magnet motor as the depth of the expansion groove is increased, as provided in the embodiments of the present invention.

[0038] Figure 7 This is a schematic diagram of a stator lamination provided in Embodiment 3 of the present invention.

[0039] Figure 8 This is a schematic diagram of another stator lamination provided in Embodiment 4 of the present invention.

[0040] Explanation of reference numerals in the attached figures:

[0041] 1. Stator lamination; 10. Stator inner circle; 100. Structural angle; 101. Positioning hole; 11. Stator tooth; 12. Stator slot; 120. Angle slot; 13. Expansion slot;

[0042] 2. Rotor; 21. Rotor core; 22. Rotor yoke; 23. Permanent magnet. Detailed Implementation

[0043] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0044] As mentioned in the background section, the stator core of a single-phase permanent magnet motor for a refrigerator compressor is typically formed by stacking several stator laminations. These stator laminations are generally square or nearly square, with four structural corners formed on their outer periphery. These four corners are used to create positioning holes for mounting the compressor motor. Furthermore, an inner stator circle is formed on the inner side of the stator laminations, and several stator teeth are evenly distributed along the circumferential edge of this inner stator circle. Stator slots are formed between adjacent stator teeth to accommodate the motor's main and auxiliary windings.

[0045] In related technologies, single-phase permanent magnet motors typically use 4k (a multiple of 4, such as 4, 8, or 12 slots) sector-shaped stator slots. This type of motor not only limits the slot area formed by the stator laminations but also restricts the cross-sectional area of ​​the winding conductors within the slots. This makes it difficult to reduce the current density of the windings, resulting in higher copper losses at rated current, leading to higher stator temperature rise and impacting motor efficiency and lifespan. Furthermore, when using sector-shaped slots, the core at the four corners is not fully utilized, resulting in low overall stator core utilization.

[0046] Based on the above, the applicant of this invention has proposed a technical solution in the embodiments of this application. Specifically, by optimizing the structure of the stator lamination, and specifically by redesigning the position of the stator slots, the slot area of ​​the key slots at the corresponding structural corner positions is increased, thereby improving the cross-sectional area of ​​the winding conductor.

[0047] The above is the core idea of ​​this invention. The technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0048] like Figures 1-8 As shown, this embodiment of the invention provides a stator lamination 1 for a single-phase permanent magnet motor, wherein a stator inner circle 10 is formed at the center position, and a plurality of stator teeth 11 are arranged on the inner wall of the stator inner circle 10. The plurality of stator teeth 11 are evenly distributed along the circumference of the stator inner circle 10, and a stator slot 12 is formed between two adjacent stator teeth 11. The number of stator slots 12 is 4k, where k≥1.

[0049] Specifically, the number of stator teeth 11 is the same as the number of stator slots 12. That is, when 4k stator teeth 11 are arranged along the inner wall of the stator inner circle 10, the number of stator slots 12 between all adjacent stator teeth 11 is the same as the total number of stator teeth 11. For example, when the number of stator teeth 11 is 4, the corresponding number of stator slots 12 is also 4. See [link to documentation] for details. Figure 1 As shown. Alternatively, when the number of stator teeth 11 is 8, the corresponding number of stator slots 12 is also 8, as detailed in [reference needed]. Figure 3 As shown.

[0050] Furthermore, the inner circle 10 of the stator has a circular outline, and the stator teeth 11 are annular segments extending in a uniform width along the radial direction of the inner circle 10. Correspondingly, the stator slots 12 formed between two adjacent stator teeth 11 are also annular segments, or fan-shaped. All stator teeth 11 are evenly distributed circumferentially along the inner circle 10, thus ensuring that all stator slots 12 are also evenly distributed circumferentially along the inner circle 10.

[0051] Based on the above, the stator lamination 1 has four structural corners 100. Among all the stator slots 12, four stator slots 12 are respectively formed into a corner slot 120. The four corner slots 120 and the four structural corners 100 are arranged in a one-to-one correspondence along the radial direction of the inner circle 10 of the stator. Furthermore, an expansion groove 13 is formed at the bottom of each corner slot 120, which is recessed toward the center away from the stator lamination 1.

[0052] It should be noted that corner slot 120 specifically refers to stator slot 12 located at a specific position. In other words, corner slot 120 is stator slot 12, but the stator slot 12 located at the position corresponding to the structural corner 100 is specifically referred to as corner slot 120.

[0053] Furthermore, regarding the formation of the expansion groove 13 and the stator groove 12, it should be noted that the expansion groove 13 and the stator groove 12 are only virtual area divisions. Since the expansion groove 13 is formed by the groove bottom of the corner groove 120 being recessed away from the center of the stator lamination 1, that is to say, the expansion groove 13 is an expansion of the area of ​​the corner groove 120, and the two form an integral groove area.

[0054] Furthermore, the stator lamination 1 can have a basically rectangular outer edge shape. For example, the stator lamination 1 can have four side portions, which are arranged in pairs opposite each other to form a basic rectangular outline. Based on this, the four structural corners 100 are located at the included angle between two adjacent side portions.

[0055] In some embodiments, structural corner 100 can be a sharp corner structure formed by the extension and intersection of adjacent side portions, or it can be a further chamfered shape based on the sharp corner structure. In this embodiment, the chamfer profile corresponding to structural corner 100 is set as an arc shape, that is, the chamfer profiles at the four structural corners 100 are located on the same circular profile. This reduces the number of locations where stress concentration defects occur on the entire surface of the stator lamination 1. For details, please refer to [link to relevant documentation]. Figure 1 and Figure 3 As shown. Of course, in other embodiments, the chamfer profile corresponding to structural angle 100 may also be of other shapes.

[0056] In specific implementation, expansion slots 13 are provided at the corner slots 120 corresponding to the four structural corners 100, thereby expanding the slot area of ​​the four corner slots 120 to a certain extent. Therefore, the total cross-sectional area of ​​the windings subsequently placed in the slots can also be increased accordingly. Due to the increase in the cross-sectional area of ​​the winding conductors, the current density of the windings can be reduced, the copper loss of the windings can also be reduced to a certain extent, and the temperature rise of the stator can be controlled. At the same time, since only the corner slots at the four structural corners 100 need to be enlarged, while the original shape of the stator slots 12 and some of them are still maintained, there is no need to re-make the stamping die structure for the development and manufacturing of the stator laminations. Without changing the overall external dimensions and stacking thickness of the stator laminations 1, the slot area of ​​the corner slots 120 at the four structural corners 100, which are sensitive to the magnetic circuit, is increased, which also reduces the development cost and time of the mold after optimization to a certain extent. Furthermore, only the stator slots 12 at the four structural corners 100 are enlarged, which will not have a significant impact on the overall structural strength of the stator laminations 1.

[0057] In summary, the stator lamination 1 for a single-phase permanent magnet motor provided in this embodiment of the invention further improves the four corner slots 120 corresponding to the four structural corners 100 by forming an expansion slot 13 at the bottom of each corner slot 120 that is recessed away from the center of the stator lamination 1. This increases the area inside the slot, allowing for the installation of more windings or a reduction in winding density. This increases the conductor cross-sectional area of ​​the windings inside the slot or reduces the current density, thereby reducing the copper loss of the windings to a certain extent and controlling the temperature rise of the stator, thus ensuring the efficiency and service life of the motor.

[0058] Since the stator lamination 1 has a low utilization rate only at the four structural corners 100, this embodiment of the invention only deepens the bottom of the four corner slots 120. When there are more than four stator slots 12, the remaining stator slots 12 retain their original bottom shape and position.

[0059] like Figure 1 and Figure 3 As shown, in some embodiments, positioning holes 101 are provided at each structural corner 100. That is, there are four positioning holes 101, which are distributed at the four structural corners 100. When assembling the compressor, all stator laminations 1 need to be stacked to form a stator core. Positioning rods can be inserted into the corresponding positioning holes 101 on all stator laminations 1 to achieve overall alignment.

[0060] Furthermore, along the radial direction of the inner circle 10 of the stator, the groove depth of each expansion groove 13 satisfies the following formula:

[0061] (1)

[0062] Where R1 is the radius of the circular profile of the chamfered contour at structural angle 100°, R2 is the radius of the circular profile of the bottom of stator slot 12, the diameter of positioning hole 101 is D, and the outer diameter of rotor located at the inner circle 10 of stator is R. 转 The thickness of the permanent magnet mounted on the rotor along the radial direction of the rotor is H. 磁 B r B is the remanence of the permanent magnet used in the motor (referring to the remanent magnetic flux density of the permanent magnet). K A magnetic flux density value is assigned to the stator core material, specifically the magnetic flux density value of the stator core material at the inflection point of the BH curve. For details, please refer to [link to relevant documentation]. Figure 5 As shown.

[0063] in, Figure 5 The horizontal axis represents the magnetic field strength of the stator core, the vertical axis represents the magnetic flux density of the core material, and the slope of the curve corresponds to the relative permeability of the core material. Figure 5 China B K The inflection point indicated is the magnetic flux density at that inflection point of the magnet material. When the magnetic flux density of the iron core exceeds B... K When the relative permeability of the core material becomes very small, the core will tend to saturate.

[0064] This formula ensures that after deepening the slot bottom through the expansion slot 13, sufficient lamination thickness is maintained between the slot bottom and the positioning hole 101, thus preventing excessively high local magnetic flux density or excessive core loss at that location. Furthermore, this formula provides a unified and quantifiable expansion slot design method for single-phase permanent magnet motors with different slot numbers.

[0065] It should be noted that the groove depth of the expansion groove 13 mentioned above specifically refers to the groove depth value corresponding to the maximum groove depth position of the expansion groove 13, and this position is located at the center line position of the expansion groove 13.

[0066] Based on the above, in one feasible approach, the extension shape of the bottom surface of the expansion groove 13 along the circumference of the inner circle 10 of the stator can be made into a perfect circular arc. This arrangement allows the corner groove 120 to form a regular groove shape, facilitating subsequent winding configuration. Of course, in other embodiments, the extension shape of the bottom surface of the expansion groove 13 can be set to other forms. This embodiment of the invention uses a perfect circular arc shape for the bottom surface of the expansion groove 13 as an example for explanation.

[0067] Specifically, the circular arc formed by the bottom surface of the expansion groove 13, based on satisfying formula (1), is such that the radius R of the circular arc formed by the bottom surface of the expansion groove 13 is... 扩 The following formula can be satisfied:

[0068] (2)

[0069] Where R2 is the radius of the circular profile where the bottom of the stator slot 12 is located, h is the depth of the expansion slot 13, and θ1 is the angle between the radial direction of the stator lamination 1 where the centerline of the corner slot 120 is located and the radial direction of the stator lamination 1 where the edge of the corner slot 120 is located. For details, please refer to [reference needed]. Figure 2 and Figure 4 As shown.

[0070] The value of θ1 further satisfies the following formula:

[0071] (3)

[0072] Where k is the ratio of the total number of stator slots 12 to 4, and θ0 is the angle between the radial direction of the stator lamination 1 where the centerline of the stator tooth 11 is located and the radial direction of the stator lamination 1 where the edge of the corner slot 120 is located. The value of θ0 can be obtained by the following formula:

[0073] (4)

[0074] Where T is the width of stator tooth 11, see details below. Figure 2 and Figure 4 As shown.

[0075] The value of cosθ1 in formula (2) can be obtained by formula (3) and formula (4), and then the radius of the circular arc where the bottom surface of the expansion groove 13 is located can be obtained. The corresponding size of the expansion groove 13 can also be determined according to the magnetic properties parameters of motors and core materials of different specifications.

[0076] Furthermore, for each corner slot, without the expansion slot 13 provided, the slot area within each corner slot 120 satisfies the following formula:

[0077]

[0078] Where R3 is the radius of the circular profile containing the slot openings of all stator slots 12, as detailed in [reference needed]. Figure 1 and Figure 3 As shown.

[0079] Based on this, while keeping the stator's external dimensions and stack thickness unchanged, the increase in slot area ΔS of each corner slot after deepening by 120 mm satisfies:

[0080]

[0081] Wherein, θ1 is the angle between the radial direction of the stator lamination 1 where the centerline of the corner groove 120 is located and the radial direction of the stator lamination 1 where the edge of the corner groove 120 is located.

[0082] It is understandable that the increased slot area of ​​each corner slot 120 is the same as the slot area of ​​the expanded slot 13. The above relationship ensures that in a series of motors with 4k slots, as k increases, the total slot area increment of the four deepened slots decreases according to the 1 / k rule, thus achieving a unified parameterized design for stator laminations 1 with different slot numbers.

[0083] Based on the above, while keeping the stator dimensions, stack thickness and number of winding turns unchanged, the total increase in the area of ​​the four corner slots (120 slots) is ΔS / (kS), which allows the cross-sectional area of ​​the winding conductors to be increased or the number of turns to be slightly adjusted, thereby reducing the winding current density.

[0084] Finite element simulation shows that, compared with the comparative motor using an undeepened slot bottom, the relative reduction in winding copper loss of the motor of the present invention under rated operating conditions satisfies the following formula:

[0085]

[0086] In other words, the reduction rate of winding copper loss is no greater than ΔP, or the relative reduction rate is less than ΔP. With this setting, the slot area increment and copper loss improvement of motors with different slot numbers can be designed and calibrated using uniform parameters through a unified ΔS / (kS) relationship.

[0087] In summary, the structural dimensions of the stator lamination 1 provided in this embodiment of the invention, by constraining the above-mentioned h, R expansion and ΔS, ensure that the local part of the stator core will not be over-saturated, and at the same time ensure that the mechanical strength of the stator core will not be significantly weakened.

[0088] In relation to the stator lamination 1 described above, this embodiment of the invention also provides a stator core, which includes a plurality of the stator laminations 1 described above.

[0089] In practice, several stator laminations 1 are stacked along the same axial direction to form a stator core. During the stacking process, positioning rods can be inserted into the corresponding positioning holes 101 on each stator lamination 1 to ensure axial positional correspondence. After the stator core is stacked as a whole, the stator slots 12 on all the stator laminations 1 together form a space area for placing the main winding and auxiliary winding.

[0090] Furthermore, this embodiment of the invention provides a single-phase permanent magnet motor, which includes the stator core as described above, and also includes a rotor 2 and a winding structure.

[0091] The stator core structure has been described in detail in the above embodiments and will not be repeated here. The single-phase permanent magnet motor provided in this embodiment has better performance by adopting the stator core of the above embodiments.

[0092] like Figure 1 and Figure 3 As shown, the rotor 2 is disposed within the cylindrical space formed by the inner circles 10 of all stator laminations 1 after stacking. Furthermore, a non-uniform air gap is formed between the outer circle of the rotor and the inner circle 10 of the stator to overcome the starting dead point and eliminate torque pulsation. Further, the rotor 2 includes a rotor core 21, a rotor yoke 22, and several permanent magnets 23 disposed on the outer circle of the rotor. The number of poles of the permanent magnets 23 matches the number of slots in the stator slots 12. In addition, the number of turns and conductor cross-sectional area of ​​the windings are designed according to the power rating and efficiency requirements.

[0093] For example, the embodiment of the present invention provides a single-phase permanent magnet motor, which is used in a refrigerator compressor. Of course, in other embodiments, the stator core provided by the present invention can also be applied to other types of permanent magnet motors, or compressors of other electrical appliances, as long as it can achieve the effect of improving motor efficiency as described above.

[0094] It should be noted that the single-phase permanent magnet motor provided in this embodiment should also include other modules or components that enable the single-phase permanent magnet motor to operate normally, such as the housing, starting auxiliary device, etc. Here, the other modules or components included in the single-phase permanent magnet motor provided in this embodiment will not be described one by one.

[0095] Based on the basic configuration of the expansion groove 13 in the diagonal groove 120, the present invention further illustrates the structural configuration of the stator lamination 1 through the following four embodiments.

[0096] Example 1

[0097] like Figure 1 and Figure 2 As shown, in this embodiment, four stator teeth 11 are evenly distributed along the circumference of the inner circle 10 of the stator, and four stator slots 12 are formed between adjacent stator teeth 11, and all four stator slots 12 are fan-shaped slots. The four stator slots 12 are respectively set at the four structural corners 100 of the stator lamination 1, so it can be understood that the four stator slots 12 are all corner slots 120, and a positioning hole 101 is opened at each of the four structural corners 100. Based on this, the stator lamination 1 has four side portions, and the four side portions are arranged opposite each other in pairs.

[0098] Without the expansion groove 13, the bottom of each of the four corner grooves 120 is an arc structure, and the bottom of all the corner grooves 120 lies on the same circular outline centered on the stator center. Further, an expansion groove 13 is provided at the bottom of each corner groove 120, and the extended shape of the bottom surface of the expansion groove 13 is a perfect arc.

[0099] This configuration causes the bottom of each corner slot 120 to deepen in the direction of the stator lamination 1 toward the positioning hole 101 along the radial direction, reducing the radial thickness of the stator lamination 1 between the bottom of the slot and the positioning hole 101, and correspondingly increasing the area inside the slot.

[0100] In this configuration, the depth of the expansion groove 13 still needs to meet the design reference of formula (1).

[0101] Please see further. Figure 6 As shown, Figure 6 This is a graph showing the changes in loss and efficiency of a four-slot single-phase permanent magnet motor as the depth of the expansion slot 13 increases, obtained through simulation analysis. Curve a represents the efficiency change, curve b represents the copper loss change, and curve c represents the iron loss change. Figure 6 The curves show that the optimal value of h is 0-5 mm. When h equals 5 mm, the stator core is close to the safety upper limit derived from the material's magnetic flux density and mechanical strength. If h increases to 6 mm, it will significantly exceed the safety upper limit, leading to local magnetic saturation in the stator core.

[0102] Finite element simulation data reveals that, compared to motors without expansion slots 13, motors with expansion slots 13 on the stator lamination 1 show a gradual decrease in copper losses and a slight increase in iron losses as h increases. Until h approaches a critical limit, the increase in total slot area is approximately 27%, and the decrease in copper losses is approximately 23%, thus significantly improving motor efficiency. However, when h equals 6 mm, stator core saturation occurs, the no-load back EMF exhibits waveform distortion, motor copper losses increase significantly, and motor efficiency decreases significantly.

[0103] Example 2

[0104] The overall structure of the stator lamination 1 in this embodiment is basically the same as that in Embodiment 1, except that the number of stator slots and the area of ​​the corner slots 120 are increased.

[0105] like Figure 3 and Figure 4As shown, in this embodiment, eight stator teeth 11 are evenly distributed along the circumference of the inner circle 10 of the stator, and eight stator slots 12 are formed between adjacent stator teeth 11, and all eight stator slots 12 are fan-shaped slots. Based on this, the stator lamination 1 has four structural corners 100, wherein the stator slots 12 corresponding to the four structural corners 100 are formed as corner slots 120.

[0106] Furthermore, the bottoms of the four corner slots 120 are all arc-shaped, and the bottoms of all the corner slots 120 lie on the same circular outline centered on the stator center. Based on this, an expansion slot 13 is further provided at the bottom of each corner slot 120, and the extended shape of the bottom surface of the expansion slot 13 is a perfect arc.

[0107] In this embodiment, the relative increase in the total slot area of ​​the four corner slots 120 is approximately ΔS / (2S), which is consistent with the parameterization of the slot area increase of the stator laminations 1 of single-phase permanent magnet motors with other slot numbers. Furthermore, in this embodiment, the depth h of the slot bottom of the expansion slot 13 also satisfies the aforementioned geometric constraint formulas (1) and (2) for h, ensuring that sufficient core cross-sectional area is maintained between the slot bottom and the positioning hole 101, avoiding excessive local magnetic flux density and excessive core loss, while ensuring that the stator core has good mechanical strength.

[0108] Compared to the stator lamination 1 without deepened slot bottoms, this embodiment increases the slot area of ​​the four corner slots 120, thereby increasing the winding arrangement space. This facilitates increasing the conductor cross-sectional area or reducing the winding current density, thus achieving the technical effects of reducing winding copper losses, reducing stator temperature rise, and improving motor efficiency. Since this embodiment is mainly used to illustrate the applicability of the invention in the case of k equal to 2 and the unified design method, the above technical effects can be understood by referring to the test results of Embodiment 1. The specific values ​​for copper loss reduction and efficiency improvement are not given here.

[0109] Example 3

[0110] like Figure 7 As shown, in this embodiment, four fan-shaped stator slots 12 are formed along the circumference of the inner circle 10 of the stator. The geometric parameters of the stator slots 12 and the expansion slots 13 are basically the same as those in Embodiment 1. The difference is that the extension shape of the bottom surface of the expansion slot 13 is an elliptical arc.

[0111] By adjusting the positions of the major axis, minor axis, and center of the ellipse, and with the same depth of the groove bottom as in Example 1, the increase in the groove area of ​​each corner groove 120 can be slightly greater than the increase in the groove area of ​​the corner groove 120 in Example 1. Correspondingly, the increase in the total groove area is slightly greater than that in Example 1. Finite element simulation shows that, with the same depth of groove bottom, the reduction in winding copper loss in this embodiment is slightly better than in Example 1, the trend of core loss is basically the same as in Example 1, and the overall efficiency is slightly further improved.

[0112] Example 4

[0113] like Figure 8 As shown, in this embodiment, four fan-shaped stator slots 12 are formed along the circumference of the inner circle 10 of the stator. The geometric parameters of the stator slots 12 and the expansion slots 13 are basically the same as those in Embodiment 1. The difference is that the extension shape of the bottom surface of the expansion slots 13 is composed of two or more straight line profiles.

[0114] By adjusting the length and inclination angle of each straight segment, the bottom of the expansion groove 13 can be deepened in the same way as the arc-shaped groove bottom in Embodiment 1. Under the same groove bottom deepening, the increase in the groove area of ​​each corner groove 120 is slightly greater than the increase in the groove area of ​​the corner groove 120 in Embodiment 1, and the increase in the total groove area is slightly greater than the increase in Embodiment 1. Simulation results show that the polygonal segment-shaped groove bottom structure can achieve copper loss reduction and efficiency improvement effects similar to or even slightly better than the elliptical arc groove bottom and arc-shaped groove bottom embodiments under the same groove bottom deepening. This further illustrates that the technical effects achieved by the stator lamination 1 design provided by the present invention do not depend on the single design that the groove bottom of the corner groove 120 must be arc-shaped.

[0115] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A stator lamination for a single-phase permanent magnet motor, characterized in that, A stator inner circle is formed at the center of the stator lamination. A plurality of stator teeth are provided on the inner wall of the stator inner circle. The plurality of stator teeth are evenly distributed along the circumference of the stator inner circle. A stator slot is formed between two adjacent stator teeth. The number of stator slots is 4k, where k≥1. The stator lamination has four structural corners. Among all the stator slots, four stator slots are respectively formed into a corner slot. The four corner slots and the four structural corners are arranged in a one-to-one radial correspondence along the inner circle of the stator. Furthermore, an expansion groove is formed at the bottom of each corner slot, which is recessed toward the center of the stator lamination.

2. The stator lamination as described in claim 1, characterized in that, All the chamfered contours at the corners of the structure are on the same circular contour, and positioning holes are provided at the positions of each corner of the structure. Along the radial direction of the inner circle of the stator, the groove depth h of the expansion groove satisfies: ， Where R1 is the radius of the circular profile of the chamfered contour at the structural corner, R2 is the radius of the circular profile of the bottom of the stator slot, D is the diameter of the positioning hole, and B... r B is the remanence of the permanent magnet in a single-phase permanent magnet motor. K To determine the magnetic flux density (R) of the stator core material of a single-phase permanent magnet motor, 转 H is the outer diameter of the rotor of a single-phase permanent magnet motor. 磁 This represents the thickness of the permanent magnet in a single-phase permanent magnet motor along the rotor radial direction.

3. The stator lamination as described in claim 2, characterized in that, Along the circumference of the inner circle of the stator, the extension shape of the bottom surface of the expansion groove is a perfect circular arc.

4. The stator lamination as described in claim 3, characterized in that, The radius R of the circular arc containing the bottom surface of the expansion groove 扩 satisfy: ， Wherein, θ1 is the angle between the radial direction of the stator lamination where the centerline of the corner groove is located and the radial direction of the stator lamination where the edge of the corner groove is located.

5. The stator lamination as described in claim 3, characterized in that, The area ΔS of each expansion groove satisfies: ， Wherein, θ2 is the angle between the radial direction of the expansion groove at the edge of the corner groove and the radial direction of the stator lamination where the centerline of the corner groove is located.

6. The stator lamination as described in claim 5, characterized in that, The relative reduction ΔP in winding copper loss satisfies: ， Where S is the area of ​​each corner groove.

7. The stator lamination as described in claim 2, characterized in that, Along the circumference of the inner circle of the stator, the extension shape of the bottom surface of the expansion groove is an elliptical arc; or, the extension shape of the bottom surface of the expansion groove is a broken line.

8. A stator core for a single-phase permanent magnet motor, characterized in that, It includes a plurality of stator laminations as described in any one of claims 1-7, wherein all the stator laminations are stacked sequentially along the axial direction of the inner circle of the stator.

9. A single-phase permanent magnet motor, characterized in that, It includes a rotor and a stator core as described in claim 8, wherein the rotor is disposed at a position on the inner circle of the stator core at the center of the stator core.

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