Stator and motor having reduced iron loss

Abstract

A stator and a motor having reduced iron loss are disclosed. The stator includes a first stator core and a second stator core. The first stator core is formed by laminating a plurality of first electrical steel sheets. The second stator core is disposed at opposite ends of the first stator core. The second stator core is formed by laminating a plurality of second electrical steel sheets. The second electrical steel sheets are formed of a different material from that of the first electrical steel sheets and have lower iron loss characteristics than the first electrical steel sheets. Accordingly, the second electrical steel sheets can reduce the iron loss of the motor while reducing material costs.

Description

Stator and motor with improved iron loss

[0001] The present invention relates to a stator and a motor with improved iron loss.

[0002] A motor is a device that obtains rotational force by converting electrical energy into mechanical energy through the electrical interaction between the stator and the rotor, thereby inducing the rotation of the rotor.

[0003] In the case of a permanent magnet motor, when power is applied to the stator coil, magnetic flux is generated around the permanent magnet of the rotor and the stator coil.

[0004] In this case, a phenomenon occurs in which magnetic flux is concentrated at one end (e.g., upper end) and the other end (e.g., lower end) of the stator core in the axial direction due to the fringing effect.

[0005] The stator core can be constructed by stacking and bonding multiple electrical steel sheets in the axial direction. Multiple teeth are arranged circumferentially spaced apart on the inner side of the stator core.

[0006] A second section may be applied to the axial upper and lower sections of the stator core, wherein the circumferential width of the teeth is narrower than that of the middle section between the axial upper and lower sections of the stator core.

[0007] However, the above-mentioned second section has a narrow circumferential width, so when the same magnetic flux flows, the magnetic flux density increases, which causes an increase in iron loss.

[0008] Prior art patent document US 11929648 B2 (hereinafter referred to as 'Patent Document 1') discloses an electric motor, a compressor, and an air conditioner.

[0009] According to Patent Document 1, a two-stage section is applied to the upper and lower parts of the stator core, and a two-stage section is also applied to the upper and lower parts of the rotor to reduce the magnetic flux density going to the stator, thereby improving the increase in iron loss of the upper and lower parts of the stator core.

[0010] However, in the case of Patent Document 1, there is a problem in that the effect of efficiency improvement is halved because the magnetic flux density decreases while the copper loss increases.

[0011] Prior art patent document CN 108702075 A (hereinafter referred to as 'Patent Document 2') discloses a permanent magnet synchronous motor, a compressor, and an air conditioner.

[0012] According to Patent Document 2, the proportion of iron loss between the stator and the rotor is overwhelmingly higher in the stator.

[0013] As a result, rotors with low iron loss use rotor cores made of low-grade materials (high iron loss materials), while stators with high iron loss use stator cores made of high-grade materials (low iron loss materials).

[0014] However, since Patent Document 2 applies high-grade materials to the entire stator core, there is a problem of increased material costs.

[0015] The objective of the present invention is to provide a stator and a motor with improved iron loss and a structure capable of solving the aforementioned problems.

[0016] The first objective is to provide a stator and motor with improved iron loss that have a structure capable of minimizing the increase in iron loss by eliminating magnetic flux concentration caused by electromagnetic properties (fringing effect).

[0017] The second objective is to provide a stator and motor with improved iron loss and a structure capable of suppressing the increase in magnetic flux density caused by the physical structure (two-stage section).

[0018] The third objective is to provide a stator and motor with improved iron loss and a structure that can reduce material costs.

[0019] As a result of intensive research, the inventors have found that the problem of the present invention or the first to fourth objectives described above can be achieved by the following embodiments of the present invention.

[0020] To achieve the above-mentioned purpose, the stator according to the present invention comprises: a back yoke, a plurality of teeth formed to protrude radially from the inner surface of the back yoke, and a plurality of slots disposed between the plurality of teeth adjacent in the circumferential direction; and a coil wound on the teeth through the slots.

[0021] The stator core comprises: a first stator core formed by stacking and joining a plurality of first electrical steel plates in the axial direction; and a second stator core formed by stacking and joining a plurality of second electrical steel plates formed of a material different from the first electrical steel plates in the axial direction, wherein the second stator core is formed by stacking and joining a plurality of second electrical steel plates formed of a material different from the first electrical steel plates in the axial direction, and is stacked and joined to at least one end of the first stator core.

[0022] Through this, the stator core can reduce iron loss by dualizing the material.

[0023] According to one example, the second stator core is provided in multiple numbers, and the multiple second stator cores can be respectively placed at one end and the other end of the first stator core.

[0024] Through this, the plurality of second stator cores are respectively positioned at the upper and lower ends of the first stator core, thereby reducing the magnetic flux density in the part where magnetic flux is concentrated.

[0025] According to one example, the second electrical steel sheet may be a low-iron loss material with relatively lower iron loss than the first electrical steel sheet.

[0026] Through this, only the parts where iron loss is concentrated can be changed to low-iron-loss materials.

[0027] According to one example, the first electrical steel sheet may be a 50PN600 iron-based metal material.

[0028] The above second electrical steel sheet may be an iron-based metal material in which one or more selected from 50PN470, 50PN400, 50PN350, 50PN330, 50PN310, 50PN290, 50PN270, and 50PN250 are combined.

[0029] The above PN stands for "Posco Non-oriented" and refers to non-oriented electrical steel sheets produced by POSCO. The number preceding PN indicates that the steel sheet thickness is 0.5 mm. The number following PN indicates magnetic loss.

[0030] Through this, low-iron loss materials can be defined by utilizing iron loss characteristics cited from the product catalog provided by POSCO.

[0031] According to one example, the first electrical steel sheet may be a 50PN600 iron-based metal material, and the second electrical steel sheet may be a 50PN440 iron-based metal material.

[0032] Through this, the iron loss characteristics of the dual-material stator core can be specifically limited and implemented.

[0033] According to one example, the axial height of the second stator core may be 0.5 to 2.5 mm.

[0034] By doing so, the axial height of the second stator core can be specifically limited, thereby maximizing the effects of reducing material costs and improving iron loss.

[0035] According to another example, the first electrical steel sheet may have a first thickness of 1 mm or less, and the second electrical steel sheet may have a second thickness smaller than the first thickness.

[0036] Through this, the effects of reducing material costs and improving iron loss can be maximized by differentiating the thickness of the electrical steel sheets.

[0037] According to another example, the thickness of the first electrical steel sheet may be 0.5 mm and the thickness of the second electrical steel sheet may be 0.35 mm.

[0038] Through this, the dualization of the steel plate thicknesses of the first stator core and the second stator core can be specifically limited.

[0039] According to another example, the plurality of teeth may be spaced apart circumferentially along the inner circumference of the back yoke.

[0040] The circumferential width of the teeth of the second stator core may be smaller than that of the first stator core.

[0041] Through this, a two-stage section with a relatively small circumferential width of teeth can be applied to the upper and lower parts of the stator core.

[0042] According to another example, a pole shoe may be provided at the radially inner end of the tooth. The radial width of the pole shoe of the second stator core may be smaller than that of the first stator core.

[0043] Through this, the above-mentioned two-stage portion can also be applied to the above-mentioned pole shoe.

[0044] According to another example, the radial width of the back yoke of the second stator core may be smaller than that of the first stator core.

[0045] Through this, the above-mentioned two-stage portion can also be applied to the above-mentioned back yoke.

[0046] The back yoke, the teeth, and the pole shoe to which the above two-stage portion is applied may provide an insulator insertion groove.

[0047] A motor according to another embodiment of the present invention comprises a rotating shaft; a rotor coupled to the rotating shaft and having a permanent magnet; and a stator having a coil and surrounding the rotor. The stator comprises a back yoke and a stator core having a plurality of teeth that protrude radially from the inner circumference of the back yoke to form a plurality of slots on the inner side of the back yoke and are arranged circumferentially spaced apart along the inner circumference of the back yoke.

[0048] The stator core comprises: a first stator core formed by laminating and bonding a plurality of first electrical steel plates; and a second stator core formed by laminating and bonding a plurality of second electrical steel plates having a thickness different from that of the first electrical steel plates, disposed at both ends of the first stator core in the axial direction of the rotation axis.

[0049] Through this, iron loss can be improved by changing the steel plate thickness only of the second stator core, where magnetic flux is concentrated among the stator cores.

[0050] According to one example of the above motor, the first electrical steel sheet may have a first thickness of 1 mm or less, and the second electrical steel sheet may have a second thickness smaller than the first thickness.

[0051] According to another example of the above motor, the thickness of the first electrical steel sheet may be 0.5 mm and the thickness of the second electrical steel sheet may be 0.35 mm.

[0052] According to an embodiment of the present invention, the following effects can be achieved.

[0053] Due to the fringing effect or the two-stage design of the stator, the iron loss of the upper and lower parts of the stator core is higher than the average iron loss of the entire stator core. To resolve this problem, only the upper and lower parts of the stator core where iron loss is concentrated can be changed to a low-iron loss material, or the thickness of the steel plate can be reduced.

[0054] Through this, not only can material costs be reduced, but iron loss can also be reduced to improve motor efficiency.

[0055] FIG. 1 is a conceptual diagram for explaining the configuration of a motor according to an embodiment of the present invention.

[0056] FIG. 2 is a cross-sectional view taken along II-II in FIG. 1, and is a conceptual diagram showing a stator core stacked and combined with a first stator core and a second stator core made of a different material relative to the first stator core.

[0057] Figure 3 is a plan view showing the stator core in Figure 2 being press-fitted into the inside of the housing.

[0058] FIG. 4 is a cross-sectional view taken along IV-IV in FIG. 3, and is a conceptual diagram showing that the circumferential width of the teeth along the axial direction of the first stator core and the second stator core is the same.

[0059] FIG. 5 is a perspective view of a motor according to another embodiment of the present invention, showing a second stator core in which two ends with different circumferential widths of teeth are applied to one end of the first stator core in the axial direction.

[0060] Figure 6 is a top view of the motor in Figure 5.

[0061] FIG. 7 is a cross-sectional view taken along VII-VII in FIG. 6, showing two ends of teeth with different circumferential widths applied to both axial ends of the first stator core.

[0062] FIG. 8 is a plan view showing the first stator core in FIG. 7 as viewed from the top.

[0063] FIG. 9 is a plan view showing the second stator core in FIG. 7 as viewed from the top.

[0064] FIG. 10 is a cross-sectional view taken along XX in FIG. 9, showing that the thickness of the electrical steel sheets of the first stator core and the second stator core are the same.

[0065] Figure 11 is a graph showing magnetic flux density according to the axial height of the stator core.

[0066] FIG. 12 is a conceptual diagram showing that the thicknesses of the electrical steel sheets of the first stator core and the second stator core are different according to another embodiment of the present invention.

[0067] Figure 13 is a graph showing the iron loss density ratio according to the axial height of the upper / lower part of the stator core.

[0068] Figure 14 is a graph showing the iron loss improvement ratio of a stator core in which part of the stator core is made of a different material compared to a stator core in which the entire stator core is changed to a high-grade material.

[0069] Hereinafter, an embodiment of the present invention, a stator and a motor with improved iron loss, will be described in detail with reference to the attached drawings.

[0070] In the following description, descriptions of some components may be omitted to clarify the features of the present invention.

[0071] 1. Definition of Terms

[0072] Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0073] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0074] As used in this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0075] In the following description, “radial” or “radial” refers to a shape extending outward from a central point like spokes of a wheel.

[0076] In the following description, “axial direction” refers to the longitudinal direction of the crankshaft.

[0077] In the following description, the term “axial direction” may refer to the vertical direction.

[0078] In the following description, the term “radial direction” refers to the longitudinal direction of a line segment extending from the center of a circle or cylinder to a point on the circumference.

[0079] In the following description, "radial direction" refers to the direction extending outward from the center of an object or point, such as a circle or a sphere.

[0080] In the following description, “circumferential direction” refers to the direction of the circumference.

[0081] The “fringe effect” described in this specification refers to the phenomenon in which magnetic flux diffuses and spreads around an air gap within a magnetic circuit. The fringe effect occurs because the magnetic flux does not flow evenly along the path of the magnetic circuit but diffuses in a curved manner near the air gap. The fringe effect can result in the magnetic flux not being evenly distributed but concentrating in a specific part near the air gap.

[0082] In the following description, the term “magnetic field” refers to a region in space where magnetic force acts, representing the spatial characteristics generated by electric current or magnets. A magnetic field indicates magnetic flux density, that is, how densely magnetic field lines are concentrated in space.

[0083] In the following description, “magnetic field” refers to a physical quantity representing the strength of a source that generates a magnetic field, and is used when explaining the cause of magnetic fields generated by electric currents or magnets.

[0084] As used in the following description, “iron loss” refers to a type of loss that occurs in electrical equipment, particularly in devices with magnetic circuits such as transformers and motors. Iron loss can consist of hysteresis loss and eddy current loss.

[0085] The aforementioned hysteresis loss is an energy loss that occurs as magnetic domains within a magnetic material rearrange when the magnetic flux changes. If the magnetic flux density changes periodically, energy can be consumed as heat during the process of the magnetic domains changing direction.

[0086] The above eddy current loss is a loss caused by induced current generated inside the iron core of an electrical device. When the magnetic flux changes, a small circuit is formed inside the iron core and current flows; when this current meets a resistor, it is converted into heat, and energy may be lost.

[0087] 2. Description of the configuration of a stator (110) and a motor equipped therewith according to an embodiment of the present invention

[0088] FIG. 1 is a conceptual diagram for explaining the configuration of a motor according to an embodiment of the present invention.

[0089] FIG. 2 is a cross-sectional view taken along II-II in FIG. 1, and is a conceptual diagram showing a stator core (111) stacked and combined with a first stator core (111a) and a second stator core (111b) of a different material from the first stator core (111a).

[0090] FIG. 3 is a plan view showing the stator core (111) in FIG. 2 being press-fitted into the inside of the housing (100).

[0091] FIG. 4 is a cross-sectional view taken along IV-IV in FIG. 3, which is a conceptual diagram showing that the circumferential width (W) of the teeth (115) along the axial direction of the first stator core (111a) and the second stator core (111b) is the same as each other.

[0092] In this embodiment, the motor can be applied to a fan motor.

[0093] More specifically, in this embodiment, the motor may be applied to an air conditioner fan motor. However, it is not limited thereto.

[0094] The motor includes a housing (100), a stator (110), and a rotor (120).

[0095] The housing (100) can form the exterior of the motor. A cover may be provided at both ends or one end of the housing (100). The cover is configured to cover both ends or one end of the housing (100). A receiving portion is formed inside the housing (100) to accommodate the stator (110) and the rotor (120).

[0096] The housing (100) can be formed in a cylindrical shape.

[0097] The stator (110) may include a stator core (111) and a stator coil (117). The stator core (111) may be formed in a cylindrical shape. A rotor receiving hole is provided on the inner side of the stator core (111).

[0098] In the following description, the stator coil (117) may be abbreviated as coil (117).

[0099] The rotor receiving hole can be formed to penetrate along the axial direction from the center of the stator core (111).

[0100] The rotor receiving hole can accommodate the rotor (120) described later. The diameter of the rotor receiving hole can be formed to be slightly larger than the diameter of the rotor (120), for example, twice as large as the air gap.

[0101] The stator core (111) may be configured to have a back yoke (113), a plurality of slots (114), and a plurality of teeth (115). The back yoke (113) may be formed in a cylindrical shape. The back yoke (113) may form the outer surface of the stator core (111).

[0102] A plurality of teeth (115) may be formed to protrude radially from the inner circumference of the back yoke (113) toward the center of the stator (110). A plurality of teeth (115) may be arranged circumferentially spaced apart along the circumference of the rotor receiving hole. A pole shoe (116) may be formed to protrude circumferentially from the inner end of the teeth (115).

[0103] A slot (114) may be formed between a plurality of adjacent teeth (115) in the circumferential direction. A plurality of slots (114) and a plurality of teeth (115) may be arranged alternately in the circumferential direction. A slot (114) may be formed to penetrate along the axial direction of a stator core (111). A slot (114) may provide a passage through which a coil (117) penetrates from one axial end of the stator core (111) toward the other axial end.

[0104] Through this, the coil (117) can be wound onto the teeth (115) of the stator core (111) through a plurality of slots (114).

[0105] The coil (117) may be composed of a plurality of phase coils. The plurality of phase coils may be provided with three strands to be connected to a three-phase AC power source. When the coil (117) receives external power, it can form a magnetic field around itself.

[0106] The rotor (120) includes a rotation axis (121) and a rotor core (122).

[0107] A rotation axis (121) is provided inside the housing (100). The rotation axis (121) may extend along a centerline passing through the center of the housing (100) in the longitudinal direction of the housing (100). The rotation axis (121) is positioned at the center of the housing (100). The rotation axis (121) is rotatably installed inside the housing (100).

[0108] The rotation axis (121) can be rotatably supported by bearings. Multiple bearings may be provided. Multiple bearings may support both ends of the rotation axis (121).

[0109] The rotor (120) may include a permanent magnet (123) or a rotor bar to generate a magnetic field. The rotor bar may be formed of a metal such as aluminum, which is a conductor. In this embodiment, the rotor (120) is shown configured with a permanent magnet (123).

[0110] The permanent magnet (123) may be composed of a spoke-type permanent magnet (123). Here, a spoke refers to a form in which the permanent magnet (123) is arranged radially from the center of the rotor (120). A spoke-type permanent magnet (123) motor having such a radial arrangement structure can optimize the magnetic flux path and increase the magnetic flux density to improve the efficiency of the motor. However, the shape of the permanent magnet (123) is not limited to this and can be implemented in various forms.

[0111] Permanent magnets (123) may be provided in multiple numbers. Multiple permanent magnets (123) may be spaced apart in the circumferential direction of the rotor core (122). Permanent magnets (123) may extend along the radial direction of the rotor core (122). Permanent magnets (123) may be formed in the shape of a rectangular body.

[0112] A three-phase power supply from an external source can be applied to the coil (117). Through this, a magnetic field can be generated around the coil (117). A magnetic field can be generated in the stator core (111) around which the coil (117) is wound.

[0113] The magnetic flux density and magnetic field may vary depending on the axial height of the stator core (111).

[0114] The magnetic flux density of the axial end portion and the other end portion of the stator core (111) can be increased by the fringing effect compared to the intermediate portion between the axial end portion and the other end portion of the stator core (111).

[0115] The magnetic flux density of the axial end and the other end of the stator core (111) can increase as they move away from the axial center of the stator core (111). Here, the axial end and the other end of the stator core (111) may each be the upper and lower end of the stator core (111).

[0116] The upper and lower parts of the stator core (111) have an imbalance in magnetic flux density compared to the center of the stator core (111). The upper and lower parts of the stator core (111) have an increased iron loss, which causes a problem of reduced motor efficiency.

[0117] To improve the above iron loss, the stator (110) according to the present invention provides a material dual-material stator core (111).

[0118] The stator core (111) may be configured to include a first stator core (111a) and a second stator core (111b).

[0119] The first stator core (111a) can be combined by stacking a plurality of first electrical steel sheets (112a).

[0120] The first electrical steel sheet (112a) may include a ring-shaped first back yoke (113a) described above; a plurality of first teeth (115a) spaced apart in the circumferential direction along the inner circumference of the first back yoke (113a); and a plurality of first slots (114a) each spaced between the circumferentially adjacent first teeth (115a).

[0121] A plurality of first teeth (115a) can form the first slot (114a).

[0122] A first pole shoe (116a) may be formed to protrude in the circumferential direction at the inner end of each of the plurality of first teeth (115a).

[0123] The first electrical steel sheet (112a) includes a first surface, a second surface, and a first curved surface. The first surface and the second surface are flat. The first curved surface has a predetermined curvature. The first curved surface can form the outer surface of the first electrical steel sheet (112a).

[0124] The first curved surface may be extended in the circumferential direction. The first curved surface may connect the first surface and the second surface of the first electrical steel sheet (112a). A thickness of the first electrical steel sheet (112a) may be formed between the first surface and the second surface of the first electrical steel sheet (112a). The first electrical steel sheet (112a) may have a first thickness.

[0125] Multiple first electrical steel sheets (112a) may all have the same thickness.

[0126] A plurality of first electrical steel sheets (112a) adjacent in the axial direction can be laminated and bonded by making surface contact with each other in the axial direction. A first surface of the first electrical steel sheet (112a) can form the upper surface of the first electrical steel sheet (112a). A second surface of the first electrical steel sheet (112a) can form the lower surface of the first electrical steel sheet (112a).

[0127] A second surface of one of a plurality of first electrical steel sheets (112a) adjacent in the axial direction can be laminated and bonded by being in surface contact with the first surface of another of the plurality of first electrical steel sheets (112a).

[0128] The first electrical steel sheet (112a) may be a non-oriented electrical steel sheet. The first electrical steel sheet (112a) may be an iron-based metal material. The non-oriented electrical steel sheet has uniform magnetic properties in all directions.

[0129] The second stator core (111b) can be formed by stacking and combining a plurality of second electrical steel sheets (112b). The second stator core (111b) can be positioned at one axial end of the first stator core (111a) or at both axial ends of the first stator core (111a). In this embodiment, the second stator core (111b) is shown positioned at both axial ends of the first stator core (111a).

[0130] For example, one axial end of the first stator core (111a) may be the top of the first stator core (111a). The other axial end of the first stator core (111a) may be the bottom of the first stator core (111a). The second stator core (111b) may be positioned at the top and bottom of the first stator core (111a), respectively. The second stator core (111b) is stacked and coupled to both ends of the first stator core (111a), respectively.

[0131] The axial heights of the first stator core (111a) and the second stator core (111b) may differ from each other. The axial height of the second stator core (111b) is smaller than the axial height of the first stator core (111a). The axial height of the first stator core (111a) refers to the sum of the thicknesses of the plurality of first electrical steel sheets (112a). The axial height of the second stator core (111b) refers to the sum of the thicknesses of the plurality of second electrical steel sheets (112b).

[0132] The axial height of the second stator core (111b) may be 0.5mm to 2.5mm.

[0133] The second electrical steel sheet (112b) may include a second back yoke (113b) in the shape of a ring as described above; a plurality of second teeth (115b) spaced apart in the circumferential direction along the inner circumference of the second back yoke (113b); and a plurality of second slots (114b) each spaced between the plurality of second teeth (115b) adjacent in the circumferential direction.

[0134] Multiple second teeth (115b) can form the second slot (114b).

[0135] A second pole shoe (116b) may be formed to protrude in the circumferential direction at the inner end of each of the plurality of second teeth (115b).

[0136] The second electrical steel sheet (112b) includes a first surface, a second surface, and a second curved surface. The first surface and the second surface are flat. The second curved surface has a predetermined curvature. The second curved surface may have the same curvature as the first curved surface. The second curved surface may form the outer surface of the second electrical steel sheet (112b).

[0137] The second curved surface may be extended in the circumferential direction. The second curved surface may connect the first surface and the second surface of the second electrical steel plate (112b). A thickness of the second electrical steel plate (112b) may be formed between the first surface and the second surface of the second electrical steel plate (112b). The second electrical steel plate (112b) may have a second thickness.

[0138] Multiple second electrical steel sheets (112b) may all have the same thickness.

[0139] The first thickness of the first electrical steel plate (112a) and the second thickness of the second electrical steel plate (112b) may be the same or different from each other. In this embodiment, the first thickness of the first electrical steel plate (112a) and the second thickness of the second electrical steel plate (112b) are shown to be the same.

[0140] A plurality of axially adjacent second electrical steel sheets (112b) can be laminated and bonded by making surface contact with each other in the axial direction. A first surface of the second electrical steel sheet (112b) can form the upper surface of the second electrical steel sheet (112b). A second surface of the second electrical steel sheet (112b) can form the lower surface of the second electrical steel sheet (112b).

[0141] One second surface of one of the plurality of axially adjacent second electrical steel plates (112b) may be in surface contact with the other first surface of the plurality of second electrical steel plates (112b) and may be laminated and bonded.

[0142] The second electrical steel sheet (112b) may be a non-oriented electrical steel sheet. The second electrical steel sheet (112b) may be an iron-based metal material. However, the second electrical steel sheet (112b) is a different material from the first electrical steel sheet (112a). The second electrical steel sheet (112b) differs from the first electrical steel sheet (112a) in that it is a low-iron loss material with lower iron loss.

[0143] Low iron loss material refers to a material that has a low iron loss value based on POSCO's product catalog.

[0144] Table 1, cited from POSCO’s product catalog, is as follows.

[0145] [Table 1]

[0146]

[0147] In Table 1 above, the iron loss indicated inside the square box has different values ​​depending on the specifications. The value indicated inside the square box represents the iron loss (watt loss) per unit weight. The unit of iron loss is watt (W) or watt per kilogram (W / kg). The unit of iron loss may also be expressed as watt per pound (W / lb).

[0148] Watt (W) is used to represent the power loss occurring in the entire iron core. Watt per kilogram (W / kg) or watt per pound (W / lb) is used to express iron loss as loss per unit weight of the material. This is primarily used when comparing the material performance of electrical equipment.

[0149] 1.0T / 50Hz represents the iron loss at a frequency of 50Hz and a magnetic flux density of 1.0T.

[0150] 1.5T / 50Hz represents the iron loss at a frequency of 50Hz and a magnetic flux density of 1.5T.

[0151] 1.0T / 60Hz represents the iron loss at a frequency of 60Hz and a magnetic flux density of 1.0T.

[0152] 1.5T / 60Hz represents the iron loss at a frequency of 50Hz and a magnetic flux density of 1.5T.

[0153] 1 Tesla (T) represents a magnetic flux density of 1 Weber (Wb / m²) per square meter.

[0154] Magnetic flux density (B) indicates the extent to which magnetic flux passes through a given area and is used to express the strength of the magnetic field.

[0155] Therefore, a magnetic flux density of 1.5 T means that the magnetic flux is distributed at a magnetic flux density of 1.5 Weber per square meter.

[0156] The iron loss indicated in the square box can be defined as a low-iron loss steel plate as the value decreases.

[0157] The specifications and values ​​shown in Table 1 are representative values ​​representing electromagnetic characteristics. The representative values ​​of electromagnetic characteristics shown in Table 1 may be used as reference values ​​for other specifications other than those in Table 1.

[0158] The iron loss of the electrical steel sheet (112) can exhibit electromagnetic characteristics.

[0159] The specification can be represented as **PN-Core. Here, * is a natural number. PN stands for "Posco Non-oriented". The above P is derived from the first letter of the company name Posco. The above N stands for Non-oriented.

[0160] In other words, PN-Core is an abbreviation referring to non-oriented electrical steel sheets produced by POSCO.

[0161] For example, in 50PN400, the 50 indicates that the thickness of the steel plate is 0.50 mm.

[0162] The above 400 represents the magnetic loss of the electrical steel sheet (112).

[0163] Specifically, 400 may mean that when the electrical steel sheet (112) is magnetized at 50 Hz at a magnetic flux density of 1.5 T, the iron loss (watt loss) per unit weight is 400 W / kg. However, this value may be a relative value.

[0164] The test can be performed in accordance with IEC 60404-2 (or JIS C 2550-1) by dividing the specimen in the rolling direction and the specimen in the direction perpendicular to rolling in half.

[0165] Table 1 shows information on the amount of iron loss measured by applying magnetic fields of 1.0T / 50Hz, 1.5T / 50Hz, 1.0T / 60Hz, and 1.5T / 60Hz.

[0166] In order to obtain future rights, the iron loss characteristics of the electrical steel sheet (112) applied to other companies can be determined through the above test method.

[0167] These iron loss values ​​are an important factor affecting the efficiency of electrical equipment, and the lower the iron loss, the higher the electrical efficiency.

[0168] In this embodiment, the first electrical steel sheet (112a) of the first stator core (111a) may have iron loss characteristics of 50PN600 material. The second electrical steel sheet (112b) of the second stator core (111b) may have iron loss characteristics of 50PN440 material. However, the second electrical steel sheet (112b) of the second stator core (111b) may be implemented as a low iron loss steel sheet that is a combination of one or more selected from 50PN470, 50PN400, 50PN350, 50PN330, 50PN310, 50PN290, 50PN270, and 50PN250.

[0169] According to Table 1, the first electrical steel sheet (112a) made of 50PN600 material can have iron losses of 2.00 (0.91) W / kg (W / lb), 4.40 (2.00) W / kg (W / lb), 2.51 (1.14) W / kg (W / lb), and 5.63 (2.55) W / kg (W / lb) respectively when magnetic fields of 1.0T / 50Hz, 1.5T / 50Hz, 1.0T / 60Hz, and 1.5T / 60Hz are applied respectively.

[0170] The second electrical steel sheet (112b) made of 50PN400 material can have iron losses of 1.41 (0.64) W / kg (W / lb), 3.18 (1.44) W / kg (W / lb), 1.82 (0.83) W / kg (W / lb), and 4.01 (1.82) W / kg (W / lb) respectively when magnetic fields of 1.0T / 50Hz, 1.5T / 50Hz, 1.0T / 60Hz, and 1.5T / 60Hz are applied respectively.

[0171] The second electrical steel sheet (112b) made of 50PN470 material can have iron losses of 1.55 (0.70) W / kg (W / lb), 3.37 (1.53) W / kg (W / lb), 2.04 (0.93) W / kg (W / lb), and 4.36 (1.98) W / kg (W / lb) respectively when magnetic fields of 1.0T / 50Hz, 1.5T / 50Hz, 1.0T / 60Hz, and 1.5T / 60Hz are applied respectively.

[0172] Although the second electrical steel sheet (112b) made of 50PN440 material is not shown in Table 1, the amount of iron loss can be measured by using interpolation methods, etc. by referring to the representative values ​​shown in Table 1.

[0173] The second electrical steel plate (112b) of the second stator core (111b) is a low-iron loss steel plate of a different material compared to the second electrical steel plate (112b) of the second stator core (111b).

[0174] Through this, the second stator core (111b), where iron loss is concentrated, is made of a low iron loss material, so that iron loss can be reduced without reducing the amount of magnetic flux.

[0175] In addition, the increase in material costs can be minimized by applying a low-iron loss material only to the axial ends of the stator core (111) where iron loss is concentrated.

[0176] 3. Description of the configuration of the stator (210) according to another embodiment of the present invention

[0177] FIG. 5 is a perspective view of a motor according to another embodiment of the present invention, showing a second stator core (211b) with two ends having different circumferential widths of teeth applied to one end of the first stator core (211a) in the axial direction.

[0178] Figure 6 is a top view of the motor in Figure 5.

[0179] FIG. 7 is a cross-sectional view taken along VII-VII in FIG. 6, showing two ends of teeth with different circumferential widths applied to both axial ends of the first stator core (211a).

[0180] FIG. 8 is a plan view showing the first stator core (211a) in FIG. 7 as viewed from above.

[0181] FIG. 9 is a plan view showing the second stator core (211b) in FIG. 7 as viewed from above.

[0182] FIG. 10 is a cross-sectional view taken along XX in FIG. 9, showing that the thickness of the electrical steel sheets (112) of the first stator core (211a) and the second stator core (211b) are the same.

[0183] FIG. 11 is a graph showing magnetic flux density according to the axial height of the stator core (111).

[0184] This embodiment differs from the embodiments of FIGS. 1 to 4 described above in that the circumferential width (W1, W2) of the teeth (215) varies along the axial direction of the stator core (211).

[0185] In this embodiment, the circumferential width (W2) of the tooth (215) of the second stator core (211b) is formed to be narrower than the circumferential width (W1) of the tooth (215) of the first stator core (211a). One side of the second tooth (215b) of the second stator core (211b) may be formed circumferentially concave from one side of the first tooth (215a) of the first stator core (211a).

[0186] In this specification, the upper and lower portions of the stator core (211), in which the circumferential width (W1, W2) of the teeth (215) is formed narrowly compared to the middle portion of the stator core (211), may be referred to as the two-stage portion.

[0187] In the case of the stator (210) to which the above-mentioned two-stage portion is applied, the radial width of the second pole shoe (216b) of the second stator core (211b) may be formed to be narrower than the radial width of the first pole shoe (216a) of the first stator core (211a). The inner surface of the second pole shoe (216b) of the second stator core (211b) positioned toward the second slot (214b) may be formed radially concave from the inner surface of the first pole shoe (216a) of the first stator core (211a).

[0188] Additionally, the radial width of the second back yoke (213b) of the second stator core (211b) may be formed to be narrower than the radial width of the first back yoke (213a) of the first stator core (211a). The inner surface of the second back yoke (213b) of the second stator core (211b), which is positioned toward the center of the second back yoke (213b), may be formed concavely in the radial direction from the inner surface of the first back yoke (213a) of the first stator core (211a).

[0189] Through this, the area of ​​the second slot (214b) of the second stator core (211b) can be expanded more significantly along the inner circumference of the slot (214) compared to the area of ​​the first slot (214a) of the first stator core (211a).

[0190] The second slot (214b) of the expanded second stator core (211b) may provide an insulator insertion groove (224), which is a space into which an insulator (not shown), such as insulating paper, is inserted and coupled.

[0191] An insulator may be installed to surround the second back yoke (213b), second teeth (215b), and second pole shoe (216b) of the second stator core (211b) along the inner circumference of the second slot (214b). The insulator may include a first insulator configured to surround the second back yoke (213b) and a second insulator configured to surround the second teeth (215b) and the second pole shoe (216b).

[0192] The thickness of the insulator may be the difference between the circumferential width (W1) of the first tooth (215a) and the circumferential width (W2) of the second tooth (215b) divided by 2. The thickness of the insulator may be the difference between the radial width of the first back yoke (213a) and the radial width of the second back yoke (213b). The thickness of the insulator may be the difference between the radial width of the first pole shoe (216a) and the radial width of the second pole shoe (216b).

[0193] By doing so, when the insulator surrounds the second back yoke (213b), the second tooth (215b), and the second pole shoe (216b) along the inner circumference of the second slot (214b), the insulator can be in the same plane as the inner surface of the first back yoke (213a), the first tooth (215a), and the first pole shoe (216a) of the first stator core (211a).

[0194] Additionally, the insulator inserted into the insulator insertion groove (224) can maintain electrical insulation between the coil (217) and the stator core (211).

[0195] In the case of the stator (210) and motor to which the above-mentioned two-stage section is applied, when the magnetic flux moves from the first stator core (211a), which is the middle part of the stator core (211), to the second stator core (211b), which is the upper and lower part of the stator core (211), the width of the path (magnetic flux width) of the path where the magnetic flux moves becomes narrow, so the magnetic flux density is concentrated (increased) in the second stator core (211b), and the iron loss increases.

[0196] To improve this, the second stator core (211b) can be implemented with a steel plate having a low iron loss compared to the first stator core (211a).

[0197] The thickness of the first electrical steel plate (212a) of the first stator core (211a) and the thickness of the second electrical steel plate (212b) of the second stator core (211b) may be the same as each other.

[0198] Other components are identical or similar to the embodiments of FIGS. 1 to 4 described above, so a redundant description will be omitted.

[0199] 4. Description of the configuration of the stator (310) according to another embodiment of the present invention

[0200] FIG. 12 is a conceptual diagram showing that the thicknesses of the electrical steel sheets (312) of the first stator core (311a) and the second stator core (311b) are different according to another embodiment of the present invention.

[0201] This embodiment differs from the embodiments of FIGS. 1 to 9 described above in that the thickness of the electrical steel sheet (312) varies along the axial direction of the stator core (311).

[0202] In this embodiment, the thickness (t2) of the second electrical steel plate (312b) of the second stator core (311b) is formed to be thinner than the thickness (t1) of the first electrical steel plate (312a) of the first stator core (311a).

[0203] For example, the first electrical steel sheet (312a) may have a thickness of 0.5 mm. The second electrical steel sheet (312b) may have a thickness of 0.35 mm, 0.30 mm, or 0.27 mm.

[0204] As the thickness of the electrical steel sheet (312) decreases, the eddy current path is shortened, and eddy current loss can be reduced. When a thin electrical steel sheet (312) is used, the induced current dissipates more quickly on the surface of the electrical steel sheet (312), so iron loss is reduced.

[0205] Accordingly, the thickness (t2) of the second electrical steel plate (312b) of the second stator core (311b) is thinner than the thickness (t1) of the first electrical steel plate (312a) of the first stator core (311a), so that iron loss is reduced at the upper and lower parts of the stator core (311) where iron loss is concentrated, thereby improving motor efficiency.

[0206] Other components are identical or similar to the embodiments of FIGS. 1 to 10 described above, so a redundant description will be omitted.

[0207] Below, we will explain the effect of improving iron loss through the material conversion of the stator (110).

[0208] FIG. 13 is a graph showing the iron loss density ratio according to the axial height of the upper / lower portions of the stator core (111).

[0209] Referring to FIG. 13, the iron loss generated according to the axial height of the upper and lower parts of the stator core (111) due to the concentration effect of magnetic flux density caused by the fringing effect is concentrated at a maximum of 120% higher than the average iron loss of the entire stator core (111).

[0210] The axial height of the upper portion of the stator core (111) refers to the height obtained by adding the thickness of the electrical steel sheet (112) at the top of the stator core (111) located furthest upward from the center of the stator core (111) that divides the stacking length of the stator core (111) into two equal parts, and the thickness of the plurality of electrical steel sheets (112) stacked along the axial direction toward the center of the stator core (111).

[0211] The axial height of the lower portion of the stator core (111) refers to the height obtained by adding the thickness of the electrical steel plate (112) at the bottom of the stator core (111) located furthest downward from the center of the stator core (111), and the thickness of the plurality of electrical steel plates (112) stacked along the axial direction toward the center of the stator core (111).

[0212] The axial heights of the upper and lower parts of the stator core (111) are equal to each other. A test was conducted to measure the iron loss density ratio of the upper and lower parts of the stator core (111) relative to the average iron loss of the entire stator core (111), with the axial height of each of the upper and lower parts of the stator core (111) ranging from 0.5 mm to 3.0 mm.

[0213] As a result, it can be seen that as the axial height of the upper and lower parts of the stator core (111) increases from 0.5 mm to 2.0 mm, the iron loss density ratio decreases from a maximum of 120% to 112%, then remains at a high level of 110% or more up to the 2.5 mm point, and then decreases again as it increases to 3.0 mm with an inflection point.

[0214] Based on this data, it is determined that replacing the electrical steel sheet (112) with a low iron loss steel sheet is most effective up to the point where the axial height of the upper and lower parts of the stator core (111) is 2.5 mm.

[0215] FIG. 14 is a graph showing the iron loss improvement ratio of a stator core (111) in which part of the stator core (111) is made of a different material compared to a stator core (111) in which the entire stator core (111) is changed to a high-grade material.

[0216] According to the present embodiment, the dual-material stator core (111) can change only the second stator core (111b), which is 18.2% of the total stator core (111), to a low-iron loss material. The dual-material stator core (111) can improve iron loss by 42% compared to the iron loss improvement effect when the entire stator core (111) is changed to a low-iron loss material.

[0217] Therefore, by changing only a part of the stator core (111) where iron loss is concentrated to a low-iron loss material, the effect of improving iron loss can be maximized while reducing material costs.

Claims

1. A stator core having a back yoke, a plurality of teeth protruding radially from the inner surface of the back yoke, and a plurality of slots disposed between the plurality of teeth adjacent in the circumferential direction; and It includes a coil wound on the tooth through the slot, The above stator core is, A first stator core formed by stacking and combining a plurality of first electrical steel sheets in the axial direction; and A second stator core comprising a plurality of second electrical steel plates formed of a material different from the first electrical steel plate and laminated and combined in the axial direction, wherein the second stator core is laminated and combined to at least one end of the first stator core. Status 2. In Paragraph 1, The above second stator core is provided in a plurality of units, and the plurality of second stator cores are each disposed at one end and the other end of the first stator core. Status 3. In Paragraph 1, The above second electrical steel sheet is a low-iron loss material having relatively lower iron loss than the above first electrical steel sheet, Status 4. In Paragraph 1, The above first electrical steel sheet is a ferrous metal material of 50PN600, and The above second electrical steel sheet is a ferrous metal material composed of one or more selected from 50PN470, 50PN400, 50PN350, 50PN330, 50PN310, 50PN290, 50PN270, and 50PN250, and The above PN is an abbreviation for "Posco Non-oriented," referring to non-oriented electrical steel sheets produced by POSCO, the number preceding PN indicates that the steel sheet thickness is 0.5mm, and the number following PN indicates magnetic loss, Status 5. In Paragraph 1, The first electrical steel sheet is a 50PN600 iron-based metal material, and the second electrical steel sheet is a 50PN440 iron-based metal material, Status 6. In Paragraph 1, The axial height of the second stator core is 0.5 to 2.5 mm, Status 7. In Paragraph 1, The first electrical steel sheet has a first thickness of 1 mm or less, and the second electrical steel sheet has a second thickness smaller than the first thickness. Status 8. In Paragraph 1, The thickness of the first electrical steel sheet is 0.5 mm, and the thickness of the second electrical steel sheet is 0.35 mm. Status 9. In Paragraph 1, The plurality of teeth are arranged circumferentially spaced apart along the inner circumference of the back yoke, and The second stator core has a smaller circumferential width of the teeth compared to the first stator core. Status 10. In Paragraph 1, A pole shoe is provided at the radially inner end of the above tooth, and The second stator core has a smaller radial width of the pole shoe compared to the first stator core. Status 11. In Paragraph 1, The second stator core has a smaller radial width of the back yoke compared to the first stator core. Status 12. Rotation axis; A rotor coupled to the above-mentioned rotational axis and equipped with a permanent magnet; and It is equipped with a coil and includes a stator that surrounds the rotor, The above stator is, It includes a back yoke and a stator core having a plurality of teeth that protrude radially from the inner circumference of the back yoke to form a plurality of slots on the inner side of the back yoke and are arranged circumferentially spaced apart along the inner circumference of the back yoke. The above stator core is, A first stator core composed of a plurality of first electrical steel sheets laminated and bonded together; and A second stator core comprising a plurality of second electrical steel plates having a thickness different from that of the first electrical steel plate, which are arranged at both ends of the first stator core in the axial direction of the rotation axis and are formed by laminating and combining them, motor.

13. In Paragraph 12, The first electrical steel sheet has a first thickness of 1 mm or less, and the second electrical steel sheet has a second thickness smaller than the first thickness. motor.

14. In Paragraph 12, The thickness of the first electrical steel sheet is 0.5 mm, and the thickness of the second electrical steel sheet is 0.35 mm. motor.

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