COIL FOR MOTOR

Abstract

A coil for a superconducting motor is proposed, which can achieve cooling performance and is expected to provide structural stability. The coil for a motor comprises a coil former on which a superconducting coil is wound, and a reinforcement made of a reinforced plastic with reinforcing fibers that surrounds one side surface of the coil former.

Description

BACKGROUND AREA

[0001] The present disclosure relates generally to a coil for a motor, and more particularly to a coil for a motor by which cooling performance can be achieved and structural stability can be expected. EXPLANATION OF THE BACKGROUND

[0002] In general, the development of drive motors is required to improve the performance and fuel efficiency of electric vehicles (EVs) or hybrid electric vehicles (HEVs) that use electricity as their primary propulsion.

[0003] In 1911, Heike Kamerlingh-Onnes of Leiden University in the Netherlands discovered a phenomenon during an experiment measuring the electrical resistance of mercury in which the electrical resistance suddenly disappears at an absolute temperature of 4.2 K (minus 268.8 °C). As a result, low-temperature superconductors such as NbTi and SnTi began to be used in applications requiring high magnetic fields.

[0004] In 1987, Johannes Bednorz and Karl Muller discovered a high-temperature superconductor in Switzerland. Since then, active research has been conducted to improve the critical temperature and critical current density of high-temperature superconductors.

[0005] Accordingly, recent research has focused on the technology for using superconductors in motors to improve their performance. Within this research, an internal permanent magnet superconducting synchronous motor (IPMSM) has been proposed.

[0006] The foregoing statements are intended only to contribute to an understanding of the background of the present disclosure and do not imply that the present disclosure falls within the scope of the related art. SUMMARY OF THE INVENTION

[0007] Accordingly, the present disclosure has been developed in consideration of the above-mentioned problems, and the present disclosure aims to propose a coil for a superconducting motor, whereby cooling performance can be achieved and structural stability can be expected.

[0008] The object of the present disclosure is not limited to the above description, and other objects not expressly disclosed herein will be clearly understood by those skilled in the art from the following description.

[0009] A coil for a motor may include: a bobbin on which a superconducting coil is wound; and a reinforcement comprising a reinforced plastic with a reinforcing fiber, the reinforcement being formed to surround a side surface of the bobbin.

[0010] The coil body may be made of a material selected from aluminum (Al), an Al alloy, steel, a steel alloy, stainless steel, and an electrical steel sheet, and the reinforcement may be made of carbon fiber reinforced plastic (CFRP).

[0011] The coil body may comprise: a core on which the superconducting coil is wound; and a cover configured to cover an outer portion of the superconducting coil, wherein the cover is spaced from the core by a gap in which the superconducting coil is wound on the core, and wherein the reinforcement surrounds a side surface of the cover.

[0012] The reinforcement may surround the cover of the coil body in an area corresponding to an area in which the superconducting coil is wound.

[0013] The reinforcement may surround the cover of the coil at a height corresponding to a height at which the superconducting coil is wound.

[0014] The height of an upper portion of the reinforcement may be less than or equal to the height of an upper portion of a winding of the superconducting coil, and the height of a lower portion of the reinforcement may be less than or equal to the height of a lower portion of the winding of the superconducting coil.

[0015] The superconducting coil may be wound in a racetrack shape and includes a pair of linear sections running parallel to each other and a pair of arcuate sections connecting the respective ends of the pair of linear sections. The ratio of the thickness of the cover covering the linear sections of the superconducting coil to the thickness of the reinforcement may range from about 2:1 to about 2:2.

[0016] The thickness of the reinforcement can range from approximately 0.05 mm to 5 mm.

[0017] The coil body may be made of a material selected from aluminum (Al), an Al alloy, steel, a steel alloy, stainless steel, and an electrical steel sheet, and the reinforcing fiber may comprise a glass fiber.

[0018] A motor (e.g., a motor for a vehicle) may include: a superconducting coil; and a bobbin, the coil comprising: a bobbin on which the superconducting coil is wound; and a reinforcement comprising a reinforced plastic including a reinforcing fiber, the reinforcement being formed to surround a side surface of the bobbin.

[0019] According to the present disclosure, the CFRP reinforcement can be attached to the side surface of the coil former on which the superconducting coil is wound to structurally protect the side parts of the coil former. Thus, it is possible to minimize the thickness of the coil while maximizing the performance of the superconducting coil.

[0020] In addition, it is possible to maintain the electrical properties and driving stability of the superconducting coil by reducing the displacement of the superconducting coil in a high magnetic field environment.

[0021] In addition, it is possible to maximize the performance of the superconducting coil by reducing the superconducting quenching, in which superconductivity is lost and resistance increases rapidly, by achieving cooling performance and structural stability, thereby increasing the specific power of the superconducting motor. SHORT DESCRIPTION OF THE CHARACTERS

[0022] The above and other objects, features, and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. Figure 1 is a schematic view illustrating the degree of displacement versus area of ​​a coil in a superconducting motor using superconducting coils. Fig. 2 is a perspective view illustrating a coil for a superconducting motor. Fig. Figure 3 is a schematic view illustrating the coil of a superconducting motor. Fig. Figure 4 is a view illustrating the cross section of the coil of a superconducting motor. Fig. 5A is a view illustrating the tension rate of a side cover of a coil bobbin according to a comparative example. Fig. 5B is a view illustrating the stress rate occurring at a side lid portion of a coil bobbin according to an example of the present disclosure. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments disclosed in the present disclosure will be described in detail with reference to the accompanying drawings, in which identical or similar constituent parts are given the same reference numerals regardless of the reference numerals of the drawings, and repeated description thereof will be omitted.

[0024] When it is determined in the description of the present disclosure that the detailed description of the related art would obscure the gist of the present disclosure, the detailed description thereof will be omitted. Furthermore, the accompanying drawings are merely intended to facilitate the understanding of the exemplary embodiments contained herein, and thus, the technical idea contained herein is not limited by the accompanying drawings, and it can be understood that it includes all changes, equivalents, and substitutions that fall within the spirit and technical scope of the present disclosure.

[0025] It should be understood that while the terms "first," "second," etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used merely to distinguish one element from another.

[0026] When an element is described as being "coupled," "connected," or "linked" to another element, it may be directly coupled or connected to the other element, or there may be intervening elements. In contrast, when an element is described as being "directly coupled" or "directly connected" to another element, it is understood that no intervening elements are present.

[0027] As used here, the singular forms “a” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0028] It should also be understood that terms such as "comprising", "including", "having", etc., when used in this specification, indicate the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

[0029] First, a coil for a superconducting motor can be a coil on which superconducting coils are wound. For example, the coil can be used as a rotor coil in an internal permanent magnet superconducting synchronous motor (IPMSM) or other motors. The coil for a superconducting motor is not limited to the rotor coil but can be a stator coil if superconducting coils are provided on the stator, or as a coil for other hardware elements.

[0030] In general, a superconducting IPMSM is characterized by generating an electromagnetic field using a superconducting material and having high efficiency and high power due to the permanent magnets it contains.

[0031] In superconducting IPMSM, it is generally necessary to construct a housing, such as a coil, to achieve cooling performance and structural stability when superconducting coils are provided on the rotor.

[0032] Because superconductivity generates a strong magnetic field of 5T or more, as described here, an improved coil structure may be required to be safe against strong magnetic fields. To generate stronger magnetic fields, for example, the thickness of one or more parts (e.g., one or more body parts that house a coil structure) of the coil may be reduced to enlarge the cavity or internal space of the coil that houses one or more elements such as the coil structure. The enlarged cavity or space would make it possible to accommodate a coil structure that generates stronger magnetic fields. As the thickness of the inner wall is reduced, a safer structure for the coil may be required.

[0033] In addition, in the design of the coil, the material and structure of the coil are designed together, and the safety of the coil is achieved by the strength of the material and the structure.

[0034] Fig. Figure 1 is a schematic view illustrating the degree of displacement versus area of ​​a coil in a superconducting motor with superconducting coils. As shown in Fig. 1, a superconducting coil 20 is wound on a bobbin 10, a part of which surrounds the outer portion of the superconducting coil 20 to separate the superconducting coil 20 and an adjacent pole 100 from each other and at the same time protect the superconducting coil 20.

[0035] The coil former 10 may be made of a material with high thermal conductivity, such as aluminum (Al), an Al alloy, steel, a steel alloy, stainless steel, or an electrical steel sheet. During motor operation, the superconducting coil 20 may be displaced by a strong magnetic field generated by the superconducting coil 20. A portion of the coil 10, e.g., a relatively thin region of the structure of the coil 10 surrounding the outer portion of the superconducting coil 20 between the coil 10 and the adjacent pole 100, may be damaged.

[0036] Therefore, to prevent damage to the sensitive parts of the coil, the thickness and material of the coil are important factors in the safety design of the coil construction.

[0037] However, the material properties of the coil are limited, and increasing the coil thickness reduces the clearance and / or area for the superconducting coil (e.g., reducing the number of turns of the superconducting coil). This can adversely affect the performance of the superconducting coil.

[0038] In this regard, the present disclosure proposes a coil for a superconducting motor provided with a reinforcement surrounding a bobbin of the coil, whereby cooling performance can be achieved and structural stability can be expected.

[0039] Fig. 2 is a perspective view illustrating a coil for a superconducting motor, Fig. 3 is a plan view illustrating the coil for a superconducting motor, and Fig. Figure 4 is a cross-sectional view illustrating the coil for a superconducting motor.

[0040] As in the Fig. 2 to 4, the coil for a motor generally comprises: a bobbin 10 on which a superconducting coil 20 is wound; and a reinforcement 30 made of a reinforced plastic containing reinforcing fibers and surrounding a side surface of the bobbin 10.

[0041] The coil former 10 is designed such that the superconducting coil 20 can be wound thereon. The coil former 10 comprises a core 11, onto which the superconducting coil 20 is wound, and a cover 12, which is spaced from the core 11 by a gap in which the superconducting coil 20 is wound onto the core 11 and which is designed to cover the outer portion of the superconducting coil 20.

[0042] The superconducting coil 20 may be wound on the bobbin 10 in a racetrack shape and may have a pair of linear portions extending parallel to each other and a pair of arcuate portions each connecting the corresponding ends of the pair of linear portions.

[0043] Thus, the outer peripheral portion of the core 11 of the coil body 10 is provided in a racetrack shape to correspond to the inner peripheral shape of the superconducting coil 20 wound on the core 11.

[0044] Similarly, the inner peripheral portion of the cover 12 of the coil former 10 may be formed into a racetrack shape to match the outer peripheral shape of the superconducting coil 20 wound on the core 11. The portions of the cover 12 of the coil former 10 covering the curved portions of the superconducting coil 20 may be thicker, while the portions of the cover 12 of the coil former 10 covering the linear portions of the superconducting coil 20 may be thinner.

[0045] Thus, the outer peripheral surface of the cover 12 of the coil body 10 can have a substantially rectangular shape.

[0046] The coil former 10 can be made of a material with high thermal conductivity, such as aluminum, an aluminum alloy, steel, a steel alloy, stainless steel, or an electrical steel sheet. In this case, the material of the coil former 10 has the required thermal conductivity, but the rigidity may be insufficient. Thus, during motor operation, the cover 12 of the coil former 10 may change or deform due to the displacement of the superconducting coil 20.

[0047] To solve such problems, the reinforcement 30 in the present disclosure may be provided on the outer peripheral surface of the coil body 10.

[0048] The reinforcement 30 may be made of a material that has higher rigidity and lower thermal contraction and expansion than the material of the coil body 10. Thus, the coil can be designed in such a way that the rigidity is maintained with a small overall thickness.

[0049] The reinforcement 30 can, for example, consist of a reinforced plastic with reinforcing fibers. The reinforcement 30 can, for example, consist of carbon fiber reinforced plastic (CFRP).

[0050] CFRP is a composite material consisting of carbon fibers and a thermosetting resin. CFRP exhibits high specific intensity, excellent fatigue / creep properties, excellent weathering / chemical resistance, low thermal contraction / elongation, and similar characteristics. For example, CFRP is about four times lighter than steel, while its strength is about nine times that of steel.

[0051] The reinforcement 30 may be configured to surround the cover 12 of the coil body 10 in a region corresponding to a region in which the superconducting coil 20 is wound, in order to prevent the coil from being damaged or broken according to the displacement of the superconducting coil 20.

[0052] The reinforcement 30 can be wound on the cover 12 of the coil body 10 at the same height as the superconducting coil 20.

[0053] The height of the top of the reinforcement 30 may be equal to or less than the height of the top of the winding of the superconducting coil 20, while the height of the bottom of the reinforcement 30 may be equal to or less than the height of the bottom of the winding of the superconducting coil 20.

[0054] In particular, since the thickness of the reinforcement 30 determines the overall thickness of the coil, the reinforcement 30 can be designed to be so thin (e.g., from about 0.05 mm to about 5 mm for some coils) that its stiffness is not compromised.

[0055] For example, the ratio of the thickness of the reinforcement 30 to the thickness of the cover 12 covering the linear sections of the superconducting coil 20 can be kept in a range of 2:1 to 2:2.

[0056] If the reinforcement 30 is thicker than the thickness in a range of the ratio of the thickness of the cover to the reinforcement, the thickness of the cover 12 of the bobbin 10 may be reduced or the number of turns of the superconducting coil 20 may be reduced, thereby adversely reducing the efficiency of the motor.

[0057] In contrast, the structural stability of the coil cannot be achieved when the reinforcement 30 is thinner than the thickness in a range of the ratio between the thickness of the cover and the reinforcement.

[0058] As described above, the reinforcement 30 may be a composite material composed of a carbon fiber and a thermosetting resin. The carbon fiber may be a filament fiber composed of relatively long filaments or a continuous fiber oriented in a specific direction. The carbon fiber may also be produced by weaving a continuous fiber.

[0059] Since the reinforcement 30 is oriented in a certain direction, the reinforcement 30 can be wound to surround the outer surface of the coil body 10 along the direction of the carbon fiber when forming the reinforcement 30.

[0060] Here, the CFRP of the reinforcement 30 can be manufactured as a foil or tape, which is wound around the outer circumferential surface of the coil body 10. The direction of the winding can be clockwise or counterclockwise with respect to the view in Fig. 3.

[0061] Hereinafter, the present disclosure will be described with reference to a comparative example and an example.

[0062] In the comparative example, a coil containing only a coil former without reinforcement was used. Here, the thickness of the coil former, i.e., an area covering linear sections of a superconducting coil, was set to 3 mm.

[0063] In contrast, in the example according to the present disclosure, a reinforcement was attached to the outer peripheral surface of the coil body. Here, the thickness of the coil body, i.e., a region covering linear portions of a superconducting coil, was set to 2 mm, and the thickness of the reinforcement was set to 1 mm.

[0064] To achieve at least one of the above-mentioned objects, according to the present disclosure, there is provided a coil for a motor, the coil comprising: a bobbin on which a superconducting coil is wound; and a reinforcement comprising a reinforced plastic with reinforcing fibers and surrounding a side surface of the bobbin.

[0065] The coil former can be made of a material selected from aluminum (Al), an Al alloy, steel, a steel alloy, stainless steel, and an electrical steel sheet. The reinforcement can be made of carbon fiber reinforced plastic (CFRP).

[0066] The coil body may comprise: a core on which the superconducting coil is wound; and a cover spaced from the core by a gap in which the superconducting coil is wound on the core, and configured to cover an outer portion of the superconducting coil. The reinforcement may surround a side surface of the cover.

[0067] The reinforcement may surround the cover of the coil body in an area corresponding to an area in which the superconducting coil is wound.

[0068] The reinforcement can surround the lid of the coil at the same height at which the superconducting coil is wound.

[0069] The height of the top of the reinforcement can be equal to or less than the height of the top of the winding of the superconducting coil. The height of a bottom of the reinforcement can be equal to or less than the height of a bottom of the winding of the superconducting coil.

[0070] The superconducting coil may be wound in a racetrack shape and include a pair of linear sections running parallel to each other and a pair of arcuate sections connecting the respective ends of the pair of linear sections. The ratio of the thickness of the cover covering the linear sections of the superconducting coil to the reinforcement may be in a range of 2:1 to 2:2.

[0071] For the coils thus prepared, the tension rate of the linear section of each coil body was measured during the operation of the motor, and the results are shown in the Fig. 5A and Fig. 5B illustrates.

[0072] Fig. 5A is a view illustrating the stress rate occurring at a side portion of the lid of a coil bobbin according to a comparative example, and Fig. 5B is a view illustrating the stress rate occurring at a side portion of the lid of a coil bobbin according to an example of the present disclosure.

[0073] As in the Fig. 5A and Fig. As illustrated in Figure 5B, a stress of 105.01 MPa was measured for the corresponding section according to the comparative example, while a stress of 93.953 MPa was measured for the corresponding section according to the example.

[0074] Thus, it can be seen that the stress occurring on the lateral portion of the cover of the coil body according to the example was reduced by 10.5% compared to that of the comparative example.

[0075] Although embodiments of the present disclosure have been described for illustrative purposes, it will be apparent to those skilled in the art that various modifications, additions, and substitutions are possible without departing from the scope and spirit of the present disclosure as disclosed in the appended claims.

Claims

[1] Coil for a motor, the coil comprising: a coil body on which a superconducting coil is wound; and a reinforcement comprising a reinforced plastic with a reinforcing fiber, the reinforcement being formed to surround a side surface of the coil body. [2] The coil according to claim 1, wherein the coil body is made of one selected from aluminum (Al), an Al alloy, steel, a steel alloy, stainless steel and an electrical steel sheet, and wherein the reinforcement is made of carbon fiber reinforced plastic (CFRP). [3] The coil of claim 1, wherein the coil body comprises: a core on which the superconducting coil is wound; and a lid configured to cover an outer portion of the superconducting coil, the lid being spaced from the core by a gap in which the superconducting coil is wound onto the core, and wherein the reinforcement surrounds a side surface of the lid. [4] The coil according to claim 3, wherein the reinforcement surrounds the cover of the coil body in a region corresponding to a region in which the superconducting coil is wound. [5] The coil of claim 4, wherein the reinforcement surrounds the cover of the coil at a height corresponding to a height at which the superconducting coil is wound. [6] The coil of claim 4, wherein the height of an upper portion of the reinforcement is less than or equal to the height of an upper portion of a winding of the superconducting coil, and wherein a height of a lower portion of the reinforcement is less than or equal to a height of a lower portion of the winding of the superconducting coil. [7] The coil of claim 3, wherein the superconducting coil is wound in a racetrack shape and includes a pair of linear portions extending parallel to each other and a pair of arcuate portions each connecting the corresponding ends of the pair of linear portions. The ratio between the thickness of the cover covering the linear portions of the superconducting coil and the thickness of the reinforcement is in the range of about 2:1 to about 2:

2. [8] The coil of claim 2, wherein the thickness of the reinforcement is in the range of about 0.05 mm to 5 mm. [9] The coil according to claim 1, wherein the coil body is made of one selected from aluminum (Al), an Al alloy, steel, a steel alloy, stainless steel and an electrical steel sheet, and wherein the reinforcing fiber comprises a glass fiber. [10] An engine comprising: a superconducting coil; and a coil, the coil comprising: a coil body on which the superconducting coil is wound; and a reinforcement comprising a reinforced plastic with a reinforcing fiber, the reinforcement being formed to surround a side surface of the coil body.

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