Electric motor

Abstract

In the present invention, an electric motor is introduced in which a plurality of slits are formed in the rotor, and as the eddy current resistance relative to the area increases, eddy current loss is reduced and motor efficiency is improved.

Description

Technology Field

[0001] The present invention relates to an electric motor, and more specifically, to an electric motor that reduces eddy current losses through a rotor. Background Technology

[0003] Recently, active research and development is underway regarding hybrid and electric vehicles, which are environmentally friendly and fuel-efficient forms of automobiles that utilize combustion engines.

[0004] Hybrid vehicles drive the vehicle using two power sources by combining a conventional engine with a motor powered by electric energy, whereas electric vehicles are driven solely by an electric motor; this offers the advantages of reduced environmental pollution from exhaust gases and improved fuel efficiency.

[0005] These hybrid or electric vehicles are equipped with high-capacity batteries as a driving force to operate the electric motor; they supply power to the motor when necessary and charge the battery with electrical energy generated from a regenerative power source when the vehicle decelerates or stops.

[0006] As such, an electric motor can be largely composed of a rotor equipped with a number of magnetic bodies, such as permanent magnets, and a stator that generates electromagnetic force to rotate the rotor.

[0007] Since these electric motors are responsible for driving the vehicle, efficiency is considered important; as driving range and output improve depending on motor efficiency, measures to reduce electric motor losses are required.

[0008] The matters described above as background technology are intended only to enhance understanding of the background of the present invention and should not be construed as an acknowledgment that they constitute prior art already known to those skilled in the art. The problem to be solved

[0010] The problem that the present invention aims to solve is to provide an electric motor that improves motor efficiency by reducing eddy current losses through the rotor in an AFPM (Axial Flux Permanent Magnet Motor). means of solving the problem

[0012] An electric motor according to the present invention for achieving the above objective comprises: a stator; and a rotor disposed facing the stator and having a plurality of slits formed along the circumferential direction.

[0013] The rotor is characterized by having permanent magnets arranged along its circumference, and the permanent magnets are AFPM (Axial Flux Permanent Magnet).

[0014] The rotor is characterized by being made of carbon steel.

[0015] The rotor is characterized by each slit being formed to extend along the circumferential direction with respect to the axis center.

[0016] The rotor is characterized by having a plurality of slits arranged at regular intervals along the circumferential direction.

[0017] The rotor is characterized by having a plurality of slits arranged radially spaced apart.

[0018] Multiple slits arranged in a radial direction are characterized by the fact that the extension length of the slits gradually increases toward the outer side.

[0019] A plurality of slits arranged in a radial direction are characterized by being aligned in a straight line at one end, which is the rotational direction of the rotor, and arranged diagonally at the other end due to the different lengths of each slit.

[0020] The number and shape of the slits in the rotor are characterized by being determined based on the total eddy current loss of the rotor, which is calculated by comparing the eddy current loss of the rotor's back yoke with the eddy current loss of the permanent magnet.

[0021] The spacing between the slits in the rotor is characterized by being determined based on the total eddy current loss of the rotor, which is calculated by comparing the eddy current loss of the rotor's back yoke with the eddy current loss of the permanent magnet. Effects of the invention

[0023] An electric motor with a structure as described above has multiple slits formed in the rotor, and as the eddy current resistance increases relative to the area, eddy current losses are reduced, thereby improving motor efficiency. Brief explanation of the drawing

[0025] FIG. 1 is a drawing showing an electric motor according to an embodiment of the present invention. FIG. 2 is a drawing showing an embodiment of a rotor in an electric motor according to the present invention. FIG. 3 is a drawing showing an electric motor according to another embodiment of the present invention. FIG. 4 is a drawing showing another embodiment of a rotor in an electric motor according to the present invention. FIG. 5 is a drawing showing another embodiment of a rotor in an electric motor according to the present invention. FIG. 6 is a diagram showing the difference in current density vectors through a rotor according to the present invention. FIG. 7 is a table showing the eddy current loss reduction efficiency through a rotor according to the present invention. Specific details for implementing the invention

[0026] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Identical or similar components regardless of drawing symbols are given the same reference number, and redundant descriptions thereof will be omitted.

[0027] The suffixes "module" and "part" used for components in the following description are assigned or used interchangeably solely for the ease of drafting the specification, and do not inherently possess distinct meanings or roles.

[0028] In describing the embodiments disclosed in this specification, if it is determined that a detailed description of related prior art may obscure the essence of the embodiments disclosed in this specification, such detailed description is omitted. Furthermore, the attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the technical concept disclosed in this specification is not limited by the attached drawings; it should be understood that they include all modifications, equivalents, and substitutions that fall within the spirit and technical scope of the present invention.

[0029] 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.

[0030] 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.

[0031] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0032] In this specification, terms such as “comprising” or “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0033] Hereinafter, an electric motor according to a preferred embodiment of the present invention will be examined with reference to the attached drawings.

[0035] As shown in FIGS. 1 and 2, the electric motor according to the present invention comprises a stator (100); and a rotor (200) disposed facing the stator (100) and having a plurality of slits (210) formed along the circumferential direction.

[0036] The electric motor according to the present invention may be an axial flux permanent magnet motor (AFPM) and includes a stator (100) and a rotor (200). Such a stator (100) and a rotor (200) may be provided inside a housing.

[0037] The stator (100) may be composed of a stator core (110) and a coil (120). The stator core (110) holds the wound coil (120) and provides a path for the magnetic flux. This stator core (110) may be formed in a circular shape. The coil (120) receives current from an external power source and generates a magnetic flux that interacts with the rotor (200). The stator (100) may be applied in various embodiments in which the stator core (110) and the coil (120) are applied.

[0038] Meanwhile, the rotor (200) may be composed of a shaft (220) and a rotor core (230).

[0039] The shaft (220) is connected to the rotor core (230) and can be installed in the housing via a bearing. The rotor core (230) can be formed in a circular shape, just like the stator core (110).

[0040] Additionally, the rotor core (230) may be configured as a pair with the stator (100) in between. That is, as shown in FIG. 3, the stator (100) is provided between the pair of rotors (200), and the pair of rotors (200) are arranged to face each other, so that the rotor (200) placed on one side and the rotor (200) placed on the other side can be rotated.

[0041] Thus, the electric motor according to the present invention can be configured as a single type consisting of one rotor (200) and one stator (100) and a dual type consisting of two rotors (200) and one stator (100), and this can be selectively applied depending on the purpose of use and design.

[0042] Meanwhile, a permanent magnet (240) is provided in the rotor core (230). This permanent magnet (240) is an AFPM (Axial Flux Permanent Magnet) and can be configured along the circumference of the rotor core (230). This permanent magnet (240) interacts with the coil (120) provided in the stator (100) to generate rotational force, and as the rotor core (230) rotates due to the rotational force, the shaft (220) can be rotated.

[0043] In particular, the rotor (200) of the present invention has a plurality of slits (210) formed along the circumferential direction, and each slit (210) is formed to extend along the circumferential direction with respect to the axis center.

[0044] The slit (210) may be composed of a hole or a groove, and the slit (210) creates an air insulation effect, thereby reducing eddy current loss as the resistance of eddy currents in the rotor (200) increases.

[0045] Additionally, the slits (210) can be formed in multiple numbers along the circumferential direction in the rotor (200), and by being formed to extend along the circumferential direction with respect to the axis center, the resistance to eddy currents by the slits (210) can be secured relative to the same area.

[0046] In detail, as shown in FIG. 2, the rotor (200) may have a plurality of slits (210) spaced apart at regular intervals along the circumferential direction.

[0047] In this way, each slit (210) spaced apart along the circumferential direction in the rotor (200) is arranged to maintain a constant spacing, so that the resistance of the eddy current is generated uniformly, and the stability of the rotor (200) rotational operation and the current density can be distributed uniformly.

[0048] Additionally, as shown in FIGS. 4 and 5, the rotor (200) may have a plurality of slits (210) arranged radially spaced apart.

[0049] That is, in the present invention, an air insulation effect is generated according to the slit (210) formed in the rotor (200), and the effect of increasing resistance to eddy currents can be increased depending on the number of slits (210). Accordingly, the rotor (200) can have a plurality of slits (210) arranged in a radial direction from the center, thereby securing an additional number of slits (210). At this time, it is preferable that the slits (210) are arranged in a radial direction with equal spacing at regular intervals, and the number of slits (210) and the spacing distances can be determined based on experimental data regarding eddy current resistance.

[0050] In addition, in the present invention, the slit (210) has a curved shape as it extends along the circumferential direction of the rotor (200), making it easy to arrange in the radial direction, which provides a design advantage.

[0051] Meanwhile, as another embodiment, a plurality of slits (210) arranged in a radial direction may be formed such that the extension length of the slits (210) gradually increases as they move outward.

[0052] Referring to FIG. 5, a plurality of slits (210) may be arranged radially on the rotor (200) and formed with different lengths. In particular, each slit (210) is formed to gradually increase in length as it extends outward, so that the length of each slit (210) is set to match the circumference of the rotor (200), thereby enabling a uniform air insulation effect through each slit (210).

[0053] In addition, a plurality of slits (210) arranged in a radial direction may be aligned in a straight line at one end, which is the rotational direction of the rotor (200), and arranged diagonally at the other end due to different lengths of each slit.

[0054] As can be seen in FIG. 5, each slit (210) arranged radially in the rotor (200) may have one end aligned with a straight extension and the other end arranged diagonally relative to one end of each slit (210) as the length of each slit (210) differs. Here, one side of the slit (210) may be the direction of rotation of the rotor (200).

[0055] Through the shape and arrangement of these slits (210), a path of magnetic flux can be formed in the rotor (200) in accordance with the rotational direction of the rotor (200).

[0057] Meanwhile, the number and shape of the slits (210) in the rotor (200) can be determined based on the total eddy current loss of the rotor (200) by comparing the eddy current loss of the back yoke of the rotor (200) with the eddy current loss of the permanent magnet (240).

[0058] Additionally, the spacing between the slits (210) in the rotor (200) can be determined based on the total eddy current loss of the rotor (200) by comparing the eddy current loss of the back yoke of the rotor (200) with the eddy current loss of the permanent magnet (240).

[0059] According to one embodiment, as the number of slits (210) increases and the thickness is formed thicker, the effect of increasing output through increased resistance can be secured, and as the number of slits (210) decreases and the thickness is formed thinner, mechanical stability can be secured. In addition, a difference in the amount of eddy current loss occurs depending on the spacing between the slits (210).

[0060] Accordingly, the number, shape, and spacing of the slits (210) can be determined according to the purpose of use based on experimental data regarding the application of the slits (210) to the rotor (200).

[0062] Meanwhile, the rotor (200) can be made of carbon steel.

[0063] This carbon steel material can be made of S45C, and due to the characteristics of the carbon steel, it can function as a magnetic flux path as a soft magnetic material, offers high processability, and reduces costs.

[0064] In addition, when the rotor (200) is made of carbon steel, if the carbon steel material is formed into a laminated structure, the laminated surface is insulated, thereby increasing the path of eddy currents and reducing losses due to perfect currents.

[0066] As described above, the rotor (200) according to the present invention can achieve the effect of reducing eddy current loss through the application of a slit (210).

[0067] That is, as shown in FIG. 6, when comparing the basic model without a slit and the model with the slit (210) applied, it can be seen that in the case of the model with the slit (210) applied, the current density vector has increased in some sections, which means that the cross-sectional area of ​​the space where current can flow has decreased, and thus the eddy current has been reduced.

[0068] Additionally, as shown in FIG. 7, compared to the basic model without a slit, the eddy current loss of the permanent magnet (240) increased in the model with the slit (210), but as the proportion of the back yoke in the total eddy current loss of the rotor (200) increased, it can be seen that the overall eddy current loss decreased.

[0070] An electric motor with a structure as described above has multiple slits formed in the rotor, and as the eddy current resistance increases relative to the area, eddy current losses are reduced, thereby improving motor efficiency.

[0072] Although the present invention has been illustrated and described in relation to specific embodiments, it will be obvious to those skilled in the art that the present invention can be modified and changed in various ways without departing from the technical spirit of the invention as provided by the following claims. Explanation of the symbols

[0074] 100: Stator 110: Stator core 120:Coil 200: Rotor 210:Slit 220: Shaft 230: Rotor core 240: Permanent magnet

Claims

Claim 1 An electric motor comprising: a stator; and a rotor disposed facing the stator, made of carbon steel, and having a plurality of slits arranged radially spaced apart along the circumferential direction; wherein the plurality of slits arranged radially are formed such that the extension length of the slits gradually increases as they extend outward, and one end of each slit is aligned in a straight line while the other end is arranged diagonally, and the number, shape, and spacing of the slits in the rotor are determined based on the total eddy current loss of the rotor derived by comparing the eddy current loss generated in the back yoke of the rotor with the eddy current loss generated in the permanent magnet. Claim 2 An electric motor according to claim 1, characterized in that permanent magnets are arranged along the circumference of the rotor, and the permanent magnets are AFPM (Axial Flux Permanent Magnet). Claim 3 delete Claim 4 An electric motor according to claim 1, characterized in that the rotor is formed such that each slit extends along the circumferential direction with respect to the axis center. Claim 5 An electric motor according to claim 1, wherein the rotor is characterized by having a plurality of slits spaced apart at regular intervals along the circumferential direction. Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 delete Claim 10 delete

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