Switched reluctance motor including permanent magnets

Abstract

The present disclosure relates to a switched reluctance motor including permanent magnets, and more specifically, a permanent magnet [Stator-PM] and coil windings are arranged on a stator, the coil windings are arranged as alternating tooth windings, and the magnetic flux of the coil windings and the magnetic flux of the permanent magnets are in opposite directions. A magnetic flux path guide for the permanent magnets is added, and when no current flows in the coil windings, the magnetic flux of the permanent magnets hardly flows through the air gap and rotor, and circulates only inside the stator, suppressing cogging torque. When current is applied to the coil windings, the induced magnetic flux (N pole) generated by the applied current and the magnetic flux of the permanent magnets (N pole) act as a repulsive force between the same poles, concentrating the magnetic field in the air gap. The magnetic flux generated by the permanent magnets in the air gap and the magnetic flux generated by the windings are added, increasing the electromagnetic force, improving electromagnetic torque and efficiency. Even though a permanent magnet is included, induced voltage and cogging torque are suppressed. The paper focuses on a switched reluctance motor that includes multiple permanent magnet modules and can suppress the external torque.

Description

[Technical Field]

[0001] The present disclosure relates to a switched reluctance motor including a permanent magnet, and more particularly to a switched reluctance motor using a permanent magnet in which the generation of cogging torque is prevented while the torque and efficiency of the motor are improved by adjusting the magnetic flux path formed by the permanent magnet using a magnetic flux path guide. [Background technology]

[0002] A switched reluctance motor (SRM) is a type of electric motor that operates on the principle of reluctance torque. It consists of a rotor with salient poles and a stator with concentrated windings, and is characterized by the absence of brushes or commutators involved in the motor's operation. SRMs operate on the principle that the magnetic circuit is always formed in the direction that minimizes reluctance. When current is applied to the stator coil, magnetic flux is generated in the salient poles of the stator, causing the salient poles of the rotor to face the salient poles of the stator, generating torque that rotates the rotor. The direction of this torque varies depending on the current applied to the motor and the rotor position. Switched reluctance motors have the advantages of a simple structure, the ability to withstand high speeds, and low rotor loss, but there are limitations to increasing power density, and noise and vibration caused by torque ripple can make them difficult to use.

[0003] Cogging torque refers to the torque generated in an electric motor when the salient poles of the stator do not face each other while the rotor is stationary. This torque is generated by the interaction between the salient poles of the rotor and the stator, and can cause vibration and noise in the electric motor. In conventional permanent magnet motors, methods have been used to minimize problems caused by cogging torque, such as optimizing the design of the rotor and stator salient poles and controlling the current waveform applied to the stator windings. However, these methods have many problems, such as significantly increasing manufacturing costs and not being able to completely eliminate cogging torque.

[0004] Therefore, there is a need in the industry for a switched reluctance motor that is based on a cost-effective design and completely eliminates cogging torque. Patent Document 1 discloses a vacuum motor equipped with a time difference generator that utilizes bipolar balancing motion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Korean Patent No. 1604637 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to provide a switched reluctance motor that prevents the generation of cogging torque. For example, an object of the present disclosure is to provide a switched reluctance motor that includes a plurality of permanent magnet modules coupled to a stator, and that prevents the generation of cogging torque by adjusting the magnetic flux path formed by the permanent magnets.

[0007] However, the technical problems that this disclosure aims to solve are not limited to the above-mentioned technical problems, and may include a variety of technical problems within the scope that is obvious to an ordinary engineer based on the content described below. [Means for solving the problem]

[0008] To achieve the above object, according to one embodiment of the present disclosure, a switched reluctance motor is disclosed, which includes a stator including a plurality of excitation modules, and a rotor that rotates about a rotation axis by magnetic interaction with the stator, and the excitation modules may have one or more permanent magnet modules that suppress cogging torque of the motor.

[0009] In one embodiment of the present disclosure, the rotor is capable of rotating about the rotation axis within the stator. In one embodiment of the present disclosure, the permanent magnet (Stator-PM) module is located at the center of a coil wound around the excitation module and may include one or more permanent magnets and one or more magnetic flux path guides coupled to the permanent magnets.

[0010] In one embodiment of the present disclosure, the permanent magnet modules may be arranged at regular intervals along the circumferential direction of the stator. In one embodiment of the present disclosure, the excitation module may include a plurality of first salient poles arranged along the circumferential direction of the stator; one or more first slots located between the plurality of first salient poles; and a coil wound around the plurality of first salient poles.

[0011] In one embodiment of the present disclosure, the spacing between the excitation modules may be the same as the width of the first salient pole, and the width of the first slot may be less than or equal to twice the width of the first salient pole. In one embodiment of the present disclosure, the rotor has a plurality of second salient poles, and the width of the second salient poles can be equal to or greater than the width of the first salient poles.

[0012] In one embodiment of the present disclosure, the current applied to the coil may be in a direction such that the direction of the magnetic field induced by the current reinforces the magnetic field around the coil generated by the permanent magnet module. In one embodiment of the present disclosure, the stator may further include a flux barrier between the plurality of excitation modules.

[0013] In one embodiment of the present disclosure, the rotor is capable of rotating around the rotation axis outside the stator. In one embodiment of the present disclosure, the stator includes a plurality of stator modules that are out of phase with each other, and the plurality of stator modules can be located on the same rotation axis.

[0014] To achieve the above object, an electric motor structure is disclosed according to one embodiment of the present disclosure, which includes a stator including a plurality of excitation modules, and a rotor that rotates about a rotation axis by magnetic interaction with the stator, and the excitation modules may include one or more permanent magnet modules that suppress cogging torque of the electric motor. [Effects of the Invention]

[0015] The present disclosure makes it possible to provide a switched reluctance motor that prevents the generation of cogging torque. For example, the present disclosure makes it possible to provide a switched reluctance motor that includes a plurality of permanent magnet modules coupled to a stator, and in which the stator permanent magnet (Stator-PM) forms magnetic flux of the permanent magnet only inside the stator due to a magnetic flux path guide, thereby preventing the generation of cogging torque and achieving high torque and power density.

[0016] In addition, the switched reluctance motor of the present disclosure has coil windings and permanent magnets (Stator-PM) arranged on the stator, the coil windings are arranged as alternating tooth windings, and a magnetic flux path guide for the permanent magnets is added, so there is no generated voltage, energy consumption during field-weakening control of the motor is low, and the risk of demagnetization due to external magnetic fields is reduced. Furthermore, compared to conventional methods, the switched reluctance motor of the present disclosure has no bearing current, and while conventional rotor permanent magnets (Rotor-PM) are difficult to disassemble, assemble, and replace bearings due to the strong attractive force that acts between the magnetic field created by the permanent magnet and the stator core (ferromagnetic material), the stator permanent magnets (Stator-PM) of the present disclosure do not act on the magnetic field, making disassembly, assembly, and bearing replacement easy.

[0017] On the other hand, the effects of the present disclosure are not limited to the effects described above, and can include a variety of effects within a range that is obvious to a person of ordinary skill in the art from the content described below. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a three-dimensional view of a switched reluctance motor according to one embodiment of the present disclosure. [Figure 2] FIG. 1 is a three-dimensional diagram illustrating a rotor and a stator included in a switched reluctance motor according to one embodiment of the present disclosure. [Figure 3] 3a and 3b are plan views showing a switched reluctance motor and an excitation module of the switched reluctance motor, respectively, according to an embodiment of the present disclosure. [Figure 4] FIG. 1 is a plan view illustrating a switched reluctance motor and coils according to one embodiment of the present disclosure. [Figure 5] FIG. 2 is a plan view illustrating the direction of current applied to a switched reluctance motor and an electric motor according to one embodiment of the present disclosure. [Figure 6]FIG. 2 is a plan view illustrating the magnetic field generated by the excitation module and magnets of a switched reluctance motor when no current is applied to the excitation module, according to one embodiment of the present disclosure. [Figure 7] FIG. 2 is a plan view illustrating the magnetic field formed by the rotor, excitation module, and magnets of a switched reluctance motor when current is applied to the excitation module, according to one embodiment of the present disclosure. [Figure 8] FIG. 2 is a plan view illustrating the magnetic field formed by the rotor, excitation module, and magnets of a switched reluctance motor when current is applied to the excitation module, according to one embodiment of the present disclosure. [Figure 9] FIG. 2 is a plan view illustrating the magnetic field formed across a switched reluctance motor when current is applied to an excitation module, according to one embodiment of the present disclosure. [Figure 10] FIG. 1 is a three-dimensional view of a switched reluctance motor in which the rotor is located outside the stator, according to one embodiment of the present disclosure. [Figure 11] FIG. 1 is a three-dimensional diagram illustrating a rotor and a stator included in a switched reluctance motor in which the rotor is located external to the stator, according to one embodiment of the present disclosure. [Figure 12] FIG. 2 is a plan view illustrating the magnetic field formed across a switched reluctance motor in which the rotor is located outside the stator when current is applied to the excitation module, according to one embodiment of the present disclosure. [Figure 13] FIG. 1 is a three-dimensional view of a switched reluctance motor configured with multiple stators, according to one embodiment of the present disclosure. [Figure 14] 1 is a three-dimensional diagram illustrating a rotor and a stator included in a switched reluctance motor configured with multiple stators according to one embodiment of the present disclosure. FIG. [Figure 15] FIG. 1B is a plan view illustrating the magnetic field formed across the switched reluctance motor when current is applied to the switched reluctance motor and excitation module, when the permanent magnet module includes two permanent magnets, according to one embodiment of the present disclosure. [Figure 16] FIG. 1C is a plan view illustrating the magnetic field formed across the switched reluctance motor when current is applied to the switched reluctance motor and excitation module, where the permanent magnet module includes four permanent magnets, according to one embodiment of the present disclosure. [Figure 17] FIG. 1 is a plan view illustrating a switched reluctance motor in which the rotor is located outside the stator and the magnetic field formed throughout the switched reluctance motor when current is applied to the excitation module, when the permanent magnet module includes two permanent magnets, according to one embodiment of the present disclosure. [Figure 18] FIG. 1 is a plan view illustrating a switched reluctance motor in which the rotor is located outside the stator and the magnetic field formed throughout the switched reluctance motor when current is applied to the excitation module, when the permanent magnet module includes four permanent magnets, according to one embodiment of the present disclosure. [Figure 19] FIG. 1 is a circuit diagram illustrating an example of an asymmetric half-bridge converter for controlling a switched reluctance motor, in accordance with an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, a "switched reluctance motor including a permanent magnet" based on the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments described herein are provided to enable those skilled in the art to easily understand the technical concept of the present disclosure, and the present disclosure is not limited to these embodiments. Furthermore, the matters shown in the accompanying drawings are schematic drawings for the purpose of easily explaining the embodiments of the present disclosure, and may differ from the actual embodied form.

[0020] However, the components shown below are merely examples for realizing the present disclosure, and therefore, in other embodiments of the present disclosure, other components can be used without departing from the spirit and scope of the present disclosure.

[0021] Furthermore, expressions such as "having," "including," or "including" a particular element, or "including" a particular element, are open-ended expressions and merely indicate the presence of the element in question, and should not be construed as excluding the presence or addition of other elements.

[0022] A switched reluctance motor according to the present disclosure may include a stator including a plurality of excitation modules, a rotor that rotates about a rotation axis by magnetic interaction with the stator, and a plurality of permanent magnet modules coupled to the stator. The plurality of permanent magnet modules coupled to the stator may include permanent magnets and one or more magnetic flux path guides coupled to the permanent magnets. The permanent magnet module may be located at the center of a coil wound around the switched reluctance motor.

[0023] When the rotor has a permanent magnet, a rotor-PM motor generates cogging torque due to the attractive force between the magnetic field created by the permanent magnet and the stator core (ferromagnetic material).

[0024] In a switched reluctance motor according to the present disclosure, a permanent magnet (Stator-PM) is placed at the center of the coil, the coil windings are alternate-tooth windings, and the magnetic flux generated by the coil windings is arranged to reinforce the magnetic flux generated by the permanent magnet. A magnetic flux path guide for the permanent magnet is added, making it possible to individually control the magnetic field generated by the permanent magnet and the magnetic field generated by the coil wound around the stator of the motor. As a result, when no current flows through the coil windings, almost no magnetic flux from the permanent magnet is generated in the air gap or rotor, and is generated only inside the stator, thereby suppressing cogging torque. On the other hand, when current is applied to the coil windings, the magnetic flux generated by the applied current and the magnetic flux from the permanent magnet are added together, increasing the electromagnetic force, improving electromagnetic torque and efficiency, and resulting in the effect of not generating induced voltage or cogging torque despite the presence of the permanent magnet.

[0025] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings using Figures 1 to 14. Various descriptions are provided herein to facilitate understanding of the present disclosure. However, it is apparent that the embodiments can be implemented without such specific descriptions. Additionally, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless otherwise specified or clear from the context, "X utilizes A or B" shall mean one of the natural inclusive permutations. That is, if X utilizes A; X utilizes B; or X utilizes both A and B, then "X utilizes A or B" can apply to any of these. Additionally, the term "and / or" as used herein should be understood to refer to and include all possible combinations of one or more of the associated listed items.

[0026] Additionally, the predicate "comprises" and / or the modifier "comprises" should be understood to mean that the feature and / or component in question is present. However, the predicate "comprises" and / or the modifier "comprises" should be understood not to exclude the presence or addition of one or more other further features, components and / or groups thereof. Additionally, unless a specific number is specified or the context is clear that a singular form is indicated, the singular form in this specification and claims should generally be construed to mean "one or more."

[0027] Furthermore, the term "at least one of A or B" should be interpreted as meaning "when only A is included," "when only B is included," or "when a combination of A and B is included."

[0028] The description of the embodiments set forth herein is provided to enable one of ordinary skill in the art to make and practice the invention. Various modifications to these embodiments will be apparent to those of ordinary skill in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the present disclosure. Thus, the present disclosure is not intended to be limited by the embodiments set forth herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0029] FIG. 1 is a three-dimensional diagram of a switched reluctance motor according to one embodiment of the present disclosure.

[0030] The switched reluctance motor of the present disclosure may include a stator 100 and a rotor 300. The rotor 300 may be located inside the stator 100, share the same rotation axis as the stator 100, and rotate about the rotation axis by magnetic interaction with the stator.

[0031] Although not shown in Figure 1, for operation of a switched reluctance motor, a current-carrying winding can be coupled to the stator 100. In the present disclosure, the coils can be wound in an alternate teeth wound manner, but other winding methods that produce a similar effect can be used without limitation.

[0032] The stator 100 may include multiple permanent magnet modules 110. The permanent magnet modules 110 are coupled to the stator and can adjust the magnetic field generated by the permanent magnets in accordance with the current applied to the stator coils. The permanent magnet modules 110 may include a magnetic flux path guide that connects the south and north poles of the permanent magnets. The magnetic flux path guide of the permanent magnets can concentrate the magnetic field generated by the permanent magnets only in the area surrounding the permanent magnets, using the same principle as the iron core included in an electric motor.

[0033] The permanent magnet module of the present disclosure can be located at the center of the coil wound around the electric motor, where the center of the coil can refer to the coordinates on a line perpendicular to the plane formed by the coil wound around the electric motor.

[0034] By adding permanent magnet modules and magnetic flux path guides to the electric motor of the present disclosure, it is possible to suppress the induced voltage or cogging torque of the electric motor, increase the power density, and improve the efficiency of the electric motor.

[0035] FIG. 2 is a three-dimensional diagram illustrating a rotor and a stator included in a switched reluctance motor according to one embodiment of the present disclosure.

[0036] The rotor (300) may be separate from the stator (100), and the rotor (300) and stator (100) may include multiple salient poles (teeth) for magnetic interaction.

[0037] FIG. 3a is a top view illustrating a switched reluctance motor according to one embodiment of the present disclosure.

[0038] The switched reluctance motor of the present disclosure may include a stator 100 and a rotor 300. The stator 100 may include an excitation module 140, which is a unit having one or more permanent magnet modules 110, and the stator may be composed of multiple excitation modules 140 having the same shape. The excitation modules may be arranged in a symmetrical structure around the rotation axis of the stator.

[0039] Flux barriers (not shown) may be disposed between the excitation modules 140 constituting the stator 100. The flux barriers (not shown) may serve to block mutual interference caused by the magnetic fields generated by the excitation modules.

[0040] Each excitation module may include a plurality of first salient poles arranged along the circumferential direction of the stator 100 and one or more first slots located between the first salient poles. The spacing between the excitation modules may be the same as the width of the first salient poles, and the width of the first slots may be equal to or less than twice the width of the first salient poles.

[0041] In the present disclosure, the rotor may have a plurality of second salient poles, and the width of the plurality of second salient poles of the rotor may be equal to or greater than the width of the first salient pole.

[0042] In the embodiment shown in Figure 3a, the stator (100) may include six excitation modules, and each excitation module (140) may include one permanent magnet module (110) and four salient poles. In the present disclosure, the number of salient poles of the stator (100) can be calculated as follows:

[0043]

number

[0044] In this case, S_teeth is the number of salient poles included in the stator, M_p is the number of salient poles present in one excitation module, P is the number of phases composed of excitation modules having a mutually symmetrical structure, and n can mean an integer.

[0045] Also, in the present disclosure, the angle of the salient poles in the stator can be calculated as shown in Equation 2.

[0046]

number

[0047] In this case, S_pa is the angle between the salient poles included in the stator, where P is the number of phases composed of excitation modules having a mutually symmetrical structure, n is an integer, and d is a predetermined constant.

[0048] In addition, in the present disclosure, the number of salient poles that the rotor has can be calculated as shown in Equation 3.

[0049]

number

[0050] In this case, R_p can mean the number of salient poles included in the rotor, Spa the angle of the salient poles in the stator, and R_pd an integer (for example, 3).

[0051] For example, in the embodiment shown in FIG. 2, the stator (100) may be configured with six excitation modules and have 24 salient poles, in which case the rotor (300) may have 22 salient poles.

[0052] FIG. 3b is a top view illustrating an excitation module of a switched reluctance motor according to one embodiment of the present disclosure.

[0053] As described above, the switched reluctance motor of the present disclosure may include a plurality of excitation modules 140, and each excitation module 140 may include a permanent magnet module and a plurality of salient poles 141. The salient poles 141 included in the excitation module 140 may contribute to rotating the rotor by magnetically interacting with the salient poles of the rotor.

[0054] The permanent magnet module (110) of the present disclosure is located at the center of the coil (130) wound around the excitation module (140) of the electric motor, and can include one or more permanent magnets and one or more magnetic flux path guides coupled to the permanent magnets. As shown in Fig. 4 described below, in the present disclosure, the coil (130) is wound across multiple first salient poles included in the excitation module (140), i.e., included in the stator, so that the permanent magnet module (110) can be located between adjacent first salient poles. One or more permanent magnets included in the permanent magnet module (110) may be magnetized from south to north and may be arranged within the motor with the south to north magnetization direction perpendicular to the circumferential direction. An example of a permanent magnet with a south to north magnetization direction perpendicular to the circumferential direction is shown in Figure 3b.

[0055] As an alternative to the above description, multiple permanent magnets may be arranged inside the permanent magnet module 110 so that the direction of magnetization from south pole to north pole coincides with the circumferential direction. In this case, the permanent magnets may be arranged so that the same poles face each other. In other words, if one permanent magnet module 110 includes two permanent magnets, the permanent magnets may be arranged symmetrically, with the north pole of the left permanent magnet facing outward from the permanent magnet module, and the north pole of the right permanent magnet facing outward from the permanent magnet module.

[0056] The magnetic flux path guide included in the permanent magnet module 110 can be a conductor that connects a portion of the permanent magnet included in the permanent magnet module 110 that is close to the south pole and a portion of the permanent magnet included in the permanent magnet module 110 that is close to the north pole. As a result, in the present disclosure, the magnetic flux path guide included in the permanent magnet module can concentrate the magnetic field generated by the permanent magnet included in the permanent magnet module inside the magnetic flux path guide while suppressing the magnetic field generated outside the permanent magnet module when no current is applied to the motor.

[0057] FIG. 4 is a plan view illustrating a switched reluctance motor and coils according to one embodiment of the present disclosure.

[0058] The switched reluctance motor of the present disclosure includes a stator 100, and coils 130 to which current is applied can be wound around some salient poles of the stator. In accordance with the basic principles of electric motors, the coils 130 form a magnetic field around the rotor, and can contribute to the rotation of the rotor through magnetic interaction with the rotor.

[0059] In the present disclosure, the coil 130 wound in the switched reluctance motor may be in the form of alternate teeth winding, distributed winding, or single layer winding. However, it will be obvious to those skilled in the art that the coil can be wound in other well-known ways through simple design changes, and the coil form of the present disclosure is not limited to the exemplary winding ways described above.

[0060] In one embodiment of the present disclosure, the permanent magnet module 110 can be positioned in the center of the coil 130. In this case, the coil 130 can be wound around the permanent magnet module 110.

[0061] FIG. 5 is a plan view illustrating a switched reluctance motor and the direction of current applied to the motor according to one embodiment of the present disclosure.

[0062] In the present disclosure, a current can be applied to a coil wound around the stator (100). If the current (310) applied to the coil flows out of the plane, it can be designated as "O." If the current (320) applied to the coil flows into the plane, it can be designated as "X." According to Ampere's law, when a current flows through a wound coil, a magnetic field is formed around the coil, and the direction of the magnetic field is in the form of concentric circles in a plane perpendicular to the current. The direction of the magnetic field is also the same as when a screw is turned clockwise.

[0063] When the coil (130) is wound around the stator (100) as shown in FIG. 4, the current flowing through the stator (100) and around the stator can be shown as in FIG.

[0064] FIG. 6 is a top view illustrating the magnetic field generated by the excitation module and magnets of a switched reluctance motor when no current is applied to the excitation module (140), according to one embodiment of the present disclosure.

[0065] When no current is applied to the excitation module (140), no current flows through the coils wound around the excitation module (140). Therefore, the magnetic field generated by the currents (310 and 320) flowing through the coils also disappears. In this case, the only element generating a magnetic field in the entire switched reluctance motor is the permanent magnet module (110) included in the excitation module (140). The permanent magnet module (110) can be positioned so that its north pole faces the center of the stator (100) and its south pole faces the outside of the stator (100). In this case, the magnetic field (400) generated by the permanent magnet is concentrated and distributed around the permanent magnet by the magnetic flux path guide of the permanent magnet included in the permanent magnet module (110), and is generated only inside the stator (100). Therefore, the rotor (300) away from the permanent magnet module (110) is not affected by the magnetic field of the permanent magnet included in the permanent magnet module (110).

[0066] As described above, when no current is applied to the excitation module 140, the rotor 300 rotates or stops due to inertia, and no cogging torque is generated by an external magnetic field. In conventional motors including permanent magnets, the magnetic field generated by the permanent magnets constantly affects the rotor, resulting in a period during rotor operation when cogging torque, which is a torque in the opposite direction to the rotor's motion, is generated. By adopting a permanent magnet module 110 including a permanent magnet magnetic flux path guide as disclosed herein, the magnetic field affecting the rotor can be minimized, thereby eliminating the generation of cogging torque.

[0067] FIG. 7 is a plan view illustrating the magnetic field generated by the rotor, excitation module, and magnets of a switched reluctance motor when current is applied to the excitation module, according to one embodiment of the present disclosure. When a current is applied to the excitation module, i.e., when a current is applied to the coil included in the excitation module, the direction of the magnetic field induced by the current applied to the coil can be the same as the magnetic field around the coil generated by the permanent magnet module 110. Hereinafter, the interaction between the magnetic field generated by the current applied to the coil and the magnetic field generated by the permanent magnet module 110 will be described with reference to FIG. 7.

[0068] When a current is applied to the excitation module, a current (310) is generated in a direction into the plane and a current (320) is generated in a direction out of the plane. A clockwise magnetic field is generated around the current (310) that enters the plane, and a counterclockwise magnetic field is generated around the current (320) that exits the plane. As shown in Figure 7, when the north pole of the permanent magnet module (110) faces the center of the stator (100) and the south pole faces the outside of the stator (100), the magnetic field (410) emanating from the north pole of the permanent magnet module (110) does not directly enter the south pole along the magnetic flux path guide, but interacts with the magnetic field (420) generated by the current. The magnetic field (410) emanating from the permanent magnet interacts with the magnetic field (420) generated by the current, is guided from the salient pole of the stator (100) through the air gap and the salient pole of the rotor (300), then circulates around the magnetic field (420) generated by the current, and finally enters the south pole. Furthermore, when a current is applied to an excitation module, the magnetic field generated by the permanent magnet and the current does not interfere with other excitation modules due to the air gap between the excitation modules that make up the motor.

[0069] A switched reluctance motor operates based on the principle that torque is generated in the direction that minimizes the inductance of the magnetic circuit. In the case of the present disclosure, when current is applied to a switched reluctance motor, torque is generated in the direction that the salient poles of the stator (100) and rotor (300) face each other.

[0070] In this case, the magnetic field (410) formed by the permanent magnet module and the magnetic field (420) generated by the current at each location are concentrated in the air gap area due to the repulsive force between the same poles, and the magnetic field in the area of ​​the salient pole of the stator (100) is concentrated in the air gap area, and the magnetic flux generated by the permanent magnet and the magnetic flux generated by the winding are added in the air gap, increasing the magnetic field strength. The magnitude of the torque generated in the rotor is proportional to the strength of the magnetic field that the rotor is affected by, so the effect of increasing the torque of the electric motor is obtained.

[0071] Referring to FIG. 6, the switched reluctance motor of the present disclosure can be controlled and operated by a circuit such as an asymmetric half bridge. Specifically, when the salient poles of the stator and the salient poles of the rotor do not match, torque can be applied in the direction in which the salient poles match, i.e., in the direction of rotation, by applying current to the coils. When the salient poles of the stator and the salient poles of the rotor match, no current can be applied to the coils, minimizing the magnetic field affecting the rotor and allowing the rotor to rotate due to inertia. In this case, it is possible to reduce the change in the magnetic field, i.e., to prevent the generation of cogging torque, which normally occurs when the salient poles of the stator and the salient poles of the rotor match. This results in the motor operating more efficiently without being affected by cogging torque.

[0072] FIG. 8 is a plan view illustrating the magnetic field generated by the rotor, excitation module, and magnets of a switched reluctance motor when current is applied to the excitation module, according to one embodiment of the present disclosure.

[0073] According to one embodiment of the present disclosure, in a switched reluctance motor, the permanent magnet module (110) may be implemented with its north pole facing the outside of the stator (100) and its south pole facing the inside of the stator (100). In this case, the direction of the current applied to the coil wound around the stator (100) may be opposite to that of the embodiment shown in Figure 7, and at each point in the motor, the magnetic field (420) generated by the current may be oriented to reinforce the magnetic field (410) generated by the permanent magnet. Specifically, the magnetic field (410) generated by the permanent magnet starts from the north pole, spreads outside the stator, is guided toward the rotor along the magnetic field (420) generated by the current, passes through the rotor and the salient poles of the stator, and then returns to the south pole of the permanent magnet.

[0074] Using the same principle, when implemented as described above, the motor can be operated while eliminating the effects of cogging torque, resulting in increased power density, torque, and efficiency of the motor.

[0075] FIG. 9 is a plan view illustrating the magnetic field formed across a switched reluctance motor when current is applied to the excitation module, according to one embodiment of the present disclosure.

[0076] In one embodiment of the present disclosure, a switched reluctance motor can be controlled by applying current only to the coils wound around some of the excitation modules. For example, at a specific time when the switched reluctance motor is operated, current can be applied only to the coils of the excitation modules of the stator (100) whose salient poles face the salient poles of the rotor (300) or whose salient poles are close to the salient poles of the rotor (300). That is, in the case of FIG. 9 , current can be applied only to the coils of the excitation modules located at the 12 o'clock and 6 o'clock positions. In this case, the magnetic fields generated by the permanent magnet modules and the magnetic fields generated by the currents in the 12 o'clock and 6 o'clock positions generate torque in the rotational direction on the rotor. In the excitation modules located in other positions, the rotor is not affected by the magnetic fields due to the magnetic flux path guide of the permanent magnets. Therefore, the switched reluctance motor can be controlled so that torque in the rotational direction is generated on the rotor while cogging torque is not generated in the remaining excitation modules.

[0077] In one embodiment of the present disclosure, a switched reluctance motor can be implemented in a manner in which the permanent magnet modules (110 and 120) included in the multiple excitation modules that make up the stator are arranged alternately. For example, among the multiple excitation modules that make up the stator, the permanent magnet module included in the excitation module at the 12 o'clock position can be arranged so that its north pole faces the inside of the stator and its south pole faces the outside of the stator, and the permanent magnet module included in the excitation module adjacent to the excitation module at the 12 o'clock position can be arranged so that its north pole faces the outside of the stator and its south pole faces the inside of the stator. Figure 9 shows the magnetic fields when current is applied to the coils and when current is not applied when the orientation of the permanent magnet modules is arranged alternately.

[0078] In this embodiment, as in the above-described embodiment, when current is applied, the magnetic field generated by the current and the magnetic field generated by the permanent magnet are oriented in directions that reinforce each other, and the induced magnetic field generated by the current and the magnetic field of the permanent magnet concentrate in the gap due to the repulsive force between the same poles, and the magnetic field generated by the permanent magnet and the magnetic field generated by the current are added together in the gap, resulting in an increase in the magnitude of the torque.

[0079] FIG. 10 is a three-dimensional diagram of a switched reluctance motor in which the rotor is located outside the stator, according to one embodiment of the present disclosure.

[0080] In one embodiment of the present disclosure, the switched reluctance motor can be implemented with the rotor (300) located outside the stator (100).

[0081] In this case, the rotor and stator can be arranged in a manner that shares the same rotation axis. A magnetic field is generated by the permanent magnet module 120 included in the stator 100 and current applied to the coils wound around the stator 100, and torque in the rotational direction is generated in the rotor 300 due to the influence of the magnetic field. The schematic configuration of each component when the rotor 300 and stator 100 are separated is shown in Figure 11. FIG. 12 is a plan view illustrating the magnetic field generated across a switched reluctance motor in which the rotor is external to the stator when current is applied to the excitation module, according to one embodiment of the present disclosure.

[0082] As in the embodiment in which the rotor (300) is located inside the stator (100), when a current is applied, the magnetic field lines coming out from the north pole of the permanent magnet module included in the excitation module of the stator (100) are formed so that, due to the induced magnetic field generated by the applied current, a repulsive force acts between the magnetic field of the permanent magnet and the same pole, causing the magnetic field to concentrate in the air gap area, circumnavigate the rotor pole, and re-enter the south pole again; when no current is applied, they are formed so that they follow the magnetic flux path guide of the permanent magnet and enter directly into the south pole inside the stator.

[0083] FIG. 13 is a three-dimensional diagram of a switched reluctance motor configured with multiple stators, according to one embodiment of the present disclosure.

[0084] The switched reluctance motor of the present disclosure may be configured to include multiple stators and one rotor, rather than including only one stator and one rotor. For example, the switched reluctance motor of the present disclosure may be embodied to include a first stator (100), a second stator (200), and a rotor (300). In this case, the switched reluctance motor may be controlled so that different currents are applied to each stator, and the currents applied to each stator may be controlled so that the torques applied to the rotor are in the same direction.

[0085] Each stator may include a different number of excitation modules, the excitation modules may include permanent magnet modules arranged in different ways, and the coils may be wound in different ways.

[0086] As shown in Figure 13, when a switched reluctance motor is configured with multiple stators and rotors, the torque applied to the rotor is equivalent to the sum of the torques generated by each stator. Therefore, when a switched reluctance motor is configured to include multiple stators, the output of the motor can be increased. Figure 14 shows an example of the configuration of each component when the first stator (100), second stator (200), and rotor (300) are separated.

[0087] FIG. 15 is a plan view illustrating a switched reluctance motor and the magnetic field formed across the switched reluctance motor when current is applied to the excitation module, where the permanent magnet module includes two permanent magnets, according to one embodiment of the present disclosure.

[0088] The permanent magnet module (111) of the present disclosure may include two permanent magnets with the same pole on the opposing faces. As in the embodiment where the permanent magnet module includes only one permanent magnet, when a current is applied, the magnetic field lines emanating from the north pole of each permanent magnet constituting the permanent magnet module (111) are formed such that, due to the induced magnetic field generated by the applied current, the magnetic field of the permanent magnet acts on the same poles, concentrating in the air gap region, circling the rotor poles, and re-entering the south pole again; when no current is applied, the magnetic field lines are formed such that they follow the magnetic flux path guide of the permanent magnet module and enter the south pole directly inside the stator.

[0089] FIG. 16 is a plan view illustrating the magnetic field formed across a switched reluctance motor when current is applied to the switched reluctance motor and excitation module, where the permanent magnet module includes four permanent magnets, according to one embodiment of the present disclosure.

[0090] The permanent magnet module 112 of the present disclosure can include four permanent magnets with the same pole on opposite sides. As in the embodiment where the permanent magnet module includes only one permanent magnet, when a current is applied, the magnetic field lines emanating from the north pole of each permanent magnet constituting the permanent magnet module 112 are formed such that, due to the induced magnetic field generated by the applied current, the magnetic field of the permanent magnet acts on the same poles, concentrating the magnetic field in the air gap region, circling the rotor poles, and then re-entering the south pole. When no current is applied, the magnetic field of the permanent magnet is formed such that it follows the magnetic flux path guide and enters directly into the south pole inside the stator.

[0091] As described above, the permanent magnet module included in the switched reluctance motor of the present disclosure may be embodied in a form including not only one permanent magnet but also multiple permanent magnets, and the number of permanent magnets included in the permanent magnet module may vary depending on the size and design purpose of the motor.

[0092] FIG. 17 is a plan view illustrating a switched reluctance motor in which the rotor is located outside the stator and the magnetic field formed throughout the switched reluctance motor when current is applied to the excitation module, when the permanent magnet module includes two permanent magnets, according to one embodiment of the present disclosure.

[0093] As in the embodiment in which the rotor 300 is located inside the stator 100, the permanent magnet modules included in the excitation module of the stator 100 may each include two permanent magnets. When current is applied, the magnetic field of the permanent magnets is induced by a repulsive force between the same poles, concentrating the magnetic field in the air gap region, circling the rotor poles, and then re-entering the south pole. When no current is applied, the magnetic flux of the permanent magnets follows the magnetic flux path guide and enters the south pole directly inside the stator.

[0094] FIG. 18 is a plan view illustrating a switched reluctance motor in which the rotor is located outside the stator and the magnetic field formed throughout the switched reluctance motor when current is applied to the excitation module, when the permanent magnet module includes four permanent magnets, according to one embodiment of the present disclosure.

[0095] As in the embodiment in which the rotor 300 is located inside the stator 100, the permanent magnet modules included in the excitation module of the stator 100 may each include two permanent magnets. When current is applied, the magnetic field of the permanent magnets is induced by a repulsive force between the same poles, concentrating the magnetic field in the air gap region, circling the rotor poles, and then re-entering the south pole. When no current is applied, the magnetic field of the permanent magnets is formed along the magnetic flux path guide, directly entering the south pole inside the stator.

[0096] FIG. 19 is a circuit diagram illustrating an example of an asymmetric half-bridge converter for controlling a switched reluctance motor according to one embodiment of the present disclosure.

[0097] Asymmetric half-bridge converters can usually be composed of semiconductor switches (mainly MOSFETs or IGBTs), which can serve to control the flow of current and thus the operation of the converter.

[0098] In one embodiment of the present disclosure, the operation of an asymmetric half-bridge converter is broadly divided into three modes: excitation mode, freewheeling mode, and demagnetization mode. The soft chopping control method, in which only one switch operates, is more advantageous than hard chopping in terms of current ripple, filter capacitor capacity, noise, and efficiency, and also lowers the switching frequency. When a fixed applied voltage is used, the inductance increases, further reducing the switching frequency. It is possible to apply current to the coils of a switched reluctance motor only during a portion of the motor's operating time. During the period when current is applied to the coils, a magnetic field is generated around the coils. This magnetic field interacts with the magnetic field generated by the permanent magnet module of the present disclosure to apply torque to the rotor.

[0099] In the section where no current is applied, no magnetic field is generated around the coil due to the current, and the magnetic field generated by the permanent magnet module is formed only around the permanent magnet module due to the magnetic flux path guide of the permanent magnet. Therefore, the rotor is not affected by the magnetic field, and there is no cogging torque generated by the magnetic field during the operation of a normal switched reluctance motor.

[0100] The description of the embodiments set forth herein is provided to enable any person skilled in the art to use or practice the present disclosure. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments without departing from the scope of the present disclosure. Thus, the present disclosure is not intended to be limited by the embodiments set forth herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0101] As described above, the relevant contents of the best mode for carrying out the invention have been described.

Claims

1. a stator including a plurality of excitation modules; and a rotor that rotates about an axis of rotation due to magnetic interaction with the stator; Including, The excitation module includes: one or more permanent magnet modules that suppress the cogging torque of the electric motor; Including, Switched reluctance motor.

2. In claim 1, The rotor is Rotating around the rotation axis inside the stator, Switched reluctance motor.

3. In claim 1, The permanent magnet module is located at the center of a coil wound around the excitation module, one or more permanent magnets; and one or more magnetic flux path guides coupled with the permanent magnets; Including, Switched reluctance motor.

4. In claim 3, The one or more permanent magnet modules include: are arranged at regular intervals along the circumferential direction of the stator, Switched reluctance motor.

5. In claim 1, The excitation module includes: a plurality of first salient poles arranged along the circumferential direction of the stator; one or more first slots located between the plurality of first salient poles; and a coil wound around the plurality of first salient poles; Including, Switched reluctance motor.

6. In claim 5, the spacing between the excitation modules is equal to the width of the first salient pole; a width of the first slot is equal to or less than twice the width of the first salient pole; Switched reluctance motor.

7. In claim 5, the rotor has a plurality of second salient poles, The width of the second salient pole is equal to or greater than the width of the first salient pole. Switched reluctance motor.

8. In claim 5, the current applied to the coil is such that the direction of the magnetic field induced by the current reinforces the magnetic field around the coil, which is generated by the permanent magnet module; Switched reluctance motor.

9. In claim 1, The stator includes: a flux barrier between the excitation modules; further comprising: Switched reluctance motor.

10. In claim 1, The rotor is Rotating around the rotation axis outside the stator, Switched reluctance motor.

11. In claim 1, The stator includes: a plurality of stator modules out of phase; the plurality of stator modules are located on the same rotation axis; Switched reluctance motor.

12. a stator including a plurality of excitation modules; and a rotor that rotates about an axis of rotation due to magnetic interaction with the stator; Including, The excitation module includes: one or more permanent magnet modules that suppress the cogging torque of the electric motor; Including, Structure of an electric motor.

Images