POWER SUPPLY DEVICE FOR A FIELD-WINDING MOTOR AND FIELD-WINDING MOTOR INCLUDING THE SAME

Abstract

A power supply device for a field-wound motor, comprising: a brush (200) arranged in a holder (300); an armature (410) connected to the brush (200) and arranged in the holder (300); a slip ring (100) that is electrically connected to or electrically disconnected from the brush (200); a support spring (430) surrounding the brush (200) between the slip ring (100) and the armature (410); a coil (420) arranged outside the holder (300) so as to overlap the support spring (430) and the armature (410); a first power terminal (510) connected to the brush (200) and supplying a first drive current; a second power terminal (520) connected to the coil (420) and supplying a second drive current; anda dust removal part (310) formed in a side surface of the holder (300); .wherein, when the second drive current is applied to the coil (420), a first axial force is generated to move the armature (410) toward the slip ring (100), and the brush (200) and the slip ring (100) are electrically connected due to movement of the armature (410); wherein a second axial force is generated by the support spring (430) to move the armature (410) away from the slip ring (100), the first axial force is greater than the second axial force, and when the second drive current is applied, the brush (200) and the slip ring (100) are electrically connected.

Description

[0001] CROSS-REFERENCE TO A RELATED APPLICATION

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2016-0098523, filed on August 2, 2016, and Korean Patent Application No. 10-2016-0084290, filed on July 4, 2016, the disclosures of which are incorporated herein by reference in their entirety. BACKGROUND area

[0003] The present disclosure relates to a power supply device for a field winding motor and to a field winding motor including the same. Description

[0004] A hybrid vehicle or an electric vehicle, which is important as an environmentally friendly vehicle, is powered by an electric motor that obtains torque using electrical energy.

[0005] More specifically, a general electric vehicle runs by using the torque of an electric motor as energy. A general hybrid vehicle runs in an electric vehicle (EV) mode, where it uses only the torque of an electric motor as energy, or in a hybrid electric vehicle (HEV) mode, where it uses both the torque of an internal combustion engine and the torque of an electric motor as energy.

[0006] The development of a wound rotor synchronous motor (WRSM) as an electric motor used as a power source of such an environmentally friendly vehicle has been actively carried out to date.

[0007] In an existing WRSM, since current is supplied to a coil using a carbon brush and a slip ring, mechanical wear continuously occurs. As the length of the brush shortens due to mechanical wear, the pressure of a support spring pressing the brush may change, the contact resistance between the brush and the slip ring may increase, and the current supply may be unstable.

[0008] Furthermore, in the existing WRSM, since the brush is pressed into contact with the slip ring using the support spring, the brush and slip ring cannot be quickly separated in the event of a failure, and consequently, the power supply cannot be stopped. If the power supply is not stopped in the event of a failure, a fire may break out, and the power supply device and other components of an electric motor may be damaged.

[0009] Furthermore, the brush maintains mechanical contact with an outer peripheral surface of the slip ring to supply a current to a coil, and as a result, dust such as metal powder may be generated due to friction and abrasion of the brush.

[0010] If such dust accumulates in a cover that houses the brush, a connection may be created between different electrical polarities of the brush and the slip ring, causing failure of a power supply device.

[0011] In addition, since an electric motor used in a hybrid vehicle controlled in an EV mode and a HEF mode has a function of assisting driving performance, unlike a general electric motor, ensuring precise current control and regulation and durability are important considerations. State of the art document Patent Document 1: Korean Patent Application Publication No. KR 10 2004 0 023 063 A1 Patent Document 2: Korean Patent No. KR 10 0 357 995 B1

[0012] JP S54-173 207 U describes a brush pressing device for an electric motor or generator with brush commutation, wherein the contact force of the brush is controlled by a solenoid.

[0013] DE 16 38 374 A describes a motor whose brushes can be lifted by means of an electromagnet.

[0014] GB 556 501 A describes a device for controlling the power of a generator, wherein the motor brushes are pressed against the motor commutator with a predetermined force and the pressure of the brushes against the motor commutator is reduced when the generator power reaches a predetermined value.

[0015] DE 10 2009 020 915 A1 describes an alternating current generator having a rotor with a rotating shaft provided with a pair of collector rings and a pair of brushes.

[0016] DE 10 2004 061 896 A1 describes an electric motor with a brush holder which has guide areas for guiding a brush which can be displaced longitudinally.

[0017] JP S56- 52 472 U describes a brush holding device for an electric motor with an electric brush which is slidably held in a brush holding tube and is pressed against a commutator surface by a spring. BRIEF OVERVIEW

[0018] Various aspects of the present disclosure provide a power supply device for a field winding motor capable of preventing unstable power supply caused by abrasion of a brush and stopping power supply in case of failure, and a field winding motor incorporating the same.

[0019] Furthermore, various aspects of the present disclosure provide a power supply device for a field winding motor capable of discharging dust to the outside of a holder that houses a brush and a slip ring, preventing moisture and foreign matter from entering the holder from the outside, and controlling a position of the brush to reliably supply current to a coil, and a field winding motor including the same.

[0020] In accordance with the present invention, there is provided a power supply apparatus for a field wound motor having the features defined in independent claim 1.

[0021] Advantageous further training results from the dependent subclaims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view illustrating a field winding motor installed with a power supply device for a field winding motor in accordance with a first embodiment; Fig. 2 is a view illustrating a state in which a current is applied to a coil from the power supply device for the field winding motor according to the first embodiment; Fig. 3 is a view illustrating a state in which no current is supplied to the coil from the power supply device for the field winding motor shown in Fig. 2 is shown; Fig. 4 is a view illustrating a state in which a current is applied to a coil of a power supply device for a field winding motor according to a second embodiment; Fig. Fig. 5 is a view illustrating a state in which no current is supplied to the coil from the power supply device for the field winding motor shown in Fig. 4 is shown; Fig. 6 is a cross-sectional view illustrating a field winding motor installed with a power supply device for a field winding motor in accordance with a third embodiment; Fig. 7 is a view illustrating a state in which a current is applied to a coil from the power supply device for the field winding motor in accordance with the third embodiment; and Fig. Fig. 8 is a view illustrating a state in which no current is supplied to the coil from the power supply device for the field winding motor shown in Fig. 7 is shown. DETAILED DESCRIPTION

[0022] Reference will now be made in detail to the present disclosure, embodiments of which are illustrated in the accompanying drawings and described below, so that one of ordinary skill in the art to which the present disclosure belongs could easily put the present disclosure into practice. It should be understood that the present disclosure is not limited to the following embodiments, but various changes may be made to the forms. Throughout the drawings, the same reference numerals and symbols will be used to designate the same or similar components, and specific portions will be omitted for brevity.

[0023] It will further be understood that the terms "comprise", "include", "have", etc., used in the present patent specification specify the presence of mentioned features, integers, steps, operations, elements, components, and / or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0024] With reference to Fig. 1 to Fig. 3, a field winding motor 1 including a power supply device 50 for a field winding motor (hereinafter referred to as a power supply device) according to a first embodiment includes a motor housing 10, a rotor 20, a rotation shaft 30, and the power supply device 50.

[0025] In the following, descriptions assume that a direction from a brush 200 to a slip ring 100 is defined as a forward direction and that a direction from the slip ring 100 to the brush 200 is defined as a reverse direction when Fig. 1 is considered.

[0026] According to one embodiment, the rotor 20 is installed in the motor housing 10 to rotate on the rotating shaft 30. At this time, the power supply device 50 may be installed on an upper side of the motor housing 10.

[0027] Since the field-winding motor 1 includes the power supply device 50, the brush 200 and the slip ring 100 can be electrically connected by moving an armature 410 with a constant axial force in the forward direction even when the brush 200 is worn. Accordingly, the field-winding motor 1 can reliably supply a drive current to a coil of an electric motor regardless of the wear of the brush 200.

[0028] With reference to Fig. 1 and Fig. 2, the power supply device 50 according to the first embodiment includes a holder 300, the brush 200, a support spring 430, the slip ring 100, the armature 410, a coil 420, and a power generator 500. At this time, the power supply device 50 is a device for generating a magnetic flux in a rotor 20 by applying a current to the coil 420 wound around the rotor 20 through the brush 200, which closely contacts the slip ring 100.

[0029] On the other hand, according to one embodiment, a cavity (not shown) is formed in the holder 300 such that the brush 200, the support spring 430, and the armature 410 are installed therein. A coil 420 may be installed outside the holder 300.

[0030] Furthermore, the slip ring 100 is installed on the rotating shaft 30 of the field-wound motor 1, and includes a pair of slip rings, namely, a first slip ring 110 and a second slip ring 120, as a power transmission medium for applying a current to the coil wound around the rotor 20. The first slip ring 110 and the second slip ring 120 may be installed at one end of the rotating shaft 30, and more specifically, they may be tightly fixed to an outer peripheral surface of the rotating shaft 30 in a state where they are spaced apart from each other in a longitudinal direction of the rotating shaft 30.

[0031] At this time, the first slip ring 110 and the second slip ring 120 may be connected to a positive pole (+) and a negative pole (-) of the coil wound around the rotor 20, and they may be engaged and rotated according to the rotation of the rotary shaft 30.

[0032] The brush 200 is attached to the armature 410 and is moved toward the slip ring 100 or away from the slip ring 100 by movement of the armature 410. That is, the brush 200 and the armature 410 can be coupled together, and the brush 200 can be moved by the movement of the armature 410.

[0033] At this time, the brush 200 may include a pair of brushes, ie, a first brush 210 and a second brush 220. The first brush 210 and the second brush 220 may be arranged perpendicular to an extending direction of the rotating shaft 30 such that ends thereof contact outer peripheral surfaces of the first slip ring 110 and the second slip ring 120, respectively.

[0034] Furthermore, the brush 200 and the slip ring 100 may be spaced apart from each other by a certain distance d. By the solenoid 400, which will be described later, the brush 100 and the slip ring 200 may be brought into close contact with each other or separated from each other, and as a result, a current may be applied to the coil wound around the rotor 20 or an applied current may be removed.

[0035] On the other hand, the solenoid 400 includes the armature 410, the coil 420, and the support spring 430. At this time, the armature 410 may be installed at one end of the brush 200, specifically, at a rear end of the brush 200.

[0036] Furthermore, the coil 420 may be installed outside the holding device 300. The support spring 430 may be formed of a non-conductive material, may surround an external surface of the brush 100, and may be installed between the armature 410 and the slip ring 200.

[0037] More specifically, a support member 320 may protrude toward an inner side of the retainer 300 from an upper surface of the retainer 300. Both ends of the support spring 430 may be supported by a side surface of the armature 410 and the support member 320, respectively.

[0038] On the other hand, the power generator 500 includes a first power terminal 510 and a second power terminal 520. Each of the first power terminal 510 and the second power terminal 520 may include a positive (+) terminal and a negative (-) terminal.

[0039] At this time, the first power terminal 510 is connected to the brush 200 through the holder 300 and the armature 410 and supplies a direct current, i.e., a first drive current for driving an electric motor, to a coil of the electric motor. Furthermore, the second power terminal 520 supplies a direct current, i.e., a second drive current, to the coil 420.

[0040] Furthermore, in accordance with one embodiment, a first power supply unit (not shown) may be provided to supply the first drive current to the first power terminal 510. A second power supply unit (not shown) may be provided to supply the second drive current to the second power terminal 520.

[0041] The coil 420 may be wound outside the retaining device 300 so that it overlaps the support spring 430 and the armature 410. The second drive current may be supplied to the coil 420 to move the armature 410 toward the slip ring 100.

[0042] At this time, the armature 410 is moved in the forward direction, for example, toward the slip ring 100, by an electromagnetic force generated by the second drive current supplied to the coil 420. The brush 200 contacts the slip ring 100 due to the movement of the armature 410.

[0043] Specifically, since a first axial force is generated by the second drive current supplied to the coil 420 and the armature 410 is moved in the forward direction, the brush 200 and the slip ring 100 are electrically connected.

[0044] Since the brush 200 and the slip ring 100 contact each other, the first drive current supplied to the brush 200 is supplied to a coil of an electric motor through the slip ring 100. A north (N) pole and a south (S) pole can be generated by applying the first drive current to the coil of an electric motor wound around the rotor 20, thereby adjusting an electromotive force according to a magnitude of an applied current.

[0045] Here, the first axial force between the brush 200 and the slip ring 100 can be controlled by controlling the second drive current applied to the coil 420, thereby constantly maintaining a resistance between the brush 200 and the slip ring 100 and reliably supplying the first drive current to the coil of the electric motor.

[0046] On the other hand, a second axial force is generated by the support spring 430 such that the armature 410 is moved away from the slip ring 100. However, since the first axial force generated by the second drive force is greater than the second axial force generated by the support spring 430, the brush 200 and the slip ring 100 are electrically connected when the second drive current is applied to the coil 420. That is, since the first output is greater than the second output, the brush 200 and the slip ring 100 are electrically connected.

[0047] With reference to Fig. 3, when the supply of the second current to the coil 420 is stopped, that is, when the second current is not applied to the coil 420, the armature 410 is moved away from the slip ring 100 by the second axial force generated by the support spring 430. Accordingly, the brush 200 and the slip ring 100 are spaced apart from each other and are electrically separated.

[0048] When the system power is turned off, the support spring 430 can maintain the certain distance d between the brush 200 and the slip ring 100, thereby ensuring safety in the event of failure caused by a blocking phenomenon due to the infiltration of moisture.

[0049] In this case, even in the case where the first drive current is supplied to the brush 200, the brush 200 and the slip ring 100 can be spaced apart from each other and they can be electrically separated, thereby stopping supply of current to the coil of the electric motor in the failure case.

[0050] That is, regardless of the application or disconnection of the first drive current, it is possible to control or regulate an electrical connection and a separation between the brush 200 and the slip ring 200 and a current supply to the coil of the electric motor solely by controlling or regulating the second drive current.

[0051] In the above-mentioned power supply device 50 for the field-winding motor according to the first embodiment, even when the brush 200 is abraded, the armature 410 can be moved toward the slip ring 100 with a certain axial force, thereby electrically connecting the brush 200 and the slip ring 100. Therefore, a drive current can be reliably supplied to the coil of the electric motor regardless of the abrasion of the brush 200.

[0052] Furthermore, in the above-mentioned power supply device 50 for the field-winding motor according to the first embodiment, the brush 200 and the slip ring 100 can be electrically disconnected by cutting off the second drive current applied to the coil 420 in the event of a failure. Therefore, it is possible to stop the supply of current to the coil of the electric motor in the event of a failure.

[0053] With reference to Fig. 4 and Fig. 5, a power supply device 60 for a field winding motor in accordance with a second embodiment includes a holder 300, a brush 200, a support spring 430, a slip ring 100, an armature 410, a coil 420, and a power generator 500a.

[0054] In the description of a configuration and driving of the power supply device 60 according to the second embodiment, detailed descriptions of the same configuration and driving as in the first embodiment described above will be omitted.

[0055] The power generator 500a according to the second embodiment includes a first power terminal 510a and a second power terminal 520. Each of the first power terminal 510a and the second power terminal 520 may include a positive (+) terminal and a negative (-) terminal.

[0056] At this time, the first power terminal 510a is connected to the brush 200 through the armature 410 inside the holding device 300 and supplies a direct current, ie, a first drive current for driving an electric motor, to a coil of the electric motor. Furthermore, the second power terminal 520 supplies a direct current, ie, a second drive current, to a coil 420.

[0057] Furthermore, according to the second embodiment, a single power supply unit (not shown) may be provided to supply the first drive current and the second drive current to the first power terminal 510a and the second power terminal 520, respectively.

[0058] At this time, the power supply unit may generate the first drive current and the second drive current, and may supply the first drive current and the second drive current to the first power terminal 510a and the second power terminal 520, respectively.

[0059] However, the present disclosure is not limited thereto. The power supply unit does not need to distinguish between the first drive current and the second drive current, and may generate a single common drive current to jointly supply the generated single common drive current to the first power terminal 510a and the second power terminal 520.

[0060] At this time, the power supply unit may generate the first drive current and the second drive current such that the first drive current and the second drive current have different current values or the same current value.

[0061] On the other hand, when the first drive current and the second drive current are generated as common drive currents having the same current value, the first current terminal 510a and the second current terminal 520 may be connected to each other, and the second drive current (or the common drive current) supplied to the second current terminal 520 may be supplied to the coil 420.

[0062] As described above, a single power supply unit can be provided to generate the first drive current and the second drive current (or the common drive currents), thereby reducing the cost of a product.

[0063] Since the second drive current (or the common drive current) is supplied to the coil 420 and a first axial force is generated to move the armature 410 toward the slip ring 100, the brush 200 and the slip ring 100 are electrically connected.

[0064] A second axial force is generated by the support spring 430 such that the armature 410 is moved away from the slip ring 100. However, since the first axial force generated by the second drive force (or the common drive current) is greater than the second axial force generated by the support spring 430, the brush 200 and the slip ring 100 are electrically connected when the second drive current (or the common drive current) is applied to the coil 420.

[0065] When the supply of the second current (or the common drive current) applied to the coil 420 is stopped, that is, when the second current is not applied to the coil 420, the armature 410 is moved away from the slip ring 100 by the second axial force generated by the support spring 430. Accordingly, the brush 200 and the slip ring 100 are spaced apart from each other and are electrically disconnected.

[0066] When the system power is turned off, the support spring 430 can maintain a certain distance between the brush 200 and the slip ring 100, thereby ensuring safety in the event of a failure caused by a blocking phenomenon due to moisture infiltration.

[0067] In this case, also the first drive current (or the common drive current) is not supplied to the brush 200, and the brush 200 and the slip ring 100 are spaced apart from each other and electrically separated, thereby stopping supply of current to the coil of the electric motor in the event of failure.

[0068] In the above-mentioned power supply device 60 for the field-winding motor according to the second embodiment, even when the brush 200 is worn, the armature 410 can be moved toward the slip ring 100 with a certain axial force, thereby electrically connecting the brush 200 and the slip ring 100. Therefore, regardless of the wear of the brush 200, a drive current can be reliably supplied to the coil of the electric motor.

[0069] Furthermore, in the above-mentioned power supply device 60 for the field-winding motor according to the second embodiment, the brush 200 and the slip ring 100 can be electrically disconnected in the event of a failure by simultaneously cutting off the first drive current (or the common drive current) supplied to the coil and the second drive current applied to the coil 420. Therefore, failure and damage to components provided in an electric motor in the event of a failure can be prevented.

[0070] On the other hand, with reference to Fig. 6 to Fig. 8, a power supply device 70 for a field winding motor 1a in accordance with a third embodiment includes a holder 300, a brush 200, a support spring 430, a slip ring 100, an armature 410, a coil 420, a power generator 500a, and a dust removal part 310.

[0071] Therefore, in the power supply device 70 for the field winding motor 1a according to the third embodiment, the armature 410 can be linearly moved by a certain distance by the coil 420, and the dust removal part 310 can be opened and closed by the linear movement of the armature 410, thereby preventing failure of the power supply device 70 caused by connection between different electrical polarities of the brush 200 and the slip ring 100 caused by intrusion of external foreign matter and dust.

[0072] In the description of a configuration and driving of the power supply device 70 according to the third embodiment, detailed descriptions of the same configuration and driving as in the first embodiment described above will be omitted.

[0073] On the other hand, a cavity (not shown) is formed in the holder 300 such that the brush 200, the support spring 430, and the armature 410 are installed therein. The dust removal part 310 may be formed in the shape of a hole extending through a side surface of the holder 300. That is, based on a state in which a current is applied to the coil 420, the dust removal part 310 may penetrate through a side surface of the holder 300, specifically, through a bottom surface thereof, such that it fits with an opening and closing part 411.

[0074] Furthermore, the opening and closing part 411 may be formed in the armature 410 to selectively open and close the dust removal part 310. Specifically, the opening and closing part 411 may protrude outward from a lower portion of the armature 410 so as to closely contact an inner side of the lower surface of the holder 300.

[0075] With reference to Fig. 7 and Fig. 8, when a current is applied to the coil 420, the armature 410 is moved linearly along an inner surface of the holder 300 by generated magnetism, and the support spring 430 is deformed by compression due to kinetic energy of the armature 410. Furthermore, when no current is applied to the coil 420, the support spring 430 applies a spring force to the armature 410 and a support member 320. As a result, the brush 200 is spaced apart from the slip ring 100 by a certain distance d, and the dust removal member 310 is maintained in a state opened by the opening and closing member 410.

[0076] At this time, when the brush 200 is moved by a certain distance d by the linear movement of the armature 410 to closely contact the slip ring 100, a current is applied to a coil wound around a rotor 20. Furthermore, the opening and closing part 411 is moved along the inside surface of the holder 300 by the certain distance d by which the brush 200 is moved, and it closes the dust removal part 310.

[0077] External moisture and external foreign matter can be prevented from entering the holder 300 through the dust removal part 310, thereby preventing failure of the power supply device 70 caused by connection between different electrical polarities of the brush 200 and the slip ring 100 caused by the external foreign matter and dust.

[0078] At this time, the power supply device 70 returns to a state shown in Fig. 8, by removing the current applied to the coil 420. That is, when the current applied to the coil 420 is removed, a generated magnetism disappears, and the armature 410 and the opening and closing part 411 formed in the armature 410 return to an original position by a second axial force generated by the support spring 430.

[0079] Since the armature 410 and the opening and closing part 411 return to the original position and the brush 200 is separated from the slip ring 100, the current applied to the coil wound around the rotor 20 is removed and the dust removal part 310, which has been closed by the opening and closing part 411, is opened.

[0080] Therefore, dust generated due to abrasion of the brush 200 can be discharged to the outside of the holder 300 through the dust discharge part 310, thereby preventing failure of the power supply device 70 caused by connection between different electrical polarities of the brush 200 and the slip ring 100 caused by the dust.

[0081] In addition, since the brush 200 is reliably separated from or closely contacts the slip ring 100 by the linear movement of the armature 410, a current can be reliably supplied to the coil wound around the rotor 20, thereby accurately controlling a current.

[0082] Although the specific embodiments of the present disclosure have been described for illustrative purposes, the scope of the present disclosure is in no way limited to the above-mentioned embodiments of the present disclosure. One skilled in the art can easily devise many other embodiments by adding, modifying, omitting, or supplementing elements without departing from the principle of the present disclosure.

Claims

[1] Power supply device for a field winding motor, comprising: a brush (200) arranged in a holding device (300); an armature (410) connected to the brush (200) and arranged in the holding device (300); a slip ring (100) that is electrically connected to or electrically separated from the brush (200); a support spring (430) surrounding the brush (200) between the slip ring (100) and the armature (410); a coil (420) arranged outside the holding device (300) so as to overlap the support spring (430) and the armature (410); a first power terminal (510) connected to the brush (200) and supplying a first drive current; a second power terminal (520) connected to the coil (420) and supplying a second drive current; and a dust removal part (310) formed in a side surface of the holder (300); . wherein, when the second drive current is applied to the coil (420), a first axial force is generated to move the armature (410) toward the slip ring (100), and the brush (200) and the slip ring (100) are electrically connected due to a movement of the armature (410); wherein a second axial force is generated by the support spring (430) to move the armature (410) away from the slip ring (100), the first axial force is greater than the second axial force, and then, when the second drive current is applied, the brush (200) and the slip ring (100) are electrically connected. [2] The power supply device according to claim 1, further comprising: a first power supply unit that supplies the first drive current to the first power terminal (510); and a second power supply unit that supplies the second drive current to the second power terminal (520). [3] The power supply device according to claim 1, further comprising a power supply unit that supplies the first drive current and the second drive current, wherein a current value of the second drive current is different from or identical to the current value of the first drive current. [4] The power supply device according to claim 3, wherein the power supply unit jointly supplies a drive current to the first power terminal (510) and the second power terminal (520). [5] The power supply device according to claim 1, wherein the first power terminal (510) has a positive terminal and a negative terminal, is connected to the brush (200) through the holder (300) and the armature (410), and supplies the first drive current to a coil of the field winding motor, the first drive current being a direct current. [6] The power supply device according to claim 1, wherein the second power terminal (520) has a positive terminal and a negative terminal and supplies the second drive current to the coil (420), the second drive current being a direct current. [7] The power supply device according to claim 1, wherein an axial force between the brush (200) and the slip ring (100) is controlled by controlling a magnitude of the second drive current applied to the coil (420). [8] The power supply device according to claim 1, wherein a second axial force is generated by the support spring (430) to move the armature (410) away from the slip ring (100), and then, when the supply of the second drive current is stopped, the brush (200) and the slip ring (100) are separated by the second axial force and are electrically separated. [9] The power supply device according to claim 8, wherein an electrical connection or an electrical separation between the brush (200) and the slip ring (100) is controlled by the application or the disconnection of the second drive current independently of the application or the disconnection of the first drive current. [10] The power supply device according to claim 1, wherein the coil (420) installed outside the holder (300) is further configured to move the armature (410) along an inside surface of the holder (300) to open and close the dust discharge part. [11] The power supply device according to claim 10, wherein a second axial force is generated by the support spring (430) surrounding the brush (200) between the slip ring (100) and the armature (410) such that the armature (410) is moved away from the slip ring (100). [12] Field winding motor comprising: a motor housing (10); a rotary shaft (30) formed in a center of the motor housing (10); a rotor (20) installed in the motor housing so as to rotate on the rotary shaft (30); and the power supply device as claimed in any one of claims 1 to 11 and which is arranged perpendicular to an extension direction of the rotation shaft (30) on one side of the motor housing (10).

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