Motor

Abstract

This motor is provided with: a rotor that can rotate around a central axis; a stator that faces the rotor in the axial direction with a gap therebetween; and a circuit that supplies an electrical current to the stator. The stator comprises a first stator disposed to one axial-direction side of the rotor and a second stator disposed to the other axial-direction side of the rotor. The first stator comprises a plurality of first coil sections that are mounted on a first stator core and are disposed in a circumferential direction with gaps therebetween. The second stator comprises a plurality of second coil sections that are mounted on a second stator core and are disposed in the circumferential direction with gaps therebetween. The circuit section comprises a connecting circuit section that connects the first coil sections and the second coil sections in series. The connecting circuit section can toggle between a first energized state, in which the electrical current is supplied to both the first coil sections and the second coil sections, and a second energized state, in which the electrical current is supplied to only the first coil sections or the second coil sections.

Description

motor

[0001] This application claims priority to Japanese Patent Application No. 2024-124691, filed on July 31, 2024, the contents of which are incorporated herein by reference.

[0002] An axial gap motor in which a rotor is disposed axially opposite a stator has been disclosed (for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-053333

[0004] In a motor, when the rotor rotates, an induced voltage is generated in each of the multiple coils attached to the stator. Furthermore, the induced voltage generated in each coil increases as the rotational speed of the rotor increases. Therefore, in the motor described in Patent Document 1, the voltage applied to the coils decreases as the rotational speed of the rotor increases. This limits the range of rotational speeds that the rotor can output.

[0005] In view of the above circumstances, one aspect of the present invention has an object to provide a motor that can widen the rotational speed range of the rotor.

[0006] One aspect of the motor of the present invention includes a rotor rotatable about a central axis, a stator facing the rotor at an axial distance, and a circuit unit supplying current to the stator. The stator includes a first stator disposed on one axial side of the rotor and a second stator disposed on the other axial side of the rotor. The first stator includes a first stator core surrounding the central axis and a plurality of first coil portions attached to the first stator core and spaced apart along the circumferential direction. The second stator includes a second stator core surrounding the central axis and a plurality of second coil portions attached to the second stator core and spaced apart along the circumferential direction. The circuit unit includes a connection circuit unit connecting the first coil portions and the second coil portions in series. The connection circuit unit is switchable between a first current-carrying state in which current is supplied to both the first coil portions and the second coil portions and a second current-carrying state in which current is supplied to only one of the first coil portions and the second coil portions.

[0007] According to one aspect of the present invention, the rotational speed range of the rotor in a motor can be widened.

[0008] FIG. 1 is a cross-sectional view showing a motor according to an embodiment. FIG. 2 is a cross-sectional view showing a stator according to an embodiment, taken along line II-II in FIG. 1. FIG. 3 is a perspective view showing a stator according to an embodiment. FIG. 4 is a block diagram showing a circuit section according to an embodiment. FIG. 5 is a block diagram showing a circuit section in a first current-carrying state according to an embodiment. FIG. 6 is a block diagram showing a circuit section in a second current-carrying state according to an embodiment. FIG. 7 is a diagram showing a driving torque of a rotor according to an embodiment.

[0009] Hereinafter, motors according to embodiments of the present invention will be described with reference to the drawings. Note that the scope of the present invention is not limited to the following embodiments, and can be modified as desired within the scope of the technical concept of the present invention. In addition, in the following drawings, the scale and number of components may differ from the actual structure in order to make each component easier to understand.

[0010] In the following description, the Z axis is indicated in the figures as appropriate. The Z axis is the direction in which the central axis J of the embodiment described below extends. The central axis J shown in each figure is a virtual axis. In the following description, the direction in which the central axis J extends, i.e., the direction parallel to the Z axis, is referred to as the "axial direction." The radial direction centered on the central axis J is simply referred to as the "radial direction." The circumferential direction centered on the central axis J is simply referred to as the "circumferential direction." The side of the axial direction toward which the arrow of the Z axis points (+Z side) is referred to as the "upper side" or "one axial side." The side of the axial direction opposite to the side toward which the arrow of the Z axis points (-Z side) is referred to as the "lower side" or "other axial side." Note that the terms "upper side" and "lower side" are simply names used to describe the relative positional relationships of the various components, and the actual positional relationships may be other than those indicated by these names.

[0011] The circumferential direction is indicated by the arrow θ in each drawing. The side of the circumferential direction toward which the arrow θ points is called the "one circumferential side." The opposite side of the circumferential direction to the side toward which the arrow θ points is called the "other circumferential side." The one circumferential side (+θ side) is the side that moves clockwise around the central axis J when viewed from above. The other circumferential side (-θ side) is the side that moves counterclockwise around the central axis J when viewed from above.

[0012] As shown in Figure 1, the motor 10 of this embodiment is a thin motor whose axial dimension is smaller than its radial dimension. The motor 10 is an axial gap motor in which a stator 50 faces a rotor 40 at an axial distance. The motor 10 includes a housing 11, a rotor 40, a shaft 44, a stator 50, a bus bar 60, and a circuit unit 70. The motor 10 includes a stator 50 on each axial side of the rotor 40.

[0013] The housing 11 has a substantially cylindrical shape centered on a central axis J. The housing 11 accommodates the rotor 40, the stator 50, the bus bars 60, and the circuit section 70 therein. In this embodiment, the housing 11 is made of a metal material such as aluminum. The housing 11 may also be made of a material other than a metal material, such as resin. The housing 11 includes a first housing 12, a second housing 15, and a circuit accommodating section 18.

[0014] The first housing 12 is the upper portion of the housing 11. The first housing 12 is generally cylindrical and protrudes axially about a central axis J. The first housing 12 is open downward. The first housing 12 has a first peripheral wall 13 and a top wall 14.

[0015] The first peripheral wall portion 13 has a generally cylindrical shape that protrudes in the axial direction about the central axis J. The first peripheral wall portion 13 surrounds one of the stators 50, which is disposed above the rotor 40, from the radially outer side.

[0016] The top wall portion 14 is generally disk-shaped and centered on the central axis J. The plate surface of the top wall portion 14 faces the axial direction. The radial outer edge of the top wall portion 14 is connected to the upper end of the first circumferential wall portion 13. The top wall portion 14 is disposed above the rotor 40 and the stator 50. The top wall portion 14 is provided with a first housing portion 14a, a top wall recess 14c, and a first holding portion 14e.

[0017] The first accommodating portion 14a and the top wall recess 14c are each a recess recessed upward from the downward-facing surface of the top wall portion 14. When viewed in the axial direction, the first accommodating portion 14a has a substantially annular shape centered on the central axis J. When viewed in the axial direction, the top wall recess 14c has a substantially circular shape centered on the central axis J. The top wall recess 14c is provided radially inward of the first accommodating portion 14a.

[0018] The first retaining portion 14e protrudes downward from the radial outer edge of the top wall recess 14c. The first retaining portion 14e is generally cylindrical and centered on the central axis J. A first bearing 81 is attached to the inner peripheral surface of the first retaining portion 14e. The first bearing 81 is generally annular and centered on the central axis J. The first bearing 81 contacts the surface of the top wall recess 14c facing downward in the axial direction. This determines the axial position of the first bearing 81. In this embodiment, the first bearing 81 is a ball bearing. The first bearing 81 may also be a sliding bearing.

[0019] The second housing 15 is disposed below the first housing 12. The second housing 15 is generally cylindrical and protrudes axially about a central axis J. The second housing 15 is open on the upper side. The second housing 15 is fixed to the first housing 12. The second housing 15 has a second peripheral wall portion 16 and a bottom wall portion 17.

[0020] The second circumferential wall portion 16 has a generally cylindrical shape that protrudes in the axial direction about the central axis J. The second circumferential wall portion 16 surrounds the other stator 50, which is disposed below the rotor 40, from the radially outer side. The upper end of the second circumferential wall portion 16 is fixed to the lower end of the first circumferential wall portion 13. In this way, the second housing 15 is fixed to the first housing 12.

[0021] The bottom wall portion 17 has a generally annular plate shape centered on the central axis J. The plate surface of the bottom wall portion 17 faces the axial direction. The bottom wall portion 17 is disposed below the stator 50 and the rotor 40. The bottom wall portion 17 is provided with a second accommodating portion 17a, a bottom wall recess 17c, a first hole 17e, a plurality of second holes 17g, and a second holding portion 17h.

[0022] The second accommodating portion 17a and the bottom wall recess 17c are each recesses recessed downward from the upward-facing surface of the bottom wall portion 17. When viewed in the axial direction, the second accommodating portion 17a has a substantially annular shape centered on the central axis J. When viewed in the axial direction, the second accommodating portion 17a overlaps with the first accommodating portion 14a. When viewed in the axial direction, the bottom wall recess 17c has a substantially circular shape centered on the central axis J. The bottom wall recess 17c is provided radially inward of the second accommodating portion 17a.

[0023] The first hole portion 17e and each of the plurality of second hole portions 17g are holes that penetrate the bottom wall portion 17 in the axial direction. When viewed in the axial direction, the first hole portion 17e has a generally circular shape centered on the central axis J. The first hole portion 17e is provided radially inward from the inner circumferential surface of the bottom wall recess 17c. When viewed in the axial direction, each of the second hole portions 17g has a generally circular shape. Each of the second hole portions 17g is provided radially outward from the second accommodating portion 17a. The second hole portions 17g are provided at intervals along the circumferential direction.

[0024] The second retaining portion 17h protrudes upward from the radial outer edge of the bottom wall recess 17c. The second retaining portion 17h is generally cylindrical and centered on the central axis J. A second bearing 82 is attached to the inner peripheral surface of the second retaining portion 17h. The second bearing 82 is generally annular and centered on the central axis J. The second bearing 82 comes into axial contact with the surface of the bottom wall recess 17c facing upward. This determines the axial position of the second bearing 82. In this embodiment, the second bearing 82 is a ball bearing. The second bearing 82 may also be a plain bearing.

[0025] The circuit accommodating portion 18 is disposed below the second housing 15. The circuit accommodating portion 18 is generally cylindrical and protrudes axially about the central axis J. The circuit accommodating portion 18 opens upward. The upper end of the circuit accommodating portion 18 is fixed to the lower end of the second peripheral wall portion 16. This fixes the circuit accommodating portion 18 to the second housing 15. The interior of the circuit accommodating portion 18 is connected to the interior of the first housing 12 and the interior of the second housing 15 via the first hole 17e and each of the second hole portions 17g. The circuit accommodating portion 18 is provided with a board holding portion 18a and a hole 18c. The board holding portion 18a is columnar and protrudes upward. In this embodiment, the circuit accommodating portion 18 is provided with multiple board holding portions 18a.

[0026] The hole 18c is a hole that axially penetrates the circuit accommodating portion 18. When viewed from the axial direction, the hole 18c has a substantially circular shape centered on the central axis J. When viewed from the axial direction, the hole 18c overlaps with the first hole 17e.

[0027] The rotor 40 has a substantially circular ring shape centered on a central axis J. The rotor 40 is rotatable about the central axis J. The rotor 40 faces the stator 50 with a gap therebetween in the axial direction. In the axial direction, the rotor 40 is disposed between one stator 50 and the other stator 50. The rotor 40 has a holder 41 and a magnet 42.

[0028] The holder 41 has a substantially circular ring shape centered on the central axis J. The holder 41 faces the stator 50 with a gap in the axial direction. The radially outer end of the holder 41 is located radially outward of the stator 50. The holder 41 faces the first housing 12 and the second housing 15 with a gap in the radial direction. The holder 41 is provided with a plurality of magnet accommodating portions 41a.

[0029] Each magnet housing portion 41a is a hole that penetrates the holder 41 in the axial direction. The magnet housing portions 41a are provided at intervals along the circumferential direction. Each magnet housing portion 41a faces the stator 50 in the axial direction. In this embodiment, the holder 41 is provided with 40 magnet housing portions 41a. The number of magnet housing portions 41a provided in the holder 41 may be 39 or less, or may be 41 or more.

[0030] In this embodiment, the magnet 42 is composed of a plurality of magnet pieces 42a. In this embodiment, the magnet 42 is composed of 40 magnet pieces 42a. Each magnet piece 42a is housed inside a different magnet housing portion 41a. Each magnet piece 42a is fixed to the inner surface of the magnet housing portion 41a. This holds the magnet 42 in the holder 41. The magnet pieces 42a are arranged at intervals along the circumferential direction. Each magnet piece 42a faces the stator 50 in the axial direction. In other words, the magnet 42 faces the stator 50 in the axial direction. Each magnet piece 42a has magnetic poles whose magnetization direction faces the axial direction. In this embodiment, the magnetic poles of magnet pieces 42a arranged adjacent to each other in the circumferential direction are opposite to each other.

[0031] The shaft 44 has a generally cylindrical shape extending in the axial direction around the central axis J. The shaft 44 is disposed radially inward of the rotor 40 and the stator 50. The shaft 44 passes axially through the holder 41. The outer peripheral surface of the shaft 44 is fixed to the inner peripheral surface of the holder 41. This allows the shaft 44 to rotate together with the rotor 40 around the central axis J. An upper portion of the shaft 44 is supported by a first bearing 81 so as to be rotatable around the central axis J. A lower portion of the shaft 44 is supported by a second bearing 82 so as to be rotatable around the central axis J. The lower end of the shaft 44 protrudes outside the housing 11 through the first hole 17e and the hole 18c.

[0032] The stator 50 faces the rotor 40 with an axial gap therebetween. The stator 50 has a first stator 51 and a second stator 56. In this embodiment, the motor 10 is a double-stator, single-rotor axial gap motor.

[0033] The first stator 51 is disposed above the rotor 40, i.e., on one axial side (+Z side). The first stator 51 faces the rotor 40 with an axial gap between them. As shown in FIG. 2 , the first stator 51 has a first stator core 52, an insulator 53, and a first coil portion 54.

[0034] The first stator core 52 is annular and surrounds the central axis J. More specifically, the first stator core 52 is substantially annular and centered on the central axis J. As shown in FIG. 1 , the first stator core 52 has a back yoke 52a and teeth 52c. The back yoke 52a is substantially annular and plate-shaped and centered on the central axis J. The plate surface of the back yoke 52a faces the axial direction. The back yoke 52a is accommodated in the first accommodating portion 14a of the first housing 12. The back yoke 52a is fixed to the inner surface of the first accommodating portion 14a. This fixes the first stator 51 to the first housing 12.

[0035] The teeth 52c are columnar and protrude downward from the back yoke 52a. The teeth 52c face the magnets 42 at an axial distance. This causes the first stator core 52 to face the rotor 40 in the axial direction. As shown in FIG. 2 , the teeth 52c are generally trapezoidal with long sides extending radially. The first stator core 52 has a plurality of teeth 52c. In this embodiment, the first stator core 52 has 36 teeth 52c. The number of teeth 52c included in the first stator core 52 may be 35 or less, or 37 or more. The teeth 52c are arranged at approximately equal intervals along the circumferential direction.

[0036] The insulators 53 insulate the first stator core 52 from the first coil portion 54. The insulators 53 are attached to the first stator core 52. In this embodiment, the first stator 51 has 36 insulators 53. Each insulator 53 is attached to a different tooth portion 52c.

[0037] The first coil portions 54 are attached to the tooth portions 52c via the insulators 53. In this way, the first coil portions 54 are attached to the first stator core 52. The first coil portions 54 are formed by coils wound around the outer peripheral surfaces of the tooth portions 52c. The first stator 51 has a plurality of first coil portions 54. In this embodiment, the first stator 51 has 36 first coil portions 54. Each first coil portion 54 is attached to a different tooth portion 52c. The first coil portions 54 are arranged at intervals from one another in the circumferential direction.

[0038] The multiple first coil portions 54 include multiple first U-phase coil portions 54U, multiple first V-phase coil portions 54V, and multiple first W-phase coil portions 54W. In the present embodiment, the multiple first coil portions 54 have three phases. The number of phases of the multiple first coil portions 54 is not limited to the number of phases in the present embodiment and may be, for example, six. In the present embodiment, the multiple first coil portions 54 include twelve first U-phase coil portions 54U, twelve first V-phase coil portions 54V, and twelve first W-phase coil portions 54W. The first U-phase coil portions 54U are spaced apart from one another in the circumferential direction. The first V-phase coil portions 54V are arranged on the other circumferential side (−θ side) of different first U-phase coil portions 54U. Each first W-phase coil portion 54W is disposed on the other circumferential side of a mutually different first V-phase coil portion 54V and on one circumferential side (+θ side) of a mutually different first U-phase coil portion 54U. Currents that are shifted in electrical angle by 120° from one another are supplied to first U-phase coil portion 54U, first V-phase coil portion 54V, and first W-phase coil portion 54W from circuit unit 70. When current is supplied to each first coil portion 54, each first coil portion 54 forms an electromagnet with magnetic poles oriented in the axial direction.

[0039] As shown in FIG. 1 , the second stator 56 is disposed below the rotor 40, i.e., on the other axial side (−Z side). The second stator 56 faces the rotor 40 with an axial gap between them. The second stator 56 includes a second stator core 57, a plurality of insulators (not shown), and a second coil portion 59. In this embodiment, the shape and arrangement of each component of the second stator 56 are substantially plane-symmetrical to the shape and arrangement of each component of the first stator 51, with a plane perpendicular to the axial direction as the plane of symmetry. Therefore, in the following description of the second stator 56, description of the same shape, arrangement, and the like as those of the first stator 51 may be omitted.

[0040] The second stator core 57 is annular and surrounds the central axis J. More specifically, the second stator core 57 is substantially annular and centered on the central axis J. The second stator core 57 has a back yoke 57a and teeth 57c. The back yoke 57a is substantially annular and plate-shaped and centered on the central axis J. The back yoke 57a is accommodated in the second accommodating portion 17a of the second housing 15. The back yoke 57a is fixed to the inner surface of the second accommodating portion 17a. This fixes the second stator 56 to the second housing 15.

[0041] The teeth 57c are columnar and protrude upward from the back yoke 57a. The teeth 57c face the magnets 42 at an axial distance. This causes the second stator core 57 to face the rotor 40 in the axial direction. Although not shown, like the teeth 52c described above, the teeth 57c are generally trapezoidal with their long sides extending in the radial direction. The second stator core 57 has 36 teeth 57c. The teeth 57c are arranged at approximately equal intervals in the circumferential direction.

[0042] A plurality of insulators (not shown) insulate the second stator core 57 from the second coil portion 59. Each insulator 53 is attached to a different tooth portion 57c.

[0043] The second coil portions 59 are attached to the tooth portions 57c via insulators (not shown). In this way, the second coil portions 59 are attached to the second stator core 57. The second coil portions 59 are formed by coils wound around the outer peripheral surfaces of the tooth portions 57c. The second stator 56 has a plurality of second coil portions 59. Although not shown, in this embodiment, the second stator 56 has 36 second coil portions 59. Each second coil portion 59 is attached to a different tooth portion 57c. As shown in FIG. 3, the second coil portions 59 are arranged at intervals from one another in the circumferential direction.

[0044] The plurality of second coil portions 59 include a plurality of second U-phase coil portions 59U, a plurality of second V-phase coil portions 59V, and a plurality of second W-phase coil portions 59W. The number of phases of the plurality of second coil portions 59 is three. In the present embodiment, the plurality of second coil portions 59 includes twelve second U-phase coil portions 59U, twelve second V-phase coil portions 59V, and twelve second W-phase coil portions 59W. The second U-phase coil portions 59U are arranged spaced apart from one another in the circumferential direction. The second V-phase coil portions 59V are arranged on the other circumferential side (−θ side) of different second U-phase coil portions 59U. The second W-phase coil portions 59W are arranged on the other circumferential side (−θ side) of different second V-phase coil portions 59V and on one circumferential side (+θ side) of different second U-phase coil portions 59U. When viewed in the axial direction, second U-phase coil portions 59U overlap with different first U-phase coil portions 54U. When viewed in the axial direction, second V-phase coil portions 59V overlap with different first V-phase coil portions 54V. When viewed in the axial direction, second W-phase coil portions 59W overlap with different first W-phase coil portions 54W. Currents that are 120° apart in electrical angle are supplied from circuit unit 70 to second U-phase coil portion 59U, second V-phase coil portion 59V, and second W-phase coil portion 59W, respectively. When current is supplied to each second coil portion 59, each second coil portion 59 forms an electromagnet with its magnetic poles oriented in the axial direction.

[0045] As shown in Fig. 1, the circuit unit 70 is housed inside the circuit accommodating portion 18. The circuit unit 70 generates a current to be supplied to the stator 50 from a current supplied by an external power supply. That is, the circuit unit 70 supplies a current to the stator 50. The circuit unit 70 has a circuit board 71. As shown in Fig. 4, the circuit unit 70 has an inverter circuit unit 72, a connection circuit unit 75, and a control unit 79.

[0046] As shown in FIG. 1 , the circuit board 71 is plate-shaped and extends in a direction perpendicular to the axial direction. The circuit board 71 is held by a plurality of board holders 18a. This allows the circuit unit 70 to be held in the housing 11. The circuit board 71 is provided with a board hole 71a. The shaft 44 passes through the board hole 71a in the axial direction. Although not shown, an inverter circuit unit 72 and a connection circuit unit 75 are mounted on the circuit board 71. The control unit 79 may be mounted on the circuit board 71, or may be mounted on a board other than the circuit board 71 (not shown).

[0047] The inverter circuit unit 72 shown in FIG. 4 generates three-phase AC current from current supplied by an external power supply (not shown) and supplies the AC current to the first coil units 54 and the second coil units 59. Although not shown, the inverter circuit unit 72 is electrically connected to the external power supply (not shown). In this embodiment, the inverter circuit unit 72 includes a plurality of switching elements 72a and a plurality of third connection lines 72b. In this embodiment, the inverter circuit unit 72 includes six switching elements 72a. The number of switching elements 72a included in the inverter circuit unit 72 may be five or less, or seven or more. Each switching element 72a is mounted on a circuit board 71. In this embodiment, the switching elements 72a are insulated gate bipolar transistors (IGBTs). The switching elements 72a may be power semiconductor elements other than IGBTs. For example, the switching element 72a may be a field effect transistor such as a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0048] In this embodiment, the inverter circuit unit 72 has three third connection lines 72 b. Each third connection line 72 b connects two switching elements 72 a. One of the U-phase current, the V-phase current, and the W-phase current generated by the switching elements 72 a flows through each third connection line 72 b.

[0049] The connection circuit section 75 connects in series the first coil section 54 and the second coil section 59. The connection circuit section 75 has a first connection line 76, a first switching element 76a, a second connection line 77, and a second switching element 77a.

[0050] In the present embodiment, connection circuit unit 75 has a plurality of first connection lines 76. The plurality of first connection lines 76 include a U-phase connection line 76U, a V-phase connection line 76V, and a W-phase connection line 76W. U-phase connection line 76U connects first U-phase coil unit 54U and second U-phase coil unit 59U in series. V-phase connection line 76V connects first V-phase coil unit 54V and second V-phase coil unit 59V in series. W-phase connection line 76W connects first W-phase coil unit 54W and second W-phase coil unit 59W in series. As a result, first connection line 76 connects first coil unit 54 and second coil unit 59 in series. A first switching element 76a is arranged on first connection line 76.

[0051] The first switching element 76a can switch the connection state between the first coil portion 54 and the second coil portion 59 between an electrically connected state and an electrically isolated state. In this embodiment, the connection circuit unit 75 has two first switching elements 76a. In this embodiment, each first switching element 76a is arranged on the U-phase connecting line 76U and the W-phase connecting line 76W. Note that the connection circuit unit 75 only needs to have two or more first switching elements 76a, and the first switching element 76a may be arranged on the V-phase connecting line 76V.

[0052] Second connection line 77 connects U-phase connection line 76U, V-phase connection line 76V, and W-phase connection line 76W. That is, U-phase connection line 76U, V-phase connection line 76V, and W-phase connection line 76W are each connected by second connection line 77. More specifically, one end of second connection line 77 is connected to a portion of U-phase connection line 76U that is closer to first U-phase coil unit 54U than first switching element 76a. The other end of second connection line 77 is connected to a portion of W-phase connection line 76W that is closer to first W-phase coil unit 54W than first switching element 76a. A central portion of second connection line 77 is connected to V-phase connection line 76V. Two second switching elements 77a are arranged on second connection line 77.

[0053] One second switching element 77a is disposed in a portion of the second connection line 77 between a connection portion with the U-phase connection line 76U and a connection portion with the V-phase connection line 76V. One second switching element 77a is capable of switching the connection state between the U-phase connection line 76U and the V-phase connection line 76V between an electrically connected state and an electrically insulated state. The other second switching element 77a is disposed in a portion of the second connection line 77 between a connection portion with the V-phase connection line 76V and a connection portion with the W-phase connection line 76W. The other second switching element 77a is capable of switching the connection state between the V-phase connection line 76V and the W-phase connection line 76W between an electrically connected state and an electrically insulated state.

[0054] As shown in FIG. 1 , the bus bars 60 electrically connect the stator 50 and the circuit unit 70. In this embodiment, the motor 10 includes a plurality of bus bars 60. Each bus bar 60 is passed axially through the second hole 17g. The plurality of bus bars 60 includes a first bus bar 61, a second bus bar 62, and a third bus bar 63.

[0055] The first bus bar 61 electrically connects the first coil portion 54 and the circuit portion 70. More specifically, as shown in FIG. 4 , the first bus bar 61 electrically connects one end of the first coil portion 54 and the inverter circuit portion 72. In the present embodiment, the plurality of bus bars 60 includes a plurality of first bus bars 61. The plurality of first bus bars 61 include first bus bars 61U, 61V, and 61W. One end of each of the first bus bars 61U, 61V, and 61W is connected to a different third connection line 72b. A U-phase current flows through the first bus bar 61U. The other end of the first bus bar 61U is connected to one end of the first U-phase coil portion 54U. A V-phase current flows through the first bus bar 61V. The other end of the first bus bar 61V is connected to one end of the first V-phase coil portion 54V. A W-phase current flows through the first bus bar 61W. The other end of first bus bar 61W is connected to one end of first W-phase coil portion 54W. Thus, first U-phase coil portion 54U, first V-phase coil portion 54V, and first W-phase coil portion 54W are electrically connected to inverter circuit portion 72 via first bus bars 61U, 61V, 61W, respectively.

[0056] As shown in FIG. 1 , the second bus bar 62 electrically connects the first coil portion 54 and the circuit portion 70. More specifically, as shown in FIG. 4 , the second bus bar 62 electrically connects the other end of the first coil portion 54 and one end of the first connection line 76. In the present embodiment, the plurality of bus bars 60 includes a plurality of second bus bars 62. The plurality of second bus bars 62 includes second bus bars 62U, 62V, and 62W. One end of the second bus bar 62U is connected to the other end of the first U-phase coil portion 54U, and the other end of the second bus bar 62U is connected to one end of the U-phase connection line 76U. One end of the second bus bar 62V is connected to the other end of the first V-phase coil portion 54V, and the other end of the second bus bar 62V is connected to one end of the V-phase connection line 76V. One end of second bus bar 62W is connected to the other end of first W-phase coil portion 54W, and the other end of second bus bar 62W is connected to one end of W-phase connecting line 76W. As a result, first U-phase coil portion 54U, first V-phase coil portion 54V, and first W-phase coil portion 54W are electrically connected to connection circuit portion 75 via second bus bars 62U, 62V, 62W, respectively.

[0057] As shown in FIG. 1 , third bus bar 63 electrically connects second coil portion 59 and circuit portion 70. More specifically, as shown in FIG. 4 , third bus bar 63 electrically connects the other end of first connection line 76 and second coil portion 59. In the present embodiment, the plurality of bus bars 60 includes a plurality of third bus bars 63. The plurality of third bus bars 63 includes third bus bars 63U, 63V, and 63W. One end of third bus bar 63U is connected to the other end of U-phase connecting line 76U, and the other end of third bus bar 63U is connected to one end of second U-phase coil portion 59U. One end of third bus bar 63V is connected to the other end of V-phase connecting line 76V, and the other end of third bus bar 63V is connected to one end of second V-phase coil portion 59V. One end of third bus bar 63W is connected to the other end of W-phase connecting line 76W, and the other end of third bus bar 63W is connected to one end of second W-phase coil portion 59W. As a result, second U-phase coil portion 59U, second V-phase coil portion 59V, and second W-phase coil portion 59W are electrically connected to connection circuit portion 75 via third bus bars 63U, 63V, 63W. Furthermore, first coil portion 54 and second coil portion 59 are connected in series via second bus bar 62, connection circuit portion 75, and third bus bar 63.

[0058] The other end of second U-phase coil portion 59U, the other end of second V-phase coil portion 59V, and the other end of second W-phase coil portion 59W are electrically connected to each other. The other end of second U-phase coil portion 59U, the other end of second V-phase coil portion 59V, and the other end of second W-phase coil portion 59W may be electrically connected in circuit portion 70 via a fourth bus bar (not shown), or may be electrically connected at a location other than circuit portion 70.

[0059] The control unit 79 controls the operation of each of the switching elements 72a, each of the first switching elements 76a, and each of the second switching elements 77a. In this way, the control unit 79 controls the operation of each of the inverter circuit unit 72 and the connection circuit unit 75. The control unit 79 is, for example, a computer having a processor such as a CPU (Central Processing Unit). Although not shown in the figure, the control unit 79 is electrically connected to each of the switching elements 72a, each of the first switching elements 76a, and each of the second switching elements 77a.

[0060] As described above, the control unit 79 controls the operation of each switching element 72 a. This causes the inverter circuit unit 72 to generate an AC current with a desired waveform and supply the current to the stator 50. More specifically, the inverter circuit unit 72 generates a three-phase AC current with a desired waveform from a current supplied by an external power supply (not shown) and supplies the current to the stator 50.

[0061] The control unit 79 controls the operation of each of the first switching elements 76a and each of the second switching elements 77a to switch the connection circuit unit 75 between a first conduction state S1 and a second conduction state S2. The control unit 79 electrically connects the first coil unit 54 and the second coil unit 59 using each of the first switching elements 76a and electrically insulates the first connection lines 76 from each other using each of the second switching elements 77a, thereby switching the connection circuit unit 75 to the first conduction state S1. That is, in the first conduction state S1, each of the first switching elements 76a electrically connects the first coil unit 54 and the second coil unit 59. Furthermore, each of the second switching elements 77a electrically insulates the first connection lines 76 from each other in the first conduction state S1. Therefore, as shown in FIG. 5 , in the first conduction state S1, the current generated by the inverter circuit unit 72 is supplied to both the first coil unit 54 and the second coil unit 59. Therefore, in the first current-carrying state S1, each of the first coil portion 54 and the second coil portion 59 constitutes an electromagnet with its magnetic poles facing in the axial direction.

[0062] The control unit 79 electrically insulates the first coil portion 54 from the second coil portion 59 using each first switching element 76a and electrically connects each of the multiple first connection lines 76 using each second switching element 77a, thereby placing the connection circuit unit 75 in the second current-carrying state S2. That is, in the second current-carrying state S2, each first switching element 76a electrically insulates the first coil portion 54 from the second coil portion 59. Also, each second switching element 77a electrically connects each of the multiple first connection lines 76. As a result, in the second current-carrying state S2, the connection circuit unit 75 insulates the first coil portion 54 from the second coil portion 59. Therefore, as shown in FIG. 6 , in the second current-carrying state S2, the current generated by the inverter circuit unit 72 is supplied to the first coil portion 54, but the current generated by the inverter circuit unit 72 is not supplied to the second coil portion 59. That is, in the second current-carrying state S2, current is supplied to only one of the first coil portion 54 and the second coil portion 59. Therefore, in the second current-carrying state S2, the first coil portion 54 constitutes an electromagnet with its magnetic poles facing the axial direction, but the second coil portion 59 does not constitute an electromagnet.

[0063] From the above, the connection circuit section 75 can be switched between a first current flow state S1 in which current is supplied to both the first coil section 54 and the second coil section 59, and a second current flow state S2 in which current is supplied to only one of the first coil section 54 and the second coil section 59.

[0064] In the second current-carrying state S2, current may be supplied only to the second coil portion 59. In this case, the first bus bar 61 electrically connects the inverter circuit portion 72 and one end of the second coil portion 59, the second bus bar 62 electrically connects the other end of the second coil portion 59 and one end of the first connection line 76, and the third bus bar 63 electrically connects the other end of the first connection line 76 and the first coil portion 54.

[0065] In the first current-carrying state S1 in which current is supplied to both the first coil portion 54 of the first stator 51 and the second coil portion 59 of the second stator 56, the magnetic fields formed by the first coil portion 54 and the second coil portion 59 are combined, increasing the strength of the magnetic field formed by the stator 50. This increases the electromagnetic force applied to the magnets 42 of the rotor 40, enabling the rotor 40 to obtain a large driving torque.

[0066] When the rotor 40 rotates about the central axis J, an induced voltage is generated in the coils 54, 59 to which current is supplied from the circuit unit 70. The induced voltage generated in the coils 54, 59 increases as the rotation speed of the rotor 40 increases. Therefore, as the rotation speed of the rotor 40 increases, the drive torque of the rotor 40 decreases.

[0067] As described above, in the first current-carrying state S1, current is supplied to both the first coil portion 54 and the second coil portion 59, and thus an induced voltage is generated in each of the first coil portion 54 and the second coil portion 59. Furthermore, the induced voltages generated in the first coil portion 54 and the second coil portion 59 increase as the rotational speed of the rotor 40 increases. As a result, in the first current-carrying state S1, the drive torque of the rotor 40 decreases significantly as the rotational speed of the rotor 40 increases. Therefore, in the first current-carrying state S1, it is difficult to increase the maximum rotational speed of the rotor 40, and therefore it is difficult to widen the rotational speed range of the rotor 40.

[0068] In the second current-carrying state S2, in which current is supplied only to the first coil portion 54 of the first stator 51, as described above, only the first coil portion 54 constitutes an electromagnet, and therefore the magnetic field strength generated by the stator 50 is weaker than in the first current-carrying state S1. Therefore, compared to the first current-carrying state S1, the electromagnetic force applied to the magnet 42 of the rotor 40 is weaker, resulting in a lower drive torque of the rotor 40 in the low-speed rotation range. However, since no induced voltage is generated in the second coil portion 59, to which no current is supplied, the induced voltage generated in the stator 50 in the high-speed rotation range can be reduced compared to the first current-carrying state S1. As a result, in the second current-carrying state S2, the decrease in drive torque of the rotor 40 in the high-speed rotation range can be suppressed compared to the first current-carrying state S1, thereby increasing the maximum rotation speed of the rotor 40. Therefore, in the second current-carrying state S2, the rotation speed range of the rotor 40 can be expanded compared to the first current-carrying state S1.

[0069] FIG. 7 is a diagram illustrating the drive torque of the motor 10 of this embodiment. The horizontal axis of FIG. 7 represents the number of rotations per minute of the rotor 40, or the rotation speed Vr of the rotor 40. The vertical axis of FIG. 7 represents the drive torque T of the rotor 40. The drive torque shown by the dashed line in FIG. 7 is the first drive torque T1. The first drive torque T1 is the drive torque of the rotor 40 in the first current-carrying state S1. The drive torque shown by the solid line in FIG. 7 is the second drive torque T2. The second drive torque T2 is the drive torque of the rotor 40 in the second current-carrying state S2.

[0070] As shown in FIG. 7 , in a rotational speed range lower than the switching speed Vc, the first driving torque T1 is greater than the second driving torque T2. As described above, in the first current-carrying state S1, current is supplied to both the first coil portion 54 and the second coil portion 59, thereby increasing the magnetic field strength generated by the stator 50. In contrast, in the second current-carrying state S2, current is supplied only to the first coil portion 54, thereby reducing the magnetic field strength generated by the stator 50 compared to the first current-carrying state S1. As a result, the electromagnetic force applied to the magnets 42 of the rotor 40 is smaller in the second current-carrying state S2 than in the first current-carrying state S1. Therefore, in a rotational speed range lower than the switching speed Vc, the first driving torque T1 is greater than the second driving torque T2.

[0071] The decrease in the first driving torque T1 relative to the increase in the rotational speed Vr of the rotor 40 is greater than the decrease in the second driving torque T2. Therefore, in a rotational speed range higher than the switching speed Vc, the second driving torque T2 is greater than the first driving torque T1. As described above, in the first current-carrying state S1, an induced voltage is generated in each of the first coil portion 54 and the second coil portion 59, whereas in the second current-carrying state S2, no induced voltage is generated in the second coil portion 59. Therefore, as described above, the induced voltage generated in the stator 50 can be reduced in the second current-carrying state S2 compared to the first current-carrying state S1, thereby suppressing a decrease in the driving torque in a high-speed rotational speed range. Therefore, in the high-speed rotational speed range, the second driving torque T2 is greater than the first driving torque T1. Furthermore, the maximum rotational speed V2 of the rotor 40 in the second current-carrying state S2 is faster than the maximum rotational speed V1 of the rotor 40 in the first current-carrying state S1. Therefore, the rotational speed range of the rotor 40 in the second current-carrying state S2 is wider than the rotational speed range of the rotor 40 in the first current-carrying state S1.

[0072] In this embodiment, the control unit 79 sets the connection circuit unit 75 to the first current-carrying state S1 when the rotational speed Vr of the rotor 40 is less than a predetermined switching speed Vc, and sets the connection circuit unit 75 to the second current-carrying state S2 when the rotational speed Vr of the rotor 40 is equal to or greater than the switching speed Vc. This increases the drive torque of the rotor 40 in a low-speed rotation range below the switching speed Vc. It also increases the drive torque of the rotor 40 in a high-speed rotation range above the switching speed Vc, and broadens the rotational speed range of the rotor 40. Furthermore, because the drive torque of the rotor 40 can be increased in both the low-speed rotation range and the high-speed rotation range, the drive efficiency of the motor 10 can be improved.

[0073] According to this embodiment, the stator 50 has a first stator 51 arranged above the rotor 40, i.e., on one axial side (+Z side), and a second stator 56 arranged below the rotor 40, i.e., on the other axial side (-Z side). The first stator 51 has a first stator core 52 surrounding the central axis J and a plurality of first coil portions 54 attached to the first stator core 52 and arranged at intervals from each other along the circumferential direction. The second stator 56 has a second stator core 57 surrounding the central axis J and a plurality of second coil portions 59 attached to the second stator core 57 and arranged at intervals from each other along the circumferential direction. The circuit unit 70 includes a connection circuit unit 75 that connects the first coil unit 54 and the second coil unit 59 in series. The connection circuit unit 75 is switchable between a first current-carrying state S1, in which current is supplied to both the first coil unit 54 and the second coil unit 59, and a second current-carrying state S2, in which current is supplied to only one of the first coil unit 54 and the second coil unit 59. Therefore, as described above, in the low-speed rotation range, setting the connection circuit unit 75 to the first current-carrying state S1 increases the drive torque of the rotor 40 in the low-speed rotation range. Furthermore, in the high-speed rotation range, setting the connection circuit unit 75 to the second current-carrying state S2 suppresses a decrease in the drive torque of the rotor 40 in the high-speed rotation range, thereby increasing the maximum rotation speed of the rotor 40. This widens the rotational speed range of the rotor 40. Therefore, the drive torque of the rotor 40 can be increased in both the low-speed rotation range and the high-speed rotation range by switching the connection circuit unit 75 between the first current-flow state S1 and the second current-flow state S2 in accordance with the rotation speed Vr of the rotor 40. This allows the rotation speed range of the rotor 40 to be widened and the drive efficiency of the motor 10 to be improved.

[0074] According to this embodiment, the connection circuit unit 75 has a first connection line 76 that connects the first coil unit 54 and the second coil unit 59 in series, and a first switching element 76a is arranged on the first connection line 76. The first switching element 76a electrically connects the first coil unit 54 and the second coil unit 59 in a first current-carrying state S1 and electrically insulates the first coil unit 54 from the second coil unit 59 in a second current-carrying state S2. For example, even in a configuration in which the circuit unit 70 has two inverter circuit units 72, one inverter circuit unit 72 is electrically connected to the first coil unit 54 and the other inverter circuit unit 72 is electrically connected to the second coil unit 59, it is possible to realize a state in which current is supplied to both the first coil unit 54 and the second coil unit 59 and a state in which current is supplied to only one of the first coil unit 54 and the second coil unit 59. However, in a circuit unit 70 having such a configuration, the number of inverter circuits 72 included in the circuit unit 70 increases, which increases the manufacturing cost and number of steps required for manufacturing the circuit unit 70. In contrast, in the present embodiment, the first switching element 76a can switch the connection circuit unit 75 between the first current-carrying state S1 and the second current-carrying state S2, which prevents an increase in the number of inverter circuits 72 included in the circuit unit 70. Therefore, an increase in the manufacturing cost and number of steps required for manufacturing the circuit unit 70 can be prevented.

[0075] According to the present embodiment, connection circuit unit 75 has a plurality of first connection lines 76, the plurality of first coil units 54 including first U-phase coil unit 54U, first V-phase coil unit 54V, and first W-phase coil unit 54W, the plurality of second coil units 59 including second U-phase coil unit 59U, second V-phase coil unit 59V, and second W-phase coil unit 59W, and the plurality of first connection lines 76 including a U-phase connection line 76U connecting first U-phase coil unit 54U and second U-phase coil unit 59U in series, a V-phase connection line 76V connecting first V-phase coil unit 54V and second V-phase coil unit 59V in series, and a W-phase connection line 76W connecting first W-phase coil unit 54W and second W-phase coil unit 59W in series. The U-phase connecting line 76U, the V-phase connecting line 76V, and the W-phase connecting line 76W are each connected by a second connecting line 77, and a plurality of second switching elements 77a are arranged on the second connecting line 77. The plurality of second switching elements 77a electrically insulate the plurality of first connecting lines 76 from one another in the first current-carrying state S1 and electrically connect the plurality of first connecting lines 76 to one another in the second current-carrying state S2. Therefore, the second switching elements 77a can switch the connection circuit unit 75 between the first current-carrying state S1 and the second current-carrying state S2, thereby preventing an increase in the number of inverter circuits 72 included in the circuit unit 70. This more effectively prevents an increase in the manufacturing cost and man-hours of the circuit unit 70.

[0076] According to the present embodiment, the motor 10 includes a plurality of bus bars 60 electrically connecting the stator 50 and the circuit unit 70. The circuit unit 70 has an inverter circuit unit 72 that generates a current. The plurality of bus bars 60 includes a first bus bar 61 electrically connecting one end of the first coil unit 54 to the inverter circuit unit 72, a second bus bar 62 electrically connecting the other end of the first coil unit 54 to one end of the first connection line 76, and a third bus bar 63 electrically connecting the other end of the first connection line 76 to the second coil unit 59. Therefore, the first bus bar 61, the second bus bar 62, and the third bus bar 63 enable both the inverter circuit unit 72 and the connection circuit unit 75 to be mounted on the same circuit board 71, and the first coil unit 54 and the second coil unit 59 to be connected in series via the connection circuit unit 75. Therefore, the configuration of the circuit unit 70 can be simplified compared to a configuration in which the inverter circuit unit 72 and the connection circuit unit 75 are mounted on different circuit boards. Therefore, an increase in the manufacturing cost and manufacturing steps of the circuit section 70 can be more effectively suppressed.

[0077] According to this embodiment, the connection circuit unit 75 is set to the first current-carrying state S1 when the rotational speed Vr of the rotor 40 is less than a predetermined switching speed Vc, and is set to the second current-carrying state S2 when the rotational speed Vr of the rotor 40 is equal to or greater than the switching speed Vc. Therefore, as described above, in the low-speed rotation range below the switching speed Vc, the drive torque of the rotor 40 can be increased by setting the connection circuit unit 75 to the first current-carrying state S1. Furthermore, in the high-speed rotation range above the switching speed Vc, the decrease in drive torque of the rotor 40 can be suppressed by setting the connection circuit unit 75 to the second current-carrying state S2. Therefore, the rotational speed range of the rotor 40 can be more preferably widened, and the drive efficiency of the motor 10 can be more preferably improved.

[0078] The present invention is not limited to the above-described embodiment, and other configurations and methods may be adopted within the scope of the technical concept of the present invention. For example, the first switching elements may be arranged in each of the U-phase connecting line and the V-phase connecting line, or in each of the V-phase connecting line and the W-phase connecting line. Furthermore, the connection circuit unit may have three first switching elements, and in this case, it is preferable that each first switching element is arranged in each of the U-phase connecting line, the V-phase connecting line, and the W-phase connecting line.

[0079] Although the embodiments of the present invention have been described above, the configurations and combinations thereof in the embodiments are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments.

[0080] The present technology can be configured as follows. (1) A motor including: a rotor rotatable about a central axis; a stator facing the rotor with an axial gap; and a circuit unit supplying current to the stator, wherein the stator has a first stator arranged on one axial side of the rotor and a second stator arranged on the other axial side of the rotor; the first stator has a first stator core surrounding the central axis and a plurality of first coil units attached to the first stator core and spaced apart along the circumferential direction; the second stator has a second stator core surrounding the central axis and a plurality of second coil units attached to the second stator core and spaced apart along the circumferential direction; the circuit unit has a connection circuit unit connecting the first coil units and the second coil units in series, and the connection circuit unit is switchable between a first current-carrying state in which current is supplied to both the first coil units and the second coil units, and a second current-carrying state in which the current is supplied to only one of the first coil units and the second coil units. (2) The motor described in (1), wherein the connection circuit section has a first connection line that connects the first coil section and the second coil section in series, and a first switching element is disposed on the first connection line, and the first switching element electrically connects the first coil section and the second coil section in the first current-carrying state and electrically insulates the first coil section and the second coil section in the second current-carrying state.(3) the plurality of second coil portions include a second U-phase coil portion, a second V-phase coil portion, and a second W-phase coil portion; the plurality of first connection lines include a U-phase connection line connecting the first U-phase coil portion and the second U-phase coil portion in series, a V-phase connection line connecting the first V-phase coil portion and the second V-phase coil portion in series, and a W-phase connection line connecting the first W-phase coil portion and the second W-phase coil portion in series; the U-phase connection line, the V-phase connection line, and the W-phase connection line are each connected by a second connection line; and a plurality of second switching elements are arranged on the second connection line, and the plurality of second switching elements electrically insulate the plurality of first connection lines from each other in the first current-carrying state and electrically connect the plurality of first connection lines to each other in the second current-carrying state. (4) The motor according to (2) or (3), further comprising: a plurality of bus bars electrically connecting the stator and the circuit unit, the circuit unit having an inverter circuit unit that generates the current, the plurality of bus bars including a first bus bar electrically connecting one end of the first coil unit to the inverter circuit unit, a second bus bar electrically connecting the other end of the first coil unit to one end of the first connection line, and a third bus bar electrically connecting the other end of the first connection line to the second coil unit. (5) The motor according to any one of (1) to (4), further comprising: a connection circuit unit that is set to the first current-carrying state when a rotational speed of the rotor is less than a predetermined switching speed, and that is set to the second current-carrying state when the rotational speed of the rotor is equal to or greater than the switching speed.

[0081] 10...motor, 40...rotor, 50...stator, 51...first stator, 52...first stator core, 54...first coil portion, 54U...first U-phase coil portion, 54V...first V-phase coil portion, 54W...first W-phase coil portion, 56...second stator, 57...second stator core, 59...second coil portion, 59U...second U-phase coil portion, 59V...second V-phase coil portion, 59W...second W-phase coil portion, 60...bus bar, 61...first bus bar, 62...second bus bar, 63...third bus bar, 70...circuit section, 72...inverter circuit section, 75...connection circuit section, 76...first connection line, 76a...first switching element, 76U...U-phase connection line, 76V...V-phase connection line, 76W...W-phase connection line, 77...second connection line, 77a...second switching element, J...central axis, S1...first current-carrying state, S2...second current-carrying state, Vc...switching speed, Vr...rotor rotation speed

Claims

1. A motor comprising: a rotor rotatable about a central axis; a stator facing the rotor with an axial gap; and a circuit unit supplying current to the stator, wherein the stator has a first stator arranged on one axial side of the rotor and a second stator arranged on the other axial side of the rotor, the first stator having a first stator core surrounding the central axis and a plurality of first coil units attached to the first stator core and spaced apart along the circumferential direction, the second stator having a second stator core surrounding the central axis and a plurality of second coil units attached to the second stator core and spaced apart along the circumferential direction, the circuit unit having a connection circuit unit connecting the first coil units and the second coil units in series, and the connection circuit unit switchable between a first current-carrying state in which current is supplied to both the first coil units and the second coil units, and a second current-carrying state in which the current is supplied to only one of the first coil units and the second coil units.

2. The motor described in claim 1, wherein the connection circuit section has a first connection line that connects the first coil section and the second coil section in series, a first switching element is arranged on the first connection line, and the first switching element electrically connects the first coil section and the second coil section in the first current-carrying state and electrically insulates the first coil section and the second coil section in the second current-carrying state.

3. The connection circuit unit has a plurality of the first connection lines, the plurality of first coil units including a first U-phase coil unit, a first V-phase coil unit, and a first W-phase coil unit, the plurality of second coil units including a second U-phase coil unit, a second V-phase coil unit, and a second W-phase coil unit, the plurality of first connection lines including a U-phase connection line connecting the first U-phase coil unit and the second U-phase coil unit in series, a V-phase connection line connecting the first V-phase coil unit and the second V-phase coil unit in series, and a W-phase connection line connecting the first W-phase coil unit and the second W-phase coil unit in series, the U-phase connection line, the V-phase connection line, and the W-phase connection line are each connected by a second connection line, and a plurality of second switching elements are arranged on the second connection line, 3. The motor according to claim 2, wherein the second switching elements electrically insulate the first connection lines from one another in the first current-carrying state, and electrically connect the first connection lines to one another in the second current-carrying state.

4. The motor according to claim 2, further comprising a plurality of bus bars electrically connecting the stator and the circuit section, the circuit section having an inverter circuit section that generates the current, the plurality of bus bars including a first bus bar electrically connecting one end of the first coil section and the inverter circuit section, a second bus bar electrically connecting the other end of the first coil section and one end of the first connection line, and a third bus bar electrically connecting the other end of the first connection line and the second coil section.

5. A motor as claimed in any one of claims 1 to 4, wherein the connection circuit unit is set to the first current-carrying state when the rotational speed of the rotor is less than a predetermined switching speed, and is set to the second current-carrying state when the rotational speed of the rotor is equal to or greater than the switching speed.

Images