Winding field rotor and rotating electric machine

Abstract

A winding field rotor (60) that can be applied to a winding field type rotating electric machine (40) comprises: a rotor core (70) that has main pole parts (72) which are provided for each of magnetic poles arranged in the circumferential direction and which protrude in the radial direction; and field windings (80, 180). The field windings are formed by winding conductive wires (90, 190) around the main pole parts with the radial direction as the winding-axis direction. The conductive wires comprises, as conductors, strands (91, 191) that are aggregates in which a plurality of wire elements (91a, 191a) are twisted. The conductive wires are wound around the main pole parts so that the direction, in which the conductive wires are to rotate due to the centrifugal force acting on the conductive wires while the winding field rotor rotates, coincides with the direction in which the twisting of the strands tightens.

Description

Wound field rotor, rotating electric machine CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2023-118860, filed on July 21, 2023, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a wound field rotor and a rotating electric machine including the wound field rotor.

[0003] Patent Document 1 describes the use of a wire strand, which is a bundle of multiple wires made of copper or a copper alloy, as the rotor coil of a variable-speed generator-motor. A reinforcing member is joined to the end of the wire strand to prevent deformation of the coil end portion due to centrifugal force acting when the rotor rotates.

[0004] Japanese Patent Application Laid-Open No. 2015-180175

[0005] In Patent Document 1, a reinforcing member is used to prevent deformation (e.g., unraveling) caused by centrifugal force acting on the end of a twisted wire such as a wire strand. However, the reinforcing member cannot sufficiently prevent deformation caused by centrifugal force acting on a portion of the twisted wire far from the end.

[0006] In view of the above, an object of the present disclosure is to provide a technique for preventing a twisted wire from unwinding when a rotor rotates, when a twisted wire is provided as a field winding.

[0007] The first disclosure relates to a wound field rotor that is applied to a wound field type rotating electric machine, comprising: a rotor core that is provided for each circumferentially arranged magnetic pole and has main pole portions that protrude in the radial direction; and a field winding, wherein the field winding is configured by winding a conductor around each main pole portion with the radial direction as the winding axis direction, and the conductor has a twisted wire that is an assembly of multiple strands twisted together as a conductor, and the conductor is wound around each main pole portion so that the direction in which the conductor tends to rotate due to centrifugal force acting on the conductor when the wound field rotor rotates coincides with the direction in which the twist of the twisted wire is tightened.

[0008] In the first disclosure, the conducting wire that constitutes the field winding has a stranded wire as a conductor, which is an assembly of multiple strands twisted together. The conducting wire is wound around each main pole portion so that the direction in which the conducting wire tends to rotate due to centrifugal force acting on the conducting wire when the rotor rotates coincides with the direction in which the twist of the stranded wire tightens. Therefore, the twist of the stranded wire tightens when the rotor rotates. This prevents the stranded wire from unwinding when the rotor rotates.

[0009] A second disclosure is a wound field rotor that is applied to a wound field type rotating electric machine, comprising: a rotor core having main pole portions that are provided for each circumferentially arranged magnetic pole and that protrude in the radial direction; and a field winding, wherein the field winding is configured by winding a conductor around each main pole portion with the radial direction as the winding axis direction, and the conductor wire comprises a stranded wire that is an assembly of a plurality of strands twisted together as a conductor, when the main pole portion is viewed along the radial direction from the rotation center axis side of the wound field rotor toward the main pole portion, a portion of the field winding that is located to the right of the main pole portion is defined as a right portion, and a portion of the field winding that is located to the left of the main pole portion is defined as a left portion, when the right portion is viewed from the axial direction that is the direction in which the rotation center axis extends, the twist direction of the stranded wire that constitutes the right portion is counterclockwise, and when the left portion is viewed from the axial direction, the twist direction of the stranded wire that constitutes the left portion is clockwise.

[0010] In the second disclosure, the conductors of the field winding are twisted wires, which are an assembly of multiple strands twisted together. The twisted wires of the right portion of the field winding are twisted counterclockwise, e.g., Z-twist. In this case, the twisted direction of the twisted wires of the right portion coincides with the direction in which the conductors of the right portion tend to rotate due to centrifugal force acting on the conductors of the right portion as the rotor rotates. The twisted wires of the left portion of the field winding are twisted clockwise, e.g., S-twist. In this case, the twisted direction of the twisted wires of the left portion coincides with the direction in which the conductors of the left portion tend to rotate due to centrifugal force acting on the conductors of the left portion as the rotor rotates. Therefore, according to the second disclosure, the twist of the twisted wires of the right and left portions is tightened when the rotor rotates. This prevents the twisted wires from unwinding when the rotor rotates.

[0011] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is an overall configuration diagram of a control system for a rotating electric machine according to a first embodiment, Fig. 2 is a diagram showing an inverter and its peripheral configuration, Fig. 3 is a cross-sectional view of a rotor provided in the rotating electric machine, Fig. 4 is a diagram showing a resonant circuit provided in the rotor, Fig. 5 is a cross-sectional view of a conductor constituting a field winding, Fig. 6 is an external view of stranded wires constituting the conductor, Fig. 7 is a diagram explaining centrifugal force acting on the conductor when the rotor rotates, Fig. 8 is a cross-sectional view of a rotor provided in a rotating electric machine according to a second embodiment, Fig. 9 is a cross-sectional view of a conductor constituting a field winding, and Fig. 10 is a diagram showing a holding member attached to the end of a conductor according to another embodiment.

[0012] 1 , the control system includes a DC power supply 10, an inverter 20, a control unit 30, and a rotating electric machine 40. The rotating electric machine 40 is a wound-field type synchronous machine, and more specifically, a synchronous induction excitation type rotating electric machine. In this embodiment, the control unit 30 controls the rotating electric machine 40 so that the rotating electric machine 40 functions as an integrated starter generator (ISG) or a motor generator (MG), which also functions as a motor and generator. For example, the rotating electric machine 40, the inverter 20, and the control unit 30 may form an electromechanical integrated drive device, or the rotating electric machine 40, the inverter 20, and the control unit 30 may each be formed by a respective component.

[0013] An overview of the rotating electric machine 40 will be described using Fig. 1. The rotating electric machine 40 includes a housing 41, and a stator 50 and a rotor 60 housed within the housing 41. The rotating electric machine 40 of this embodiment is an inner rotor type in which the rotor 60 is disposed radially inside the stator 50.

[0014] The stator 50 includes a stator core 51 and a stator winding 52 wound around the stator core 51. The stator core 51 is made of laminated steel plates made of a soft magnetic material, and has an annular back yoke and a plurality of teeth protruding radially inward from the back yoke. The stator winding 52 is made of, for example, copper wire, and includes U-, V-, and W-phase windings 52U, 52V, and 52W that are arranged with a 120° electrical angle offset from one another.

[0015] The rotor 60 includes a rotor core 70 and a field winding 80. The rotor core 70 is made of a soft magnetic material, such as laminated steel plates. The field winding 80 may be made of, for example, aluminum wire or copper wire.

[0016] A rotating shaft 32 is inserted through the central hole of the rotor core 70. The rotating shaft 32 is rotatably supported by the housing 41 via bearings 42. The stator 50 and the rotor 60 are both arranged coaxially with the rotating shaft 32. In the following description, the direction in which the rotating shaft 32 extends is referred to as the axial direction, the direction extending radially from the center of the rotating shaft 32 is referred to as the radial direction, and the direction extending circumferentially around the rotating shaft 32 is referred to as the circumferential direction.

[0017] As shown in FIG. 2 , the inverter 20 includes a series connection of U-, V-, and W-phase upper-arm switches SUp, SVp, and SWp and U-, V-, and W-phase lower-arm switches SUn, SVn, and SWn. First ends of U-, V-, and W-phase windings 52U, 52V, and 52W are connected to the connection points between the U-, V-, and W-phase upper-arm switches SUp, SVp, and SWp and the U-, V-, and W-phase lower-arm switches SUn, SVn, and SWn. Second ends of the U-, V-, and W-phase windings 52U, 52V, and 52W are connected to the neutral point. That is, in this embodiment, the U-, V-, and W-phase windings 52U, 52V, and 52W are star-connected. In this embodiment, each of the switches SUp to SWn is an IGBT. A freewheel diode is connected in anti-parallel to each of SUp, SVp, SWp, SUn, SVn, and SWn.

[0018] The collectors of the U-, V-, and W-phase upper-arm switches SUp, SVp, and SWp are connected to a positive terminal of a DC power supply 10. The emitters of the U-, V-, and W-phase lower-arm switches SUn, SVn, and SWn are connected to a negative terminal of the DC power supply 10. A smoothing capacitor 11 is connected in parallel to the DC power supply 10.

[0019] As shown in Fig. 3, in the rotor 60, the rotor core 70 has a cylindrical portion 71 as a cylindrical yoke portion, a plurality of main pole portions 72 provided for each magnetic pole aligned in the circumferential direction and protruding radially outward from the cylindrical portion 71, and flange portions 74 extending radially from the tip ends of the main pole portions 72. In this embodiment, the main pole portions 72 are provided at equal intervals in the circumferential direction. Note that the Z-axis direction shown in Fig. 3 and other figures is a direction parallel to the rotational center axis O of the rotation shaft 32 of the rotor 60.

[0020] The field winding 80 includes a first winding portion 81 and a second winding portion 82. In each main pole portion 72, the first winding portion 81 is wound radially outward, and the second winding portion 82 is wound radially inward relative to the first winding portion 81. In each main pole portion 72, the winding directions of the first winding portion 81 and the second winding portion 82 are the same. Furthermore, of circumferentially adjacent main pole portions 72, the winding directions of the winding portions 81, 82 wound around one are opposite to the winding directions of the winding portions 81, 82 wound around the other. Therefore, the magnetization directions of circumferentially adjacent main pole portions 72 are opposite to each other.

[0021] The field winding 80 is configured by winding a conductor 90 around each main pole 72 with the radial direction of the rotor 60 as the winding axis. The field winding 80 includes a straight portion extending along the Z-axis direction on the radial side surface of the main pole 72 and a transition portion connecting the ends of the straight portion and extending circumferentially around the rotor 60. FIG. 3 shows a cross section of the straight portion of the field winding 80. The straight portion is longer than the transition portion, and most of the conductor 90 constitutes the straight portion. When viewed along the radial direction of the rotor 60 from the rotation center axis O of the rotor 60 toward each main pole 72, the straight portion extends in the vertical direction on both radial sides of each main pole 72. The transition portions extend in the horizontal direction above and below each main pole 72. Note that hereinafter, the positive direction of the Z-axis shown in FIG. 3 may be referred to as the upward direction, and the negative direction of the Z-axis may be referred to as the downward direction.

[0022] The central axis of the main pole portion 72, which passes through the central rotation axis O of the rotating shaft 32 of the rotor 60 and extends radially, is defined as a first axis B1. Furthermore, the axis that passes through the central positions in the circumferential direction of the first axes B1 adjacent to each other in the circumferential direction and the central rotation axis O and extends radially is defined as a second axis B2. The first axis B1 corresponds to the d-axis, and the second axis B2 corresponds to the q-axis.

[0023] 4 shows an electrical circuit on the rotor 60 side, which includes windings 81, 82 wound around a common main pole 72. The rotor 60 is provided with a diode 83 as a rectifying element and a capacitor 84. A first end of the first winding 81 is connected to the cathode of the diode 83, and a first end of the second winding 82 is connected to the second end of the first winding 81. An anode of the diode 83 is connected to the second end of the second winding 82. A capacitor 84 is connected in parallel to the second winding 82. Alternatively, the first end of the first winding 81 may be connected to the anode of the diode 83, and the second end of the second winding 82 may be connected to the cathode of the diode 83.

[0024] In this embodiment, a series resonant circuit is formed by the first winding portion 81, the capacitor 84, and the diode 83, and a parallel resonant circuit is formed by the second winding portion 82 and the capacitor 84.

[0025] 2, the control unit 30 is an electronic control unit (ECU) that generates drive signals that turn on and off the switches SUp to SWn that configure the inverter 20. Specifically, the control unit 30 generates drive signals that turn on and off the arm switches SUp to SWn in order to convert the DC power output from the DC power supply 10 into AC power and supply the AC power to the U-, V-, and W-phase windings 52U, 52V, and 52W, and supplies the generated drive signals to the gates of the arm switches SUp to SWn.

[0026] The control unit 30 turns on and off each of the switches SUp to SWn so that a composite current of the fundamental current and the high-frequency excitation current flows through each of the phase windings 52U, 52V, and 52W. The fundamental current is a current that mainly generates torque in the rotating electric machine 40. The high-frequency excitation current is a current with a higher frequency than the fundamental current, and is a current that mainly excites the field winding 80 and causes a field current to flow through the field winding 80. The phase currents flowing through the phase windings 52U, 52V, and 52W are shifted by 120 electrical degrees.

[0027] Note that some or all of the functions of the control unit 30 may be configured in hardware, for example, using one or more integrated circuits, etc. Also, the functions of the control unit 30 may be configured, for example, using software recorded on a non-transitory physical recording medium and a computer that executes the software.

[0028] 5 and 6 , the conductor 90 constituting the field winding 80 includes a stranded wire 91, which is an assembly of a plurality of stranded wires 91a. The stranded wires 91a are conductors whose surfaces are covered with a polymer insulating layer such as enamel. The conductor 90 is a coated conductor in which the stranded wires 91, which are an assembly of stranded wires 91a, are covered with an insulating coating 92. The field winding 80 is configured by winding the conductor 90 around the main pole portion 72, and insulation is ensured between the conductors 90 that overlap each other in the radial direction, and between the conductor 90 and the rotor core 70.

[0029] As shown in Fig. 5, the cross section perpendicular to the axial direction of the wire 91a is circular, and the cross section perpendicular to the axial direction of the conductor 90 is also circular. While Fig. 5 exemplarily illustrates a case in which four wires 91a of substantially the same shape, size, and material are twisted together to form the stranded wire 91, this is not limitative. The number of wires 91a is not limited to four. Alternatively, the stranded wire may be formed by twisting together a plurality of wires of different shapes, sizes, and materials.

[0030] The wires 91a are preferably made of at least carbon fiber and configured as a carbon fiber composite. This reduces the weight of the wires 91a, thereby reducing the weight of the conductor 90 and the field winding 80. Furthermore, reducing the weight of the field winding 80 reduces the centrifugal force acting on the field winding 80 when the rotor 60 rotates, allowing the thickness of the flange 74 to be thinned, and ultimately the radial size of the rotor 60 to be reduced. Nanocarbon fibers such as carbon nanotubes and carbon nanofibers can be suitably used as the carbon fibers, and they may be those in which part of the carbon is substituted with boron or the like. The stranded wire 91 can be configured, for example, as follows.

[0031] (A) All of the strands 91a constituting the stranded wire 91 are made of carbon fiber.

[0032] (B) Of all the wires 91a constituting the stranded wire 91, some of the wires are made of carbon fiber, and the remaining wires are made of a material other than carbon fiber (for example, copper or aluminum).

[0033] (C) All of the wires 91a constituting the stranded wire 91 are wires (composite wires) made of a mixture of carbon fiber and a metal material.

[0034] (D) Of all the wires 91a constituting the twisted wire 91, some of the wires are wires (composite wires) made of a mixed material of carbon fiber and a metal material, and the remaining wires are wires made of a material other than the mixed material (for example, wires made of carbon fiber, wires made of copper, or wires made of aluminum).

[0035] The conductor 90 has a twisted wire 91, which is an assembly of multiple wires 91a, as a conductor. This reduces the electrical resistance in the path through which eddy currents flow compared to a conductor made of a single wire. The greater the number of wires 91a, the smaller the cross-sectional area per wire 91a, resulting in a greater eddy current attenuation effect. Furthermore, in the field winding 80, the wires 91a are twisted, creating portions in each wire 91a where the magnetic field is applied in opposite directions, thereby canceling out back electromotive force. This also reduces eddy currents. In a rotating electric machine 40 using a synchronous induction excitation method, the frequency of the high-frequency excitation current used to excite the rotor 60 is relatively high. The higher the frequency of the high-frequency excitation current, the larger the eddy currents that can be generated in the field winding 80 of the rotor 60, which tends to increase eddy current losses. Therefore, in the rotating electric machine 40, by forming the field winding 80 using the conductor 90 having the twisted wire 91 as a conductor, the effect of reducing eddy currents can be more significantly obtained.

[0036] Stranded wires 91Z and 91S having different twisting directions can be suitably used as the twisted wire 91. When multiple element wires 91a are twisted counterclockwise (left-handed) from the negative side to the positive side of the Z axis, the Z-twisted stranded wire 91Z shown in Fig. 6(a) is formed. When multiple element wires 91a are twisted clockwise (right-handed) from the negative side to the positive side of the Z axis, the S-twisted stranded wire 91S shown in Fig. 6(b) is formed.

[0037] The conductor 90 is wound around the main pole portion 72 so that the direction in which the conductor 90 rotates due to the centrifugal force acting on the conductor 90 when the rotor 60 rotates coincides with the direction in which the twist of the twisted wire 91 that makes up the conductor 90 tightens.

[0038] As shown in FIG. 7 , when the main poles 72 are viewed radially from the central axis O of rotation of the rotor 60 toward the main poles 72, the portion of the field winding 80 located to the right of the main poles 72 is referred to as the right portion 80R, and the portion located to the left of the main poles 72 is referred to as the left portion 80L. When the right portion 80R is viewed axially, the twisted wires 91 constituting the right portion 80R are twisted counterclockwise and are Z-twisted in this embodiment. When the left portion 80L is viewed axially, the twisted wires 91 constituting the left portion 80L are twisted clockwise and are S-twisted in this embodiment. Such a field winding 80 may be formed, for example, from conductor wires 90 twisted so that Z-twisted portions and S-twisted portions alternately appear.

[0039] 7 is a diagram for simply explaining the direction in which the conductor 90 rotates due to the centrifugal force acting on the conductor 90 when the rotor 60 rotates. As shown by the arrow ROT in FIG. 7 , when the rotor 60 rotates around the central axis of rotation O, a centrifugal force CR acts on the right portion 80R of the conductor 90, and a centrifugal force CL acts on the left portion 80L of the conductor 90. The directions of the centrifugal forces CR and CL are parallel to the radial direction of the rotor 60, and are directed from the central axis of rotation O side toward the periphery of the rotor 60.

[0040] The centrifugal force CR acts as a force that rotates each conductor wire 90 in the right portion 80R counterclockwise as viewed from the positive direction of the Z axis, as indicated by the rotation direction KR. The rotation direction KR can also be considered a direction of rotation in a left-handed screw direction. In the right portion 80R, the twisted wire 91 is a Z-twisted twisted wire 91Z. The twisted direction of the twisted wire 91Z is the direction in which the twist tightens when each conductor wire 90 in the right portion 80R is rotated counterclockwise as viewed from the positive direction of the Z axis. Therefore, the direction in which each conductor wire 90 rotates due to the centrifugal force CR (rotation direction KR) coincides with the direction in which the twist of the twisted wire 91Z tightens.

[0041] The centrifugal force CL acts as a force that rotates each conductor wire 90 in the left portion 80L clockwise as viewed from the positive direction of the Z axis, as indicated by the rotation direction KL. The rotation direction KL can also be considered a direction of rotation in a right-handed screw direction. In the left portion 80L, the twisted wire 91 is an S-twisted twisted wire 91S. The twisted direction of the twisted wire 91S is the direction in which the twist is tightened when each conductor wire 90 in the left portion 80L is rotated counterclockwise as viewed from the positive direction of the Z axis. Therefore, the direction in which the conductor wire 90 rotates due to the centrifugal force CL (rotation direction KL) coincides with the direction in which the twist of the twisted wire 91S is tightened.

[0042] As shown in the rotation directions KR and KL, when the rotor 60 rotates, the centrifugal forces CR and CL acting on each conductor 90 tend to rotate each conductor 90 in a direction such that the surface farthest from the main pole portion 72 around which the conductor 90 is wound faces away from the rotation center axis O of the rotor 60 toward the periphery.

[0043] As described above, when the rotor 60 rotates, the conductor 90 rotates in a direction such that the surface farthest from the main pole portion 72 moves from the central axis O of the rotor 60 toward the periphery. Therefore, it is preferable that the conductor 90 be wound around the main pole portion 72 so that this direction of rotation coincides with the direction in which the twist of the twisted wire 91 is tightened.

[0044] In this embodiment, the straight portions are longer than the crossover portions, and most of the conductor 90 constitutes the straight portions. Therefore, if the direction in which the conductor 90 tends to rotate due to centrifugal force acting on the conductor 90 when the rotor 60 rotates is configured to coincide with the direction in which the twist of the stranded wires 91 constituting the conductor 90 is tightened at the straight portions, the effect of suppressing unraveling of the stranded wires 91 as a whole can be sufficiently obtained. Even if some of the conductors 90 constituting the field winding 80 do not coincide with the direction in which the twist of the stranded wires 91 is tightened, as long as the direction in which the twist of the stranded wires 91 is tightened for most of the other conductors 90, it can be said that the field winding 80 is configured by winding the conductor 90 around each main pole portion 72 so that the direction in which the conductor 90 tends to rotate due to centrifugal force acting on the conductor 90 when the rotor 60 rotates coincides with the direction in which the twist of the stranded wires 91 is tightened. In order to obtain the effect of suppressing the unwinding of the twisted wires 91 in the field winding 80, the proportion of the portion of the conductors 90 constituting the field winding 80 that coincides with the direction in which the twist of the twisted wires 91 is tightened should be 60% or more, and preferably 70% or more.

[0045] The centrifugal forces CR and CL act in a direction from the rotational center axis O of the rotor 60 toward the periphery, regardless of the rotation direction of the rotor 60. For this reason, if the conductor 90 is wound around the main pole portion 72 such that the stranded wire 91 is Z-twisted in the right portion 80R and S-twisted in the left portion 80L in the cross section shown in Figure 3, as in the field winding 80, the centrifugal forces CR and CL will tighten the twist of the stranded wire 91, regardless of the rotation direction of the rotor 60.

[0046] As shown in Fig. 5, the cross section perpendicular to the axial direction of the wire 91a is circular, and the cross section perpendicular to the axial direction of the conductor 90 is also circular. As shown in Fig. 3, the conductor 90 is wound around the main pole portion 72 with the axial positions of adjacent conductors 90 in the circumferential direction of the rotor 60 shifted from each other in the radial direction of the rotor 60. More specifically, the conductor 90 is wound around the main pole portion 72 so that the circles representing the cross sections of the conductor 90 are approximately closest packed in the cross section of the rotor 60 shown in Fig. 3. By winding the conductor 90 around the main pole portion 72 in this manner, the space factor of the field winding 80 in the rotor 60 can be increased, and ultimately the output of the rotating electric machine 40 can be improved. In addition, since the gaps between adjacent conductors 90 are small and each conductor 90 is less likely to move, the positional relationship between each conductor 90 in the circumferential and radial directions of the rotor 60 is prevented from shifting, and the twisted wires 91 that make up each conductor 90 are prevented from untwisting.

[0047] Second Embodiment A rotating electric machine may be provided with a rotor 160 having a field winding 180 as shown in Figures 8 and 9 instead of the field winding 80 according to the first embodiment. In Figures 8 and 9, the same reference numerals are used for components similar to those of the first embodiment, and descriptions thereof will be omitted. The field winding 180 has a first winding portion 181 and a second winding portion 182. The field winding 180 differs from the field winding 80 only in the conductor 190 and the way it is wound, and the first winding portion 181 is similar to the first winding portion 81, and the second winding portion 182 is similar to the second winding portion 82, and therefore descriptions thereof will be omitted.

[0048] As shown in Figure 9, the conducting wire 190 constituting the field winding 180 has a stranded wire 191, which is an assembly of a plurality of strands 191a, as a conductor. Like the strands 91a, the strands 191a are conductors whose surfaces are covered with a polymer insulating layer. The conducting wire 190 is a coated conducting wire in which the stranded wire 191, which is an assembly of strands 191a, is covered with an insulating coating 192. The material constituting the conducting wire 190 is the same as the material constituting the conducting wire 90.

[0049] 9, the cross section perpendicular to the axial direction of the wire 191a is rectangular, for example, a rectangular shape. The cross section perpendicular to the axial direction of the conductor 190 is rectangular, for example, a rectangular shape. The stranded wire 91 is formed by twisting together wires 191a that are substantially the same in shape, size, and material.

[0050] The conductor 190 constituting the field winding 180 is wound around the main pole portion 72 so that the twist direction of the stranded wire 191 coincides with the direction in which the conductor 190 tends to rotate due to centrifugal force acting on the conductor 190 when the rotor 160 rotates, which coincides with the direction in which the twist of the stranded wire 191 is tightened. When the rotor 160 tries to rotate, the conductor 190 tends to rotate in a direction in which the surface farther from the main pole portion 72 faces away from the rotational center axis O of the rotor 160 toward the periphery. For this reason, it is preferable that the conductor 190 be wound around the main pole portion 72 so that this rotation direction coincides with the direction in which the twist of the stranded wire 191 is tightened.

[0051] In the field winding 180, similar to the field winding 80, in the right portion 180R, each strand 191 of each conductor 190 is Z-twisted, and in the left portion 180L, each strand 191 of each conductor 190 is S-twisted. In the field winding 180 as well, the straight portions are longer than the crossover portions, and most of the conductor 190 constitutes a straight portion. For this reason, if the direction in which the conductor 190 tends to rotate due to the centrifugal force acting on the conductor 190 when the rotor 160 rotates is configured to match the direction in which the twist of the strands 191 constituting the conductor 190 is tightened, it is possible to sufficiently obtain the effect of suppressing the unwinding of the strands 191.

[0052] As shown in FIG. 8 , the conductors 190 are wound around the main pole portions 72 such that the axial positions of adjacent conductors 190 in a direction perpendicular to the radial direction of the rotor 160 are approximately the same in the radial direction of the rotor 160. More specifically, the conductors 190 are wound around the main pole portions 72 so that the rectangles representing the cross sections of the conductors 190 are approximately closest-packed in the cross section of the rotor 160 shown in FIG. 8 . By winding the conductors 190 around the main pole portions 72 in this manner, the space factor of the field winding 180 in the rotor 160 can be increased, and ultimately the output of the rotating electric machine 40 can be improved. Furthermore, because the gaps between adjacent conductors 190 are small and the conductors 190 are less likely to move, misalignment of the conductors 190 in the circumferential and radial directions of the rotor 60 is suppressed, and untwisting of the stranded wires 191 constituting each conductor 190 is suppressed.

[0053] The conductor 190 having a rectangular cross section shown in Figures 8 and 9 can be manufactured, for example, by compression molding the conductor 90 having a circular cross section as shown in Figure 5. With the field winding 180 according to the second embodiment, compression molding reduces the gaps between adjacent conductors 190, and also reduces the gaps between adjacent strands 191a that make up the conductor 190, so that the effect of increasing the space factor of the field winding 180 in the rotor 160 can be more significantly achieved.

[0054] Other Embodiments The above embodiment may be modified as follows.

[0055] In the first and second embodiments, a retaining member may be attached to the end of the conductor 90, 190 to maintain the twisted state of the twisted wires 91, 191. Using the conductor 90 as an example, for example, as shown in FIG. 10( a), a retaining member 95 includes a retaining portion 96 that holds the end of the conductor 90. As shown in FIG. 10( b), by holding the end of the conductor 90 in the retaining portion 96, the twisted wire at the end of the conductor 90 can be prevented from unraveling. The retaining member 95 is made of a conductive material, and the side of the retaining member 95 opposite the retaining portion 96 serves as a terminal. For example, the field winding 80 may be configured such that a retaining member 95 is attached to the end of each conductor 90 wound around each main pole portion 72, and the conductor 90 wound around each main pole portion 72 is electrically connected via the retaining member 95 of the conductor 90 wound around each main pole portion 72.

[0056] The capacitor 84 that constitutes the resonant circuit of the rotor 60 may be connected in parallel to the first winding portion 81 instead of the second winding portion 82. Also, the capacitor 84 does not have to be provided in the resonant circuit.

[0057] The rotating electric machine is not limited to an inner rotor type rotating electric machine, and may be an outer rotor type rotating electric machine. In this case, the main pole portion protrudes radially inward from the rotor core.

[0058] The rotating electric machine is not limited to a star-connected rotating electric machine, and may be a delta-connected rotating electric machine.

[0059] The stator core may not have teeth.

[0060] The configuration for passing a field current through the field winding is not limited to the circuit shown in Fig. 4, and may include, for example, a configuration including brushes electrically connected to the field winding and a power supply electrically connected to the brushes. In this case, it is not necessary to apply a high-frequency excitation voltage to the stator winding to induce a field current.

[0061] The rotating electric machine is not limited to a rotating electric machine used as an in-vehicle main engine, but may be, for example, a rotating electric machine used as an ISG (Integrated Starter Generator) that is a motor and generator.

[0062] The mobile body on which the control system is mounted is not limited to a vehicle, but may be, for example, an aircraft or a ship. Furthermore, the control system is not limited to a system mounted on a mobile body, but may be a stationary system.

[0063] The following describes characteristic configurations extracted from the above-described embodiments. [Configuration 1] A wound field rotor (60) for use in a wound field rotating electric machine (40), comprising: a rotor core (70) having main pole portions (72) provided for each circumferentially arranged magnetic pole and projecting in the radial direction; and a field winding (80, 180), wherein the field winding is configured by winding a conductor (90, 190) around each main pole portion with the radial direction as the winding axis direction, the conductor having a stranded wire (91, 191) as a conductor which is an assembly of a plurality of strands (91 a, 191 a) twisted together, and the conductor is wound around each main pole portion so that the direction in which the conductor tends to rotate due to centrifugal force acting on the conductor when the wound field rotor rotates coincides with the direction in which the twist of the stranded wire is tightened. [Configuration 2] A wound field rotor (60) applicable to a wound field type rotating electric machine (40), comprising: a rotor core (70) having main pole portions (72) provided for each circumferentially arranged magnetic pole and projecting in a radial direction; and a field winding (80, 180), wherein the field winding is configured by winding a conductor wire (90, 190) around each of the main pole portions with the radial direction as a winding axis direction, the conductor wire comprising a twisted wire (91, 191) that is an assembly of a plurality of strands (91 a, 191 a) twisted together as a conductor, when the main pole portion is viewed in the radial direction from the rotation center axis side of the wound field rotor toward the main pole portion, a portion of the field winding located to the right of the main pole portion is a right portion (80R, 180R), and a portion located to the left of the main pole portion is a left portion (80L, 180L), The wound field rotor according to the present invention is characterized in that, when viewed from the axial direction, which is the direction in which the central axis of rotation extends, the stranded wires constituting the right portion are twisted counterclockwise (KR), and when viewed from the axial direction, the stranded wires constituting the left portion are twisted clockwise (KL).[Configuration 4] The wound field rotor according to Configuration 3, comprising the stranded wire: A stranded wire in which all of the element wires constituting the strand are made of carbon fiber, A stranded wire in which, of all of the element wires constituting the strand, some are made of carbon fiber and the remaining element wires are made of a material other than carbon fiber, A stranded wire in which all of the element wires constituting the strand are wires made of a mixed material of carbon fiber and a metal material, or A stranded wire in which, of all of the element wires constituting the strand, some are wires made of a mixed material of carbon fiber and a metal material and the remaining element wires are wires made of a material other than the mixed material. [Configuration 5] The wound field rotor according to any of Configurations 1 to 4, wherein a holding member (95) that maintains the twisted state of the stranded wire is attached to an end of the conductor. [Configuration 6] The wound field rotor according to any one of configurations 1 to 5, wherein the wires and the conductors have circular cross sections perpendicular to the axial direction, and the conductors are wound around the main pole portion with the axial positions of adjacent conductors in the circumferential direction shifted from each other in the radial direction. [Configuration 7] The wound field rotor according to any one of configurations 1 to 5, wherein the conductors are configured by compression molding. [Configuration 8] A rotating electric machine (40) comprising: the wound field rotor according to any one of configurations 1 to 7; and a stator (50) including a stator winding (52), wherein a high-frequency current flowing in the stator winding induces a voltage in the field winding, causing a field current to flow.

[0064] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A wound field rotor (60) for use in a wound field type rotating electric machine (40), comprising: a rotor core (70) having main pole portions (72) provided for each of the magnetic poles arranged in the circumferential direction and projecting in the radial direction; and a field winding (80, 180), wherein the field winding is configured by winding a conductor (90, 190) around each of the main pole portions with the radial direction as the winding axis direction, the conductor having a twisted wire (91, 191) as a conductor which is an assembly of a plurality of strands (91a, 191a) twisted together, and the conductor is wound around each of the main pole portions such that the direction in which the conductor rotates due to centrifugal force acting on the conductor when the wound field rotor rotates coincides with the direction in which the twist of the twisted wire is tightened.

2. A wound field rotor (60) applied to a wound field type rotating electric machine (40), comprising: a rotor core (70) having main pole portions (72) provided for each magnetic pole arranged in the circumferential direction and projecting in the radial direction; and a field winding (80, 180), wherein the field winding is configured by winding a conductor wire (90, 190) around each of the main pole portions with the radial direction as the winding axis direction, the conductor wire comprising a twisted wire (91, 191) which is an assembly of a plurality of strands (91a, 191a) twisted together as a conductor, when the main pole portion is viewed in a direction from the rotation center axis side of the wound field rotor toward the main pole portion along the radial direction, a portion of the field winding located to the right of the main pole portion is defined as a right portion (80R, 180R), and a portion located to the left of the main pole portion is defined as a left portion (80L, 180L), a wound field rotor, wherein when the right portion is viewed from an axial direction, which is a direction in which the central axis of rotation extends, the twisted wire constituting the right portion is twisted in a counterclockwise direction (KR), and when the left portion is viewed from the axial direction, the twisted wire constituting the left portion is twisted in a clockwise direction (KL).

3. A wound field rotor according to claim 1 or 2, wherein the wires are made of at least carbon fiber.

4. The wound field rotor according to claim 3, comprising the stranded wire: a stranded wire in which all of the element wires constituting the stranded wire are made of carbon fiber; a stranded wire in which, of all of the element wires constituting the stranded wire, some element wires are made of carbon fiber and the remaining element wires are made of a material other than carbon fiber; a stranded wire in which all of the element wires constituting the stranded wire are element wires made of a mixed material of carbon fiber and a metal material; or a stranded wire in which, of all of the element wires constituting the stranded wire, some element wires are made of a mixed material of carbon fiber and a metal material and the remaining element wires are made of a material other than the mixed material.

5. A wound field rotor according to claim 1 or 2, wherein a holding member (95) for holding the twisted state of the twisted wires is attached to an end of the conductor.

6. A wound field rotor as claimed in claim 1 or 2, wherein a cross section perpendicular to the axial direction of said wires and said conductors is circular, and said conductors are wound around said main pole portion with the axial positions of adjacent conductors in the circumferential direction shifted from each other in the radial direction.

7. A wound field rotor according to claim 1 or 2, wherein the conductor wire is formed by compression molding.

8. A rotating electric machine (40) comprising: a wound field rotor as defined in claim 1 or 2; and a stator (50) including a stator winding (52), wherein a high frequency current flows through the stator winding to induce a voltage in the field winding, thereby causing a field current to flow.

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