Field-winding rotating electric machine

Abstract

In this field-winding rotating electric machine, a rotor (60) has: a rotor core having a main pole part which is provided for each of magnetic poles arranged in the circumferential direction and projects in a radial direction; and a field winding (70) wound around the main pole part. The rotor is provided with a circuit module (102) having a capacitor (91) connected to the field winding. The capacitor is a multilayer capacitor in which a dielectric (151) and an electrode (152) are laminated. In the circuit module, the lamination direction of the dielectric and the electrode is arranged orthogonal to the radial direction of the rotor.

Description

Wound-field type rotating electric machine CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2023-111699, filed on July 6, 2023, the contents of which are incorporated herein by reference.

[0002] The disclosure in this specification relates to a wound field type rotating electric machine.

[0003] In a wound-field rotating electric machine, the rotor has a rotor core with multiple main poles (magnetic salient poles) provided for each circumferentially arranged magnetic pole, and a field winding wound around the main poles. Also, a known configuration has a circuit module provided as an electrical component at the axial end of the rotor (see, for example, Patent Document 1). The circuit module has a capacitor, and the field winding and the capacitor form a resonant circuit.

[0004] Japanese Patent Application Laid-Open No. 2020-124100

[0005] As described above, in a wound-field rotating electric machine in which a circuit module having a capacitor is provided at the axial end of the rotor, the circuit module rotates integrally with the rotor when the rotor rotates. In this case, there is a concern that the centrifugal force of the rotation may cause deformation of the capacitor. Specifically, when a multilayer capacitor is used and the dielectric and electrodes are stacked radially, centrifugal force acts in the stacking direction. This may cause deformation of the dielectric layers and electrode layers, leading to defects such as cracks. Since multilayer capacitors are thought to be composed of a laminate of thin films, there is a concern that the thin films may bend or break if centrifugal force acts in the stacking direction.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a wound-field type rotating electric machine that can suppress the occurrence of capacitor malfunctions due to centrifugal force in a circuit module that rotates integrally with the rotor.

[0007] The present disclosure relates to a wound-field rotating electric machine comprising: a stator having a stator winding; a rotor having a rotor core with main pole portions provided for each circumferentially arranged magnetic pole and protruding radially; and a field winding wound around the main pole portions, wherein a high-frequency current flows through the stator winding to induce a field current in the field winding; and a circuit module provided to be rotatable integrally with the rotor and having a capacitor connected to the field winding, the capacitor being a laminated capacitor in which a dielectric and an electrode are laminated, and the laminated direction of the dielectric and the electrode is arranged in the circuit module perpendicular to the radial direction of the rotor.

[0008] In a wound-field rotating electric machine in which a circuit module having a stacked capacitor is arranged to rotate integrally with the rotor, there is a concern that defects may occur due to centrifugal force in relation to the stacking direction of the capacitor. In consideration of this, the capacitor is arranged so that the stacking direction of the dielectric and electrodes is perpendicular to the radial direction of the rotor. In this case, bending due to centrifugal force inside the capacitor is suppressed. As a result, defects in the capacitor due to centrifugal force can be suppressed in the circuit module that rotates integrally with the rotor.

[0009] 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, Fig. 2 is a diagram showing an inverter and its peripheral configuration, Fig. 3 is a cross-sectional view of a rotor and a stator, Fig. 4 is a diagram showing an electric circuit provided in the rotor, Fig. 5 is a perspective view showing the overall configuration of the rotor, Fig. 6 is an exploded perspective view of the rotor, Fig. 7 is a longitudinal cross-sectional view of the rotor, Fig. 8 is an exploded perspective view of a winding unit in a rotor main section, Fig. 9 is a cross-sectional view of the rotor main section, Fig. 10 is a perspective view of a circuit module, Fig. 11 is a perspective view of a component holder, Fig. 12 is a perspective view showing an arrangement of capacitors and diodes, Fig. 13 is a perspective view of a bus bar, and Fig. 14 is a perspective view of a capacitor and diode. 15 is a longitudinal cross-sectional view showing the arrangement of the capacitors in the circuit module, FIG. 16 is a longitudinal cross-sectional view showing the capacitors after resin molding, FIG. 17 is a longitudinal cross-sectional view showing the arrangement of the capacitors in the circuit module, FIG. 18 is a plan view showing the arrangement of the capacitors and bus bars lined up in the circumferential direction, FIG. 19 is a longitudinal cross-sectional view showing the capacitors after resin molding, FIG. 20 is a plan view showing the arrangement of the capacitors lined up in the circumferential direction, FIG. 21 is a plan view showing the arrangement of the capacitors lined up in the circumferential direction, and FIG. 22 is a front view showing the arrangement of the capacitors lined up in the circumferential direction.

[0010] DETAILED DESCRIPTION OF THE INVENTION A rotating electric machine according to an embodiment of the present disclosure will now be described with reference to the drawings. Rotating electric machines are used as a power source for driving electric vehicles such as electric vehicles and hybrid vehicles.

[0011] First, a control system including a rotating electric machine will be described with reference to Fig. 1. The control system includes a DC power supply 10, an inverter 20, a control device 30, and a rotating electric machine 40. The rotating electric machine 40 is a wound-field type synchronous machine. For example, the rotating electric machine 40, the inverter 20, and the control device 30 may be configured as an electromechanical integrated drive device, or the rotating electric machine 40, the inverter 20, and the control device 30 may each be configured as a separate component.

[0012] The rotating electric machine 40 includes a housing 41, and a stator 50 and a rotor 60 housed in the housing 41. The rotating electric machine 40 of this embodiment is an inner rotor type rotating electric machine in which the rotor 60 is disposed radially inside the stator 50.

[0013] The stator 50 includes a stator core 51 and a stator winding 52. 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 an electrical angle offset of 120° from one another.

[0014] The rotor 60 includes a rotor core 61 and a field winding 70. The field winding 70 may be made of, for example, aluminum wire, which has a low specific gravity and is easily formed. The field winding 70 is not limited to aluminum wire, and may be made of, for example, copper wire or CNT (carbon nanotube). A rotating shaft 32 is attached to the center hole of the rotor core 61. The rotating shaft 32 is rotatably supported by bearings 42 and 43 in the housing 41.

[0015] As shown in FIG. 2 , the inverter 20 includes a series connection of upper-arm switches SUp, SVp, and SWp for U, V, and W phases and lower-arm switches SUn, SVn, and SWn for U, V, and W phases. First ends of U-, V-, and W-phase windings 52U, 52V, and 52W are connected to the connection points between the upper-arm switches SUp, SVp, and SWp and the lower-arm switches SUn, SVn, and SWn for each phase. 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 stator winding 52 is star-connected. However, the stator winding 52 may also be delta-connected. In this embodiment, each of the switches SUp to SWn is an IGBT. A freewheel diode is connected in antiparallel to each of the switches SUp to SWn.

[0016] The collectors of the upper arm switches SUp, SVp, SWp of each phase are connected to the positive terminal of a DC power supply 10. The emitters of the lower arm switches SUn, SVn, SWn of each phase are connected to the negative terminal of the DC power supply 10. A smoothing capacitor 11 is connected in parallel to the DC power supply 10.

[0017] Next, the stator 50 and the rotor 60 will be described with reference to FIG.

[0018] 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.

[0019] The stator core 51 is made of laminated steel plates made of a soft magnetic material and has an annular back yoke 51a and multiple teeth 51b protruding radially inward from the back yoke 51a. Multiple slots 54 are formed between adjacent teeth 51b in the circumferential direction. The stator winding 52 is formed by accommodating the phase windings of each phase in a predetermined order in each of these slots 54. For example, the stator 50 may employ a segment coil structure using multiple conductor segments. However, the structure of the stator winding 52 is arbitrary.

[0020] The rotor core 61 is made of a soft magnetic material, for example, laminated steel plates. The rotor core 61 has a cylindrical portion 61a and a plurality of main pole portions 62 that protrude radially outward from the cylindrical portion 61a. A field winding 70 is wound around the main pole portions 62 by concentrated winding. In this embodiment, eight main pole portions 62 are provided at equal intervals in the circumferential direction.

[0021] The field winding 70 includes a first winding portion 71a and a second winding portion 71b. The first winding portion 71a is wound radially outward around each main pole portion 62, and the second winding portion 71b is wound radially inward relative to the first winding portion 71a. In each main pole portion 62, the winding directions of the first winding portion 71a and the second winding portion 71b are the same. Furthermore, among circumferentially adjacent main pole portions 62, the winding directions of the winding portions 71a, 71b wound around one main pole portion 62 are opposite to those of the winding portions 71a, 71b wound around the other main pole portion 62. Therefore, the magnetization directions of adjacent main pole portions 62 are opposite to each other. In the rotor 60, the main pole portions 62 in the rotor core 61 and the field winding 70 wound around each main pole portion 62 form a plurality of magnetic poles (field poles) arranged circumferentially.

[0022] FIG. 4 shows an electrical circuit on the rotor 60 side, including the winding portions 71a, 71b wound around the main pole portion 62. The first winding portion 71a and the second winding portion 71b are connected in series, and a capacitor portion CC, which is composed of a plurality of first capacitors 91, is connected in parallel to the second winding portion 71b. In this embodiment, the capacitor portion CC is configured as a parallel connection of, for example, eleven first capacitors 91. In addition, a second capacitor 92 is connected in parallel to the series connection of the first winding portion 71a and the second winding portion 71b. The second capacitor 92 is provided for noise suppression. In this embodiment, one second capacitor 92 is provided. The first capacitor 91 and the second capacitor 92 are multilayer ceramic capacitors and have the same configuration.

[0023] A diode 93 serving as a rectifying element is connected between both ends of the series-connected body made up of the winding portions 71 a and 71 b. That is, the first end of the first winding portion 71 a is connected to the cathode of the diode 93, and the first end of the second winding portion 71 b is connected to the second end of the first winding portion 71 a. The anode of the diode 93 is connected to the second end of the second winding portion 71 b.

[0024] In this embodiment, the first winding portion 71a, the first capacitor 91, and the diode 93 form a series resonant circuit, and the second winding portion 71b and the first capacitor 91 form a parallel resonant circuit. If the first resonant frequency, which is the resonant frequency of the series resonant circuit, is f1 and the second resonant frequency, which is the resonant frequency of the parallel resonant circuit, is f2, these resonant frequencies f1 and f2 are expressed by the following equations (1) and (2). L1 is the inductance of the first winding portion 71a, L2 is the inductance of the second winding portion 71b, and C is the capacitance of the first capacitor 91. f1=1 / (2π√(L1×C)) (1) f2=1 / (2π√(L2×C)) (2) When a high-frequency excitation current flows through the stator winding 52, fluctuations due to high-frequency components of the main magnetic flux occur in the magnetic circuit including the stator core 51 and the rotor core 61. Fluctuations in the main magnetic flux generate induced voltages in each of the winding portions 71a and 71b, inducing currents in the winding portions 71a and 71b. If induced voltages of the same polarity are generated in the winding portions 71a and 71b, the induced currents in the winding portions 71a and 71b do not cancel each other out, resulting in an increase in the induced current. The diode 93 rectifies the current flowing in each of the winding portions 71a and 71b in one direction. This causes a field current to flow through the field winding 70 in the direction rectified by the diode 93, exciting the field winding 70.

[0025] 2, the control device 30 is mainly configured with a microcomputer (corresponding to a computer) that includes a CPU. The control device 30 generates drive signals that turn on and off the switches SUp to SWn that constitute the inverter 20. Specifically, the control device 30 generates drive signals that turn on and off the switches SUp to SWn to convert 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 switches SUp to SWn.

[0026] The control device 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 high-frequency current with a higher frequency than the fundamental current, and is a current that mainly excites the field winding 70. It is also possible to use a harmonic current as the high-frequency current. The phase currents flowing through the phase windings 52U, 52V, and 52W are shifted by 120 electrical degrees.

[0027] Next, a more detailed description will be given of the configuration of the rotor 60. Fig. 5 is a perspective view showing the overall configuration of the rotor 60, Fig. 6 is an exploded perspective view of the rotor 60, and Fig. 7 is a vertical cross-sectional view of the rotor 60.

[0028] The rotor 60 is broadly divided into a rotor main section 101, a circuit module 102 provided at one of the axial ends of the rotor main section 101, and coil end covers 103, 104 as annular members attached to one and the other axial ends of the rotor main section 101. As described with reference to FIG. 3 , the rotor main section 101 includes a rotor core 61 and a field winding 70, and a rotating shaft 32 is attached to the center hole of the rotor core 61. The field winding 70 is composed of a plurality of winding units 110 arranged in a circumferential direction. The circuit module 102 is fixed to the rotating shaft 32 with the rotating shaft 32 inserted through the hollow portion. As shown in FIG. 7 , in the field winding 70 (winding unit 110), the portion radially facing the rotor core 61 is a coil side portion CS, and the portion axially outward of the rotor core 61 is a coil end portion CE. The circuit module 102 is provided at a position axially opposite to the coil end portion CE of the field winding 70 .

[0029] Fig. 8 is an exploded perspective view of the winding unit 110 in the rotor main section 101, and Fig. 9 is a cross-sectional view showing the cross-sectional structure of a portion of the rotor main section 101. The rotor main section 101 has a plurality of winding units 110, one for each magnetic pole of the rotor 60. Each winding unit 110 is formed in an annular shape with the axial direction as the longitudinal direction, and is assembled to the rotor core 61 with the main pole section 62 of the rotor core 61 inserted into the hollow portion.

[0030] The winding unit 110 has a first coil module 111 that is located radially outward when attached to the main pole 62, and a second coil module 112 that is located radially inward. The first coil module 111 is a coil module that corresponds to the first winding portion 71a, and the second coil module 112 is a coil module that corresponds to the second winding portion 71b.

[0031] The first coil module 111 has an annular coil body 121 formed by multiple windings of a conductor material made of a rectangular wire in the circumferential and radial directions, and a thin plate-like insulator 122 provided integrally with the coil body 121. The insulator 122 has a portion that extends circumferentially and covers the outer peripheral portions on the radially outer and inner sides of the coil body 121, and a portion that extends radially and covers the hollow portion of the coil body 121. In other words, the outer peripheral portion on the radially outer side and the inner peripheral portion and hollow portion of the coil body 121 are insulated and coated with the insulator 122.

[0032] The second coil module 112 has an annular coil body 123 formed by multiple windings of a conductor material made of a rectangular wire in the circumferential and radial directions, and a thin plate-like insulator 124 provided integrally with the coil body 123. The insulator 124 has a portion that extends circumferentially and covers the outer peripheral portions on the radially outer and inner sides of the coil body 123, and a portion that extends radially and covers the hollow portion of the coil body 123. In other words, the outer peripheral portion on the radially outer side, the inner peripheral portion on the radially inner side, and the hollow portion of the coil body 123 are insulated and coated with the insulator 124.

[0033] The coil bodies 121 and 123 are air-core coils configured as, for example, α-winding coils. The flat wire used for the coil bodies 121 and 123 has a substantially rectangular cross section (specifically, a substantially rectangular shape) and is composed of a conductor portion made of aluminum or the like and an insulating layer covering the conductor portion. However, it is also possible to use a round wire with a circular cross section as the conductor material.

[0034] As shown in Fig. 9, the first coil module 111 has two radially wound layers of conductor wire, while the second coil module 112 has six radially wound layers. The coil modules 111, 112 have different numbers of circumferential windings (i.e., the number of rows of conductor wire in the circumferential direction), with the number of windings being greater on the radially outer side than on the radially inner side. This improves the space factor of the field winding 70. Ignoring the space factor, it is also possible to make the number of circumferential windings the same for all of the radially arranged coil bodies 121, 123.

[0035] Furthermore, in the rotor main section 101, holding plates 125 and 126 are provided between the main pole sections 62 of the rotor core 61 to maintain the assembled state of the first coil module 111 and the second coil module 112 when these coil modules 111 and 112 are assembled to each main pole section 62. The holding plate 125 is attached to the radial outside of the first coil module 111, and the holding plate 126 is attached between the first coil module 111 and the second coil module 112.

[0036] 6, the rotor 60 has a coil end ring 81 attached to the axial end of the winding unit 110. As shown in FIG. 7, the coil end ring 81 is disposed radially between the coil end portion of the first coil module 111 and the coil end portion of the second coil module 112, and is sandwiched axially between the retaining plate 126 and the coil end cover 103.

[0037] Next, the circuit module 102 will be described with reference to FIGS.

[0038] The circuit module 102 includes a first capacitor 91, a second capacitor 92, a diode 93, a component holder 130, a first bus bar 141, a second bus bar 142, and a third bus bar 143. The component holder 130 is made of an electrically insulating material such as synthetic resin.

[0039] As shown in FIG. 11 , the component holder 130 includes a ring-shaped main body 131. The main body 131 includes a C-shaped bottom plate 131a, an outer peripheral wall 131b extending axially from a radially outer end of the bottom plate 131a, and an inner peripheral wall 131c extending axially from a radially inner end of the bottom plate 131a. The main body 131 also includes a first side wall 131d extending axially from one of the circumferential ends of the bottom plate 131a, and a second side wall 131e extending axially from the other of the circumferential ends of the bottom plate 131a. The wall height (axial height) of each of the wall portions 131b to 131e is greater than the heights of the first capacitor 91 and the second capacitor 92.

[0040] In the main body 131, a C-shaped storage section 132 is formed by a bottom plate 131a and each of the walls 131b to 131e, and the first capacitor 91 and the second capacitor 92 are stored in the storage section 132. Note that within the space, a partition section 131f that separates the storage space for the first capacitor 91 from the space for the second capacitor 92 is formed so as to extend in the axial direction from the bottom plate 131a.

[0041] A central hole 133 through which the rotary shaft 32 is inserted is formed in the main body 131. Specifically, the central hole 133 is formed by the inner peripheral surface of the inner peripheral wall portion 131c.

[0042] The component holder 130 includes an element mounting portion 134 on which the diode 93 is mounted. The element mounting portion 134 extends radially outward from a circumferential position on the inner circumferential wall portion 131c where the outer circumferential wall portion 131b is not mounted. The element mounting portion 134 also extends radially outward from an axially intermediate position on the inner circumferential wall portion 131c. The diode 93 is fixed to the element mounting portion 134 with a fastener such as a bolt.

[0043] The component holder 130 has a plurality of winding fixing portions 135 that protrude radially outward from the main body portion 131. In this embodiment, the number of winding fixing portions 135 provided is the same as the number of main pole portions 62; specifically, eight winding fixing portions 135 are provided at equal intervals in the circumferential direction. Each winding fixing portion 135 extends radially outward from a central position in the axial direction of the outer circumferential wall portion 131b.

[0044] Each winding fixing portion 135 has a plurality of insertion holes 136 formed therethrough in the axial direction. As shown in Fig. 8 , in the rotor main portion 101, in each winding unit 110, two conductor ends 127 are drawn out from the axial end of the first coil module 111, and six conductor ends 128 are drawn out from the axial end of the second coil module 112. Note that in the first coil module 111, the first winding portion 71a is formed of a single air-core coil, so two conductor ends 127 are drawn out, and in the second coil module 112, the second winding portion 71b is formed of three air-core coils aligned in the radial direction, so six conductor ends 128 are drawn out.

[0045] The conductor ends 127 of two circumferentially adjacent first coil modules 111 are inserted one by one into the insertion holes 136, and the conductor ends 127 are connected to each other by welding or the like, thereby connecting the first coil modules 111 in the circumferential direction in series. The conductor ends 128 of two circumferentially adjacent second coil modules 112 are inserted one by one into the insertion holes 136, and the conductor ends 128 are connected to each other by welding or the like, thereby connecting the second coil modules 112 in the circumferential direction in series.

[0046] 12 to 14, eleven first capacitors 91 and one second capacitor 92 are arranged in an annular shape on an imaginary circle centered on the axis J of the rotor 60. Each of the capacitors 91, 92 has a rectangular parallelepiped or cubic shape.

[0047] A first bus bar 141 having an arc shape (specifically, a C-shape) is electrically connected to a first terminal of each first capacitor 91. A second bus bar 142 having an arc shape (specifically, a C-shape) is electrically connected to a second terminal of each first capacitor 91 and second capacitor 92. A third bus bar 143 having an arc shape is electrically connected to a first terminal of the second capacitor 92. The third bus bar 143 is a separate member from the first bus bar 141 and is disposed at a distance from the first bus bar 141. When the rotor 60 is viewed from the axial direction, the bus bars 141 to 143 are disposed so as to form an annular shape around the axis J.

[0048] Each of the bus bars 141 to 143 is a plate-shaped wiring member, and is arranged with its plate surface oriented in the axial direction. In this embodiment, the first bus bar 141 and the third bus bar 143 are arranged side by side in the circumferential direction, and the second bus bar 142 is arranged so as to face the bus bars 141 and 143 in the axial direction. Each of the first capacitors 91 is arranged between the first bus bar 141 and the second bus bar 142, and the second capacitor 92 is arranged between the third bus bar 143 and the second bus bar 142.

[0049] The first bus bar 141 is provided with a first connection terminal 141a electrically connected to the second end of the first winding portion 71a and the first end of the second winding portion 71b. The second bus bar 142 is provided with a second connection terminal 142a electrically connected to the second end of the second winding portion 71b and the anode of the diode 93. The third bus bar 143 is provided with a third connection terminal 143a electrically connected to the first end of the first winding portion 71a and the cathode of the diode 93.

[0050] Incidentally, when the rotor 60 rotates, the circuit module 102 rotates integrally with the rotor 60. In this case, there is a concern that the capacitors 91, 92, which are multilayer ceramic capacitors (multilayer capacitors), may suffer from defects due to centrifugal force in relation to their lamination direction. Specifically, if the lamination direction of the capacitors 91, 92 in the circuit module 102 is radial, there is a concern that deformation of the dielectric layers and electrode layers of the capacitors 91, 92 may occur, leading to defects such as cracks. Therefore, in this embodiment, the lamination direction of the capacitors 91, 92 is set to a specific direction, thereby suppressing deformation of the capacitors 91, 92 due to centrifugal force during rotor rotation.

[0051] Fig. 15 is a diagram schematically showing the arrangement of the first capacitor 91 in the circuit module 102. In Fig. 15, the up-down direction is the axial direction, and the bottom side of the figure is the field winding 70 side. In Fig. 15, the left-right direction is the radial direction.

[0052] In the component holder 130 of the circuit module 102, a first bus bar 141 and a second bus bar 142 are arranged in positions axially opposing each other within an accommodation portion 132 formed in a main body portion 131, and a first capacitor 91 is arranged between these bus bars 141, 142. The first capacitor 91 has a dielectric 151, a plurality of internal electrodes 152 embedded in the dielectric 151 at predetermined intervals, and a pair of external electrodes 153 electrically connected to the internal electrodes 152. The internal electrodes 152 are thin-film shaped and arranged parallel to each other.

[0053] The first capacitor 91 has a laminated structure in which dielectrics 151 and internal electrodes 152 are alternately stacked, and external electrodes 153 on both sides are alternately connected to a plurality of internal electrodes 152 arranged in the stacking direction. Specifically, in the first capacitor 91, ends of the plurality of internal electrodes 152 are exposed on a pair of opposing surfaces of the dielectric 151, and a pair of external electrodes 153 are connected to the exposed portions of the internal electrodes 152. Furthermore, one of the pair of external electrodes 153 is electrically connected to the first bus bar 141, and the other external electrode 153 is electrically connected to the second bus bar 142. The pair of external electrodes 153 correspond to the first terminal and second terminal of the first capacitor 91. The first capacitor 91 is a multilayer ceramic chip capacitor.

[0054] The first capacitor 91 is arranged such that a pair of external electrodes 153 are oriented so as to be separated radially inward and outward. Although a specific configuration is not shown, the external electrode 153 on the left side of the figure is preferably electrically connected to the first bus bar 141 and insulated from the second bus bar 142 by forming an electrical insulating layer between them. The external electrode 153 on the right side of the figure is preferably electrically connected to the second bus bar 142 and insulated from the first bus bar 141 by forming an electrical insulating layer between them.

[0055] In the circuit module 102, the first capacitor 91 is arranged so that the lamination direction of the dielectric 151 and the internal electrodes 152 is perpendicular to the radial direction of the rotor 60, i.e., the up-and-down direction (axial direction) in Fig. 15. In this case, in the first capacitor 91, the internal electrodes 152 arranged in the lamination direction are oriented so as to extend in the radial direction. This prevents problems such as bending of the dielectric 151 or the internal electrodes 152 due to centrifugal force acting on the first capacitor 91 during rotation of the rotor 60.

[0056] The first capacitor 91 and each of the bus bars 141, 142 may be bonded to each other with a conductive adhesive, thereby electrically connecting and mechanically coupling the first capacitor 91 and each of the bus bars 141, 142. In this case, the effect of suppressing movement (misalignment) of the first capacitor 91 due to centrifugal force can be improved compared to a configuration using solder, which is a common bonding method.

[0057] Alternatively, the outer electrode 153 of the first capacitor 91 and the bus bars 141, 142 may be joined to each other by welding, which can further increase the joining strength of the first capacitor 91.

[0058] Detailed explanation of the second capacitor 92 will be omitted, but it has a configuration similar to that of the first capacitor 91, and in the circuit module 102, the stacking direction of the dielectric 151 and the internal electrode 152 is arranged perpendicular to the radial direction of the rotor 60.

[0059] In the circuit module 102, the capacitors 91, 92 may be molded with a resin material. Specifically, as shown in FIG. 16A, the housing portion 132 of the component holder 130 may be filled with a resin material to form a resin molded portion 161. The resin material may be a thermosetting resin such as epoxy resin. In this case, the capacitors 91, 92 and the bus bars 141 to 143 are embedded in the resin molded portion 161 in the housing portion 132 of the component holder 130. In FIG. 16A, the resin molded portion 161 is formed with the capacitors 91, 92 entirely covered with the resin material in the housing portion 132.

[0060] 16(b), each capacitor 91, 92 may have a resin molded portion 161 provided only on the radially outer side. In other words, the inner peripheral portion of each capacitor 91, 92, which is the radially inner side, is not resin molded. If each capacitor 91, 92 were entirely resin molded, the difference in linear expansion between the capacitors 91, 92 and the resin material would increase thermal stress on the capacitors 91, 92, raising concerns about the occurrence of defects due to this. In consideration of this, in the configuration shown in FIG. 16(b), the inner peripheral portion of each capacitor 91, 92, which is the radially inner side, is not resin molded.

[0061] 16(a) and 16(b), each capacitor 91, 92 is configured to be molded with a resin material in an area including at least the outer peripheral portion that is the radially outer side within the housing portion 132. This enhances the effect of suppressing defects in each capacitor 91, 92 due to centrifugal force.

[0062] The configuration of the circuit module 102 may be modified as shown in Fig. 17. In Fig. 17, the positions of the first bus bar 141 and the second bus bar 142 within the accommodation portion 132 are different from those of Fig. 15, and the bus bars 141, 142 are disposed in positions facing each other in the radial direction. Specifically, the first bus bar 141 and the second bus bar 142 are disposed with their bus bar plate surfaces extending in the axial direction, with the first bus bar 141 on the radially inner side and the second bus bar 142 on the radially outer side, and the first capacitor 91 is attached therebetween.

[0063] In the first capacitor 91, the pair of external electrodes 153 are arranged radially inward and outward, as in Fig. 15. The lamination direction of the first capacitor 91 is perpendicular to the radial direction of the rotor 60, as in Fig. 15. Although not shown, the second capacitor 92 may also have a similar configuration.

[0064] Fig. 18 is a plan view showing the capacitors 91, 92 and the bus bars 141 to 143 of the configuration shown in Fig. 17 arranged in the accommodation section 132 of the component holder 130. In Fig. 18, the second bus bar 142 is arranged in an annular shape so as to surround all of the capacitors 91, 92 from the radially outer side. The first bus bar 141 is arranged radially inward with the first capacitor 91 in between, and the third bus bar 143 is arranged radially inward with the second capacitor 92 in between. According to the configurations shown in Figs. 17 and 18, the second bus bar 142 is arranged so as to be in contact with the outer peripheral surfaces of the capacitors 91, 92 in the radial direction, which enables the second bus bar 142 to support the centrifugal force acting on the capacitors 91, 92.

[0065] The second bus bar 142 surrounds the circumferentially arranged capacitors 91, 92 from the radially outer side and has a length of at least a semicircle in plan view. As a result, when centrifugal forces are generated in the circumferentially arranged capacitors 91, 92 as the rotor 60 rotates, the centrifugal forces act from the capacitors 91, 92 in opposite radial directions on the second bus bar 142. In this case, the forces acting in opposite directions from the capacitors 91, 92 prevent the second bus bar 142 from being displaced in the radial direction, thereby preventing the capacitors 91, 92 from being misaligned.

[0066] It is also possible to arrange the first bus bar 141 and the third bus bar 143 radially outward from the capacitors 91 and 92 , and arrange the second bus bar 142 radially inward from the capacitors 91 and 92 .

[0067] Fig. 19 is a diagram showing a configuration in which the first capacitor 91 is molded with a resin material in the circuit module 102 shown in Fig. 17. In Fig. 19, a resin molded portion 161 is provided only on the radially outer side of the housing portion 132 of the component holder 130. However, the resin molded portion 161 may be formed so as to entirely cover the first capacitor 91 and the bus bars 141, 142 within the housing portion 132 of the component holder 130.

[0068] According to the present embodiment described above in detail, the following excellent effects can be obtained.

[0069] In the circuit module 102, the capacitors 91, 92 are arranged so that the lamination direction of the dielectric 151 and the internal electrode 152 is perpendicular to the radial direction of the rotor 60. In this case, bending due to centrifugal force inside the capacitors is suppressed. As a result, it is possible to suppress malfunctions of the capacitors 91, 92 due to centrifugal force in the circuit module 102, which rotates integrally with the rotor 60.

[0070] Since each of the capacitors 91, 92 is configured to be resin molded in an area that includes at least the outer peripheral portion that is the radially outer side, defects in each of the capacitors 91, 92 due to centrifugal force can be more effectively suppressed.

[0071] If the capacitors 91, 92 were entirely resin-molded, the difference in linear expansion between the capacitors 91, 92 and the resin material would increase thermal stress on the capacitors 91, 92, raising concerns about the occurrence of defects. In consideration of this, the inner peripheral portions of the capacitors 91, 92, which are the radially inner sides, are not resin-molded. This allows the capacitors 91, 92 to have increased resistance to both centrifugal force and thermal stress.

[0072] In the circuit module 102, one of the bus bars 141 to 143 is arranged so as to contact the outer peripheral surface on the radially outer side of each of the capacitors 91, 92. This allows the bus bars to support the centrifugal force acting on each of the capacitors 91, 92, thereby further increasing the resistance of the capacitors 91, 92 to the centrifugal force.

[0073] In the circuit module 102, for example, the second bus bar 142 surrounds the circumferentially arranged capacitors 91, 92 from the radial outside and has a length of at least a semicircle in plan view, thereby preventing a problem such as displacement of the second bus bar 142 due to a radially biased force acting on the second bus bar 142 during rotor rotation.

[0074] (Other Embodiments) The above embodiment may be modified as follows, for example.

[0075] In the rotating electric machine 40, if the circuit module 102 is provided at a position axially opposite the coil end portion CE of the field winding 70, there is a concern that the heat from the field winding 70 will affect each of the capacitors 91, 92, causing temperature differences within the capacitors. In a multilayer capacitor, there is a concern that temperature differences will occur within the capacitor due to differences in the way heat is transferred within the capacitor depending on the stacking direction. For example, if the dielectric 151 and the internal electrode 152 are stacked in the axial direction, temperature differences are likely to occur within the capacitor in the axial direction, causing relatively large expansion in the portion close to the field winding 70. This raises concerns that deformation due to thermal expansion will occur at the end of the capacitor on the high-temperature side, leading to defects such as cracks.

[0076] In consideration of this, as shown in FIG. 20 , the stacking direction of the capacitors 91, 92 may be orthogonal to the radial direction of the rotor 60 and circumferential to the rotor 60. In this case, by stacking the capacitors in the circumferential direction, the dielectric 151 and the internal electrodes 152, which have different heat transfer coefficients, each extend in the axial direction. Therefore, unlike when the dielectric 151 and the internal electrodes 152 are oriented orthogonal to the axial direction (when the stacking direction is axial), the temperature distribution inside the capacitor can be made uniform even when heat is transmitted from the field winding 70. This suppresses deformation of the capacitors 91, 92 due to differences in thermal expansion. In other words, the configuration of FIG. 20 can suppress both defects that may occur in the capacitors 91, 92 of the circuit module 102 due to centrifugal force and defects that may occur due to heat from the field winding.

[0077] In FIG. 20, the first capacitors 91 are arranged in pairs, with two adjacent capacitors arranged circumferentially, and at the circumferential center of each pair of capacitors, the radially inner capacitor side surface is perpendicular to the radial direction.

[0078] As shown in FIG. 21, the radially inner side surface of each of the capacitors 91, 92 arranged in the circumferential direction may be perpendicular to the radial direction at the circumferential center.

[0079] The capacitors 91, 92 may be arranged in the component holder 130 in the orientation shown in Figures 22(a) and 22(b). In Figures 22(a) and 22(b), the up-down direction is the axial direction, and the left-right direction is the circumferential direction. In Figure 22(a) , the first capacitor 91 is arranged such that the stacking direction of the dielectric 151 and the internal electrode 152 is the axial direction (i.e., a direction perpendicular to the radial direction of the rotor 60), and the pair of external electrodes 153 extend in the radial direction. The pair of external electrodes 153 are arranged at positions on both circumferential sides of the first capacitor 91. In other words, in the first capacitor 91, one external electrode 153 is provided on one circumferential side surface of the approximately rectangular parallelepiped dielectric 151, and the other external electrode 153 is provided on the other circumferential side surface of the dielectric 151.

[0080] 22(b) differs from FIG. 22(a) in that the stacking direction of the first capacitor 91 is the circumferential direction, and a pair of external electrodes 153 are provided on both axial sides of the first capacitor 91, extending in the radial direction. The configuration of FIG. 22(b) corresponds to the configuration of FIG. 20. The configurations of FIGS. 22(a) and 22(b) can prevent problems such as deformation (bending, etc.) of the external electrodes 153 of each capacitor 91, 92 due to centrifugal force during rotor rotation.

[0081] The first capacitor 91 constituting the resonant circuit may be connected in parallel to the first winding portion 71 a instead of the second winding portion 71 b. Also, in the resonant circuit, the anode of the diode 93 may be connected to the first winding portion 71 a side of the series-connected first and second winding portions 71 a, 71 b, and the cathode of the diode 93 may be connected to the second winding portion 71 b side.

[0082] In the rotor 60, the second winding portion 71b may be disposed radially outward (closer to the stator 50) than the first winding portion 71a.

[0083] In the stator 50, the stator core may not be provided with teeth.

[0084] 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 both a motor and a generator.

[0085] The moving body on which the rotating electric machine system is mounted is not limited to a vehicle, but may be, for example, an aircraft or a ship. Furthermore, the rotating electric machine system is not limited to a system mounted on a moving body, but may be a stationary system.

[0086] The technical concepts extracted from the above-described embodiments are described below. [Configuration 1] A wound-field type rotating electric machine (40) comprising: a stator (50) having a stator winding (52); a rotor (60) having a rotor core (61) having main pole portions (62) provided for each circumferentially arranged magnetic pole and projecting in the radial direction, and a field winding (70) wound around the main pole portions, in which a high-frequency current flows through the stator winding for inducing a field current in the field winding; and a circuit module (102) provided to be rotatable integrally with the rotor and having capacitors (91, 92) connected to the field winding, the capacitors being multilayer capacitors in which a dielectric (151) and an electrode (152) are multilayered, and the multilayer capacitors are arranged in the circuit module such that the multilayer direction of the dielectric and the electrode is perpendicular to the radial direction of the rotor. [Configuration 2] The wound-field rotating electric machine according to Configuration 1, wherein the capacitor is molded with a resin material over an area including at least the outer peripheral portion of the circuit module, which is radially outward. [Configuration 3] The wound-field rotating electric machine according to Configuration 2, wherein the inner peripheral portion of the capacitor, which is radially inward, is not molded with resin. [Configuration 4] The wound-field rotating electric machine according to any one of Configurations 1 to 3, wherein the capacitor has a layered structure in which a plurality of internal electrodes (152) serving as the electrodes are embedded in the dielectric, and the dielectric and the internal electrodes are layered together, and ends of the internal electrodes are exposed on a pair of opposing surfaces of the dielectric and a pair of external electrodes (153) are provided, and the layering direction of the dielectric and the internal electrodes is perpendicular to the radial direction of the rotor, and the pair of external electrodes are arranged on both sides in the circumferential direction. [Configuration 5] A wound-field rotating electric machine according to any one of configurations 1 to 3, wherein the circuit module is provided at a position axially facing a coil end portion of the field winding that is axially outward of the rotor core, and the lamination direction of the capacitor is oriented perpendicular to the radial direction of the rotor and in the circumferential direction.[Configuration 6] The wound-field rotating electric machine according to any one of Configurations 1 to 5, wherein in the circuit module, the capacitors are arranged in a line in the circumferential direction, each of the capacitors is electrically connected to the field winding via a bus bar (141-143), and the bus bar is arranged so as to contact the outer peripheral surface of the capacitor on the radially outer side. [Configuration 7] The wound-field rotating electric machine according to Configuration 6, wherein the bus bar surrounds the circumferentially arranged capacitors from the radially outer side, and has a length of at least a semicircle in a plan view seen from the axial direction.

[0087] 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 type rotating electric machine (40) comprising: a stator (50) having a stator winding (52); a rotor (60) having a rotor core (61) having main pole portions (62) arranged for each magnetic pole arranged in the circumferential direction and protruding in the radial direction; and a field winding (70) wound around the main pole portion, in which a high-frequency current flows through the stator winding for inducing a field current in the field winding; and a circuit module (102) provided so as to rotate integrally with the rotor and having a capacitor (91, 92) connected to the field winding, the capacitor being a laminated capacitor in which a dielectric (151) and an electrode (152) are laminated, and in the circuit module, the laminated direction of the dielectric and the electrode is arranged perpendicular to the radial direction of the rotor.

2. A wound-field type rotating electric machine according to claim 1, wherein said capacitor is molded with a resin material over an area including at least the radially outer peripheral portion of said circuit module.

3. A wound-field type rotating electric machine according to claim 2, wherein the capacitor has an inner peripheral portion that is radially inward and is not resin-molded.

4. The wound-field type rotating electric machine according to any one of claims 1 to 3, wherein the capacitor has a laminated structure in which the dielectric and the internal electrodes are laminated by embedding a plurality of internal electrodes (152) as the electrodes in the dielectric, and the ends of each of the internal electrodes are exposed on a pair of opposing surfaces of the dielectric and a pair of external electrodes (153) are provided, the lamination direction of the dielectric and the internal electrodes is perpendicular to the radial direction of the rotor, and the pair of external electrodes are arranged in a direction extending in the radial direction of the rotor.

5. A wound-field type rotating electric machine as claimed in any one of claims 1 to 3, wherein the circuit module is provided at a position axially opposing a coil end portion of the field winding that is axially outboard of the rotor core, and the lamination direction of the capacitor is oriented perpendicular to the radial direction of the rotor and in the circumferential direction.

6. A wound field type rotating electric machine according to any one of claims 1 to 3, wherein in the circuit module, the capacitors are arranged in a row in the circumferential direction, each of the capacitors is electrically connected to the field winding via a bus bar (141 to 143), and the bus bar is arranged so as to be in contact with the radially outer outer peripheral surface of the capacitor.

7. A wound-field type rotating electric machine according to claim 6, wherein the bus bar radially surrounds the capacitors arranged in the circumferential direction, and has a length of at least a semicircle when viewed in a plan view from the axial direction.

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