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EP-4742515-A1 - FIELD-WINDING ROTATING ELECTRIC MACHINE

EP4742515A1EP 4742515 A1EP4742515 A1EP 4742515A1EP-4742515-A1

Abstract

A wound-field rotating electrical machine has a rotor (60) which includes a rotor core having main poles, one for each of magnetic poles arranged in a circumferential direction of the rotor. The main poles protrudes in a radial direction of the rotor. A field winding (70) is wound around the main poles. The rotor includes a circuit module (102) equipped with a capacitor (91) connected to the field winding. The capacitor is made of a multilayer capacitor in which layers of a dielectric (151) and electrodes (152) are stacked on one another. In the circuit module, a stacking direction, in which the layers of the dielectric and the electrodes are stacked, is oriented perpendicular to the radial direction of the rotor.

Inventors

  • YOSHIMURA, MASATAKA

Assignees

  • DENSO CORPORATION

Dates

Publication Date
20260513
Application Date
20240703

Claims (7)

  1. A wound-field rotating electrical machine (40) comprising: a stator (50) which includes a stator winding (52); a rotor (60) which includes a rotor core (61) and a field winding (70), the rotor core having main poles (62) which are provided one for each of magnetic poles arranged adjacent to each other in a circumferential direction of the rotor, the main poles protruding in a radial direction of the rotor, the field winding being wound on the main poles; and a circuit module (102) which is rotatable along with the rotor and includes a capacitor (91, 92) connected to the field winding, wherein a high-frequency current flows through the stator winding to induce a flow of field current in the field winding, the capacitor is made of a multilayer capacitor in which a dielectric (151) and electrodes (152) are stacked and which is disposed in the circuit module to have a stacking direction in which the dielectric and the electrodes are stacked and which is oriented orthogonally to the radial direction of the rotor.
  2. The wound-field rotating electrical machine as set forth in claim 1, wherein the capacitor is molded with resin in a region radially outside an outer periphery thereof in the circuit module.
  3. The wound-field rotating electrical machine as set forth in claim 2, wherein the capacitor is not molded with the resin in a region radially inside an inner periphery thereof.
  4. The wound-field rotating electrical machine as set forth in any one of claims 1 to 3, wherein the capacitor has a multilayer structure in which a plurality of internal electrodes (152) which serve as the electrodes are embedded in the dielectric to form a stack of the internal electrodes and layers of the dielectric, the dielectric has first and second opposed surfaces on which the internal electrodes are exposed and to which external electrodes (153) are attached, and a stacking direction in which the layers of the dielectric and the internal electrodes are stacked on one another is oriented perpendicular to the radial direction of the rotor, and the external electrodes are arranged to extend in the radial direction of the rotor.
  5. The wound-field rotating electrical machine as set forth in any one of claims 1 to 3, wherein the circuit module is arranged to axially face a coil end of the field winding which is located axially outside the rotor core, the stacking direction of the capacitor is oriented perpendicular to the radial direction of the rotor and along the circumferential direction of the rotor.
  6. The wound-field rotating electrical machine as set forth in any one of claims 1 to 3, wherein the capacitor includes a plurality of capacitors, the capacitors are arranged in the circumferential direction in the circuit module and electrically connected to the field winding using a busbar (141 to 143), the busbar is arranged in contact with radially outer peripheral surfaces of the capacitors.
  7. The wound-field rotating electrical machine as set forth in claim 6, wherein the busbar surrounds the capacitors, which are arranged in the circumferential direction, from radially outside the capacitors, and the busbar has at least a semicircular length extending in the axial direction.

Description

CROSS REFERENCE TO RELATED DOCUMENT The present application claims the benefit of priority of Japanese Patent Application No. 2023-111699 filed on July 6, 2023, the disclosure of which is incorporated in its entirety herein by reference. Technical Field This disclosure relates generally to a wound-field rotating electrical machine. BACKGROUND ART Conventional wound-field rotating electrical machines are equipped with a rotor which includes a rotor core having a plurality of main poles (i.e., magnetic salient poles) provided one for each magnetic pole arranged in the circumferential direction. The rotor also includes a field winding wound around the main poles. A structure is also known in which a circuit module as an electrical device is secured to an axial end of the rotor (see First Patent Literature). The circuit module includes capacitors. A resonance circuit is made of a combination of the field winding and the capacitors. PRIOR ART DOCUMENT PATENT DOCUMENT FIRST PATENT LITERATURE : Japanese patent first publication No. 2020-124100 SUMMARY OF THE INVENTION In the above-described wound-field rotating electrical machine in which the circuit module equipped with the capacitors mounted on the axial end of the rotor, the circuit module is rotated following rotation of the rotor. This leads to a risk that the capacitors may be undesirably deformed due to centrifugal force arising from the rotation of the circuit module. Specifically, when each capacitor is designed in a multilayer form in which a dielectric and electrodes are stacked in a radial direction of the rotor (which will also be referred to below as a stacking direction), centrifugal force acts on each capacitor in the stacking direction. Therefore, there is a concern that deformation may occur in the dielectric layer and the electrode layers, leading to defects such as cracks in the capacitors. A typical multilayer capacitor is considered to be composed of a stack of thin films, when centrifugal force acts in the stacking direction. Such structure leads to a risk that the thin films may be deformed or damaged. The present disclosure has been made in view of the above circumstances. It is an object of this disclosure to provide a wound-field rotating electrical machine capable of suppressing occurrence of capacitor defects due to centrifugal force in a circuit module that rotates along with a rotor. This disclosure is to provide a wound-field rotating electrical machine which comprising: (a) a stator which includes a stator winding; (b) a rotor which includes a rotor core and a field winding; (c) a circuit module. The rotor core has main poles which are provided one for each of magnetic poles arranged adjacent to each other in a circumferential direction of the rotor. The main poles protrude in a radial direction of the rotor. The field winding is wound on the main poles. The circuit module is rotatable along with the rotor and includes a capacitor connected to the field winding. A high-frequency current flows through the stator winding to induce a flow of field current in the field winding. The capacitor is made of a multilayer capacitor in which a dielectric and electrodes are stacked and which is oriented in the circuit module to have a stacking direction in which the dielectric and the electrodes are stacked. The stacking direction is oriented perpendicular to the radial direction of the rotor. The structure of the wound-field rotating electrical machine in which the circuit module equipped with the multilayer capacitor is disposed to be rotatable along with the rotor has a risk that defects may occur in the capacitor due to centrifugal force in relation to the stacking direction. In order to alleviate such a risk, the wound-field rotating electrical machine is designed to have disposed therein the capacitor which is oriented to have the stacking direction perpendicular to the radial direction of the rotor. This minimizes bending of the capacitor due to centrifugal force acting inside the capacitor, thereby avoiding defects in the capacitor in the circuit module rotating along with the rotor. BRIEF DESCRIPTION OF THE DRAWINGS The above-described object and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawings are: Fig. 1 is an overall configuration diagram of a control system of a rotating electrical machine;Fig. 2 is a diagram showing an inverter and peripheral components thereof;Fig. 3 is a cross-sectional view of a rotor and a stator;Fig. 4 is a diagram showing an electric circuit with which a rotor is equipped;Fig. 5 is a perspective view showing an overall configuration of a rotor;Fig. 6 is an exploded perspective view of a rotor;Fig. 7 is a longitudinal sectional view of a rotor;Fig. 8 is a partially exploded perspective view which illustrates winding units installed in a main body of a rotor;Fig. 9 is a p