JP2004304995A - Exciter, field unit, and motor using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exciter which is used for a motor where a field unit is arranged on the inside and outside of the exciter, with a yoke divided in circumferential direction, capable of reducing magnetic resistance and iron loss and increasing magnetic flux (B), and to provide a motor using the same. <P>SOLUTION: An exciter 3 is used for a motor where a field unit is arranged on the inside and outside of the exciter. The exciter comprises a yoke 4 and a teeth 5. At least a part of the teeth or yoke is divided, and at least a part of the yoke or teeth comprises unidirectional electromagnetic steel plate or bidirectional electromagnetic steel plate. The axis of easy magnetization of the yoke is arranged in the circumferential direction of the exciter and laminated while the axis of easy magnetization of the teeth is arranged in radial direction of the exciter and laminated. The motor uses the exciter. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an exciter that generates a moving magnetic field by passing a current and an electric motor using the same.
More specifically, the present invention relates to an exciter used for an electric motor having a field machine arranged inside and outside the exciter, and a permanent magnet electric motor using the same.

  A permanent magnet motor is a motor in which a magnetic field generated by passing a current through an exciter (stator) acts on a permanent magnet embedded in a field machine (rotor) to rotate the field machine. It is widely used as an electric motor having excellent controllability and environmental resistance, and capable of high efficiency and high power factor operation regardless of the industrial and consumer electronics fields.

10 and 11 show cross sections of a conventional electric motor. FIG. 10 is a plan sectional view, and FIG. 11 is a longitudinal sectional view.
In this conventional motor, an annular coil 23 is wound around an annular exciter core 21 along the inner and outer peripheries, and an exciter 30 including the exciter core 21 has a shaft 28 It is fixed to the supported nonmagnetic base 25. Reference numeral 22 denotes a field machine structure, which is fixed to a field machine yoke 24 fixed to a shaft 28 such that a pair of annular permanent magnets 26 are coaxially arranged on both sides of the coil structure 21 at an appropriate interval. .
However, in this conventional motor, various proposals have been made because a sufficient interlinking magnetic field cannot be obtained inside the exciter core.

For example, Patent Document 1 discloses that an exciter core is divided so that a tooth portion and a yoke portion are paired, and teeth portions are formed on both inner and outer circumferences of the exciter core. A method of obtaining a sufficient linkage magnetic field inside the core is disclosed. However, a conventional motor exciter has been made by laminating non-oriented electrical steel sheets (NO) to reduce iron loss.
A non-oriented electrical steel sheet is a steel sheet having a uniform relative magnetic permeability in any direction on the steel sheet surface, and is widely used as a material having relatively small iron loss. Sufficient magnetic properties have not been obtained for the material used for the machine.
In addition, the joint between the yoke and the teeth of the electric motor disclosed in Patent Document 1 has a hook-like shape, and the joint has a long structure. There was a problem that iron loss was large.
JP-A-10-271772

  The present invention solves the above-mentioned problems of the prior art, and is an exciter used for an electric motor in which a field machine is arranged inside and outside the exciter, wherein the yoke is divided in a circumferential direction. It is an object of the present invention to provide an exciter capable of reducing the magnetic resistance and iron loss of the above and increasing the magnetic flux density (B), and an electric motor using the same.

  The present invention relates to an exciter used for an electric motor in which a field machine is arranged inside and outside of an exciter, wherein at least a part of a tooth or a yoke is divided, and at least a part of the tooth or the yoke is one part. Oriented magnetic steel sheet or bidirectional electromagnetic steel sheet, the easy magnetization direction of the steel sheet constituting the yoke and the teeth are respectively the circumferential direction and the radial direction of the exciter, preferably, the joint between the yoke and the teeth is linear. Provided are an exciter capable of reducing magnetic resistance and iron loss and increasing magnetic flux density (B) of an exciter in which a yoke is divided in a circumferential direction and superimposing magnetic flux density (B) by providing a step and superposing the electric motor, and an electric motor using the exciter. The gist is as follows as described in the claims.

(1) An exciter used for an electric motor having a field machine disposed inside and outside of an exciter, the exciter having a yoke and teeth, and at least a part of the yoke or the teeth is divided. Has been
The yoke or at least a part of the teeth is a unidirectional magnetic steel sheet or a bidirectional magnetic steel sheet,
An exciter wherein the axes of easy magnetization of the yokes are arranged in a circumferential direction of the exciter and stacked, and the axes of easy magnetization of the teeth are arranged in a radial direction of the exciter and stacked.
(2) The exciter according to (1), wherein an exciting coil for generating a moving magnetic field is wound around the yoke.
(3) The exciter according to (1), wherein an exciting coil for generating a moving magnetic field is wound around the teeth.
(4) The exciter according to (3), wherein a winding method of the excitation coil of the teeth is a concentrated winding or a distributed winding.
(5) The exciter according to any one of (1) to (4), wherein a joining portion between the yoke and the tooth is linear, and the joining portion is overlapped by providing a step in a laminating direction.
(6) The exciter according to any one of (1) to (4), wherein the lamination direction of the yoke and the teeth (the normal direction of the surface of each laminated plate) is not the same.
(7) The exciter according to (6), wherein the yoke is arranged and laminated in an axial direction of the exciter, and the teeth are arranged and laminated in a circumferential direction of the exciter.
(8) The exciter according to (6), wherein the yoke is arranged and laminated in a radial direction of the exciter, and the teeth are arranged and laminated in an axial direction of the exciter.
(9) The exciter according to (6), wherein the yoke is arranged and laminated in a radial direction of the exciter, and the teeth are arranged and laminated in a circumferential direction of the exciter.
(10) An electric motor comprising the exciter according to any one of (1) to (9).
(11) The electric motor according to (10), wherein the field machine is made of a steel plate.
(12) The electric motor according to (10), wherein the field machine is made of one or more of an electromagnetic steel sheet, a sintered magnetic material, and a thin ultra-low carbon steel.
(13) The electric motor according to (10), wherein the field machine is made of a material obtained by coating single crystal iron powder with an insulating material.
(14) The motor according to any one of (10) to (13), wherein the electric motor has a field machine on an outer periphery, and a permanent magnet shaped along an inner wall of the field machine is attached. An electric motor according to claim 1.
(15) The electric motor according to (10) to (14), wherein the member for fixing the radial direction of the field machine on the outer peripheral side of the electric motor is a magnetic material.
(16) The electric motor according to (10) to (15), wherein the exciter of the electric motor is a stator, and the field machine is a rotor.
(17) The electric motor according to (10) to (15), wherein the exciter of the electric motor is a rotor, and the field machine is a stator.

According to the present invention, there is provided an exciter used for an electric motor in which a field machine is arranged inside and outside the exciter, wherein the direction of easy magnetization of the grain-oriented electromagnetic steel sheet forming the yoke and the teeth is set in the circumferential direction of the exciter. And radially, and preferably, by superimposing the joint portion between the yoke and the teeth with a linear step, and superposing the yoke, the magnetic resistance and iron loss of the exciter whose yoke is divided in the circumferential direction are reduced, and the magnetic flux density is reduced. An exciter that can increase (B) and an electric motor using the same can be provided, and a remarkable industrially useful effect is achieved.

  An embodiment of the present invention will be described in detail with reference to FIGS.

<First embodiment>
FIG. 1 is a diagram showing a structure of an exciter according to a first embodiment of the present invention.
In FIG. 1, 1 is an outer field machine, 2 is an inner field machine, 3 is an exciter, 4 is a yoke, 5 is a tooth, and 6 is an exciting coil.
The exciter 3 mainly includes a yoke 4 and teeth 5 arranged in the circumferential direction, and the yoke 4 and the teeth 5 are disposed between the outer field machine 1 and the inner field machine 2. And the yoke 4 is divided in the circumferential direction of the exciter 3.
In FIG. 1, the present invention is directed to an exciter used for an electric motor having an inner field machine 2 and an outer field machine 1 disposed inside and outside an exciter 3, and an electric motor using the same.
By making the field machine a double structure of the inside and the outside, the leakage magnetic flux can be minimized, and as a result, the torque of the electric motor can be increased.
As shown in FIG. 1, in the present invention, the yoke 4 is divided in the circumferential direction of the exciter 3, and the axis of easy magnetization of the grain-oriented electromagnetic steel sheet constituting the yoke 4 is aligned with the circumferential direction of the exciter 3 (of the yoke 4). The teeth 5 are arranged and stacked in such a manner that the axis of easy magnetization of the grain-oriented electromagnetic steel sheet forming the teeth 5 is arranged in the radial direction of the exciter 3 (the direction of the teeth).

Here, the grain-oriented electrical steel sheet is an electrical steel sheet in which the direction of easy magnetization is a specific direction, and has a magnetic property superior to that of the non-oriented electrical steel sheet in the direction of easy magnetization.
For example, as shown in FIG. 2, in the grain-oriented electrical steel sheet, the relative magnetic permeability μ _R in the rolling direction is significantly larger than the relative magnetic permeability μ _T in the non-rolling direction, and the magnetic flux easily flows in the rolling direction. Has nature.
Therefore, by matching the direction of the magnetic flux flowing in the yoke with the direction of easy magnetization of the grain-oriented electrical steel sheet, the flow of the magnetic flux is smoothed, and as a result, the magnetic flux density (B) can be strengthened and the magnetic flux crosses. In this case, it is possible to prevent the occurrence of a rotating magnetic field having a large magnetic resistance at a portion where the magnetic field is lost, and to reduce iron loss in the exciter.
On the other hand, a bidirectional magnetic steel sheet is an electromagnetic steel sheet having two directions of easy magnetization, and has better magnetic properties in the direction of easy magnetization than a non-oriented magnetic steel sheet. As shown in FIG. 13, in the bidirectional electrical steel sheet, the relative magnetic permeability μ _{R in the} rolling direction and the relative magnetic permeability μ _{T in the} direction perpendicular to the rolling direction are significantly larger than those in other directions. And it has the property of easily flowing magnetic flux in the vertical direction.
Therefore, the flow of the magnetic flux can be made smooth by matching the direction of the magnetic flux flowing in the yoke with the direction of easy magnetization of one of the two-directional magnetic steel sheets. As a result, the magnetic flux density (B) can be strengthened, and the occurrence of a rotating magnetic field having a large magnetic resistance at a portion where the magnetic flux intersects can be prevented, so that the iron loss of the exciter can be reduced.

Conventionally, as shown in FIG. 16, since the yoke and the teeth are stacked in the same direction, when the magnetic flux passes through the boundary between the yoke and the teeth, the direction of the magnetic flux changes in the same plane. For this reason, a rotating magnetic field having a large magnetic resistance was generated in this portion, and the iron loss was significantly increased.
In the above description, the rotating magnetic field refers to a magnetic field whose magnetic characteristics change in a curved manner depending on the position in the XY plane, as shown in FIG. 14, and a linearly changing alternating magnetic field as shown in FIG. The magnetic field is different from the magnetic field.
The inventors of the present application have measured the iron loss of various types of stators, and have found that this rotating magnetic field is easily generated in a place where the direction of the magnetic flux changes in the same plane as the steel plate surface. Then, in order to prevent the generation of the rotating magnetic field, it has been conceived that the direction of the magnetic flux need not be changed in the same plane as the steel plate surface. By changing the lamination direction of the yoke 1 and the teeth 2 to different directions, the direction change of the magnetic flux in the plane was reduced, but the generation of the rotating magnetic field was suppressed, and the iron loss was significantly reduced.
Specifically, as shown in FIG. 17, the yoke 1 may be arranged and laminated in the radial direction of the exciter, and the teeth 2 may be arranged and laminated in the axial direction of the exciter. As shown in FIG. 18, the yoke 1 may be arranged and laminated in the radial direction of the exciter, and the teeth 2 may be arranged and laminated in the circumferential direction of the exciter. As shown, the yoke 1 may be arranged and laminated in the axial direction of the exciter, and the teeth 2 may be arranged and laminated in the circumferential direction of the exciter.

Incidentally, the teeth 5 are preferably arranged in the radial direction of the exciter 3, and the outer periphery of the exciter 3 is preferably wider than the inner periphery. By making the outer peripheral side of the teeth 5 wider, the magnetic flux flowing through the outer field machine 1 can be increased, and a larger torque can be obtained.
Further, in the present invention, the winding of the exciting coil 6 may be performed irrespective of the winding method of the tooth 5 as in the related art. However, as shown in FIG. preferable.
By winding the exciting coil 6 around the yoke 4, the length of the teeth 5 can be reduced as compared with the conventional case, and as a result, the diameter and the size of the motor can be reduced.
Also, since the exciting coil 6 is concentratedly wound around the yoke 4, the coil end can be made more compact than, for example, distributed winding wound around every other yoke, so that the space around the exciter is effectively used. Therefore, the size of the electric motor can be reduced accordingly.

<Second embodiment>
FIGS. 3 and 4 are views showing the structure of an exciter according to a second embodiment of the present invention.
3 and 4, reference numeral 4 denotes a yoke, and reference numeral 5 denotes a tooth.
As shown in FIG. 3, the joint between the yoke 4 and the teeth 5 is formed into a mountain-shaped straight line, so that the joint between the yoke 4 and the tooth 5 is more easily compared to the hook type disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 10-271772. Can be shortened, so that iron loss due to the joint can be significantly reduced.
The cut surface of the steel plate has a remarkably large magnetic resistance under the influence of stress concentration due to plastic working. Therefore, it is preferable to shorten the cut length as much as possible. As in the present invention, the cut portion (joined portion) is made straight. Thereby, magnetic resistance and iron loss can be significantly reduced.

Further, as in the present embodiment, by making the shape of the joint between the yoke 4 and the teeth 5 mountain-shaped, the magnetic flux flowing from the yoke 4 to the teeth 5 is easily bent in the axial direction of the teeth 5, so that the magnetic flux The flow can be made even smoother. FIG. 4 shows a joint between the yoke 4 and the teeth 5, and is a detailed view of a portion A in FIG.
In the present embodiment, as shown in the upper part of FIG. 4, the joint between the yoke 4 and the teeth 5 is overlapped with two steps in the laminating direction.
In this way, by superposing the joint between the yoke 4 and the tooth 5 with two steps in the laminating direction, the mechanical strength of the joint can be increased, and the magnetic characteristics of the joint can be made smooth. Therefore, the magnetic resistance of the stator can be reduced as a result.
In the lower view of FIG. 4, the joining portions of the yoke 4 and the teeth 5 are overlapped with three steps in the laminating direction. By thus increasing the number of steps, the mechanical strength of the joint can be further increased, and the magnetic resistance of the exciter can be reduced.

<Third embodiment>
FIG. 5 is a diagram showing a structure of an exciter according to a third embodiment of the present invention.
In FIG. 5, reference numeral 4 denotes a yoke, and reference numeral 5 denotes a tooth.
As shown in FIG. 5, in the present embodiment, the joint between the yoke 4 and the teeth 5 has a rectangular shape.
By making the joint between the yoke 4 and the teeth 5 rectangular, the length of the joint can be shortened as compared with the mountain shape of the second embodiment, so that the magnetic resistance can be reduced accordingly. On the other hand, from the viewpoint of smoothing the flow of the magnetic flux, it is slightly inferior to the second embodiment.
In addition, the point of providing a step at the joint portion between the yoke 4 and the teeth 5 and superimposing them is the same as in the second embodiment, and a description thereof will be omitted.

<Fourth embodiment>
6 and 7 are views showing the structure of an exciter according to a fourth embodiment of the present invention.
6 and 7, reference numeral 4 denotes a yoke, and reference numeral 5 denotes a tooth.
As shown in FIGS. 6 and 7, in the present embodiment, the yoke 4 and the teeth 5
Is formed in a trapezoidal shape with the teeth side as the oblique side. By making the junction between the yoke 4 and the teeth 5 trapezoidal, the length of the junction can be shortened as compared with the mountain shape of the second embodiment, so that the magnetic resistance of the exciter is reduced accordingly. In addition, the magnetic flux can easily flow in either the outer peripheral side or the inner peripheral side of the exciter.

Specifically, FIG. 6 shows that the trapezoidal oblique side is directed to the outer peripheral side of the exciter, so that magnetic flux easily flows to the outer peripheral side, and FIG. 7 shows that the trapezoidal oblique side is directed to the outer and inner peripheral side of the exciter. Magnetic flux easily flows to the inner peripheral side.
6 and 7 is preferably determined by the side of the outer circumference or the inner circumference where a larger amount of magnetic flux flows. For example, when a larger amount of magnetic flux flows on the outer circumference side, the embodiment of FIG. 6 is preferably selected. .
In addition, the point of providing a step at the joint portion between the yoke 4 and the teeth 5 and superimposing them is the same as in the second embodiment, and a description thereof will be omitted.

<First to Fourth Common Embodiments>
FIG. 8 is a diagram showing the structure of an exciter common to the first to fourth embodiments of the present invention and an electric motor using the same. FIG. 8 is an example in which the number of poles is four and the structure of the motor is embodied, and does not limit the technical range such as the shape and position of the permanent magnet and the number of teeth of the exciter.
In FIG. 8, 1 is an outer field machine, 2 is an inner field machine, 3 is an exciter, 4 is a yoke, 5 is a tooth, 7 is an outer permanent magnet, and 8 is an inner permanent magnet. The dotted arrows in FIG. 8 show the magnetic flux density at time t0 in FIG. 9, and the thick dotted line indicates a strong magnetic flux density and the thin dotted line indicates a weak magnetic flux density.
In the present embodiment, the exciting coils (not shown) are concentratedly wound around the yoke, so that the three-phase exciting currents U, V, and W shown in FIG. 8, the flow of magnetic flux can be created in the direction indicated by the arrow in FIG.
Note that U ′, V′W ′ in FIG. 8 indicate an exciting current in which the positive, negative, and positive of U, V, and W are inverted.
In FIG. 8, exciting currents of different phases are applied to adjacent yokes. However, for example, exciting currents of the same phase may be applied by setting two adjacent yokes as a set.
Further, by applying the exciter described in the first to fourth embodiments to a motor, it is possible to provide a motor having a small iron loss and a large output torque.

Further, in the present invention, the material of the field machine is not limited, but it is preferably any one of an electromagnetic steel sheet, a sintered magnetic material, a thin ultra-low carbon steel, and a material obtained by coating a single crystal iron powder with an insulating material.
First, since the magnetic steel sheet has better magnetic properties than other materials such as ordinary steel, iron loss in the field machine can be reduced.
Furthermore, in the case of a sintered magnetic material, a field machine can be constituted by a metal powder sintered body, so that the mechanical design and the magnetic design can be performed independently, so that the degree of freedom of the field machine design is increased and the permanent magnet is generated. A field machine with high reliability, such as mechanical strength and durability, while effectively utilizing magnetic flux can be obtained.
Further, thin ultra-low carbon steel is a kind of ordinary steel, and the material cost is extremely low, so that it is easy to procure the material.
Further, a material obtained by coating single-crystal iron powder with an insulating material is, for example, coated with single-crystal iron powder having a <001> orientation in the major axis direction with an insulating resin and poured into a mold together with a thermosetting resin to form a magnetic field. The iron loss in the field machine can be reduced by making the direction of the magnetic flux flowing through the field machine coincide with the direction of easy magnetization of the single crystal iron powder.
Further, in the present invention, the exciter may be a stator and the field machine may be a rotor, or the exciter may be a rotor and the field machine may be a stator.

FIG. 12 is a diagram showing a planar structure of a field machine according to a fifth embodiment of the present invention. In FIG. 12, 31 indicates an outer field machine, and 32 indicates a permanent magnet. The force acting on the permanent magnets in the outer field machine is almost the centrifugal force due to rotation. As shown in the plan view of the motor shown in FIG. Is pressed against the field machine by centrifugal force, so there is no problem in supporting the permanent magnet from the viewpoint of strength. Further, as shown in FIG. 12, it is preferable that the permanent magnet is embedded in the field machine so that the inner circumferential surface of the field machine becomes a single circumferential surface. Further, the material of the field machine is preferably an electromagnetic steel sheet, a sintered magnetic material or a thin ultra-low carbon steel (SULC). In particular, since a three-dimensional magnetic circuit can be designed and iron loss is reduced, a single crystal iron powder is used. Is desirable. By using such a field machine, the method of fixing the permanent magnet can be simplified, and the distance between the permanent magnet and the exciter teeth can be shortened, so that the torque can be improved.
As shown in FIG. 12, the outer field machine 31 is formed by stacking steel plates in the axial direction, and the structural members 9 are arranged around the steel plate to fix the steel plates in the radial direction. When the structural member 9 is made of a magnetic material, the total magnetic flux in the outer field machine can be increased, and a higher torque can be obtained.

It is a figure showing the structure of the exciter which is a 1st embodiment of the present invention. It is a figure which shows the relationship between the direction of the magnetic flux of a unidirectional electrical steel sheet, and iron loss. It is a figure showing the structure of the exciter which is a 2nd embodiment of the present invention. It is a figure showing the structure of the exciter which is a 2nd embodiment of the present invention. It is a figure showing the structure of the exciter which is a 3rd embodiment of the present invention. It is a figure showing the structure of the exciter which is a 4th embodiment of the present invention. It is a figure showing the structure of the exciter which is a 4th embodiment of the present invention. FIG. 4 is a diagram illustrating a structure of an exciter and a motor using the same that are common to the first to fourth embodiments of the present invention. FIG. 3 is an explanatory diagram of a three-phase excitation current. It is a cross-sectional view of the conventional electric motor. It is a longitudinal section of the conventional electric motor. It is a figure showing the structure of the field machine which is a 1st-a 4th embodiment of the present invention. It is a figure showing the characteristic of relative magnetic permeability (μ) of the bidirectional electrical steel sheet used in the present invention. It is explanatory drawing of an alternating magnetic field. FIG. 4 is an explanatory diagram of a rotating magnetic field. It is a figure showing the lamination state of the conventional exciter. It is a figure showing the structure of the exciter which is a 1st embodiment of the present invention. It is a figure showing the structure of the exciter which is a 1st embodiment of the present invention. It is a figure showing the structure of the exciter which is a 1st embodiment of the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Outer field machine 2 Inner field machine 3 Exciter 4 Yoke 5 Teeth 6 Exciting coil 7 Outer permanent magnet 8 Inner permanent magnet 9 Structural member 21 Exciter core 22 Field machine structure 23 Coil 24 Field machine Yoke 25 Non-magnetic base 26 Permanent magnet 28 Shaft 29 Bearing 30 Exciter 31 Outer field machine 32 Permanent magnet

Claims (17)

An exciter used for an electric motor in which a field machine is arranged inside and outside of the exciter, the exciter having a yoke and teeth, and at least a part of the yoke or the teeth is divided. ,
At least a part of the yoke or the teeth is a unidirectional electrical steel sheet or a bidirectional electrical steel sheet,
An exciter wherein the axes of easy magnetization of the yokes are arranged in a circumferential direction of the exciter and stacked, and the axes of easy magnetization of the teeth are arranged in a radial direction of the exciter and stacked. The exciter according to claim 1, wherein an exciting coil for generating a moving magnetic field is wound around the yoke. The exciter according to claim 1, wherein an excitation coil for generating a moving magnetic field is wound around the teeth. 4. The exciter according to claim 3, wherein a winding method of the teeth is a concentrated winding or a distributed winding. The exciter according to claim 1, wherein a joining portion between the yoke and the tooth is linear, and the joining portion is overlapped with a step provided in a laminating direction. The exciter according to claim 1, wherein a laminating direction of the yoke and the teeth (referring to a normal direction of each laminated body plate surface) is not the same direction. The exciter according to claim 6, wherein the yoke is arranged and laminated in an axial direction of the exciter, and the teeth are arranged and laminated in a circumferential direction of the exciter. The yoke is arranged and laminated in the radial direction of the exciter,
The exciter according to claim 7, wherein the teeth are arranged and stacked in an axial direction of the exciter. The exciter according to claim 6, wherein the yoke is arranged and laminated in a radial direction of the exciter, and the teeth are arranged and laminated in a circumferential direction of the exciter. An electric motor comprising the exciter according to any one of claims 1 to 9. The electric motor according to claim 11, wherein the field machine is made of a steel plate. The electric motor according to claim 11, wherein the field machine is made of one or more of an electromagnetic steel sheet, a sintered magnetic material, and a thin ultra-low carbon steel. The electric motor according to claim 10, wherein the field machine is made of a material obtained by coating single crystal iron powder with an insulating material. The electric motor according to any one of claims 10 to 13, wherein the electric motor has a field machine on an outer periphery, and a permanent magnet shaped along an inner wall of the field machine is attached. . The electric motor according to claim 10, wherein a member that fixes a radial direction of the field machine on an outer peripheral side of the electric motor is a magnetic body. The electric motor according to claim 10, wherein the exciter of the electric motor is a stator, and the field machine is a rotor. The electric motor according to claim 10, wherein the exciter of the electric motor is a rotor, and the field machine is a stator.

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