CN117121351A

CN117121351A - Rotary electric machine and vehicle equipped with rotary electric machine

Info

Publication number: CN117121351A
Application number: CN202280027667.3A
Authority: CN
Inventors: 饭田贵大
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2021-04-13
Filing date: 2022-03-28
Publication date: 2023-11-24
Also published as: WO2022220089A1; JP2022162704A

Abstract

A rotating electrical machine (10), comprising: a rotor (100) that holds a permanent magnet (300); a stator (200) which holds a coil (400) facing the permanent magnet and is disposed inside the rotor; and a current sensor (420) that measures a current supplied to the coil. A space (201) is formed in the stator, and the current sensor is held in contact with a wall surface (250) that defines the space.

Description

Rotary electric machine and vehicle equipped with rotary electric machine

Citation of related application

The present application claims its priority based on japanese patent application No. 2021-067663, filed on 13, 4, 2021, the entire contents of which are incorporated herein by reference.

Technical Field

The present disclosure relates to a rotating electrical machine and a vehicle equipped with the rotating electrical machine.

Background

In recent years, with the advancement of versatility, it has become difficult to secure installation space for various devices. Therefore, for each device mounted on the vehicle, miniaturization as much as possible is demanded. Patent document 1 below proposes to use an internal space of a rotating electrical machine mounted on a vehicle as a space for disposing an inverter unit or the like.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2020-25447

Disclosure of Invention

The present inventors studied to arrange a current sensor for measuring a current supplied to a coil of a rotating electrical machine in an internal space of the rotating electrical machine. However, in such a configuration, the accuracy of measurement of the current sensor may be lowered due to an influence of a temperature rise or the like.

An object of the present disclosure is to provide a rotating electrical machine capable of accurately measuring a current supplied to a coil, and a vehicle equipped with the rotating electrical machine.

The rotating electrical machine of the present disclosure includes: a rotor that holds a permanent magnet; a stator that holds a coil opposing the permanent magnet and is disposed inside the rotor; and a current sensor that measures a current supplied to the coil. In this rotary electric machine, a space is formed inside the stator, and the current sensor is held in contact with a wall surface dividing the space.

In a rotating electrical machine in which a stator is disposed inside a rotor, that is, a so-called outer rotor type rotating electrical machine, the stator is cooled by, for example, cooling water or the like in order to suppress a temperature rise of the stator. Therefore, in the rotating electrical machine having the above-described structure, the current sensor is held in contact with the wall surface in the stator. In such a configuration, the current sensor is directly cooled together with the stator, so that an excessive temperature rise of the current sensor can be prevented. As a result, the current supplied to the coil can be accurately measured by the current sensor.

According to the present disclosure, there are provided a rotating electrical machine capable of accurately measuring a current supplied to a coil and a vehicle equipped with the rotating electrical machine.

Drawings

Fig. 1 is a diagram schematically showing a structure of a vehicle in which a rotating electrical machine according to the present embodiment is mounted.

Fig. 2 is a cross-sectional view showing the structure of the rotating electrical machine according to the present embodiment.

Detailed Description

Hereinafter, this embodiment will be described with reference to the drawings. For the sake of easy understanding, the same components are denoted by the same reference numerals as much as possible in each drawing, and repetitive description thereof will be omitted.

The vehicle 20 shown in fig. 1 is configured as an electric vehicle that runs by the driving force of the rotating electrical machine 10. The rotary electric machine 10 is a so-called "in-wheel motor", and is buried in four wheels 21 provided in the vehicle 20, respectively. The specific structure of the rotary electric machine 10 will be described later.

In addition to the rotating electrical machine 10, a battery 23, an inverter 24, a control device 25, and an overall control device 26 are mounted in the vehicle 20. The battery 23 is a device for storing electric power supplied to the rotary electric machine 10, and is, for example, a lithium ion battery.

The inverter 24 is a power converter for converting the dc power output from the battery 23 into three-phase ac power and supplying the power to each rotating electrical machine 10. The inverters 24 are provided in total in four corresponding to the respective rotating electrical machines 10. The battery 23 is connected to each inverter 24 via a high-voltage branch circuit 27 provided in the vehicle 20. The inverter 24 may convert ac power generated by each rotating electrical machine 10 into dc power and supply the dc power to the battery 23 to charge the battery, for example, when the vehicle 20 is braked. In this way, the inverter 24 is configured as a bidirectional power converter. The inverter 24 can transmit electric power separately from the four rotating electrical machines 10.

The control device 25 is a device for controlling the operation of the inverter 24. The control device 25 is provided with four inverters 24 in total. The control device 25 controls the operation of the inverter 24 so that the value of the current supplied to each rotating electrical machine 10 matches the target value. The value of the current supplied to each rotating electric machine 10 is measured by a current sensor 420 (see fig. 2) described later, and is sent to the control device 25. The control device 26 is a device for overall control of the overall operation of the vehicle 20. To achieve proper control of the rotary electric machine 10 according to the state of the vehicle 20, bidirectional communication is performed between the control device 26 and the control device 25.

The structure of the vehicle 20 may be different from that shown in fig. 1. For example, the rotating electric machine 10 may be mounted only in one of the vehicles 20, and the driving force of the rotating electric machine 10 may be distributed to the four wheels 21 via the power transmission mechanism. The vehicle 20 may be configured as a so-called "hybrid vehicle" that can travel not only by the driving force of the rotating electrical machine 10 but also by the driving force of the internal combustion engine.

A specific structure of the rotary electric machine 10 will be described with reference to fig. 2. The rotary electric machine 10 includes a rotor 100 and a stator 200.

The rotor 100 is a portion fixed relative to the wheel 21 and rotates together with the wheel 21. The one-dot chain line labeled "AX" in fig. 2 is the rotational center axis of the rotor 100. Hereinafter, this rotation center axis is also referred to as "rotation center axis AX". The rotor 100 has a plate-like portion 110, an outer tube portion 120, and a shaft portion 130.

The plate-like portion 110 is a portion formed in a substantially circular plate shape. The rotation center axis AX is perpendicular to the main surface of the plate-like portion 110, and passes through the center of the plate-like portion 110.

The outer tube 120 is a cylindrical portion formed to extend downward in fig. 2 along the rotation central axis AX from the outer peripheral end portion of the plate-like portion 110. A plurality of permanent magnets 300 are held on the inner peripheral surface of the outer tube 120. The plurality of permanent magnets 300 are arranged in a plurality of circumferential directions on the inner circumferential surface of the outer tube 120.

The shaft portion 130 is a substantially cylindrical portion formed so as to extend from the plate portion 110 along the rotation central axis AX. The central axis of the shaft portion 130 coincides with the rotation central axis AX. In the present embodiment, the inner side of the shaft portion 130 is hollow, but the shaft portion 130 may be solid. The outer peripheral surface of the shaft 130 is rotatably held by the stator 200 via a bearing 500.

The stator 200 is a portion that is attached to the vehicle 20 in a state where the rotor 100 is rotatably held as described above. The stator 200 is housed entirely inside the rotor 100. The stator 200 includes a plate-like portion 210, an outer tube portion 220, and an inner tube portion 230.

The plate-like portion 210 is a portion formed in a substantially circular plate shape. The rotation center axis AX is perpendicular to the main surface of the plate-like portion 210, and passes through the center of the plate-like portion 210. An opening 212 is formed in the center of the plate-like portion 210, and the shaft portion 130 is inserted into the opening 212. A seal for preventing invasion of foreign matter may be provided between the opening 212 and the shaft 130, or a bearing similar to the bearing 500 may be provided. The surface 211 of the plate-like portion 210 on the opposite side to the side where the inner tube portion 230 and the like are provided is a surface fixed to the vehicle 20.

The outer tube 220 is a cylindrical portion formed to extend upward in fig. 2 along the rotation central axis AX from the outer peripheral end portion of the plate-like portion 210. The coil 400 is held on the inner peripheral surface of the outer tube 220 via an adhesive 401. The coil 400 is a winding divided into three phases, and is a portion through which current supplied from the inverter 24 flows. The coil 400 is held in a state of being opposed to the permanent magnet 300. When a current flows through each phase of the coil 400, an electromagnetic force is generated between the coil 400 and the permanent magnet, and the electromagnetic force rotates the rotor 100.

A cooling flow path 221 is formed inside the outer tube 220. The cooling flow path 221 is a flow path of cooling water supplied from the outside. By flowing the cooling water through the cooling flow path 221, an excessive increase in the temperature of the entire rotating electrical machine 10 including the outer tube 220 can be prevented. As the fluid flowing through the cooling flow path 221, for example, a fluid such as a refrigerant different from the cooling water may be used. The outer tube 220 having the cooling channel 221 may be formed by combining a plurality of members via a seal, for example.

The inner tube 230 is a cylindrical portion formed to extend upward in fig. 2 along the rotation central axis AX from the peripheral portion of the opening 212 in the plate-like portion 210. The shaft portion 130 of the rotor 100 is housed inside the inner tube portion 230. The bearing 500 described above is provided between the inner peripheral surface of the inner tube 230 and the outer peripheral surface of the shaft 130. That is, the inner tube 230 is a portion that rotatably holds the rotor 100.

A space 201 is formed inside the stator 200. In the cross-sectional view of fig. 2, the space 201 is a space divided from three sides by the outer tube portion 220, the plate-like portion 210, and the inner tube portion 230. Hereinafter, the wall surface dividing the space 201 is also referred to as "wall surface 250". The wall surface 250 includes a wall surface 251 that is a surface of the plate-like portion 110 side (upper side in fig. 2) of the plate-like portion 210, a wall surface 252 that is an inner peripheral surface of the outer tube portion 220, and a wall surface 253 that is an outer peripheral surface of the inner tube portion 230.

A current sensor 420 is disposed in the space 201. The current sensor 420 is a sensor for measuring the current flowing through each phase of the coil 400. As the current sensor 420, various sensors such as a hall sensor, a magneto-resistance sensor, and a magneto-impedance sensor can be used. In the rotary electric machine 10, a total of three current sensors 420 are provided corresponding to each, but only one of the current sensors 420 is illustrated in fig. 2.

The current sensor 420 is held in contact with the wall surface 250 (specifically, the wall surface 252). The current sensor 420 may be adhered to the wall surface 250, or may be fixed by a fastening member such as a bolt. In either case, the current sensor 420 is fixed in a state in which a part thereof is in contact with the wall surface 250.

A recess 222 is formed in a portion of the outer tube 220 at a tip end thereof facing the plate-like portion 110. The recess 222 is formed in a groove shape connecting the inner side and the outer side of the outer tube 220. A lead 410 extending from the coil 400 is disposed in the recess 222. The lead 410 is a wire for supplying current to the coil 400, and is connected to a winding of the coil 400. The wire 410 extends from the coil 400 through the recess 222 and toward the space 201, and is drawn around along the wall surface 250. The lead wire 410 passes through a not-shown clamping portion provided to the current sensor 420 and is led out from the space 201 to the outside of the rotary electric machine 10 through an not-shown opening provided to the stator 200. A signal line, not shown, which connects the current sensor 420 and the control device 25, is similarly led out to the outside through an opening, not shown, provided in the stator 200. The portion of the wall surface 252 where the recess 222 is formed corresponds to an "introduction portion" for introducing the lead wire 410 extending from the coil 400 into the space 201. Instead of the recess 222, a through hole may be formed so as to penetrate the outer tube 220. In this case, the portion of the wall surface 252 where the through hole is formed corresponds to an "introduction portion".

In addition, in fig. 2, only one wire 410 extending from the coil 400 is illustrated, but in reality, a plurality of wires 410 extend from the coil 400, and the respective wires 410 are led out to the space 201. In the case where the coil 400 is provided as three phases as in the present embodiment, for example, six wires 410 are led out from the coil 400. Accordingly, the plurality of concave portions 222 are also formed according to the number of the wires 410.

In the operation of the rotating electrical machine 10, when the temperature of the current sensor 420 increases, there may be a case where the measurement accuracy of the current sensor 420 is lowered, such as a narrow range of current values that the current sensor 420 can accurately measure. However, in the present embodiment, since the current sensor 420 is held in contact with the wall surface 250, the current sensor 420 is also cooled simultaneously with the stator 200 by the cooling water passing through the cooling flow path 221. Since the temperature of the current sensor 420 can be prevented from excessively rising, the current supplied to the coil 400 can be accurately measured by the current sensor 420.

The current sensor 420 may be in contact with any one of the three wall surfaces 251, 252, 253 constituting the wall surface 250. However, in view of cooling efficiency, it is preferable that the current sensor 420 is brought into contact with the wall surface 252 on which the cooling flow path 221 is formed. The wall surface 252 corresponds to the "cooled wall surface" in the present embodiment.

In addition, during the operation of the rotary electric machine 10, electromagnetic noise, which is a fluctuation in the magnetic field around the stator 200, is generated with the three-phase alternating current in the coil 400, the movement of the permanent magnet 300, and the like. When such electromagnetic noise reaches the current sensor 420, the measurement accuracy of the current sensor 420 may be lowered even if the temperature rise can be suppressed as described above. In order to suppress electromagnetic noise reaching the current sensor 420, it is preferable to form the stator 200 using a material having as high an electric conductivity or magnetic permeability as possible.

However, even if the stator 200 is formed of such a material, a part of electromagnetic noise generated around the stator 200 enters the space 201 through the recess 222 formed as the introduction portion and reaches the current sensor 420. In order to reduce electromagnetic noise reaching the current sensor 420 through such a path, it is preferable to secure a distance between the recess 222 and the current sensor 420 as large as possible. This is because, in general, the intensity of the arriving electromagnetic noise is inversely proportional to the square of the distance.

The broken line DL shown in fig. 2 shows a position along the rotation central axis AX at the center of the space 201. In the present embodiment, the recess 222 is formed in the wall surface 250 at a position along the rotation central axis AX at one end portion (in the example of fig. 2, at a position above the broken line DL) at the other end portion. In addition, the current sensor 420 is held at a position (a position located below the broken line DL in the example of fig. 2) of the wall surface 250 along the rotation central axis AX at the other side end portion than the broken line DL. With such a configuration, the distance between the recess 222 and the current sensor 420 can be sufficiently ensured, and the influence of electromagnetic noise on the current sensor 420 can be reduced. The respective positions of the recess 222 and the current sensor 420 may also be reversed from above and below the example shown in fig. 2.

In the example of fig. 2, a current sensor 420 is disposed at a position directly below the recess 222 along the rotation center axis AX. However, the position of the current sensor 420 may be located opposite to the recess 222 with the broken line DL interposed therebetween, or may be other than the position immediately below the recess 222. That is, the respective positions of the recess 222 and the current sensor 420 in the circumferential direction may also be different from each other.

The wall surface 250 in which the recess 222 is formed and the wall surface 250 in which the current sensor 420 is held may be the same wall surface 250 (wall surface 252) as in the present embodiment, but may be different wall surfaces 250. For example, the recess 222 may be formed in the wall surface 252, and the current sensor 420 may be held by the wall surface 251.

As described above, in the present embodiment, three current sensors 420 are provided in the rotary electric machine 10. As in the current sensor 420 illustrated in fig. 2, both are held in contact with the wall surface 250 at a position closer to the plate-like portion 210 than the broken line DL. The three current sensors 420 are held at positions distributed at, for example, 120 degrees along the inner peripheral surface (i.e., the wall surface 252) of the outer cylindrical portion 220. By securing the distance between the current sensors 420 as long as possible, it is possible to prevent the influence of noise from being exerted on each of the current sensors 420. The number (3) of the current sensors 420 in the present embodiment is merely an example, and for example, four current sensors 420 may be disposed in the space 201.

The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Even if those skilled in the art make appropriate design changes to these specific examples, the present disclosure is intended to be included within the scope of the present disclosure as long as the features of the present disclosure are included. The elements, arrangement, conditions, shape, and the like included in each specific example are not limited to the examples, and may be appropriately changed. As long as technical contradiction does not occur, the elements included in the respective specific examples described above can be appropriately combined and changed.

Claims

1. A rotating electrical machine, comprising:

a rotor (100) holding permanent magnets (300);

a stator (200) that holds a coil (400) that faces the permanent magnet and is disposed inside the rotor; and

a current sensor (420) for measuring a current supplied to the coil,

a space (201) is formed in the stator, and the current sensor is held in contact with a wall surface (250) that divides the space.

2. The rotating electrical machine according to claim 1, wherein,

the plurality of wall surfaces dividing the space include a cooled wall surface (252) having a cooling flow path (221) formed inside.

3. A rotary electric machine according to claim 2, wherein,

the current sensor is abutted against the cooled wall surface.

4. A rotary electric machine according to any one of claim 1 to 3, wherein,

an introduction portion (222) for introducing a wire extending from the coil into the space is formed in a wall surface that partitions the space.

5. The rotating electrical machine according to claim 4, wherein,

the introduction portion is formed at a position of an end portion on one side of a center of the space along a rotation center axis of the rotor, of a wall surface dividing the space,

the current sensor is held at a position of an end portion of a wall surface dividing the space on the other side than a center of the space along a rotation center axis of the rotor.

6. A vehicle (20) is equipped with a rotating electrical machine (10),

the rotating electrical machine includes:

a rotor (100) holding permanent magnets (300);

a current sensor (420) for measuring a current supplied to the coil,