JP7580293B2 - Motor Unit - Google Patents

Description

The present invention relates to a motor unit.

Patent document 1 discloses a motor unit that includes a power module that controls the current flowing through the stator windings, a control board that is electrically connected to the power module, a capacitor that reduces the switching noise of the power module, and a current detector that detects the current.

JP 2015-89298 A

In the motor unit described in Patent Document 1, the components that make up the inverter device are stacked in the direction of the motor's rotation axis. In the motor unit described in Patent Document 1, if the components that make up the inverter device are made larger to increase output, there is a risk that the size of the motor unit in the direction of the rotation axis will increase accordingly.

The present invention was made in consideration of these technical issues, and aims to prevent the size of the motor unit in the direction of the rotation axis from increasing when the control components that control the motor are made high-output.

According to one aspect of the present invention, the motor unit includes a motor having a rotating shaft, an inverter unit provided at an end of the motor in the direction of the rotating shaft and controlling the operation of the motor, and a conductive member electrically connecting the motor and the inverter unit. The inverter unit includes a smoothing capacitor that smoothes a current supplied to the motor and a current sensor that detects the current supplied to the motor, the smoothing capacitor and the current sensor being integrally formed side by side in the radial direction of the motor. The inverter unit further includes a power conversion module, and a first cooling plate that cools the smoothing capacitor and the power conversion module is provided between the smoothing capacitor and the power conversion module. The first cooling plate abuts against one end face of the power conversion module in the direction of the rotating shaft. A second cooling plate that cools the power conversion module abuts against the other end face of the power conversion module in the direction of the rotating shaft.

According to the present invention, the smoothing capacitor and the current sensor are integrally formed side by side in the radial direction of the motor, so no wasted space is generated between the smoothing capacitor and the current sensor. Furthermore, because space can be secured in the direction of the motor's rotation axis, even if the motor unit becomes larger when the inverter unit that controls the motor is made to have a higher output, the size of the motor unit in the direction of the rotation axis can be prevented from increasing.

FIG. 1 is an overall view of a motor unit according to the present invention. FIG. 2 is a partial enlarged view of the inverter unit of the motor unit according to the present invention. FIG. 3 is a radial cross-sectional view of a smoothing capacitor in the motor unit of the present embodiment.

The following describes an embodiment of the present invention with reference to the drawings.

Figure 1 is an overall view of a motor unit 1 according to an embodiment of the present invention. Figure 2 is an enlarged view of the vicinity of the inverter unit 3. Figure 3 is a radial cross-sectional view of the smoothing capacitor 31.

As shown in FIG. 1, the motor unit 1 includes a motor 2, an inverter unit 3 that is disposed at the end (coil end) of the motor 2 in the rotational shaft direction and controls the operation of the motor 2, and an AC bus bar 30 that electrically connects the motor 2 and the inverter unit 3. The motor unit 1 is mounted on a vehicle and drives the vehicle by rotating the rotation shaft 11 of the motor 2. One end of the AC bus bar 30 is connected to the output terminal of a power conversion module 32 (described later), and the other end is connected to a terminal (not shown) of the coil of the motor 2.

The motor 2 includes a rotating shaft 11 and a rotor and a stator (not shown). The motor 2 receives power from the inverter unit 3 to rotate the rotor, thereby driving the rotating shaft 11 to rotate.

The housing 10 of the motor unit 1 comprises a cylindrical first housing 10a whose outer periphery follows the outer periphery of the motor 2, and a second housing 10b that closes the opening of the first housing 10a. A through hole 10c through which the rotating shaft 11 of the motor 2 passes is provided at the center of the second housing 10b. The motor 2 and the inverter unit 3 are housed in the space formed by the first housing 10a and the second housing 10b.

The inverter unit 3 converts DC power supplied from a battery (not shown) into AC power and supplies it to the motor 2 to drive the motor 2. The inverter unit 3 also charges the battery with regenerative power from the motor 2 when the vehicle is decelerating. The inverter unit 3 includes a smoothing capacitor 31, a power conversion module 32, a control board 33, and a current sensor 34. As shown in Figures 1 and 2, in the inverter unit 3, the smoothing capacitor 31, the power conversion module 32, and the control board 33 are stacked in this order from the end of the motor 2.

The smoothing capacitor 31 smoothes out noise and ripples in the DC current supplied to the power conversion module 32. As shown in FIG. 3, the smoothing capacitor 31 is formed so that its cross section viewed from the direction of the rotation axis of the motor 2 is substantially annular. The smoothing capacitor 31 is attached to a bracket 36 (see FIG. 1) fixed to the housing 10.

3, the smoothing capacitor 31 includes, for example, a plurality of capacitor elements 31a made of a film-like dielectric, and an annular case 31b that houses the plurality of capacitor elements 31a together with the current sensor 34. The plurality of capacitor elements 31a are arranged and housed in the case 31b. The case 31b is filled with a hardening resin (e.g., epoxy resin 31c), and the capacitor elements 31a and the current sensor 34 are sealed in the case 31b with the epoxy resin 31c. The smoothing capacitor 31 and the current sensor 34 are arranged radially side by side in the case 31b and are integrally formed. Note that, in this embodiment, an example in which eight capacitor elements 31a are provided is shown, but the number is not limited to this and can be changed as appropriate according to the required capacity, size, etc.

As shown in FIG. 2, the power conversion module 32 converts the DC power supplied from the battery into three-phase high-frequency power of U, V, and W, and supplies it to the motor 2 via the AC bus bar 30. The power conversion module 32 is formed in a circular ring shape on the upper surface of the smoothing capacitor 31. The power conversion module 32 is configured with semiconductor elements such as multiple switching elements (not shown) corresponding to each of the three phases.

One end of the DC bus bar 37 is connected to the input terminal 38 of the power conversion module 32, and the other end is connected to the input terminal 38 of the smoothing capacitor 31. The DC bus bar 37 is further connected to a power supply line from a battery (not shown) at any position on the DC bus bar 37.

The control board 33 receives instructions from a vehicle control unit (not shown) and controls the operation of the power conversion module 32 to adjust the power supplied to the motor 2. The control board 33 is electrically connected to the power conversion module 32 and outputs control signals to the switching elements of the power conversion module 32. A microcomputer and various electrical components are mounted on the control board 33.

The current sensor 34 is, for example, a Hall element type current sensor. As shown in Figs. 1 and 2, the AC bus bar 30 is inserted into the center of the current sensor 34, and the current sensor 34 detects the value of the current flowing through the AC bus bar 30. The current sensor 34 is connected to the control board 33 by a harness or the like, and the current value detected by the current sensor 34 is input to the control board 33.

The AC bus bars 30 consist of three AC bus bars 30 corresponding to the three phases U, V, and W of the motor 2 (see FIG. 3). The AC bus bars 30 are arranged close to the circumference of the rotating shaft 11, that is, at equal intervals on the radial inside of the smoothing capacitor 31, and extend axially from the end of the motor 2 along the rotating shaft 11.

As shown in Figs. 1 and 2, the inverter unit 3 further includes cooling plates 35a, 35b that are provided to abut against both side surfaces of the power conversion module 32. A flow path (not shown) is provided within the cooling plates 35a, 35b through which a refrigerant introduced from the outside flows. The cooling plate 35b is provided to face the smoothing capacitor 31 via the bracket 36. This allows the smoothing capacitor 31 to be efficiently cooled by the cooling plate 35b. The cooling plate 35b is also provided to face at least the switching element (not shown) of the power conversion module 32. Since the switching element generates a large amount of heat, the switching element can be efficiently cooled by providing the cooling plate 35b to face the switching element.

In the motor unit 1, when the motor 2 is made to have a high output, each component of the inverter unit 3 becomes larger. This results in the motor unit 1 becoming larger in the direction of the rotational axis of the motor 2. Therefore, in this embodiment, the smoothing capacitor 31 and the current sensor 34 are integrally formed side by side in the radial direction of the motor 2. This reduces wasted space between the smoothing capacitor 31 and the current sensor 34, and ensures space in the direction of the rotational axis of the motor 2. Therefore, even if the motor unit 1 (inverter unit 3) becomes larger when the control components that control the motor 2 are made to have a high output, the size of the motor unit 1 in the direction of the rotational axis can be prevented from increasing.

In particular, by providing the current sensor 34 and the AC bus bar 30 radially inside the smoothing capacitor 31 as in this embodiment, the dead space between the smoothing capacitor 31 and the rotating shaft 11 can be effectively utilized. Furthermore, since the smoothing capacitor 31 can be expanded to the vicinity of the inner peripheral wall of the housing 10, the size of the inverter unit 3 in the direction of the rotating shaft 11 can be suppressed. Note that, although this embodiment has been described taking as an example a case in which the current sensor 34 is provided radially inside the smoothing capacitor 31, the current sensor 34 may also be provided radially outside the smoothing capacitor 31.

Although the example has been described using a hardening resin (epoxy resin 31c) as the filler for the smoothing capacitor 31, this is not limiting. A filler (e.g., glass fiber) with a higher thermal conductivity than the epoxy resin 31c may be added to the epoxy resin 31c. When a Hall element type current sensor 34 is used, due to its structure, it cannot be placed in contact with the cooling plate 35b. However, by adding a filler with a higher thermal conductivity than the epoxy resin 31c, the heat generated in the current sensor 34 can be conducted to the cooling plate 35b through the epoxy resin 31c. This allows more heat generated by the current sensor 34 to be dissipated.

In addition, in the inverter unit 3, the smoothing capacitor 31, the power conversion module 32, and the control board 33 are arranged in a stacked manner. This configuration can reduce the dead space between them, making it possible to miniaturize the inverter unit 3. Furthermore, when increasing the output of the motor unit 1, the reduction in this dead space can be achieved, thereby preventing the motor unit 1 from becoming larger in the direction of the rotation axis, even if the components of the inverter unit 3 become larger.

The configuration, operation, and effects of the embodiment of the present invention configured as described above are summarized below.

The motor unit 1 includes a motor 2 having a rotating shaft 11, an inverter unit 3 that is provided at the end of the motor 2 in the direction of the rotating shaft 11 and controls the operation of the motor 2, and an AC bus bar 30 (conductive member) that electrically connects the motor 2 and the inverter unit 3. The inverter unit 3 includes a smoothing capacitor 31 that smoothes the current supplied to the motor 2, and a current sensor 34 that detects the current supplied to the motor 2, and the smoothing capacitor 31 and the current sensor 34 are aligned in the radial direction of the motor 2 and integrally formed.

In this configuration, the smoothing capacitor 31 and the current sensor 34 are integrally formed side by side in the radial direction of the motor 2, so no wasted space is generated between the smoothing capacitor 31 and the current sensor 34. Furthermore, because space can be secured in the direction of the rotating shaft 11 of the motor 2, even if the motor unit 1 is enlarged when the inverter unit 3 that controls the motor 2 is made to have a high output, the size of the motor unit 1 in the rotating shaft direction can be prevented from increasing.

In addition, by forming the smoothing capacitor 31 and the current sensor 34 as a single unit, when the motor unit 1 vibrates, the smoothing capacitor 31 and the current sensor 34 vibrate together, thereby suppressing the effects of vibration.

In the motor unit 1, the smoothing capacitor 31 and the current sensor 34 are provided in a single case 31b.

In this configuration, the smoothing capacitor 31 and the current sensor 34 are provided in a single case 31b, eliminating the need to integrate the smoothing capacitor 31 and the current sensor 34.

In the motor unit 1, the current sensor 34 is positioned radially inward of the motor 2 from the smoothing capacitor 31.

This configuration makes it possible to effectively utilize the dead space between the smoothing capacitor 31 and the rotating shaft 11.

In the motor unit 1, the inverter unit 3 further includes a power conversion module 32, and a cooling plate 35b is provided between the smoothing capacitor 31 and the power conversion module 32 to cool the smoothing capacitor 31 and the power conversion module 32.

In this configuration, by providing a cooling plate 35b between the smoothing capacitor 31 and the power conversion module 32, the smoothing capacitor 31 and the power conversion module 32 can be cooled by a single cooling plate 35b. This makes it possible to prevent the motor unit 1 from becoming too large.

In the motor unit 1, the power conversion module 32 has a switching element, and the switching element is arranged to face the cooling plate 35b.

In this configuration, the switching elements are arranged to face the cooling plate 35b, so that the switching elements that generate a large amount of heat can be efficiently cooled by the cooling plate 35b.

In the motor unit 1, the smoothing capacitor 31 has a capacitor element 31a made of a film-like dielectric and an epoxy resin 31c (sealing resin) for sealing the capacitor element 31a in the case 31b. The capacitor element 31a is disposed so as to face the cooling plate 35b.

In this configuration, the capacitor element 31a is arranged to face the cooling plate 35b, so that the capacitor element 31a can be efficiently cooled by the cooling plate 35b.

In the motor unit 1, the epoxy resin 31c (sealing resin) contains a filler that has a higher thermal conductivity than the epoxy resin 31c (sealing resin).

This configuration increases the thermal conductivity within the case 31b, allowing the capacitor element 31a and the current sensor 34 to be cooled efficiently.

The above-described embodiments of the present invention, the above-described embodiments, and the modified examples are merely examples of applications of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above-described embodiments.

In this embodiment, a Hall element type current sensor is used as an example of the current sensor 34, but this is not limiting and other types of current sensors, such as shunt resistors, may also be used.

The motor unit 1 of this embodiment may be mounted on an electric vehicle that runs by driving the motor unit 1 with the power of a battery mounted on the vehicle, or may be mounted on a series hybrid vehicle that has an engine and drives the motor unit 1 with the power generated by the engine. Furthermore, the motor unit 1 may be applied to devices other than vehicles.

In addition, in this embodiment, the smoothing capacitor 31, power conversion module 32, and control board 33, which are the control components of the inverter unit 3, are configured to have a circular ring shape, but this is not limited to this. As long as the AC bus bar 30 and the current sensor 34 can be arranged radially inside or outside, they may have any shape, including a polygonal shape or a combination of a curved surface and a polygonal shape. Any shape may be used as long as it corresponds to the shapes of the elements and wiring that make up each of them.

The capacitor element 31a is not limited to a film-shaped one, and the type of capacitor can be changed, such as a laminated ceramic structure. In addition, although the current sensor 34 is filled with resin inside the case 31b, the smoothing capacitor 31 and the current sensor 34 may be separate and mechanically joined.

In the above embodiment, a filler such as epoxy resin 31c with high thermal conductivity is provided around the smoothing capacitor 31 and the current sensor 34 provided in the case 31b. However, since the smoothing capacitor 31 and the current sensor 34 generate heat at different rates when the inverter is running, a filler with high heat dissipation properties may be filled only on the smoothing capacitor 31 side. Furthermore, if a capacitor with high heat resistance other than a film-shaped one, such as a multilayer ceramic capacitor, is used as the capacitor element 31a, it is possible to change so that no filler is used. Furthermore, the current sensor 34 and the smoothing capacitor 31 may be separate components and mechanically fixed when assembling the inverter unit 3.

REFERENCE SIGNS LIST 1 Motor unit 2 Motor 3 Inverter unit 11 Rotating shaft 30 AC bus bar (conductive member)
31 Smoothing capacitor 31a Capacitor element 31b Case 31c Epoxy resin (sealing resin)
32 Power conversion module 33 Control board 34 Current sensor 35a Cooling plate 35b Cooling plate

Claims (6)

A motor having a rotating shaft;
an inverter unit provided at an end of the motor in a rotation shaft direction and controlling an operation of the motor;
a conductive member electrically connecting the motor and the inverter unit,
The inverter unit includes:
a smoothing capacitor for smoothing a current supplied to the motor;
a current sensor for detecting a current supplied to the motor;
The smoothing capacitor and the current sensor are integrally formed and aligned in a radial direction of the motor ,
The inverter unit further includes a power conversion module,
a first cooling plate that cools the smoothing capacitor and the power conversion module is provided between the smoothing capacitor and the power conversion module;
the first cooling plate is in contact with one end surface of the power conversion module in the rotation axis direction,
A motor unit, comprising : a second cooling plate that cools the power conversion module, the second cooling plate being in contact with the other end face of the power conversion module in the rotational axis direction . 2. The motor unit according to claim 1,
The motor unit according to claim 1, wherein the smoothing capacitor and the current sensor are provided within a single case. 3. The motor unit according to claim 1,
The motor unit according to claim 1, wherein the current sensor is disposed radially inward of the smoothing capacitor. 2. The motor unit according to claim 1 ,
The power conversion module includes a switching element.
The motor unit according to claim 1, wherein the switching element is provided so as to face the first cooling plate and the second cooling plate . The motor unit according to claim 2 ,
The smoothing capacitor is
a capacitor element made of a film-like dielectric;
a sealing resin for sealing the capacitor element in the case,
The motor unit according to claim 1, wherein the capacitor element is disposed so as to face the first cooling plate . 6. The motor unit according to claim 5 ,
The motor unit according to claim 1, wherein the sealing resin contains a filler having a higher thermal conductivity than the sealing resin .

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