Vehicle motor drive control device

Abstract

Achieves both lightweight design and electromagnetic shielding performance. [Solution] The vehicle motor drive control device 1 comprises a power module 10 that controls the power of an electric motor that drives a vehicle, a first cover 30 which is formed in the shape of a bottomed cylindrical box with one side open and is arranged to cover the power module, and a second cover 40 which closes the opening of the first cover. The second cover is made of a first member 41 made of iron with a thickness of 0.3 mm to 0.5 mm and a second member 42 made of aluminum with a thickness of 0.3 mm or more, which are stacked with a space between the first member and the second member.

Description

Technical Field

[0001] The present invention relates to electromagnetic shielding of a motor drive control device for a vehicle.

Background Art

[0002] Generally, vehicles such as automobiles are equipped with electronic components (electrical components) for various purposes such as driving and control. In the housing of electrical components for vehicles, an electromagnetic shielding technique for shielding electromagnetic waves generated from the electrical components is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a vehicle in which the power source is electrified, a motor drive control device that controls a drive motor, called a power control unit (PCU), is mounted. In the PCU, inside the housing, an inverter (power module) that converts direct current into alternating current, a capacitor that smooths the power from the battery, and various electronic components are mounted on a control circuit board that constitutes a circuit for controlling the operation of the PCU including the inverter.

[0005] Similar to the above-described electrical components for vehicles, improvement of electromagnetic shielding is also required in the PCU. In particular, electromagnetic waves generated from the PCU pose a problem in electromagnetic shielding in the frequency band of 0.5 MHz to 1 MHz corresponding to the frequency of AM radio.

[0006] On the other hand, there is a growing demand for lighter PCUs, including their casings. If only electromagnetic shielding performance is considered, using thick aluminum material for the entire casing would be effective, but this would make the PCU heavy.

[0007] Therefore, the present invention has been made in view of the above problems, and aims to provide a vehicle motor drive control device that can achieve both weight reduction and electromagnetic wave shielding performance. [Means for solving the problem]

[0008] To solve the above problems, the vehicle motor drive control device according to the present invention comprises a power module for controlling the power of an electric motor that drives a vehicle, a first cover formed in the shape of a bottomed cylindrical box with one side open and arranged to cover the power module, and a second cover that closes the opening of the first cover, wherein the second cover is made of a first iron member with a thickness of 0.3 mm to 0.5 mm and a second aluminum member with a thickness of 0.3 mm or more, laminated with a space between the first member and the second member.

[0009] In a vehicle motor drive control device according to one aspect of the present invention, the second cover has a shielding effect of at least 40 dB against electromagnetic waves in the range of 0.5 MHz to 1 MHz.

[0010] In a vehicle motor drive control device according to one aspect of the present invention, the second cover is configured such that the first iron member is positioned closer to the power module than the second aluminum member. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a vehicle motor drive control device that can achieve both weight reduction and electromagnetic wave shielding performance. [Brief explanation of the drawing]

[0012] [Figure 1]This is a cross-sectional view showing a vehicle motor drive control device according to an embodiment of the present invention. [Figure 2] This is an enlarged cross-sectional view showing the second cover of the vehicle motor drive control device according to this embodiment. [Figure 3] This is an enlarged cross-sectional view showing a modified example of the second cover in the vehicle motor drive control device according to this embodiment. [Figure 4] This figure schematically illustrates the effect of electromagnetic shielding by the second cover in the vehicle motor drive control device according to this embodiment. [Figure 5] This graph shows the difference in electromagnetic shielding performance due to differences in materials. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0014] [Summary of the Embodiment] First, a general overview of a typical embodiment of the invention disclosed in this application will be provided. In the following description, reference numerals in the drawings corresponding to the components of the invention are indicated in parentheses as an example.

[0015] [1] A motor drive control device for a vehicle, comprising: a power module (10) for controlling the power of an electric motor that drives a vehicle; a first cover (30) formed in the shape of a bottomed cylindrical box with one side open and positioned to cover the power module; and a second cover (40) for closing the opening of the first cover, wherein the second cover is made of a first iron member (41) with a thickness of 0.3 mm to 0.5 mm and a second aluminum member (42) with a thickness of 0.3 mm or more, stacked with a space between the first member and the second member.

[0016] [2] The vehicle motor drive control device according to [1], wherein the second cover has a shielding effect of at least 40 dB against electromagnetic waves in the range of 0.5 MHz to 1 MHz.

[0017] [3] The second cover is disposed closer to the power module than the iron first member is to the aluminum second member, in the vehicle motor drive control device according to [1] or [2].

[0018] [Configuration of Vehicle Motor Drive Control Device]

[0019] FIG. 1 is a cross-sectional view showing a vehicle motor drive control device 1 according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a second cover 40 in the vehicle motor drive control device 1.

[0020] Hereinafter, for convenience of explanation, in the vehicle motor drive control device 1 shown in FIGS. 1 and 2, the longitudinal direction is the x-axis direction (left-right direction, width direction), and the short direction perpendicular to the x-axis is the z-axis direction (up-down direction, height direction). In the following description, when the positional relationship and direction of each component are described as the right side, left side, front side, rear side, upper side, and lower side, it is only to indicate the positional relationship and direction in the drawing, and does not limit the positional relationship and direction in the actual vehicle motor drive control device 1.

[0021] As shown in FIG. 1, the vehicle motor drive control device 1 mainly includes a power module 10, a water jacket 20, a first cover 30, a second cover 40, and a capacitor 50.

[0022] The power module 10 controls the power of an electric motor (not shown) that drives the vehicle. The power module 10 is a power semiconductor module device that uses, for example, Si (silicon) or SiC (silicon carbide) as a semiconductor material. Specifically, the power module 10 operates as an inverter that converts DC current and AC current to each other. The power module 10 is electrically connected by a busbar 60 to a capacitor 50 that smooths the power from a battery (not shown). The power module 10 has a first surface 11 on its lower side in the vertical direction and a second surface 12 on its upper side. In this embodiment, the direction from the first surface 11 to the second surface 12, i.e., upward, is the first direction, and the direction from the second surface 12 to the first surface 11, i.e., downward, is the second direction.

[0023] The water jacket 20 is made of resin and has internal flow channels (not shown) through which a refrigerant such as LLC (Long Life Coolant) can be circulated. The water jacket 20 has a first surface 21 on its lower side in the vertical direction and a second surface 22 on its upper side. Electronic components such as a power module 10 and a capacitor 50 are mounted on the second surface 22 of the water jacket 20.

[0024] The first cover 30 is made of an aluminum component. The first cover 30 covers the power module 10, the capacitor 50, and the second surface 22 of the water jacket 20 from the second surface 12 side of the power module 10. The first cover 30 has a box-like shape with an opening 31 at the bottom. The first cover 30 employs a dustproof structure in which the joint with the water jacket 20 is sealed in order to protect the power module 10, the capacitor 50, etc. The shape of the first cover 30 is not limited to a box shape; it is sufficient if it can cover the power module 10, etc. from above.

[0025] The second cover 40 is a plate-shaped or substantially plate-shaped component. The second cover 40 is attached to the first cover 30 by closing the opening 31. The outer periphery of the second cover 40 is formed to correspond to the outermost part of the wall surrounding the opening 31 of the first cover 30, and it can be fixed to the z-axis end face of the wall by fixing means such as screws. In the vehicle motor drive control device 1, the second cover 40 closes the box-shaped first cover 30 with the opening 31 from the outside of the first cover 30. In addition, in the vehicle motor drive control device 1, electronic components such as the power module 10 and capacitor 50 are isolated from the outside of the first cover 30 and second cover 40 by the first cover 30 and the second cover 40.

[0026] The second cover 40 has a first member 41 and a second member 42. As shown in Figure 2, the first member 41 is an iron plate, that is, an iron sheet material. The iron first member 41 has a thickness (dimension in the z-axis direction) t1 of 0.5 millimeters. The second member 42 is an aluminum plate, that is, an aluminum sheet material. The aluminum second member 42 has a thickness t2 of 0.3 millimeters. The second cover 40 has a space between the first member 41 and the second member 42, and the first member 41 and the second member 42 are stacked in the z-axis direction. The first member 41 and the second member 42 may be integrated by crimping or bolting, or by filling the space with a non-conductive material, such as an adhesive, and the space between the first member 41 and the second member 42 may be extremely small.

[0027] In the second cover 40, the iron first member 41 is positioned closer to the water jacket 20 and power module 10 than the aluminum second member 42, that is, closer to the inside of the first cover 30. With this configuration, the aluminum second member 42, rather than the iron first member 41, is in contact with the outside air, which is advantageous as a rust-preventive structure. It is also possible to position the second member 42 in the second cover 40 closer to the water jacket 20 than the first member 41.

[0028] Figure 3 is an enlarged cross-sectional view showing a modified example of the second cover 40B in the vehicle motor drive control device 1. In the modified example of the second cover 40B shown in Figure 3, the thickness t1 of the iron first member 41B is different from the thickness t1 of the first member 41 of the second cover 40 described above. Specifically, the thickness t1 of the iron first member 41B is 0.3 millimeters. As will be described in detail later, in the second cover 40 of the vehicle motor drive control device 1, the thickness t1 of the iron first members 41 and 41B can be between 0.3 millimeters and 0.5 millimeters.

[0029] [Operation of a vehicle motor drive control device] Next, the operation of the vehicle motor drive control device 1 described above will be explained.

[0030] As described above, in the vehicle motor drive control device 1, electronic components such as a power module 10 and a capacitor 50 are housed in the internal space formed by the first cover 30 and the second cover 40, both of which are made of metal. In the vehicle motor drive control device 1, by surrounding the electronic components with metal components, effects such as preventing the intrusion of dust and moisture, protecting the internal electronic components in the event of a collision, protecting the holding and connection of high-voltage wiring such as busbars 60, and providing protection against electromagnetic waves generated by the electronic components can be obtained.

[0031] In particular, if the electronic components of the vehicle motor drive control device 1 generate electromagnetic waves in a frequency band close to the frequency band of radio waves necessary for the operation of televisions, radios, mobile communications, etc., electromagnetic shielding is important because it may have an impact on the normal operation of broadcasting and communication transmission and reception, such as causing communication interference.

[0032] The power module 10 mounted on the vehicle motor drive control device 1 generates electromagnetic waves E (see Figure 1) when converting power from the battery to DC / AC. The electromagnetic waves E generated from the power module 10 include frequencies close to those of AM radio. Generally, vehicles are equipped with AM radios for purposes such as obtaining traffic information, so suppressing electromagnetic waves E from the power module 10 is important for the vehicle motor drive control device 1. The vehicle motor drive control device 1 implements electromagnetic shielding measures by housing electronic components such as the power module 10 and capacitor 50 in an internal space formed by a first cover 30 and a second cover 40, both of which are made of metal.

[0033] On the other hand, the vehicle motor drive control device 1 also requires weight reduction. Therefore, if the thickness of the metal parts used in the first cover 30 and the second cover 40 of the vehicle motor drive control device 1 is set by focusing solely on electromagnetic wave shielding measures, there is a risk that the overall weight of the device will increase.

[0034] Therefore, in the vehicle motor drive control device 1, the second cover 40, 40B is made of a first iron member 41, 41B and a second aluminum member 42, which are stacked with a space between them. The first iron members 41, 41B have a thickness t1 of 0.3 mm to 0.5 mm, and the second aluminum member 42 has a thickness t2 of 0.3 mm.

[0035] The electromagnetic shielding effect of metal parts is related to the relative conductivity / relative permeability and relative conductivity × relative permeability of the metal material. Relative conductivity / relative permeability indicates the degree of reflection loss of electromagnetic waves; the larger the value, the greater the reflection loss of electromagnetic waves. Relative conductivity × relative permeability indicates the degree of absorption loss of electromagnetic waves; the larger the value, the greater the absorption loss of electromagnetic waves. Iron has a relative conductivity / relative permeability of 0.0017, resulting in low reflection loss and a relative conductivity × relative permeability of 17, resulting in high absorption loss. Aluminum has a relative conductivity / relative permeability of 0.63, resulting in high reflection loss, but a relative conductivity × relative permeability of 0.63, resulting in low absorption loss compared to iron.

[0036] Figure 4 schematically illustrates the effect of electromagnetic shielding by the second covers 40 and 40B in the vehicle motor drive control device 1. As shown in Figure 4, in the vehicle motor drive control device 1, electromagnetic waves E1 generated from the power module 10 are incident on the first iron members 41 and 41B, which are located closer to the power module 10 than the second member 42 and have low reflection loss and high absorption loss, and most of the electromagnetic waves E1 are absorbed and attenuated by the first members 41 and 41B. Electromagnetic waves E2 that have passed through the first members 41 and 41B pass through the space between the first members 41 and 41B and the second member 42 and are incident on the second aluminum member 42, which has lower absorption loss than iron but higher reflection loss than iron. Some of the electromagnetic waves E2 are transmitted, but more than half are reflected by the aluminum second member 42. The electromagnetic waves E3 reflected by the second member 42 are again incident on the iron first members 41 and 41B, where most of them are absorbed again, and some are reflected. In this way, the present invention intends for the electromagnetic waves to be attenuated in the second cover 40 and 40B by repeatedly undergoing multiple reflections between the iron first members 41 and 41B and the aluminum second member 42.

[0037] As described above, the vehicle motor drive control device 1 is designed so that the second cover 40, 40B is made of iron first members 41, 41B and aluminum second member 42 stacked with a space between them. Due to the reflection loss and absorption loss characteristics of each material, the electromagnetic waves are attenuated by multiple reflection losses between the two materials, thereby improving the electromagnetic wave shielding effect.

[0038] Figure 5 is a graph showing the difference in shielding effect due to differences in shielding materials. All of this data is the result of actual measurements under the same conditions using the Advantest method, a measurement method developed by Advantest Corporation. In Figure 5, S1 shows the shielding performance when the second cover 40 of the present invention is configured as described above, that is, when it is composed of a first member 41 made of iron with a thickness t1 of 0.5 mm, a second member 42 made of aluminum with a thickness t2 of 0.3 mm, and space. S2 shows the shielding performance when the second cover 40B is configured as described above, that is, when it is composed of a first member 41B made of iron with a thickness t1 of 0.3 mm, a second member 42 made of aluminum with a thickness t2 of 0.3 mm, and space. For comparison, S3 shows the shielding performance of a single aluminum plate with a thickness of 3 mm. S4 shows the shielding performance of a single iron plate with a thickness of 1.2 mm. S5 shows the shielding performance of a single iron plate with a thickness of 0.8 mm.

[0039] As shown in Figure 5, comparing S1 to S5, S3 demonstrates the best shielding performance, showing the effect of a 3 mm thick aluminum plate. However, S1, which shows the shielding performance of the second cover 40 of the present invention, consisting of a 0.5 mm thick iron plate, a 0.3 mm thick aluminum plate, and space, exhibits almost the same shielding performance as S3 despite its thinner plate thickness. If the threshold for shielding performance against electromagnetic waves in the 0.5 MHz to 1 MHz frequency range, close to the AM radio frequency band, is set to 40 dB, then both S3 and S1 have a shielding performance of 40 dB or more. S2, which shows the shielding performance of the second cover 40B, which has a configuration in which the thickness of the iron plate is reduced from 0.5 mm to 0.3 mm, also exhibits a shielding performance of 40 dB or more against electromagnetic waves in the 0.5 MHz to 1 MHz range.

[0040] In contrast, S4 and S5, which represent the shielding performance of sheet metal made solely of steel, show lower shielding performance compared to S1-3. They do not achieve a shielding performance of 40 dB or more against electromagnetic waves in the 0.5 MHz to 1 MHz range, and within the tested sheet thickness range, there was no significant difference in shielding performance even when the sheet thickness was changed.

[0041] Therefore, according to the vehicle motor drive control device 1 described above, the second cover 40, 40B is made by laminating a first member 41, 41B made of an iron plate with a thickness t1 of 0.3 to 0.5 mm and a second member 42 made of an aluminum plate with a thickness t2 of 0.3 mm with a space between them, thereby providing a vehicle motor drive control device that can achieve both weight reduction and shielding performance. Regarding the shielding performance of the second cover 40, 40B, for the aluminum second member 42, there is only data for a thickness of 0.3 mm, and there is no comparative data for shielding performance when the thickness is changed. However, it is generally known that the thickness of a material does not correlate with reflection loss but does correlate with absorption loss, and it can be said that the shielding performance increases as the plate thickness increases. From these results, it can be said that in the configuration of the second cover 40, 40B, the desired effect can be obtained if the plate thickness of the aluminum second member 42 is at least 0.3 mm or more.

[0042] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and includes all aspects included in the concept and claims of the present invention. Furthermore, each component may be selectively combined as appropriate to achieve at least some of the effects described above. For example, the shape, material, arrangement, size, etc., of each component in the above embodiments may be appropriately changed depending on the specific use of the present invention.

[0043] For example, in the vehicle motor drive control device 1 described above, we explained an example where the electronic component to which electromagnetic wave shielding measures are to be taken is the power module 10, but it is possible to apply this to components other than the power module 10.

[0044] For example, in the vehicle motor drive control device 1 described above, an example was described in which the first cover 30 and the second cover 40 are box-shaped, but the shapes of the first cover 30 and the second cover 40 are not limited to the above example.

[0045] For example, the components of the second cover 40, 40B of the present invention can also be used as covers for other openings in the housing.

[0046] For example, in the vehicle motor drive control device 1 described above, the distance of the space between the first member 41 and the second member 42 is not particularly limited. [Explanation of symbols]

[0047] 1. Vehicle motor drive control device 10 Power Modules 11,21 Page 1 12,22 2nd page 20 Water Jackets 30 Cover 1 31 Opening 40, 40B Second Cover 41,41B First member 42 Second Member 50 Capacitors 60 Bus Bar E,E1,E2,E3 Electromagnetic waves

Claims

1. A power module that controls the power to the electric motor that drives the vehicle, A first cover is formed in the shape of a bottomed cylindrical box with one side open, and is positioned to cover the power module. A second cover that closes the opening of the first cover, Equipped with, The second cover is constructed by laminating a first iron member having a thickness of 0.3 mm to 0.5 mm and a second aluminum member having a thickness of 0.3 mm or more, with a space between the first and second members. Vehicle motor drive control device.

2. The second cover has a shielding effect of at least 40 dB against electromagnetic waves in the 0.5 MHz to 1 MHz range. The vehicle motor drive control device according to claim 1.

3. The second cover is configured such that the first iron member is positioned closer to the power module than the second aluminum member. A vehicle motor drive control device according to claim 1 or 2.

Images