Inverter for driving vehicle motors

Abstract

This invention provides a vehicle motor drive inverter that can suppress noise radiation from the casing acting as an antenna. [Solution] The vehicle motor drive inverter comprises a base plate 3 on which a semiconductor module 4 is mounted, housed within a housing 1. The base plate is electrically insulated and fixed to the housing, and the base plate and the housing each have a ground line independently connected to the chassis ground GND. As a result, noise transmitted to the housing is reduced, and a vehicle motor drive inverter with reduced noise radiated from the housing can be provided.

Description

Technical Field

[0001] The present invention relates to an inverter for driving a vehicle motor, and more particularly to an inverter for driving a vehicle motor with reduced radiated noise.

Background Art

[0002] Since an inverter for driving a vehicle motor handles high power, its radiated noise may cause noise interference to peripheral devices, and it is necessary to reduce the radiated noise.

[0003] Patent Document 1 discloses a power conversion device in which a control circuit board and a semiconductor module are covered with a conductive shield layer provided in a housing.

[0004] This power conversion device can shield the noise generated from the semiconductor module with a conductive shield layer, so that the noise generated from the semiconductor module can be prevented from directly causing noise interference to peripheral devices.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the power conversion device described in Patent Document 1 complicates the structure of the inverter by adding a shield layer, resulting in high manufacturing costs.

[0007] The present invention has been made in view of such problems of the prior art, and an object thereof is to provide a vehicle motor drive inverter that can suppress, with a simple structure, the noise that should be shielded by the housing from becoming an antenna and radiating the noise conducted to the housing. [Means for solving the problem]

[0008] As a result of diligent research to achieve the above objective, the inventors have found that the above objective can be achieved by insulating the base plate on which the semiconductor module is mounted from the housing that houses the base plate, and by providing independent ground lines to the base plate and the housing, respectively, and have completed the present invention.

[0009] In other words, the vehicle motor drive inverter of the present invention comprises a base plate on which a semiconductor module is mounted, housed within a casing. Furthermore, the base plate is electrically insulated and fixed to the housing. The base plate and the housing are each equipped with a ground line that is independently connected to the chassis ground. [Effects of the Invention]

[0010] According to the present invention, by insulating the base plate on which the conductor module is mounted from the housing that houses the base plate, and by providing independent ground lines to the base plate and the housing, noise transmitted to the housing is reduced, and an inverter for driving a vehicle motor with reduced noise radiated from the housing can be provided. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing an example of a vehicle motor drive inverter of the present invention. [Figure 2] This is a schematic diagram showing another example of the vehicle motor drive inverter of the present invention. [Modes for carrying out the invention]

[0012] The vehicle motor drive inverter of the present invention will be described in detail. As shown in Figure 1, the vehicle motor drive inverter of the present invention comprises a semiconductor module 4, a base plate 3 on which the semiconductor module is mounted, a bus bar 2 for connecting the semiconductor module to a battery and motor, and, if necessary, resin-coated electronic components 6 such as a smoothing capacitor, current sensor, noise suppression coil, and connector, all housed in a housing 1.

[0013] The housing 1 described above is made of a metal material such as aluminum and is electrically conductive. Furthermore, the base plate 3 not only supports the semiconductor module 4 but also acts as a cooler for the semiconductor module, and like the housing, it is made of a metal material and has excellent thermal conductivity.

[0014] As shown in Figure 1, the base plate 4 is fixed to the housing 1 via an insulating member 5, and the base plate 3 and the housing 1 are electrically insulated. The bus bar 2 is also provided in a manner that is electrically insulated from the base plate 3 and the housing 1.

[0015] Thus, even though the housing 1 is electrically isolated from the busbar 2 and base plate 3, noise generated by the semiconductor module 4 flows into the housing 1, creating an electric field, and the housing 1 acts as an antenna, radiating noise.

[0016] In other words, as shown in Figure 1, the busbar 2 and base plate 3 are arranged inside the housing facing the wall of the housing 1, and since the housing 1 and base plate 3 are conductors as described above, a potential difference is generated when a voltage is applied to the busbar 2.

[0017] Therefore, in the spaces A between busbar 2 and chassis 1, B between busbar 2 and base plate 3, and C between base plate and chassis, a capacitor-like effect occurs, i.e., parasitic capacitance is generated, causing noise to be transmitted to chassis 1 and radiated from chassis.

[0018] The inverter for vehicle motor drive of the present invention is provided with ground lines in which the base plate 3 and the housing 1 are each independently and separately connected to the chassis ground.

[0019] Therefore, the noise flowing through the base plate 3 drops to the chassis ground, making it difficult for the noise to be transmitted from the base plate 3 to the housing 1, stabilizing the ground line of the housing 1, and suppressing the noise radiated with the housing 1 as an antenna.

[0020] It is preferable that the impedance of the ground line of the base plate is lower than the impedance of the ground line of the housing.

[0021] Thereby, the noise generated in the semiconductor module 4 easily drops from the base plate 3 to the chassis ground, and the noise that has dropped to the chassis ground is difficult to be transmitted to the housing 1 via the ground line, so that the noise radiated from the housing 1 can be further reduced.

[0022] The impedance of the ground line of the base plate or the housing can be adjusted by changing the harness wire diameter or the bus bar wire diameter, or by attaching a ferrite core or a filter to the ground line.

[0023] As described above, not only by providing independent ground lines for the base plate and the housing to reduce the noise, but also by the position where the bus bar and the base plate are arranged in the housing, the noise transmitted to the housing can be reduced.

[0024] It is preferable to arrange the bus bar in proximity to the base plate so that the space distance A between the bus bar and the housing is wider than the space distance B between the bus bar and the base plate.

[0025] Because both the busbar 2a connecting the semiconductor module 4 and the battery, and the busbar 2b connecting the semiconductor module 4 and the motor are positioned close to the base plate 3, the parasitic capacitance of these busbars relative to the base plate becomes larger than the parasitic capacitance relative to the housing, making it easier for noise generated by the semiconductor module 4 to be transmitted to the base plate 3 than to the housing 1.

[0026] Similarly, by positioning the base plate 3, on which the busbar 2 is located in close proximity, with a gap between it and the enclosure 1 wall such that the spatial distance C between it and the enclosure is greater than the spatial distance B between it and all the busbars, noise transmitted to the base plate 3 is less likely to be transmitted to the enclosure 1.

[0027] In this way, by positioning the base plate 3 with a gap between it and the walls of the enclosure 1, and in conjunction with the independent ground line mentioned above, noise is less likely to be transmitted to the enclosure, and noise radiated by the enclosure acting as an antenna can be suppressed.

[0028] In this invention, "spatial distance" refers to the distance between the narrowest parts, and means the narrower spatial distance in the in-plane direction or out-of-plane direction of the base plate.

[0029] As described above, if the busbar 2 is positioned close to the base plate 3 and the space between the base plate 3 and the housing 1 is increased, the size of the housing will increase.

[0030] The vehicle motor drive inverter of the present invention allows for the placement of resin-coated electronic components 6 in the available space within the housing.

[0031] For example, as shown in Figure 2, by passing the busbar 2 through the through-hole 31 provided in the base plate 3, a single connected busbar can be placed on both the upper and lower sides of the base plate 3 via the through-hole 31. This makes it possible to place the semiconductor module 4 on the main surface of one side of the base plate 3 and the electronic components 6 in the empty space on the opposite side of the base plate 3 from the semiconductor module 1.

[0032] In this way, by passing the busbars 2 through the through holes 31 provided in the base plate 3 and arranging the busbars 2 on both sides of the base plate 3, it is possible to widen the spatial distance between the base plate 3 and the housing 1 while improving the space efficiency within the housing, thereby achieving both suppression of radiated noise from the housing 1 and miniaturization of the inverter for driving the vehicle motor. [Explanation of Symbols]

[0033] 1 cabinet 2a PN busbar (connects to battery) 2b UVW busbar (connects to motor) 3 Base plate 31 Through hole 4. Semiconductor Modules 5. Insulating material 6 Electronic Components

Claims

1. A vehicle motor drive inverter comprising a base plate on which a semiconductor module is mounted, housed within a casing, The above base plate is electrically insulated and fixed to the above housing. A vehicle motor drive inverter characterized in that the base plate and the housing each have a ground line independently connected to the chassis ground.

2. The vehicle motor drive inverter according to claim 1, characterized in that the impedance of the ground line of the base plate is lower than the impedance of the ground line of the housing.

3. Furthermore, it includes a busbar connecting the semiconductor module and the battery, and a busbar connecting the semiconductor module and the motor. The vehicle motor drive inverter according to claim 2, characterized in that all of the busbars are positioned such that the space between them and the housing is greater than the space between them and the base plate.

4. The vehicle motor drive inverter according to claim 3, characterized in that the base plate is provided at a position where the spatial distance between it and the housing is greater than the spatial distance between it and all of the busbars.

5. Furthermore, it is equipped with electronic components coated with resin, The vehicle motor drive inverter according to claim 4, characterized in that the above electronic components are arranged on the opposite side of the base plate from the semiconductor module.

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