Power conversion device

Abstract

To provide a power conversion device with which it is possible to reduce noise.SOLUTION: A power conversion device 1 comprises: first and second power module 141, 142; bus bars 11, 12; and a metal housing 9. Both power modules are juxtaposed so that respective DC-side terminals connected to the bus bars are directed toward the other power module side. The bus bars include first and second conductor part 100, 101 that are connected to the DC-side terminals of both power modules, respectively. A conductive wall part 102 electrically connected to the housing and facing the first and second conductor parts is provided between both power modules. Each of the first and second conductor parts includes a region in which a cathode bus bar 11 and an anode bus bar 12 constituting the bus bar are stacked one on top of another. One of the cathode and anode bus bars of the first conductor part faces the wall part, and one of the cathode and anode bus bars of the second conductor part, the polarity of which is different from that of the first conductor part, faces the wall part.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a power conversion device. [Background technology]

[0002] Power conversion devices installed in hybrid and electric vehicles must meet the unique standards established by each car manufacturer based on the high-voltage conductive noise standard added to the international standard for dealing with conductive noise generated by noise current. At the same time, in recent years, there has been an increasing demand for power conversion devices to be smaller, thinner, and less expensive in line with the development of electric vehicles in which they are installed. For this reason, there is a strong demand for filter devices installed in power conversion devices to improve their high-frequency noise attenuation performance while maintaining low cost and small size. Patent Document 1 discloses a mounting structure of a power module comprising a semiconductor module including a power semiconductor element, a first electrode plate and a second electrode plate respectively joined to one side and the other side of the semiconductor element, a connection terminal with a control circuit that controls the semiconductor element, and an insulating resin mold that seals the semiconductor element and the first electrode plate and the second electrode plate, and conductive first and second holding members that hold the semiconductor module from both sides via first and second insulating members that serve as dielectrics, wherein a noise suppression bypass capacitor is formed by the first electrode plate and / or second electrode plate, the first holding member and / or second holding member, and the first insulating member and / or second insulating member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-073342 A Summary of the Invention [Problem to be solved by the invention]

[0004] The invention described in Patent Document 1 leaves room for improvement in noise suppression. [Means for solving the problem]

[0005] A power conversion device according to a first aspect of the present invention includes a first power module constituting a first inverter circuit, a second power module constituting a second inverter circuit connected in parallel with the first inverter circuit, a DC bus bar that transmits DC power to the first power module and the second power module, and a metal housing that accommodates the first power module and the second power module, the first power module and the second power module being arranged in parallel such that a DC side terminal of each of the first power module and the second power module connected to the DC bus bar faces the other power module, and the DC bus bar includes a first conductor portion connected to a DC side terminal of the first power module and a second conductor portion connected to the second power module. and a second conductor portion connected to a DC side terminal of a power module, and a conductive wall portion electrically connected to the metal casing and facing the first conductor portion and the second conductor portion is provided between the first power module and the second power module, the first conductor portion includes a region in which the positive bus bar and the negative bus bar that constitute the DC bus bar are stacked, the second conductor portion includes a region in which the positive bus bar and the negative bus bar are stacked, and in the first conductor portion, one of the positive bus bar and the negative bus bar faces the wall portion, and in the second conductor portion, one of the positive bus bar and the negative bus bar, which has a polarity different from that of the first conductor, faces the wall portion. Effect of the Invention

[0006] According to the present invention, noise can be reduced. [Brief description of the drawings]

[0007] [Figure 1] Overall configuration of the power conversion device [Diagram 2] Equivalent circuit diagram of common-mode high-voltage conducted noise in a power conversion device [Diagram 3] Perspective view of a power conversion device [Figure 4]A perspective view of an upper positive bus bar and an upper negative bus bar. [Diagram 5] A perspective view of a lower positive bus bar and a lower negative bus bar. [Figure 6] A diagram showing the state in which the lower positive bus bar and the lower negative bus bar are combined with the wall portion. [Figure 7] Schematic diagram showing a first conductor portion and a second conductor portion [Figure 8] FIG. 1 is a perspective view of a comparative power conversion device according to a comparative example; [Figure 9] Equivalent circuit diagram of common-mode high-voltage conductive noise in a comparative power conversion device [Figure 10] FIG. 13 is a diagram showing frequency characteristics of common-mode high-voltage conductive noise in a power conversion device and a comparative power conversion device. [Figure 11] FIG. 1 is a perspective view of a power conversion device according to a first modified example. [Figure 12] FIG. 13 is a perspective view of a power conversion device according to a second modified example. [Figure 13] FIG. 13 is a perspective view of a power conversion device according to a third modified example. [Figure 14] Enlarged view of the wall area of ​​Figure 13 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] --First embodiment-- Hereinafter, a first embodiment of a power conversion device will be described with reference to FIGS.

[0009] FIG. 1 is an overall configuration diagram of a power conversion device 1. The power conversion device 1 converts power between a high-voltage battery 2 and a first motor 6 and a second motor 8. For example, the power conversion device 1 can convert DC power obtained from the high-voltage battery 2 into AC power and supply it to the first motor 6 and the second motor 8. For example, the power conversion device 1 can convert AC power obtained from the first motor 6 and the second motor 8 into DC power and supply it to the high-voltage battery 2. It is sufficient for the power conversion device 1 to realize at least one of conversion from DC to AC and conversion from AC to DC. A housing 9 is made of metal and serves as a reference potential for the power conversion device 1.

[0010] The power conversion device 1 is connected to a high-voltage battery 2 via a high-voltage DC cable 4 and a high-voltage line impedance stabilization network (LISN) 3. The high-voltage line impedance stabilization network 3 includes a positive LISN circuit section 31 and a negative LISN circuit section 32. The power conversion device 1 is connected to a first motor 6 via a first high-voltage AC cable 5. The first motor 6 includes coils corresponding to each of the UVW phases indicated by reference numeral 6M, and has a stray capacitance 6-Cs between the coils and the housing 9. The power conversion device 1 is connected to a second motor 8 via a second high-voltage AC cable 7. The second motor 8 includes coils corresponding to each of the UVW phases indicated by reference numeral 8M, and has a stray capacitance 8-Cs between the coils and the housing 9.

[0011] The power conversion device 1 includes a positive bus bar 11, a negative bus bar 12, a noise filter device 13, a first power module 141 constituting a first inverter circuit, a second power module 142 constituting a second inverter circuit, a first smoothing capacitor Cx1, a second smoothing capacitor Cx2, and a housing 9. The housing 9 is conductive. The housing 9 may be formed of a conductive material, or may be coated with a conductive material.

[0012] The first power module 141 includes a first switching circuit SW1 to a third switching circuit SW3, which are switching circuits corresponding to the U, V, and W phases. The second power module 142 includes a fourth switching circuit SW4 to a sixth switching circuit SW6, which are switching circuits corresponding to the U, V, and W phases. The first switching circuit SW1 includes a pair of insulated gate bipolar transistors and a pair of diodes, which constitute an upper arm and a lower arm. Reference 1-Cs1 indicates a stray capacitance between the positive electrode part and the housing of the first power module 141. Reference 1-Cs2 indicates a stray capacitance between the AC output part and the housing of the first power module 141. Reference 1-Cs3 indicates a stray capacitance between the negative electrode part and the housing of the first power module 141. The configurations of the second switching circuit SW2 to the sixth switching circuit SW6 are the same as those of the first switching circuit SW1, so a description thereof will be omitted. The second switching circuit SW2 to the sixth switching circuit SW6 also have stray capacitances similar to those of the first switching circuit SW1.

[0013] The noise filter device 13 includes a first grounding capacitor Cy1, a second grounding capacitor Cy2, and a magnetic core Lc. Hereinafter, the first grounding capacitor Cy1 and the magnetic core Lc are collectively referred to as a second noise filter unit 131. The first grounding capacitor Cy1 includes an eleventh grounding capacitor Cy11 that connects the positive bus bar 11 and the housing 9, and a twelfth grounding capacitor Cy12 that connects the negative bus bar 12 and the housing 9. The second grounding capacitor Cy2 includes a twenty-first grounding capacitor Cy21 that connects the positive bus bar 11 and the housing 9, and a twenty-second grounding capacitor Cy22 that connects the negative bus bar 12 and the housing 9. The grounding capacitors Cy1 and Cy2 and the magnetic core Lc are for reducing common mode noise.

[0014] The common mode current is caused by a voltage fluctuation to ground that occurs during a switching operation in which the switching circuits SW1 to SW6 are periodically turned on / off. This voltage fluctuation causes a common mode current to flow between the power conversion device 1 and the housings of the first motor 6 and the second motor 8 through the respective stray capacitances, and the current generates high-voltage conductive noise. The respective stray capacitances are stray capacitances 1-Cs1 to 1-Cs3 parasitic between the first power module 141 and the housing 9, stray capacitances 1-Cs4 to 1-Cs6 parasitic between the second power module 142 and the housing 9, stray capacitance 6-Cs existing between the coil 6M of the first motor 6 and the housing 9, and stray capacitance 8-Cs existing between the coil 8M of the second motor 8 and the housing 9. Therefore, in order to reduce the high-voltage conductive noise, it is necessary to reduce the common mode current. In the power conversion device 1, the configuration of the noise filter device 13 is used to deal with noise current, which is the main cause of high-voltage conducted noise, and to attenuate noise while complying with the high-voltage conducted noise standard.

[0015] (Regarding noise standards) The high-voltage conducted noise standard will be described. Noise standards generally prescribe regulatory values ​​in the frequency band from 0.15 MHz to 108 MHz. The high-voltage conducted noise standard is a standard added to CISPR25Ed4, an international standard created by the International Special Committee on Radio Interference (CISPR) in October 2016. This standard regulates noise in the FM broadcast frequency band (76 MHz to 108 MHz), which is used for various purposes, to be lower than other frequency bands. High-voltage conducted noise may cause malfunction of in-vehicle electric and electronic devices, for example. Therefore, the amount of high-voltage conducted noise generated by the power conversion device 1 must be measured before shipment, and the amount of noise must be equal to or lower than the regulatory values ​​prescribed by the laws and regulations of each country and customer requirements.

[0016] (Conventional technology and its problems) Generally, noise filter devices are used to make power conversion devices compliant with high-voltage conducted noise standards. When high voltages and large currents are required, such as in-vehicle power conversion devices, two or more power modules may be used to drive multiple motors and increase power. For example, when two power modules are used, the two power modules are often connected in series to reduce the height, and a noise filter device is also placed in series.

[0017] In such a configuration, the current paths from each power module to the installed capacitor included in the noise filter device are long, and the lengths of the two current paths are different. Specifically, the impedance due to the parasitic inductance of the current paths increases due to the long current paths. In addition, the difference in the lengths of the two current paths increases the number of resonance points caused by parasitic components present in the paths. These two problems result in a problem of deterioration of noise attenuation performance in high frequency bands such as the FM radio band.

[0018] In this embodiment, as shown in Fig. 1, a first nearby grounding capacitor Cw21 and a second nearby grounding capacitor Cw22 are provided between the positive bus bar 11 closest to the first power module 141 and the housing 9, and between the negative bus bar 12 closest to the second power module 142 and the housing 9, respectively. This provides a grounded Y capacitor near the power modules, shortening the length of the current path and reducing the path impedance. Furthermore, since the lengths of the current paths are the same, an increase in the resonance point can also be suppressed.

[0019] Fig. 2 is an equivalent circuit diagram of common mode high voltage conductive noise in the power conversion device 1. In Fig. 2, the left side of the dashed line shows the inside of the power conversion device 1. Reference symbol Vs1 is a noise source that simulates the common mode noise generated in the first power module 141. Reference symbol Cpm1 is the total parasitic capacitance that exists between the first power module 141 and the housing 9. Reference symbol Vs2 is a noise source that simulates the common mode noise generated in the second power module 142. Reference symbol Cpm2 is the total parasitic capacitance that exists between the second power module 142 and the housing 9.

[0020] Reference symbol Lg1 denotes a parasitic inductance present between P02, which is a ground point between the first power module 141 and the housing 9, and P01, which is a ground point between the first grounded capacitor Cy1 and the housing 9. Reference symbol Lg2 denotes a parasitic inductance present between P03, which is a ground point between the second power module 142 and the housing 9, and P01, which is a ground point between the first grounded capacitor Cy1 and the housing 9. Reference symbol L_bp denotes an inductance of the positive bus bar 11 up to the first grounded capacitor Cy1 that transmits DC power to the first power module 141 and the second power module 142. Reference symbol L_bn denotes an inductance of the negative bus bar 12 up to the first grounded capacitor Cy1 that transmits DC power to the first power module 141 and the second power module 142.

[0021] Symbol Ic1 is a common mode current generated from the first power module. Symbol Ic2 is a common mode current generated from the second power module. Symbol Ic3 is a common mode current of Ic1 that is bypassed by the first grounded capacitor Cy1. Symbol Ic4 is a common mode current of Ic2 that is bypassed by the first grounded capacitor Cy1. Symbol Ic5 is a common mode current that flows out of the power conversion device.

[0022] Reference symbol Ic6 is a common mode current obtained by summing up the common mode current of Ic1 that is bypassed by the first grounding capacitor Cy1 and the common mode current of Ic1 and Ic2 that is bypassed by the first nearby grounding capacitor Cw21. Reference symbol Ic7 is a common mode current obtained by summing up the common mode current of Ic2 that is bypassed by the first grounding capacitor Cy1 and the common mode current of Ic1 and Ic2 that is bypassed by the second nearby grounding capacitor Cw22. Reference symbol 3-1 is a common mode equivalent circuit of the high-voltage power supply impedance stabilization circuit network 3. Reference symbol 4-1 is a common mode equivalent circuit of the high-voltage DC cable 4.

[0023] FIG. 3 is a perspective view of the power conversion device 1. The configuration shown in FIG. 3 is the same as that shown in FIG. 1 or FIG. 2, except for a wall portion 102 described later. In FIG. 3 and subsequent drawings, mutually orthogonal XYZ axes are depicted to clearly show the correlation. The left-right direction in the figure is the X-axis, and the first power module 141, the wall portion 102, and the second power module 142 are arranged from the negative side to the positive side of the X-axis. The terminals connected to the positive bus bar 11 and the negative bus bar 12 of the first power module 141 and the second power module 142 are arranged so as to face the wall portion 102 side.

[0024] The positive bus bar 11 is composed of an upper positive bus bar 11U and a lower positive bus bar 11D. The negative bus bar 12 is composed of an upper negative bus bar 12U and a lower negative bus bar 12D. The upper positive bus bar 11U and the upper negative bus bar 12U have a shape in which the center of a flat plate extending in the XY plane is recessed toward the negative side of the Z axis. The upper positive bus bar 11U and the upper negative bus bar 12U are connected to the lower positive bus bar 11D and the lower negative bus bar 12D at the recessed portion. In FIG. 3, the upper positive bus bar 11U and the upper negative bus bar 12U overlap with a gap in the Z direction. The shapes of the positive bus bar 11 and the negative bus bar 12 will be described in detail in the following FIG. 4 and FIG. 5.

[0025] 3 is a conductor having the same potential as the housing 9. The wall 102 has a hollow or solid rectangular shape and is surrounded by the lower positive bus bar 11D and the lower negative bus bar 12D. However, the wall 102 is not in contact with the lower positive bus bar 11D and the lower negative bus bar 12D, and is adjacent to the lower positive bus bar 11D and the lower negative bus bar 12D with a very small gap therebetween that generates a capacitance as described below.

[0026] FIG. 4 is a perspective view of the upper positive bus bar 11U and the upper negative bus bar 12U. The viewpoint of FIG. 4 is the same as that of FIG. 3. The upper positive bus bar 11U and the upper negative bus bar 12U have substantially the same dimensions in the Y-axis direction. The upper positive bus bar 11U has a recessed portion toward the negative side of the Z-axis at approximately the center in the X-direction, and is cut out at two places. These recessed portions are referred to as the upper positive first connection portion 11U1 and the upper positive second connection portion 11U2. The upper negative bus bar 12U has a recessed portion toward the negative side of the Z-axis at approximately the center in the X-direction, and is cut out at two places. These recessed portions are referred to as the upper negative first connection portion 12U1 and the upper negative second connection portion 12U2.

[0027] The upper positive electrode first connection part 11U1, the upper positive electrode second connection part 11U2, the upper negative electrode first connection part 12U1, and the upper negative electrode second connection part 12U2 have approximately the same width in the X-axis direction, and do not contact each other even in the assembled state shown in Fig. 3. The upper positive electrode first connection part 11U1, the upper positive electrode second connection part 11U2, the upper negative electrode first connection part 12U1, and the upper negative electrode second connection part 12U2 have through holes used for fixing to the wall part 102. The through holes will be described later.

[0028] FIG. 5 is a perspective view of the lower positive bus bar 11D and the lower negative bus bar 12D. The viewpoint of FIG. 5 is the same as that of FIG. 3. The lower positive bus bar 11D and the lower negative bus bar 12D have substantially the same dimensions in the Y-axis direction. The approximate center of the lower positive bus bar 11D in the X-direction protrudes toward the Z-axis positive side, and two places are cut out. These protruding places are called the lower positive electrode first connection part 11D1 and the lower positive electrode second connection part 11D2. The approximate center of the lower negative bus bar 12D in the X-direction protrudes toward the Z-axis positive side, and two places are cut out. These protruding places are called the lower negative electrode first connection part 12D1 and the lower negative electrode second connection part 12D2. The lower positive electrode first connection portion 11D1, the lower positive electrode second connection portion 11D2, the lower negative electrode first connection portion 12D1, and the lower negative electrode second connection portion 12D2 have approximately the same width in the X-axis direction, and do not contact each other even in the assembled state shown in Fig. 3. The lower positive electrode first connection portion 11D1, the lower positive electrode second connection portion 11D2, the lower negative electrode first connection portion 12D1, and the lower negative electrode second connection portion 12D2 have through holes used for fixing to the wall portion 102.

[0029] Fig. 6 is a diagram showing a state in which the lower positive bus bar 11D and the lower negative bus bar 12D are combined with the wall portion 102. However, Fig. 6 shows two viewpoints, one from which the right side surface of the wall portion 102 is seen and one from which the left side surface of the wall portion 102 is seen. When the lower positive bus bar 11D and the lower negative bus bar 12D are combined, the lower positive electrode first connection portion 11D1, the lower negative electrode first connection portion 12D1, the lower positive electrode second connection portion 11D2, and the lower negative electrode second connection portion 12D2 are arranged in this order from the negative side to the positive side of the Y axis as shown in Fig. 6.

[0030] The viewpoint shown on the left in FIG. 6 shows the left side surface of wall portion 102, i.e., the side surface on the negative side of the X-axis. On the left side surface of wall portion 102, lower negative bus bar 12D is on the outside, and lower positive bus bar 11D is on the inside. The viewpoint shown on the right in FIG. 6 shows the right side surface of wall portion 102, i.e., the side surface on the positive side of the X-axis. On the right side surface of wall portion 102, lower negative bus bar 12D is on the inside, and lower positive bus bar 11D is on the outside. In other words, the polarities of the opposing bus bars on the left and right wall surfaces of wall portion 102 are different.

[0031] 3, a first power module 141 is disposed on the negative side of the wall portion 102 along the X-axis, and a second power module 142 is disposed on the positive side of the wall portion 102 along the X-axis. A portion of the lower positive bus bar 11D and the lower negative bus bar 12D that is connected to the DC side terminal of the first power module 141 is referred to as a first conductor portion 100. A portion of the lower positive bus bar 11D and the lower negative bus bar 12D that is connected to the DC side terminal of the second power module 142 is referred to as a second conductor portion 101.

[0032] 6, for convenience of drawing, the distance between each of the lower positive electrode first connection portion 11D1, the lower positive electrode second connection portion 11D2, the lower negative electrode first connection portion 12D1, and the lower negative electrode second connection portion 12D2 and the end portion of the wall portion 102 on the positive side of the Z axis is shown as being short. However, in reality, measures are taken so that no discharge occurs between the wall portion 102 and the lower positive electrode bus bar 11D and the lower negative electrode bus bar 12D on the positive side of the Z axis of the wall portion 102. For example, an insulating layer may be provided on the surface of the wall portion 102 on the positive side of the Z axis, or a sufficient insulating distance may be provided between the wall portion 102 and the lower positive electrode bus bar 11D and the lower negative electrode bus bar 12D on the positive side of the Z axis of the wall portion 102.

[0033] Fig. 7 is a schematic diagram showing the first conductor portion 100 and the second conductor portion 101. However, the upper portions of the lower positive bus bar 11D and the lower negative bus bar 12D are omitted in Fig. 7. Also, in Fig. 7, the lower positive bus bar 11D, the lower negative bus bar 12D, and the wall portion 102 are hatched so that they can be easily identified.

[0034] In the first conductor 100, the area where the lower positive bus bar 11D and the wall 102 face each other is large, and the gap between them is very small even when the insulation distance is taken into consideration. Therefore, the opposing portion of the lower positive bus bar 11D and the wall 102 can form a capacitance of about several hundred pF. In addition, by inserting an insulating material such as a mold with a high dielectric constant, it is possible to form a capacitance of about nF. The capacitance formed by the opposing portion of the lower positive bus bar 11D and the wall 102 corresponds to the first nearby ground capacitor Cw21 shown in FIG. 1. Note that the distance between the lower negative bus bar 12D and the wall 102 in the first conductor 100 is relatively long, and the generated capacitance can be ignored.

[0035] In the second conductor portion 101, the gap between the lower negative bus bar 12D and the wall portion 102 is very small, and as explained above, a capacitance occurs. This capacitance corresponds to the second nearby ground capacitor Cw22 shown in Fig. 1. Note that the distance between the lower positive bus bar 11D and the wall portion 102 in the first conductor portion 100 is relatively long, and the generated capacitance can be ignored.

[0036] (Comparative Example) 8 is a perspective view of a comparative power conversion device 1Z, which is a comparative example. The comparative power conversion device 1Z differs from the power conversion device 1 in that it does not include a wall portion 102. Since the comparative power conversion device 1Z, which is a comparative example, does not include the wall portion 102, there is no electrostatic capacitance generated between the wall portion 102 and the lower positive bus bar 11D or the lower negative bus bar 12D in the power conversion device 1. The comparative power conversion device 1Z also differs from the power conversion device 1 in that the polarities of the opposing conductor plates of the first conductor portion 100 and the second conductor portion 101 are the same.

[0037] FIG. 9 is an equivalent circuit diagram of common-mode high-voltage conductive noise in the comparative power converter 1Z. Comparing the equivalent circuit diagram of common-mode high-voltage conductive noise in the power converter 1 shown in FIG. 2 with FIG. 9, the first closely grounded capacitor Cw21 and the second closely grounded capacitor Cw22 that existed in FIG. 2 are not present. Therefore, the current paths from the noise source Vs1 of the first power module and the noise source Vs2 of the second power module to the first grounded capacitor Cy1, which is a Y capacitor, are long, and the impedance is large. Furthermore, the path length from the noise source Vs1 to the first grounded capacitor Cy1 is different from the path length from the noise source Vs2 to the first grounded capacitor Cy1, and therefore the resonance point increases.

[0038] 10 is a diagram showing frequency characteristics of common-mode high-voltage conductive noise in the power conversion device 1 and the comparative power conversion device 1Z. For example, when the target frequency band is set to 70 MHz to 110 MHz, the power conversion device 1 has a lower noise level than the comparative power conversion device 1Z over the entire target frequency range. In particular, in the vicinity of 90 MHz where the peak is present, the power conversion device 1 has an effect of reducing the noise level by 10 db compared to the comparative power conversion device 1Z.

[0039] According to the above-described first embodiment, the following advantageous effects can be obtained. (1) The power conversion device 1 includes a first power module 141 constituting a first inverter circuit, a second power module 142 constituting a second inverter circuit connected in parallel with the first inverter circuit, DC bus bars, i.e., a positive bus bar 11 and a negative bus bar 12, which transmit DC power to the first power module and the second power module, and a metal housing 9 that houses the first power module 141 and the second power module 142. The first power module 141 and the second power module 142 are arranged in parallel such that the DC side terminals connected to the DC bus bars face the other power module side. The positive bus bar 11 and the negative bus bar 12, which are DC bus bars, include a first conductor portion 100 connected to the DC side terminal of the first power module 141 and a second conductor portion 101 connected to the DC side terminal of the second power module 142. Between the first power module 141 and the second power module 142, a conductive wall portion 102 is provided, which is electrically connected to the metallic housing 9 and faces the first conductor portion 100 and the second conductor portion 101. The first conductor portion 100 includes a region in which the positive bus bar 11 and the negative bus bar 12 constituting the DC bus bar are stacked. The second conductor portion 101 includes a region in which the positive bus bar 11 and the negative bus bar 12 are stacked. In the first conductor portion 100, either the positive bus bar 11 or the negative bus bar 12 faces the wall portion 102. In the second conductor portion 101, either the positive bus bar 11 or the negative bus bar 12, which has a polarity different from that of the first conductor portion 100, faces the wall portion.

[0040] Therefore, the first conductor 100 and the wall 102 form the 21st grounded capacitor Cy21, and the second conductor 101 and the wall 102 form the 22nd grounded capacitor Cy22, so that a path for conducted noise can be formed as shown in Fig. 2. This has the effect of shortening the noise path to reduce impedance, and of equalizing the path lengths of the two paths to reduce resonance points. In addition, the capacitances of the 21st grounded capacitor Cy21 and the 22nd grounded capacitor Cy22 can be easily changed by adjusting the respective positions of the lower positive bus bar 11D and the lower negative bus bar 12D.

[0041] (Variation 1) 11 is a perspective view of a power conversion device 1A in Modification 1. The power conversion device 1A differs from the first embodiment in that it includes two walls, i.e., a first wall 103 facing the first conductor portion 100 and a second wall 104 facing the second conductor portion 101, instead of the wall portion 102. The first wall 103 and the second wall 104 are electrically connected only via the housing 9.

[0042] According to the first modification, the following advantageous effects can be obtained. (2) The wall portion 102 has a first wall 103 facing the first conductor portion 100 and a second wall 104 facing the second conductor portion 101, and the first wall 103 and the second wall 104 are provided with a space between them. In this case, the space between the first wall 103 and the second wall 104 can be used for another purpose.

[0043] (Variation 2) 12 is a perspective view of a power converter 1B in Modification 2. The power converter 1B differs from the first embodiment in that a U-shaped wall 105 is provided instead of the wall portion 102.

[0044] According to the second modification, the following advantageous effects can be obtained. (3) The wall portion has a U-shape facing the first conductor portion 100 and also facing the second conductor portion 101. Therefore, the number of parts is reduced compared to the first modification, and since the upper part of the U-shape is open, the space can be used for other purposes.

[0045] (Variation 3) 13 is a perspective view of a power converter 1C in Modification 3. The power converter 1C differs from the first embodiment in that an insulator 106 is provided between the wall portion 102 and the first conductor portion 100 and between the wall portion 102 and the second conductor portion 101.

[0046] Fig. 14 is an enlarged view of the vicinity of the wall portion 102 in Fig. 13. This figure corresponds to Fig. 7 in the first embodiment. As shown in Fig. 14, the wall portion 102 is surrounded by an insulator 106. Therefore, the capacitance of the first nearby grounding capacitor Cw21 formed by the lower positive bus bar 11D and the wall portion 102 in the first conductor portion 100, and the capacitance of the second nearby grounding capacitor Cw22 formed by the lower negative bus bar 12D and the wall portion 102 in the second conductor portion 101 are also affected by the dielectric constant of the insulator 106.

[0047] 14, there is a gap between the lower positive bus bar 11D and the insulator 106, and there is also a gap between the lower negative bus bar 12D and the insulator 106, but these gaps do not have to exist. Also, the insulator 106 does not have to be arranged at the end of the wall portion 102 on the positive side of the Z axis. Furthermore, the insulator 106 may be arranged only on one side surface, or may be arranged between at least one of the first conductor portion 100 and the second conductor portion 101 and the wall portion 102.

[0048] According to the third modification, the following advantageous effects can be obtained. (4) An insulator 106 is disposed between the first conductor 100 and the wall 102, and between the second conductor 101 and the wall 102. Therefore, by changing the material of the insulator 106 in addition to the physical distance, the dielectric constant can also be used to adjust the capacitance of the first nearby ground capacitor Cw21 and the second nearby ground capacitor Cw22.

[0049] The above-mentioned embodiments and modifications may be combined with each other. Although various embodiments and modifications have been described above, the present invention is not limited to these. Other aspects that are conceivable within the scope of the technical idea of ​​the present invention are also included in the scope of the present invention. [Explanation of symbols]

[0050] 1, 1A, 1B, 1C: Power conversion device 9: Housing 11: Positive bus bar 11D: Lower positive bus bar 11U: Upper positive bus bar 12: Negative bus bar 12D: Lower negative bus bar 12U: Upper negative bus bar 100: First conductor section 101: Second conductor section 102: Wall 103: 1st wall 104:Second wall 105 :U-shaped wall 106: Insulator 141: First power module 142: Second power module Cy1: First ground capacitor Cw21: First adjacent ground capacitor Cw22: Second adjacent ground capacitor

Claims

1. a first power module constituting a first inverter circuit; a second power module constituting a second inverter circuit connected in parallel with the first inverter circuit; a DC bus bar that transmits DC power to the first power module and the second power module; a metal housing that houses the first power module and the second power module, the first power module and the second power module are arranged in parallel such that a DC side terminal connected to the DC bus bar faces the other power module, the DC bus bar includes a first conductor portion connected to a DC side terminal of the first power module and a second conductor portion connected to a DC side terminal of the second power module, a conductive wall portion is provided between the first power module and the second power module, the wall portion being electrically connected to the metal casing and facing the first conductor portion and the second conductor portion; the first conductor portion includes a region in which a positive bus bar and a negative bus bar that constitute the DC bus bar are stacked, the second conductor portion includes a region in which the positive bus bar and the negative bus bar are stacked, The first conductor portion is configured such that one of the positive bus bar and the negative bus bar faces the wall portion, The second conductor portion has a polarity different from that of the first conductor portion, and one of the positive bus bar and the negative bus bar faces the wall portion.

2. The power conversion device according to claim 1, A power conversion device in which the wall portion has a first wall facing the first conductor portion and a second wall facing the second conductor portion, the first wall and the second wall being arranged with a space between them.

3. The power conversion device according to claim 1, The wall portion of the power conversion device has a U-shape that faces the first conductor portion and faces the second conductor portion.

4. The power conversion device according to claim 1, The power conversion device, wherein an insulator is disposed between the first conductor portion and the wall portion and between the second conductor portion and the wall portion.

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