Power converter

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 Art

[0002] Power conversion devices mounted on hybrid vehicles and electric vehicles need to meet the individual standards established by each car manufacturer based on the high-voltage conductive noise standard added to the international standard regarding countermeasures against conductive noise generated by noise current. At the same time, in line with the development of electric vehicles on which the power conversion device is mounted, in recent years, there has been an increasing demand for miniaturization, low profile, and cost reduction. Therefore, there is a strong demand for the filter device provided in the power conversion device to improve high-frequency noise attenuation performance while maintaining cost reduction and miniaturization. Patent Document 1 discloses a semiconductor module including a power semiconductor element, a first electrode plate and a second electrode plate respectively joined to one surface and the other surface of the semiconductor element, connection terminals for a control circuit that controls the semiconductor element, and an insulating resin mold that seals the semiconductor element, the first electrode plate, and the second electrode plate, and a conductive first holding member and a second holding member that hold the semiconductor module from both sides via a first insulating member and a second insulating member that become inductors, and a noise suppression bypass capacitor is formed by the first electrode plate and / or the second electrode plate, the first holding member and / or the second holding member, the first insulating member and / or the second insulating member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the invention described in Patent Document 1, there is 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 comprises 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 busbar for transmitting DC power to the first power module and the second power module, and a metal housing for housing the first power module and the second power module, wherein the first power module and the second power module are arranged in parallel such that the respective DC terminals connected to the DC busbar face toward the other power module, and the DC busbar is on the DC side of the first power module The power module includes a first conductor portion connected to a terminal and a second conductor portion connected to the DC side terminal of the second power module, wherein a conductive wall portion is provided between the first power module and the second power module, electrically connected to the metal housing and facing the first conductor portion and the second conductor portion, the first conductor portion includes a region in which the positive and negative busbars constituting the DC busbar are stacked, the second conductor portion includes a region in which the positive and negative busbars constituting the DC busbar are stacked, in the first conductor portion either the positive busbar or the negative busbar faces the wall portion, and the second conductor portion is the first conductor Department Either the positive or negative busbar, which has a different polarity, faces the wall. [Effects of the Invention]

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

[0007] [Figure 1] Overall configuration diagram of the power conversion device [Figure 2] Equivalent circuit diagram of common-mode high-voltage conducted noise in a power converter. [Figure 3] Perspective view of a power converter [Figure 4]Perspective view of the upper positive and lower negative busbars. [Figure 5] Perspective view of the lower positive and lower negative busbars. [Figure 6] This diagram shows the lower positive and lower negative busbars combined with the wall section. [Figure 7] Schematic diagram showing the first and second conductor sections. [Figure 8] Perspective view of the comparative example power converter. [Figure 9] Comparative Example: Equivalent Circuit Diagram of Common-Mode High-Voltage Conducted Noise in a Power Converter [Figure 10] Figure showing the frequency characteristics of common-mode high-voltage conducted noise in a power converter and comparative example power converter. [Figure 11] Perspective view of the power converter in modified example 1 [Figure 12] Perspective view of the power converter in modified example 2 [Figure 13] Perspective view of the power converter in modified example 3 [Figure 14] Enlarged view of the area near the wall in Figure 13. [Modes for carrying out the invention]

[0008] —First Embodiment— A first embodiment of the power converter will be described below with reference to Figures 1 to 10.

[0009] Figure 1 is an overall configuration diagram of the power converter 1. The power converter 1 converts power between the high-voltage battery 2 and the first motor 6 and the second motor 8. For example, the power converter 1 can convert the 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 converter 1 can convert the 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. The power converter 1 only needs to be able to perform at least one of the following: conversion from DC to AC, and conversion from AC to DC. The housing 9 is made of metal and serves as the reference potential for the power converter 1.

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

[0011] The power converter 1 comprises a positive busbar 11, a negative busbar 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 from a conductive material or may be coated with a conductive material.

[0012] The first power module 141 includes first to third switching circuits SW1 to SW3 which are switching circuits corresponding to each of the U, V, and W phases. The second power module 142 includes fourth to sixth switching circuits SW4 to SW6 which are switching circuits corresponding to each of 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. The symbol 1-Cs1 is the floating capacitance between the positive electrode portion of the first power module 141 and the housing. The symbol 1-Cs2 is the floating capacitance between the AC output portion of the first power module 141 and the housing. The symbol 1-Cs3 is the floating capacitance between the negative electrode portion of the first power module 141 and the housing. The configurations of the second to sixth switching circuits SW2 to SW6 are the same as that of the first switching circuit SW1, so the description thereof is omitted. Note that the second to sixth switching circuits SW2 to SW6 also have floating capacitances in the same manner as 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 also collectively referred to as a second noise filter section 131. The first grounding capacitor Cy1 includes an eleventh grounding capacitor Cy11 that connects the positive electrode bus bar 11 and the housing 9, and a twelfth grounding capacitor Cy12 that connects the negative electrode bus bar 12 and the housing 9. The second grounding capacitor Cy2 includes a twenty-first grounding capacitor Cy21 that connects the positive electrode bus bar 11 and the housing 9, and a twenty-second grounding capacitor Cy22 that connects the negative electrode bus bar 12 and the housing 9. Note that 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 fluctuations in the ground voltage that occur during the switching operation in which switching circuits SW1 to SW6 periodically turn on and off. Due to this voltage fluctuation, a common-mode current flows through each stray capacitance between the power conversion device 1 and the housings of the first motor 6 and the second motor 8, and high-voltage conduction noise is generated by this current. Each stray capacitance refers to the stray capacitances 1-Cs1 to 1-Cs3 parasitic between the first power module 141 and the housing 9, the stray capacitances 1-Cs4 to 1-Cs6 parasitic between the second power module 142 and the housing 9, the stray capacitance 6-Cs existing between the coil 6M of the first motor 6 and the housing 9, and the stray capacitance 8-Cs existing between the coil 8M of the second motor 8 and the housing 9. Therefore, in order to reduce high-voltage conduction noise, it is necessary to reduce the common-mode current. In the power conversion device 1, by using the configuration of the noise filter device 13, noise is attenuated while corresponding to the noise current, which is the main cause of high-voltage conduction noise, and also corresponding to the high-voltage conduction noise standard.

[0015] (Regarding noise standards) The high-voltage conduction noise standard will be explained. The noise standard generally defines the regulated values in the frequency band from 0.15 MHz to 108 MHz. The high-voltage conduction noise standard is a standard added in CISPR25 Ed4, an international standard created by the International Special Committee on Radio Interference (CISPR) in October 2016. This is content that regulates the noise in the FM broadcast frequency band (76 MHz to 108 MHz), which is particularly used in various applications, to be lower than that in other frequency bands. High-voltage conduction noise may cause, for example, malfunctions in in-vehicle electric and electronic devices. Therefore, the amount of high-voltage conduction noise generated in the power conversion device 1 must be actually measured at the pre-shipment stage, and the amount of noise generation must be below the regulated values specified by national regulations and customer requirement specifications.

[0016] (Conventional technology and its problems) Generally, noise filter devices are used to ensure that power converters comply with high-voltage conducted noise standards. In cases where high voltage and high current are required, such as in automotive power converters, two or more power modules may be used to drive multiple motors or to increase power. For example, when two power modules are used, they are often connected in series to reduce their height, and a noise filter device is also placed in series with them.

[0017] In this configuration, the current path from each power module to the mounting capacitor included in the noise filter device is long, and the lengths of the two current paths differ. Specifically, the longer current path increases the impedance due to parasitic inductance in the current path. Also, the difference in length between the two current paths increases the resonance points caused by parasitic components present in the paths. These two problems result in a deterioration of noise attenuation performance in high-frequency bands such as the FM radio band.

[0018] In this embodiment, as shown in Figure 1, a first proximity grounding capacitor Cw21 and a second proximity grounding capacitor Cw22 are provided between the positive busbar 11 closest to the first power module 141 and the housing 9, and between the negative busbar 12 closest to the second power module 142 and the housing 9, respectively. This provides grounding Y capacitors close to the power modules, shortening the length of the current path and reducing the impedance of the path. Furthermore, since the length of the current path becomes the same, the increase in resonance points can also be suppressed.

[0019] Figure 2 is an equivalent circuit diagram of common-mode high-voltage conducted noise in power converter 1. In Figure 2, the area to the left of the dashed line shows the interior of power converter 1. The symbol Vs1 is a noise source that simulates common-mode noise generated in the first power module 141. The symbol Cpm1 is the total parasitic capacitance between the first power module 141 and the housing 9. The symbol Vs2 is a noise source that simulates common-mode noise generated in the second power module 142. The symbol Cpm2 is the total parasitic capacitance between the second power module 142 and the housing 9.

[0020] The symbol Lg1 is the parasitic inductance between P02, the grounding point of the first power module 141 to the housing 9, and P01, the grounding point of the first ground capacitor Cy1 to the housing 9. The symbol Lg2 is the parasitic inductance between P03, the grounding point of the second power module 142 to the housing 9, and P01, the grounding point of the first ground capacitor Cy1 to the housing 9. The symbol L_bp is the inductance of the positive busbar 11 to the first ground capacitor Cy1, which transmits DC power to the first power module 141 and the second power module 142. The symbol L_bn is the inductance of the negative busbar 12 to the first ground capacitor Cy1, which transmits DC power to the first power module 141 and the second power module 142.

[0021] Code Ic1 represents the common-mode current generated from the first power module. Code Ic2 represents the common-mode current generated from the second power module. Code Ic3 represents the common-mode current of Ic1 that is bypassed by the first ground capacitor Cy1. Code Ic4 represents the common-mode current of Ic2 that is bypassed by the first ground capacitor Cy1. Code Ic5 represents the common-mode current that flows out to the outside of the power converter.

[0022] The symbol Ic6 represents the common-mode current obtained by summing 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 neighboring grounding capacitor Cw21. The symbol Ic7 represents the common-mode current obtained by summing 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 neighboring grounding capacitor Cw22. The symbol 3-1 is the common-mode equivalent circuit of the high-voltage power supply impedance stabilization network 3. The symbol 4-1 is the common-mode equivalent circuit of the high-voltage DC cable 4.

[0023] Figure 3 is a perspective view of the power converter 1. The configuration shown in Figure 3 is the same as that shown in Figure 1 or Figure 2, except for the wall section 102 which will be described later. In some of the drawings from Figure 3 onward, mutually orthogonal XYZ axes are shown to clearly illustrate the correlations. The left-right direction in the diagram is the X-axis, and the first power module 141, the wall section 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 busbar 11 and negative busbar 12 of the first power module 141 and the second power module 142 are arranged to face the wall section 102.

[0024] The positive electrode busbar 11 consists of an upper positive electrode busbar 11U and a lower positive electrode busbar 11D. The negative electrode busbar 12 consists of an upper negative electrode busbar 12U and a lower negative electrode busbar 12D. The upper positive electrode busbar 11U and the upper negative electrode busbar 12U have a shape in which the central part of a flat plate extending in the XY plane is recessed towards the negative Z axis. The upper positive electrode busbar 11U and the upper negative electrode busbar 12U are connected to the lower positive electrode busbar 11D and the lower negative electrode busbar 12D at this recessed portion. In Figure 3, the upper positive electrode busbar 11U and the upper negative electrode busbar 12U overlap with a gap in the Z direction. The shapes of the positive electrode busbar 11 and the negative electrode busbar 12 will be explained in detail in Figures 4 and 5.

[0025] The wall portion 102 shown in the lower center of Figure 3 is a conductor having the same potential as the housing 9. The wall portion 102 has the shape of a hollow or solid rectangular parallelepiped, and is surrounded by the lower positive electrode busbar 11D and the lower negative electrode busbar 12D. However, the wall portion 102 is not in contact with the lower positive electrode busbar 11D and the lower negative electrode busbar 12D, and is in close proximity to the lower positive electrode busbar 11D and the lower negative electrode busbar 12D with a very small gap separating them, which will be described later, to generate capacitance.

[0026] Figure 4 is a perspective view of the upper positive busbar 11U and the upper negative busbar 12U. The viewpoint in Figure 4 is the same as in Figure 3. The dimensions of the upper positive busbar 11U and the upper negative busbar 12U in the Y-axis direction are approximately the same. The approximate center of the upper positive busbar 11U in the X direction is recessed towards the negative Z-axis side and has two notches. These recessed areas are called the upper positive first connection part 11U1 and the upper positive second connection part 11U2. The approximate center of the upper negative busbar 12U in the X direction is recessed towards the negative Z-axis side and has two notches. These recessed areas are called the upper negative first connection part 12U1 and the upper negative second connection part 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 substantially the same width in the X-axis direction and do not come into contact with each other even in the assembled state shown in Figure 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] Figure 5 is a perspective view of the lower positive busbar 11D and the lower negative busbar 12D. The viewpoint in Figure 5 is the same as in Figure 3. The dimensions of the lower positive busbar 11D and the lower negative busbar 12D in the Y-axis direction are approximately the same. The approximate center of the lower positive busbar 11D in the X direction protrudes towards the positive Z-axis and has two notches. These protruding portions are called the lower positive first connection portion 11D1 and the lower positive second connection portion 11D2. The approximate center of the lower negative busbar 12D in the X direction protrudes towards the positive Z-axis and has two notches. These protruding portions are called the lower negative first connection portion 12D1 and the lower negative second connection portion 12D2. The lower positive electrode first connection part 11D1, the lower positive electrode second connection part 11D2, the lower negative electrode first connection part 12D1, and the lower negative electrode second connection part 12D2 have substantially the same width in the X-axis direction and do not come into contact with each other even in the assembled state shown in Figure 3. The lower positive electrode first connection part 11D1, the lower positive electrode second connection part 11D2, the lower negative electrode first connection part 12D1, and the lower negative electrode second connection part 12D2 have through holes used for fixing to the wall part 102.

[0029] Figure 6 shows the lower positive busbar 11D and lower negative busbar 12D combined with the wall portion 102. However, Figure 6 shows two viewpoints: one showing the right side of the wall portion 102 and another showing the left side of the wall portion 102. When the lower positive busbar 11D and lower negative busbar 12D are combined, as shown in Figure 6, they are arranged in the order of lower positive first connection portion 11D1, lower negative first connection portion 12D1, lower positive second connection portion 11D2, and lower negative second connection portion 12D2 from the negative side to the positive side of the Y-axis.

[0030] The viewpoint shown on the left of Figure 6 represents the left side of the wall 102, i.e., the side on the negative X-axis. On the left side of the wall 102, the lower negative busbar 12D is on the outside, and the lower positive busbar 11D is on the inside. The viewpoint shown on the right of Figure 6 represents the right side of the wall 102, i.e., the side on the positive X-axis. On the right side of the wall 102, the lower negative busbar 12D is on the inside, and the lower positive busbar 11D is on the outside. In other words, the polarity of the opposing busbars is different on the left and right walls of the wall 102.

[0031] As shown in Figure 3, the first power module 141 is located on the negative X-axis side of the wall 102, and the second power module 142 is located on the positive X-axis side of the wall 102. The portion of the lower positive busbar 11D and the lower negative busbar 12D that is connected to the DC side terminal of the first power module 141 is called the first conductor portion 100. The portion of the lower positive busbar 11D and the lower negative busbar 12D that is connected to the DC side terminal of the second power module 142 is called the second conductor portion 101.

[0032] Note that in Figure 6, for the sake of drawing convenience, the distances between the lower positive electrode first connection part 11D1, the lower positive electrode second connection part 11D2, the lower negative electrode first connection part 12D1, and the lower negative electrode second connection part 12D2 and the Z-axis positive end of the wall part 102 are shown to be shorter than they actually are. However, in reality, measures are taken to prevent discharge from occurring between the wall part 102 and the lower positive electrode busbar 11D and the lower negative electrode busbar 12D on the Z-axis positive side of the wall part 102. For example, an insulating layer may be provided on the Z-axis positive side surface of the wall part 102, or a sufficient insulating distance may be provided between the wall part 102 and the lower positive electrode busbar 11D and the lower negative electrode busbar 12D on the Z-axis positive side of the wall part 102.

[0033] Figure 7 is a schematic diagram showing the first conductor section 100 and the second conductor section 101. However, in Figure 7, the upper parts of the lower positive busbar 11D and the lower negative busbar 12D are omitted. Also in Figure 7, hatching is applied to the lower positive busbar 11D, the lower negative busbar 12D, and the wall section 102 so that they can be easily identified.

[0034] In the first conductor section 100, the area where the lower positive busbar 11D and the wall section 102 face each other is large, and the gap between them is very small even considering the insulation distance. Therefore, a capacitance of several hundred pF can be formed by the opposing portion between the lower positive busbar 11D and the wall section 102. Furthermore, by inserting an insulator such as a mold with a high dielectric constant, it is possible to form an even larger capacitance of about nF. The capacitance formed by the opposing portion between the lower positive busbar 11D and the wall section 102 corresponds to the first proximity grounding capacitor Cw21 shown in Figure 1. Note that the distance between the lower negative busbar 12D and the wall section 102 in the first conductor section 100 is relatively long, and the resulting capacitance can be ignored.

[0035] In the second conductor section 101, the gap between the lower negative busbar 12D and the wall section 102 is very small, and capacitance is generated as explained earlier. This capacitance corresponds to the second proximity grounding capacitor Cw22 shown in Figure 1. Note that the distance between the lower positive busbar 11D and the wall section 102 in the first conductor section 100 is relatively long, and the resulting capacitance can be ignored.

[0036] (Comparative example) Figure 8 is a perspective view of comparative power converter 1Z, which is a comparative example. Comparative power converter 1Z differs from power converter 1 in that it does not have a wall portion 102. Since comparative power converter 1Z does not have a wall portion 102, there is no capacitance between the wall portion 102 and the lower positive busbar 11D or lower negative busbar 12D in power converter 1. Comparative power converter 1Z also differs from power converter 1 in that the polarity of the opposing conductor plates of the first conductor portion 100 and the second conductor portion 101 is the same.

[0037] Figure 9 is the equivalent circuit diagram of common-mode high-voltage conducted noise in comparative example power converter 1Z. Comparing the equivalent circuit diagram of common-mode high-voltage conducted noise in power converter 1 shown in Figure 2 with Figure 9, the first and second proximity ground capacitors Cw21 and Cw22, which were present in Figure 2, are absent. Therefore, the current path from the noise source Vs1 of the first power module and the noise source Vs2 of the second power module to the Y capacitor, the first ground capacitor Cy1, is long, resulting in a large impedance. Furthermore, the path length from noise source Vs1 to the first ground capacitor Cy1 is different from the path length from noise source Vs2 to the first ground capacitor Cy1, which increases the resonance point.

[0038] Figure 10 shows the frequency characteristics of common-mode high-voltage conducted noise in power converter 1 and comparative example power converter 1Z. For example, when the target frequency band is set to 70MHz to 110MHz, power converter 1 has a lower noise level than comparative example power converter 1Z across the entire target frequency range. In particular, around 90MHz, where there is a peak, power converter 1 showed an effect of reducing the noise level by 10dB compared to comparative example power converter 1Z.

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

[0040] Therefore, the first conductor portion 100 and the wall portion 102 form the 21st ground capacitor Cy21, and the second conductor portion 101 and the wall portion 102 form the 22nd ground capacitor Cy22, thus forming a conducted noise path as shown in Figure 2. This has the effect of shortening the noise path and reducing impedance, and the effect of making the path lengths of the two paths equal and reducing the resonance point. In addition, the capacitances of the 21st ground capacitor Cy21 and the 22nd ground capacitor Cy22 can be easily changed by adjusting the positions of the lower positive busbar 11D and the lower negative busbar 12D, respectively.

[0041] (Variation 1) Figure 11 is a perspective view of the power converter 1A in modified example 1. The power converter 1A differs from the first embodiment in that it has two walls instead of the wall portion 102, namely a first wall 103 facing the first conductor portion 100 and a second wall 104 facing the second conductor portion 101. The first wall 103 and the second wall 104 are electrically connected only through the housing 9.

[0042] According to this modified example 1, the following 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, with the first wall 103 and the second wall 104 separated by a space. In this case, the space between the first wall 103 and the second wall 104 can be used for other purposes.

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

[0044] According to this modified example 2, the following effects can be obtained. (3) The wall portion has a U-shape that faces both the first conductor portion 100 and the second conductor portion 101. Therefore, while reducing the number of parts compared to Modification 1, the upper part of the U-shape is open, so that space can be used for other purposes.

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

[0046] Figure 14 is an enlarged view of the area around the wall portion 102 in Figure 13. This figure corresponds to Figure 7 in the first embodiment. As shown in Figure 14, an insulator 106 is arranged around the wall portion 102. Therefore, the capacitance of the first proximity ground capacitor Cw21 formed by the lower positive busbar 11D and the wall portion 102 in the first conductor portion 100, and the second proximity ground capacitor Cw22 formed by the lower negative busbar 12D and the wall portion 102 in the second conductor portion 101, are also affected by the dielectric constant of the insulator 106.

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

[0048] According to this modified example 3, the following effects can be obtained. (4) An insulator 106 is placed between the first conductor portion 100 and the wall portion 102, and between the second conductor portion 101 and the wall portion 102. Therefore, the capacitance of the first proximity grounding capacitor Cw21 and the second proximity grounding capacitor Cw22 can be adjusted by changing the material of the insulator 106 in addition to the physical distance, thereby also utilizing the dielectric constant.

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

[0050] 1, 1A, 1B, 1C: Power converter 9: Cabinet 11: Positive busbar 11D: Lower positive terminal busbar 11U: Upper positive busbar 12: Negative busbar 12D: Lower negative busbar 12U: Upper negative busbar 100: First conductor section 101: Second conductor section 102: Wall part 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 proximity grounded capacitor Cw22: Second proximity grounded capacitor

Claims

1. The first power module constitutes the first inverter circuit, A second power module constituting a second inverter circuit connected in parallel with the first inverter circuit, A DC busbar that transmits DC power to the first power module and the second power module, The system comprises 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 the respective DC terminals connected to the DC busbar face toward the other power module. The DC busbar includes a first conductor portion connected to the DC side terminal of the first power module and a second conductor portion connected to the DC side terminal of the second power module. Between the first power module and the second power module, there is a conductive wall portion that is electrically connected to the metal housing and faces the first conductor portion and the second conductor portion. The first conductor portion includes a region in which the positive and negative busbars constituting the DC busbar are stacked, The second conductor portion includes a region in which the positive electrode busbar and the negative electrode busbar are stacked, The first conductor portion is such that either the positive busbar or the negative busbar faces the wall portion. The power conversion device wherein the second conductor portion has a different polarity from the first conductor portion, and either the positive busbar or the negative busbar faces the wall portion.

2. A power conversion device according to claim 1, The wall portion comprises a first wall facing the first conductor portion and a second wall facing the second conductor portion, and the first wall and the second wall are provided separated by a space.

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

4. A power conversion device according to claim 1, An insulator is disposed between the first conductor portion and the wall portion, and between the second conductor portion and the wall portion of the power conversion device.

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