Power Converters

Abstract

A technology is provided to easily join the terminals and busbars while bringing the terminals of multiple power modules and capacitors close to each other. The power converter includes multiple power modules, capacitors, a positive busbar, and a negative busbar. Each power module includes a positive terminal and a negative terminal on the side opposite to the capacitor. The front ends of the positive terminal and the negative terminal are parallel to the side. The positive busbar includes: a positive base plate (negative base plate) joined to the positive electrode (negative electrode) of the capacitor; and a positive flange (negative flange) bent from the positive base plate (negative base plate). The positive flange (negative flange) is joined to the positive terminal (negative terminal) of the power module. The positive flange and the negative flange extend in a direction away from the capacitor.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a power converter including a plurality of power modules that accommodate switching elements for power conversion and a capacitor. Background Art

[0002] A power converter including a plurality of power modules that accommodate switching elements for power conversion is known. For example, Japanese Patent Application Laid-Open No. 2011-151992 and Japanese Patent Application Laid-Open No. 2017-99140 (Document 1) disclose such a power converter.

[0003] The power converter of document 1 also includes a capacitor connected to a plurality of power modules. The plurality of power modules are stacked along a first direction (X direction). Each power module includes a positive terminal and a negative terminal on a side facing a second direction (Y direction) intersecting the first direction. The capacitor is configured to be adjacent to the plurality of power modules in a third direction (Z direction) intersecting both the first direction and the second direction. The positive electrode of the capacitor is connected to the positive terminals of the plurality of power modules via a positive bus bar, and the negative electrode of the capacitor is connected to the negative terminals of the plurality of power modules via a negative bus bar. Summary of the invention

[0004] The terminals (positive terminals or negative terminals) of the multiple power modules are arranged in the stacking direction of the power modules. If the terminals of the power modules are close to the capacitors, it becomes difficult to join the busbars and the terminals. Therefore, in the power converter of document 1, the terminals of the power modules are arranged on the side facing the second direction, the power modules and the capacitors are arranged in the third direction, and the terminals are away from the capacitors. This specification provides a technology that seeks to easily join the terminals and the busbars while bringing the terminals of the multiple power modules close to the capacitors.

[0005] The power converter disclosed in this specification includes a plurality of power modules, a capacitor, a positive bus bar, and a negative bus bar. Each power module accommodates a switching element for power conversion. The plurality of power modules are stacked along a first direction (X direction). The capacitor is arranged next to the plurality of power modules in a second direction (Y direction) intersecting the first direction (X direction).

[0006] Each power module has a positive terminal and a negative terminal on the side opposite to the capacitor. The positive terminal is connected to the positive electrode of the switching element inside the power module, and the negative terminal is connected to the negative electrode of the switching element. The positive terminal and the negative terminal are arranged in a third direction (Z direction) intersecting both the first direction (X direction) and the second direction (Y direction). The front end of the positive terminal and the front end of the negative terminal are parallel to the side of the power module (the side on which the positive terminal and the negative terminal are provided).

[0007] The capacitor includes a positive electrode at one end surface in the third direction (Z direction) and includes a negative electrode at the other end surface.

[0008] The positive busbar includes: a positive base plate, the positive base plate is connected to the positive electrode; and a positive flange, the positive flange is bent from the positive base plate to a third direction (Z direction). The positive flange is connected to the positive terminals of multiple power modules. The negative busbar includes: a negative base plate, the negative base plate is connected to the negative electrode; and a negative flange, the negative flange is bent from the negative base plate to a third direction (Z direction). The negative flange is connected to the negative terminals of multiple power modules. The positive flange and the negative flange extend in the third direction (Z direction) in a direction separated from the capacitor.

[0009] According to the above configuration, the capacitor is adjacent to the side surface where the positive electrode terminal and the negative electrode terminal are provided. The capacitor is located near the positive electrode terminal and the negative electrode terminal.

[0010] On the other hand, the joint between the positive electrode flange and the positive terminal is located next to the capacitor in the third direction, and the joint between the negative electrode flange and the negative terminal is located next to the capacitor on the opposite side. The joint between the positive terminal and the joint between the negative terminal are respectively distributed on both sides of the capacitor, so the joint operation becomes easy. The power converter disclosed in this specification can seek to make it easy to join the terminals of multiple power modules and the capacitor while making it close to each other and joining the terminals to the busbar.

[0011] The specific contents and further improvements of the technology disclosed in this specification will be described in the following “Specific embodiments”. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a circuit diagram of an electric vehicle including the power converter of the first embodiment.

[0013] Figure 2 It is a three-dimensional diagram of a power converter.

[0014] Figure 3 is an exploded view of the power converter.

[0015] Figure 4 is a cross-sectional view of a power converter.

[0016] Figure 5 is a cross-sectional view of a power converter according to a second embodiment. DETAILED DESCRIPTION

[0017] (First Embodiment) A power converter according to a first embodiment will be described with reference to the accompanying drawings. The power converter according to the first embodiment is a device installed in an electric vehicle. The power converter converts the power of a battery into driving power for a running motor. Figure 1A block diagram of an electric power system of an electric vehicle 100 including a power converter 2 is shown.

[0018] The electric vehicle 100 includes a battery 82, a power converter 2, and two motors 83a and 83b for driving. The output shafts of the motors 83a and 83b are connected to a gear set 85. The gear set 85 is also connected to an axle 86. The gear set 85 combines the output torques of the motors 83a and 83b and transmits them to the axle 86.

[0019] The power converter 2 converts the output power (DC power) of the battery 82 into the driving power (AC power) of the motors 83a and 83b. The positive input terminal 18a of the power converter 2 is connected to the positive terminal of the battery 82, and the negative input terminal 18b is connected to the negative terminal of the battery 82.

[0020] The input terminal 18 is connected to a capacitor 6. The capacitor 6 is provided to suppress pulsation of the input current (input voltage). The input positive terminal 18a of the power converter 2 is connected to the positive electrode 6a of the capacitor 6 via the power supply positive bus 61, and the input negative terminal 18b is connected to the negative electrode 6b of the capacitor 6 via the power supply negative bus 62. The bus is a conductive component with a small internal resistance, and is typically made of a metal rod.

[0021] The power converter 2 includes two inverter circuits 13a and 13b. The DC terminals of the inverter circuits 13a and 13b are connected in parallel to the capacitor 6. The AC terminals of the inverter circuit 13a are connected to the motor 83a, and the AC terminals of the inverter circuit 13b are connected to the motor 83b.

[0022] The inverter circuit 13a has a structure in which three sets of two switching element series circuits are connected in parallel. The switching elements 9a and 9b, the switching elements 9c and 9d, and the switching elements 9e and 9f constitute a series circuit respectively. A diode is connected to each switching element in anti-parallel.

[0023] When the switching elements 9a and 9b of the series circuit are alternately turned on and off, AC power is output from the midpoint of the series circuit. AC power is output from three sets of series circuits respectively. The circuit in the range of the dotted rectangle shown by symbol 8a corresponds to the power module 8a described later. Symbols 17a and 17b represent terminals extending from the power module 8a. Symbol 17a represents a terminal (positive terminal 17a) that is conductive to the high potential side of the series circuit of the switching elements 9a and 9b. Symbol 17b represents a terminal (negative terminal 17b) that is conductive to the low potential side of the series circuit of the switching elements 9a and 9b. As described below, the markings of the positive terminal 17a and the negative terminal 17b are also used for other power modules.

[0024] Although Figure 1Although not shown, the power module 8a also includes a midpoint terminal 17c. The midpoint terminal 17c is connected to the midpoint of the series circuit of the switching elements 9a and 9b. Figure 3 The positive electrode terminal 17a, the negative electrode terminal 17b, and the midpoint terminal 17c are described below. In addition, the positive electrode terminal 17a, the negative electrode terminal 17b, and the midpoint terminal 17c are sometimes collectively referred to as terminals 17 below.

[0025] The series circuit of the switching elements 9c and 9d (and the diodes connected in anti-parallel to each switching element) constitutes the power module 8b. The series circuit of the switching elements 9e and 9f (and the diodes connected in anti-parallel to each switching element) constitutes the power module 8c. The structure of the power modules 8b and 8c is the same as that of the power module 8a. Similar to the power module 8a, the power modules 8b and 8c also include a positive terminal 17a, a negative terminal 17b, and a midpoint terminal 17c (the midpoint terminal 17c is not shown) that are respectively connected to the high potential side, the low potential side, and the midpoint of the series circuit of the two switching elements.

[0026] The switching elements 9a-9f are transistors, typically IGBTs (Insulated Gate Bipolar Transistors), but may also be other transistors, such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). The switching elements mentioned here are used for power conversion and are sometimes referred to as power semiconductor elements.

[0027] The inverter circuit 13b has the same structure as the inverter circuit 13a, and includes three power modules 8d to 8f. The structures of the power modules 8d to 8f are the same as those of the power module 8a, and therefore, the power modules 8d to 8f and their connection relationship are simplified.

[0028] exist Figure 1 In the figure, the dotted lines 8a-8f correspond to power modules respectively. The power converter 2 includes six sets of series circuits of two switching elements. As hardware, the two switching elements constituting the series circuit and the diodes connected in anti-parallel to each switching element are housed in one package (package of the power module). Hereinafter, when any one of the power modules 8a-8f is represented without distinction, it is marked as power module 8.

[0029] The high potential side terminals (positive terminals 17a) of the four power modules (four series circuits) are connected to the positive electrode 6a of the capacitor 6, and the low potential side terminals (negative terminals 17b) are connected to the negative electrode 6b of the capacitor 6. Figure 1, the conductive path within the dotted line indicated by the symbol 30 corresponds to the bus bar (positive bus bar 30) connecting the positive terminals 17a of the plurality of power modules 8 to the positive electrode 6a of the capacitor 6. The conductive path within the dotted line indicated by the symbol 40 corresponds to the bus bar (negative bus bar 40) connecting the plurality of negative terminals 17b to the negative electrode 6b of the capacitor 6. Next, the structure of the plurality of power modules 8 and the positive bus bar 30 and the negative bus bar 40 will be described.

[0030] Figure 2 A perspective view showing the hardware of the power converter 2 is shown. Figure 2 The stacking unit 20 is a perspective view of an assembly of a stacking unit 20 and a capacitor 6 connected by a positive bus bar 30 and a negative bus bar 40, and other components of the power converter 2 are omitted. The stacking unit 20 is a device in which the power modules 8 (8a-8f) and a plurality of coolers 21 described above are stacked. Figure 3 An exploded view of the power converter 2 is shown. Figure 3 is an exploded view of the assembly previously described, in Figure 3 The remaining components of the power converter 2 are also omitted in the figure. The X direction of the coordinate system in the figure corresponds to the stacking direction of the power modules 8 (8a-8f). In the following figures, the X direction also corresponds to the stacking direction.

[0031] Reference Figure 2 and Figure 3 The hardware of the power converter 2, in particular the above-mentioned assembly, will be described. The plurality of power modules 8 (8a-8f) together with the plurality of coolers 21 constitute the stacked unit 20. The power modules 8a-8f are all of the same shape. Figure 2 In the example, only the power module on the left end is labeled with the symbol 8, and the symbols for the other power modules are omitted. Figure 2 In FIG. 1 , only the cooler at the left end is denoted by reference numeral 21 as a representative, and reference numerals are omitted for the remaining coolers.

[0032] The plurality of power modules 8 and the plurality of coolers 21 are alternately stacked one by one. The power modules 8 are flat in shape, and the wide surfaces thereof are in contact with the coolers 21 .

[0033] The cooler 21 at the left end of the figure is provided with a refrigerant supply port 22a and a refrigerant discharge port 22b. Adjacent coolers 21 are connected to each other via two connecting pipes 23a and 23b. Figure 2 , Figure 3 In the figure, only the connecting pipes 23a and 23b at the left end are denoted by reference numerals, and reference numerals are omitted for the other connecting pipes. The interior of the cooler 21 is formed as a cavity (refrigerant flow path), and the connecting pipes 23a and 23b allow the refrigerant flow paths of the adjacent coolers 21 to communicate with each other.

[0034] One connecting pipe 23a of one party is located at a position overlapping with the refrigerant supply port 22a when viewed from the stacking direction. The other connecting pipe 23b is located at a position overlapping with the refrigerant discharge port 22b when viewed from the stacking direction. A refrigerant circulation device (not shown) is connected to the refrigerant supply port 22a and the refrigerant discharge port 22b. The refrigerant supplied from the refrigerant supply port 22a passes through one connecting pipe 23a and is distributed to all the coolers 21. During the refrigerant passing through the cooler 21, heat is absorbed from the adjacent power modules 8. The refrigerant that has absorbed heat is discharged from the stacking unit 20 through the other connecting pipe 23b and the refrigerant discharge port 22b. Since each power module 8 is cooled from both sides, the stacking unit 20 has a high cooling performance for the power module 8.

[0035] The main body of the power module 8 is a package that houses switching elements and diodes. The package is made of resin. The positive terminal 17a, the negative terminal 17b, and the midpoint terminal 17c extend from one narrow-width surface (Japanese: 幅狭面) of the package of each power module 8, that is, the side surface 81. Figure 2 and Figure 3 In the figure, only the side surface of the leftmost power module 8 is labeled 81, and the same side surfaces of the remaining power modules 8 are omitted from labeling. In the figure, the bus bar connected to the midpoint terminal 17c is omitted from illustration.

[0036] In the Y direction orthogonal to the stacking direction (the X direction in the figure) of the plurality of power modules 8, capacitors 6 are arranged beside the plurality of power modules 8. In other words, the capacitors 6 are arranged so as to face the side surfaces 81 of the plurality of power modules 8. Three terminals 17 (positive terminal 17a, negative terminal 17b, midpoint terminal 17c) extend from the side surface 81 of the power module 8 facing the capacitor 6. The three terminals 17 are arranged along the Z direction of the coordinate system in the figure. In addition, the three terminals 17 are each made of a wide-width plate (Japanese: 幅広板), and the wide-width surface at the front end is parallel to the side surface 81.

[0037] The capacitor 6 is provided with a positive electrode 6a on the end face facing the +Y direction, and a negative electrode 6b on the end face facing the opposite direction (-Y direction). The capacitor 6 is arranged with the positive electrode 6a and the negative electrode 6b facing the Y direction.

[0038] The positive busbar 30 has a positive base plate 31 opposite to the positive electrode 6a of the capacitor 6 and a positive flange 32 bent in an L shape from the positive base plate 31 toward the -Z direction. The positive base plate 31 is joined to the positive electrode 6a of the capacitor 6. The positive flange 32 is parallel to the flat surface of the front end of the positive terminal 17a of the plurality of power modules 8. Each positive terminal 17a is joined to one end of the extension plate 19. The other end of the extension plate 19 is joined to the positive flange 32 of the positive busbar 30. In other words, the positive terminals 17a of the plurality of power modules 8 are joined to the positive flange 32 of the positive busbar 30 via the extension plate 19, respectively.

[0039] The negative bus bar 40 includes a negative base plate 41 facing the negative electrode 6b of the capacitor 6 and a negative flange 42 bent in an L shape toward the +Z direction from the negative base plate 41. The negative base plate 41 is joined to the negative electrode 6b of the capacitor 6. The negative flange 42 faces the front ends of the negative terminals 17b of the plurality of power modules 8 and is joined to the negative terminals 17b.

[0040] The positive electrode flange 32 of the positive electrode bus bar 30 and the negative electrode flange 42 of the negative electrode bus bar 40 extend in a direction away from the capacitor 6. In other words, the positive electrode flange 32 and the negative electrode flange 42 extend in a direction away from each other.

[0041] Figure 4 A cross-sectional view of the power converter 2 is shown. Figure 4 This is a cross-sectional view of the power converter 2 cut along a plane perpendicular to the stacking direction (X direction) of the plurality of power modules 8. Figure 4 In the figure, a housing 50 for housing components such as the stacking unit 20 is also shown. Figure 4 In the figure, the busbar connected to the midpoint terminal 17c of the power module 8 and several other components are omitted.

[0042] The stacking unit 20 is fixed to the partition plate 53 of the housing 50. A substrate 54 is arranged below the stacking unit 20. The substrate 54 is fixed to the housing by bolts 52. A plurality of control terminals extend from the lower surface of the power module 8, and the control terminals are connected to the substrate 54. The substrate 54 is mounted with a control circuit of a switching element housed in the power module 8.

[0043] As described above, the negative terminal 17b of the power module 8 is joined to the negative electrode flange 42 of the negative bus bar 40, and the positive terminal 17a is joined to one end of the extension plate 19. The extension plate 19 extends in the Z direction, and the other end is joined to the positive electrode flange 32 of the positive bus bar 30. The positive base plate 31 of the positive bus bar 30 is connected to the positive electrode 6a of the capacitor 6, and the negative base plate 41 of the negative bus bar 40 is joined to the negative electrode 6b of the capacitor 6. In other words, the positive terminal 17a is connected to the positive electrode 6a of the capacitor 6 via the extension plate 19 and the positive bus bar 30, and the negative terminal 17b is connected to the negative electrode 6b of the capacitor 6 via the negative bus bar 40.

[0044] The positive bus bar 30 and the negative bus bar 40 extend further upward than the capacitor 6. In the Y direction, a bus bar module 60 is arranged next to the capacitor 6. The bus bar module 60 is arranged on the side opposite to the power module 8 with respect to the capacitor 6. The bus bar module 60 is a plate. The bus bar module 60 is fixed to the housing 50 by bolts 51.

[0045] The busbar module 60 is equipped with a positive power supply busbar 61 and a negative power supply busbar 62. The front end of the positive busbar 30 is connected to the positive power supply busbar 61, and the front end of the negative busbar 40 is connected to the negative power supply busbar 62. As described above, the positive power supply busbar 61 and the negative power supply busbar 62 are connected to the input terminal 18 of the power converter 2 (see Figure 1 ) is connected to the busbar of capacitor 6. Figure 4 As shown in detail in FIG. 1 , the capacitor 6 is joined to the positive bus bar 30 and the negative bus bar 40 and supported by the positive bus bar 30 and the negative bus bar 40. One end (upper end) of the positive bus bar 30 and the negative bus bar 40 is supported on the housing 50 via the bus bar module 60. The other end (lower end) of the positive bus bar 30 and the negative bus bar 40 is supported on the housing 50 via the plurality of power modules 8 of the stacking unit 20. The capacitor 6 itself is not in direct contact with the housing 50, but is indirectly supported on the housing 50 via the bus bars 30, 40, etc. Although the capacitor 6 is not in direct contact with the housing 50, both sides are supported by the positive bus bar 30 and the negative bus bar 40, so the vibration resistance characteristics are good.

[0046] Advantages of the above structure are described. The capacitor 6 is arranged in a manner opposite to the positive terminal 17a and the negative terminal 17b. Therefore, the capacitor 6 is close to the positive terminal 17a and the negative terminal 17b, and the positive terminal 17a and the negative terminal 17b can be shortened. In addition, the positive flange 32 of the positive busbar 30 extends in a manner separated from the capacitor 6, and the negative flange 42 of the negative busbar 40 extends in a manner separated from the capacitor 6 on the opposite side. The positive flange 32 can be easily joined to the positive terminal 17a and the negative flange 42 can be easily joined to the negative terminal 17b. The positive flange 32 is joined to the positive terminal 17a via the extension plate 19.

[0047] Alternatively, the positive electrode terminal 17 a and the positive electrode flange 32 may be joined without the extension plate 19 , and the negative electrode terminal 17 b and the negative electrode flange 42 may be joined with the extension plate 19 .

[0048] like Figure 2 , Figure 3 As shown, a plurality of power modules 8 and capacitors 6 overlap when viewed along the Y direction.

[0049] The plurality of power modules 8 and the capacitor 6 are accommodated in the housing 50. The plurality of power modules 8 are fixed to the housing 50. A plate-shaped busbar module 60 is also fixed to the housing 50. The busbar module 60 is adjacent to the capacitor 6 on the side opposite to the plurality of power modules 8. The upper ends of the positive busbar 30 and the negative busbar 40 are fixed to the busbar module 60. The lower ends of the positive busbar 30 and the negative busbar 40 are fixed to the plurality of power modules 8. The capacitor 6 is supported by the housing 50 via the positive busbar 30, the negative busbar 40, the power module 8, and the busbar module 60. The busbar module 60 supports the capacitor 6, and therefore can also be called a support plate.

[0050] The bus module 60 is provided with a positive power supply bus 61 and a negative power supply bus 62 for supplying power from the power source to the capacitor 6. The positive bus 30 is connected to the positive power supply bus 61, and the negative bus 40 is connected to the negative power supply bus 62.

[0051] (Second embodiment) Figure 5 A cross-sectional view of a power converter 2a according to a second embodiment is shown. The positive base plate 31 of the positive bus bar 30a and the negative base plate 41 of the negative bus bar 40a of the power converter 2a according to the second embodiment are shorter. The positive base plate 31 covers the lower portion of the positive electrode 6a of the capacitor 6, and the negative base plate 41 covers the lower portion of the negative electrode 6b. The upper portion of the positive electrode 6a of the capacitor 6 is connected to another positive bus bar 35, and the upper portion of the negative electrode 6b is connected to another negative bus bar 45. The upper portion of another positive bus bar 35 is connected to the positive bus bar 61 for power supply of the bus bar module 60, and the upper portion of another negative bus bar 45 is connected to the negative bus bar 62 for power supply of the bus bar module 60.

[0052] The following describes the points of attention regarding the technology described in the embodiment. The busbar module 60 corresponds to an example of a support plate. The X direction, Y direction, and Z direction of the coordinate system in the figure correspond to the first direction, the second direction, and the third direction, respectively.

[0053] The specific examples of the present invention are described above, but these are only examples and do not limit the claims. The technology described in the claims includes the content obtained by various deformations and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exert technical usefulness alone or through various combinations, and are not limited to the combinations recorded in the claims at the time of application. In addition, the technology illustrated in this specification or the drawings can achieve multiple purposes at the same time, and the situation in which one of the purposes is achieved itself has technical usefulness.

Claims

1. A power converter, It is characterized in that include: A plurality of power modules, wherein the plurality of power modules accommodate switching elements for power conversion and are stacked along a first direction; a capacitor, the capacitor being arranged beside the plurality of power modules in a second direction intersecting the first direction; and a positive bus bar and a negative bus bar, wherein the positive bus bar and the negative bus bar connect the plurality of power modules to the capacitor, A positive terminal and a negative terminal are provided on a side surface of each of the power modules that is opposite to the capacitor, and the positive terminal and the negative terminal are arranged in a third direction that intersects both the first direction and the second direction. The front end of the positive terminal and the front end of the negative terminal are parallel to the side surface, The capacitor includes a positive electrode at one end surface in the third direction and a negative electrode at the other end surface. The positive busbar includes: a positive base plate, the positive base plate is connected to the positive electrode; and a positive flange, the positive flange is bent from the positive base plate to the third direction and connected to the positive terminals of the plurality of power modules. The negative busbar includes: a negative base plate, the negative base plate is connected to the negative electrode; and a negative flange, the negative flange is bent from the negative base plate to the third direction and connected to the negative terminals of the plurality of power modules. The positive electrode flange and the negative electrode flange extend in a direction away from the capacitor in the third direction, The positive electrode terminal is joined to the positive electrode flange via an extension plate extending in the third direction, or the negative electrode terminal is joined to the negative electrode flange via an extension plate extending in the third direction.

2. The power converter according to claim 1, It is characterized in that The plurality of power modules overlap with the capacitor when viewed along the second direction.

3. The power converter according to claim 1 or 2, It is characterized in that include: A housing for housing the plurality of power modules and the capacitor; as well as a support plate supported by the housing and arranged beside the capacitor on a side opposite to the power module in the second direction, The positive bus bar or another positive bus bar connected to the positive electrode is fixed to the support plate. The negative bus bar or another negative bus bar connected to the negative electrode is fixed to the support plate. The capacitor is supported by the casing via the support plate, the power module, the positive bus bar, and the negative bus bar.

4. The power converter according to claim 3, It is characterized in that A positive power supply bus bar and a negative power supply bus bar for supplying power from a power source to the capacitor are mounted on the support plate. The positive bus bar is connected to the positive power supply bus bar, and the negative bus bar is connected to the negative power supply bus bar.

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