JP2019103380A - Electric power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of vibration resistance characteristics of a capacitor in a power conversion device in which an inverter and a capacitor are housed in a case divided into an upper case and a lower case. A case 50 of a power conversion device 2 is divided into an upper case 52 and a lower case 53. The inverters 13a and 13b are housed in the upper case 52. The inverters 13a and 13b and the capacitor 60 are connected by bus bars 30 and 40. The capacitor 60 is housed in the lower case 53. The upper case 52 has a protrusion 55 extending from the internal space 52s to the internal space 53s of the lower case 53, and the capacitor 60 is fastened to the protrusion 55 at the internal space 53s. [Selection diagram] FIG. 5

Description

  The technology disclosed herein relates to a power converter including an inverter and a capacitor.

  Patent Documents 1 and 2 disclose a power converter including an inverter and a capacitor. These power converters convert the DC power of the battery into AC power suitable for driving a motor in an electric vehicle. The capacitor is provided to smooth the pulsation of the current input to the DC end of the inverter. The inverter and the capacitor are electrically connected by a conductive member of a metal plate called a bus bar.

  In the power converters of Patent Documents 1 and 2, the inverter and the capacitor are arranged to be adjacent to each other in the horizontal direction. On the other hand, there are cases where the case is divided into upper and lower parts, electric parts are accommodated and fixed in each of the upper case and the lower case, and electric parts are connected by a bus bar, for various reasons. Patent Document 3 exemplifies such an apparatus.

JP 2017-050486 A JP, 2015-126674, A JP, 2017-121867, A

  In a power converter for a traction motor of an electric car, a large size of a capacitor is required to handle a large amount of power. For example, in order to reduce the ratio of the width and height in the horizontal direction of the case, the inverter and the capacitor can not be arranged horizontally, but are arranged vertically. If one of the inverter and the converter is fixed to the upper case and the other is fixed to the lower case, the assemblability of connecting the both with a bus bar deteriorates. When both the inverter and the capacitor are fixed to the upper case, for example, the capacitor is fixed to the upper case and disposed in the inner space of the lower case. Usually, the upper end of the capacitor is fastened to a fastening seat provided on the upper case. However, in such a structure, the capacitor is cantilevered at the upper end and the vibration resistance is not good. The present specification relates to a power conversion device in which an inverter and a capacitor are housed in a case divided into an upper case and a lower case, wherein the ratio of the width to the height of the case is reduced and the vibration resistance of the capacitor is deteriorated. Provide technology to achieve both prevention of The present specification also provides a technique for reducing the inductance of a bus bar connecting an inverter and a capacitor.

  The power conversion device disclosed in the present specification includes a case divided into an upper case and a lower case in the vertical direction, an inverter, and a capacitor. For convenience of explanation, one of the upper case and the lower case is referred to as a first divided case, and the other is referred to as a second divided case. The inverter is accommodated and fixed in the first divided case. The capacitor is connected to the inverter by a positive electrode bus bar and a negative electrode bus bar. The first divided case includes a fastening portion extending from the inner space thereof to the inner space of the second divided case. The capacitor is fastened to the fastening portion in the internal space of the second divided case. That is, the capacitor is accommodated in the internal space of the second divided case.

  To make the description easier to understand, assume that the upper case is the first split case. The lower case corresponds to the second divided case. In the power conversion device disclosed in the present specification, the inverter is accommodated in the internal space of the upper case, and the capacitor is disposed in the internal space of the lower case. Since the inverter and the capacitor do not need to be arranged in the horizontal direction, the ratio of the width to the height of the case can be reduced. Further, both the inverter and the capacitor connected by the bus bar are fixed to the upper case. Therefore, the inverter and the capacitor can be connected before connecting the upper case and the lower case, and the assemblability is also good. On the other hand, the capacitor is fastened in the inner space of the lower case. Therefore, the capacitor can be fastened substantially at the center in the vertical direction, and the vibration resistance does not deteriorate. The power conversion device disclosed in the present specification can achieve both the reduction of the ratio of the width to the height of the case and the prevention of the deterioration of the vibration resistance of the capacitor.

  The positive electrode bus bar and the negative electrode bus bar may extend close to and in parallel from the capacitor to the inverter. When the positive electrode bus bar and the negative electrode bus bar are in close proximity and parallel, the induced magnetic field generated when current flows through one of the bus bars is suppressed by the other bus bar. Therefore, the parasitic inductance of the bus bar is reduced.

  The inverter includes a stack of power modules and coolers. An example power module may include a package containing a switching element, and a plurality of terminals extending from the package and connected to a positive electrode bus bar or a negative electrode bus bar. A gap is secured between the package and the capacitor when viewed from the horizontal direction. That is, when viewed from the horizontal direction, the package and the capacitor are vertically separated. With such an arrangement, the terminals of the power module and the capacitors can be connected by linear bus bars (positive and negative bus bars). Adopting a linear bus bar reduces the inductance of the bus bar.

  In the cross section orthogonal to the stacking direction of the plurality of power modules, the capacitor has a length in the horizontal direction shorter than that in the vertical direction, and electrodes connected to the positive bus bar and the negative bus bar are on both sides in the horizontal direction of the capacitor. It is good to be arranged. Since the positive electrode bus bar and the negative electrode bus bar run in parallel, the inductance is reduced. With the above arrangement of the electrodes of the capacitor, the section in which the positive electrode bus bar and the negative electrode bus bar do not run in parallel is only the distance corresponding to the lateral length of the capacitor, and the inductance of the bus bar is reduced. The details and further improvement of the technology disclosed in the present specification will be described in the following "Forms for Carrying Out the Invention".

FIG. 1 is a block diagram of a power system of an electric vehicle including a power conversion device according to a first embodiment. It is a perspective view of an assembly of a lamination | stacking unit, a bus bar, and a capacitor | condenser. It is a disassembled perspective view of a lamination | stacking unit, a bus bar, and the assembly of a capacitor. It is sectional drawing which shows the components layout in the case of a power converter device (cut in YZ plane). It is sectional drawing which shows the components layout in the case of a power converter device (cut by XZ plane). It is sectional drawing which shows the components layout in the case of the power converter device of a modification (cut by XZ plane). It is a disassembled perspective view of the capacitor | condenser of the power converter device of 2nd Example, a lamination | stacking unit, and assembly of a bus bar. It is sectional drawing which cut the power converter device of 2nd Example by YZ plane. It is a side view of an assembly of a capacitor, a lamination unit, and a bus bar. It is a side view of an assembly of a capacitor, a lamination unit, and a bus bar of a power converter of the 2nd modification.

  (First Embodiment) The power converter of the first embodiment will be described with reference to the drawings. The power conversion device according to the embodiment is a device that is mounted on an electric vehicle and converts the power of a battery into driving power of a traveling motor. FIG. 1 shows a block diagram of a power system of an electric vehicle 100 including the power conversion device 2. The electric vehicle 100 is provided with two traveling motors 83a and 83b. Therefore, the power conversion device 2 includes two sets of inverter circuits 13a and 13b. The outputs of the two motors 83a, 83b are combined in the gearbox 85 and transmitted to the axle 86 (i.e. the drive wheels).

  Power converter 2 is connected to battery 81 via system main relay 82. The power conversion device 2 includes a voltage converter circuit 12 for boosting the voltage of the battery 81, and two sets of inverter circuits 13a and 13b for converting DC power after boosting to alternating current.

  The voltage converter circuit 12 boosts the voltage applied to the battery side terminal and outputs it to the inverter side terminal, and reduces the voltage applied to the inverter side terminal and outputs it to the battery side terminal It is a bidirectional DC-DC converter capable of performing both step-down operations. For convenience of explanation, in the following, the terminal on the battery side (low voltage side) is referred to as the input end 18, and the terminal on the inverter side (high voltage side) is referred to as the output end 19. Further, the positive electrode and the negative electrode of the input end 18 are referred to as an input positive electrode end 18a and an input negative electrode end 18b, respectively. The positive electrode and the negative electrode of the output end 19 are respectively referred to as an output positive electrode end 19a and an output negative electrode end 19b. The notations “input end 18” and “output end 19” are for convenience of explanation, and as described above, since the voltage converter circuit 12 is a bi-directional DC-DC converter, the output end Power may flow from 19 to the input end 18.

  The voltage converter circuit 12 is composed of a series circuit of two switching elements 9a and 9b, a reactor 7, a filter capacitor 5, and diodes connected in anti-parallel to the switching elements. One end of the reactor 7 is connected to the input positive end 18a, and the other end is connected to the middle point of the series circuit. The filter capacitor 5 is connected between the input positive end 18a and the input negative end 18b. The input negative electrode end 18 b is directly connected to the output negative electrode end 19 b. Switching element 9b mainly participates in the step-up operation, and switching element 9a mainly participates in the step-down operation. The voltage converter circuit 12 of FIG. 1 is well known and will not be described in detail. In addition, the circuit of the range of the dashed-lined rectangle which the code | symbol 8a shows corresponds to the power module 8a mentioned later. Reference numerals 25a and 25b indicate terminals extending from the power module 8a. The code | symbol 25a has shown the terminal (positive electrode terminal 25a) currently conduct | electrically_connected with the high electric potential side of the series circuit of switching element 9a, 9b. Reference numeral 25b represents a terminal (negative electrode terminal 25b) electrically connected to the low potential side of the series circuit of the switching elements 9a, 9b. As described below, the notation of the positive electrode terminal 25a and the negative electrode terminal 25b is also used in other power modules.

  The inverter circuit 13a has a configuration in which three series circuits of two switching elements are connected in parallel. Switching elements 9c and 9d, switching elements 9e and 9f, and switching elements 9g and 9h constitute a series circuit, respectively. A diode is connected in reverse parallel to each switching element. The high potential terminal (positive terminal 25a) of the three sets of series circuits is connected to the output positive terminal 19a of the voltage converter circuit 12, and the low potential terminal (negative terminals 25b) of the three sets of series circuits is voltage The output negative terminal 19 b of the converter circuit 12 is connected. Three-phase alternating current (U phase, V phase, W phase) is output from the middle point of three sets of series circuits. Each of the three sets of series circuits corresponds to power modules 8b, 8c and 8d described later.

  Since the configuration of the inverter circuit 13b is the same as that of the inverter circuit 13a, the illustration of the specific circuit is omitted in FIG. Similar to the inverter circuit 13a, the inverter circuit 13b also has a configuration in which three series circuits of two switching elements are connected in parallel. The high potential side terminal of the three sets of series circuits is connected to the output positive terminal 19a of the voltage converter circuit 12, and the low potential side terminal of the three sets of series circuits is connected to the output negative terminal 19b of the voltage converter circuit 12. It is done. The hardware corresponding to each series circuit is referred to as power modules 8e, 8f, 8g.

  The smoothing capacitor 6 is connected in parallel to the input terminals of the inverter circuits 13a and 13b. The smoothing capacitor 6 is, in other words, connected in parallel to the output 19 of the voltage converter circuit 12. The smoothing capacitor 6 eliminates the pulsation of the current flowing between the voltage converter circuit 12 and the inverter circuits 13a and 13b.

  The switching elements 9a to 9h are transistors and are typically IGBTs (Insulated Gate Bipolar Transistors), but may be other transistors such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). Moreover, the switching element here is used for power conversion, and may be called a power semiconductor element. The same applies to the switching elements included in the power modules 8e-8g.

  In FIG. 1, each of broken lines 8 a to 8 g corresponds to a power module. The power converter 2 includes seven sets of series circuits of two switching elements. As hardware, two switching elements constituting a series circuit and diodes connected in antiparallel to the respective switching elements are accommodated in one package. Below, when showing any one of power modules 8a-8g indifferently, it describes with the power module 8. FIG.

  The terminal (positive electrode terminal 25a) on the high potential side of the seven power modules (the series circuit of seven sets) is connected to the positive electrode of the smoothing capacitor 6, and the terminal (negative electrode terminal 25b) on the low potential side is the negative electrode of the smoothing capacitor 6. Connected to the electrode. In FIG. 1, the conductive paths in the broken line indicated by reference numeral 30 correspond to bus bars (positive bus bars) connecting the positive terminals 25 a of the plurality of power modules 8 and the positive electrodes of the smoothing capacitors 6 to each other. The conductive path in the broken line indicated by reference numeral 40 corresponds to a bus bar (negative electrode bus bar) which mutually connects the plurality of negative electrode terminals 25 b and the negative electrode of the smoothing capacitor 6. Next, the structures of the plurality of power modules 8, the positive electrode bus bar 30, and the negative electrode bus bar 40 will be described.

  FIG. 2 shows a perspective view of part of the hardware of the power conversion device 2. FIG. 2 is a perspective view of an assembly of the stacked unit 20 and the capacitor 60 connected by the bus bars 30, 40. As shown in FIG. The stacking unit 20 is a device in which the power module 8 (8a-8g) described above and a plurality of coolers 22 are stacked. The capacitor 60 is a device in which a capacitor element corresponding to the smoothing capacitor 6 of FIG. 1 is sealed.

  The plurality of power modules 8 (8 a-8 g) constitute a stacked unit 20 together with the plurality of coolers 22. Since all of the power modules 8a-8g have the same shape, in FIG. 2 and FIG. 3 described later, only the leftmost power module is represented by the reference numeral 8 and the other power modules are omitted. Moreover, in FIG. 2 and FIG. 3 mentioned later, the code | symbol 22 was attached | subjected only to two coolers of the left end, and the code | symbol was abbreviate | omitted to the other cooler.

  The stacked unit 20 almost includes the main components of the inverter circuits 13a and 13b of FIG. Therefore, the stacked unit 20 may be referred to as an "inverter". Therefore, in FIG. 2 and FIG. 3, the reference numerals of the stacked unit 20 are appended with 13a and 13b in parentheses.

  The coordinate system of a figure is demonstrated. The positive direction of the Z axis of the coordinate system in the figure corresponds to the “upper” of the power conversion device 2. That is, FIG. 2 (and FIG. 3 described later) is a view of the assembly of the laminated unit 20 and the capacitor 60 as viewed obliquely from below.

  The stacked unit 20 is a device in which a plurality of card type coolers 22 are arranged in parallel, and the card type power module 8 is sandwiched between the adjacent coolers 22. The card type power module 8 is stacked with its wide side facing the cooler 22. As mentioned earlier, the power module 8 comprises a package 108 containing switching elements. The package 108 is made of resin. Three terminals (a positive electrode terminal 25a, a negative electrode terminal 25b, and a middle point terminal 25c) extend from one side surface (lower surface) of the package 108 of each power module 8. In FIG. 2 and FIG. 3 described later, only the terminals of the power module 8 located at the left end of the stacked unit 20 are denoted by reference numerals 25a, 25b and 25c, and the remaining power modules 8 are omitted from reference numerals indicating terminals.

  The positive electrode terminal 25 a and the negative electrode terminal 25 b are, as described above, the high potential terminal and the low potential terminal of the series circuit accommodated in the power module 8. The midpoint terminal 25c is a terminal electrically connected to the midpoint of the series circuit. In other words, each of the three terminals 25 a-25 c is electrically connected to the switching element inside the power module 8. The three terminals 25a-25c extend from the side surface (bottom surface) intersecting the wide surface of the power module 8 in the negative Z-axis direction (that is, downward) in the figure (FIG. Note that it is a view from A plurality of control terminals 27 extend in the Z-axis positive direction (that is, upward) in the drawing from the surface (upper surface) opposite to one side surface on which the positive electrode terminal 25a and the like are provided. The control terminal 27 is a gate terminal electrically connected to the gate electrode of the switching element incorporated in the power module 8, and a signal terminal electrically connected to a temperature sensor or current sensor incorporated in the power module 8. is there.

  A refrigerant supply port 28 and a refrigerant discharge port 29 are provided in the cooler 22 at the right end in the figure. Adjacent coolers 22 are connected by two connecting pipes 23. One of the connection pipes 23 is positioned so as to overlap the refrigerant supply port 28 as viewed in the stacking direction. Although not hidden in FIGS. 2 and 3, the other connecting pipe is positioned so as to overlap with the refrigerant discharge port 29 when viewed from the stacking direction. A refrigerant circulation device (not shown) is connected to the refrigerant supply port 28 and the refrigerant discharge port 29. The refrigerant supplied from the refrigerant supply port 28 is distributed to all the coolers 22 through one connecting pipe 23. The refrigerant absorbs heat from the adjacent power module 8 while passing through the cooler 22. The refrigerant that has absorbed heat is discharged from the stacked unit 20 through the other connecting pipe and the refrigerant outlet 29. Since each power module 8 is cooled from its both sides, the stacked unit 20 has high cooling performance.

  All three terminals 25a-25c of each power module 8 are flat form. The positive electrode terminals 25 a of the plurality of power modules 8 are arranged in a line in the stacking direction so as to face the flat surfaces of the positive electrode terminals 25 a of the adjacent power modules 8. The negative terminals 25 b of the plurality of power modules 8 are also arranged in a line in the stacking direction so as to face the flat surfaces of the negative terminals 25 b of the adjacent power modules 8. The same applies to the midpoint terminals 25 c of the plurality of power modules 8. The positive electrode terminals 25a, the negative electrode terminals 25b, and the middle point terminals 25c of the plurality of power modules 8 are arranged in three rows.

  As described above, the capacitor 60 has a large physical size because the driving power of the traveling motor of the electric vehicle 100 flows. The capacitor 60 is long in the stacking direction (X direction in the figure) of the cooler 22 and the power module 8 of the stacked unit 20, and is lined up diagonally below the stacked unit 20 (slant upper in FIG. 2 and FIG. 3). There is. In the case of the capacitor 60, a capacitor element 61 (see FIG. 3) is accommodated. The stacked unit 20 and the capacitor 60 are connected by the positive electrode bus bar 30 and the negative electrode bus bar 40. An insulating plate 48 is sandwiched between the positive electrode bus bar 30 and the negative electrode bus bar 40. At both ends in the longitudinal direction of the capacitor 60, tabs 62 for attaching the capacitor 60 to the case are provided.

  FIG. 3 shows an exploded perspective view of an assembly of the positive electrode bus bar 30, the negative electrode bus bar 40, the laminated unit 20, and the capacitor element 61 (capacitor 60). In FIG. 3, the case of the capacitor 60 is omitted, and the internal capacitor element 61 is drawn. The capacitor element 61 corresponds to the smoothing capacitor 6 of FIG.

  The positive electrode terminals 25 a of the plurality of power modules 8 and the positive electrode 61 a of the capacitor element 61 are connected by the positive electrode bus bar 30, and the plurality of negative electrode terminals 25 b are connected with the negative electrode 61 b of the capacitor element 61 by the negative electrode bus bar 40.

  The positive electrode bus bar 30 includes a plate-like flat plate portion 31, a plurality of positive electrode terminal holes 32, and a plurality of branch portions 33. In FIG. 3, only the leftmost positive electrode terminal hole 32 and the branch portion 33 are denoted by reference numerals, and the other positive electrode terminal holes and the branch portions are omitted from reference numerals. The same applies to the negative electrode bus bar 40 and the insulating plate 48 described later.

  One end of the connection bus bar 63 is connected to one end of the flat plate portion 31. The other end of the connection bus bar 63 is connected to the positive electrode 61 a of the capacitor element 61. A plurality of positive electrode terminal holes 32 are provided in the flat plate portion 31 of the positive electrode bus bar 30, and the branch portions 33 extend in the direction orthogonal to the flat plate portion 31 from the edge of each positive electrode terminal hole 32. The positive electrode terminals 25a of the power modules 8 pass through the positive electrode terminal holes 32, and the positive electrode terminals 25a and the branch portions 33 are joined by welding.

  The negative electrode bus bar 40 includes a plate-like flat plate portion 41, a plurality of negative electrode terminal holes 42, a plurality of branch portions 43, and a plurality of positive electrode terminal holes 44. One end of the flat plate portion 41 is connected to the negative electrode 61 b of the capacitor element 61. A plurality of negative electrode terminal holes 42 are provided in the flat plate portion 41 of the negative electrode bus bar 40, and the branch portions 43 extend in the direction orthogonal to the flat plate portion 41 from the edge of each negative electrode terminal hole 42. The negative electrode terminal 25b of each power module 8 passes through each negative electrode terminal hole 42, and the negative electrode terminal 25b and the branch portion 43 are joined.

  An insulating plate 48 is sandwiched between the positive electrode bus bar 30 and the negative electrode bus bar 40. The insulating plate 48 insulates between the positive electrode bus bar 30 and the negative electrode bus bar 40. The insulating plate 48 is provided with a plurality of through holes 49.

  When the positive electrode bus bar 30, the insulating plate 48, and the negative electrode bus bar 40 are overlapped, each of the plurality of positive electrode terminal holes 44 of the negative electrode bus bar 40 and each of the plurality of through holes 49 of the insulating plate 48 overlap. The positive electrode terminal 25 a of the module 8 and the branch 33 of the positive electrode bus bar 30 pass through. The positive electrode terminal 25a and the branch part 33 do not touch the positive electrode terminal hole 44 of the negative electrode bus bar 40, and both are insulated.

  The flat plate portion 31 of the positive electrode bus bar 30 and the flat plate portion 41 of the negative electrode bus bar 40 both have a plate shape and face each other in close proximity. To be precise, the flat plate portion 31 and the flat plate portion 41 are stacked with the insulating plate 48 interposed therebetween. The flat plate portion 31 of the positive electrode bus bar 30 and the flat plate portion 41 of the negative electrode bus bar 40 extend close to and parallel to the stacked unit 20 from the capacitor 60 (capacitor element 61). When a current flows in one of the bus bars, a magnetic field is generated around the bus bar due to the current. There is a positive correlation between the magnitude of the magnetic field and the inductance of the bus bar (the larger the magnetic field, the larger the inductance). When the flat plate portion 31 of the positive electrode bus bar 30 and the flat plate portion 41 of the negative electrode bus bar 40 face each other, an eddy current is generated in the other bus bar by the magnetic field of one of the bus bars. The generation of the eddy current weakens the magnetic field of one of the bus bars. The fact that the magnetic field is weakened means that the inductance is reduced. The inductance of the bus bar can be reduced by causing the flat portions 31 and 41 of the bus bar to approach each other closely.

  The component layout inside the case of the power converter 2 will be described with reference to FIGS. 4 and 5. FIG. 4 is a cross-sectional view of the side plate of the case 50 on the X axis positive side cut in the coordinate system in the drawing. FIG. 5 is a cross-sectional view in which the side plate of the case 50 on the Y-axis negative side is cut. The case 50 of the power conversion device 2 is divided into an upper case 52 and a lower case 53 in the vertical direction. The lower case 53 is located below the upper case 52. The upper case 52 is open at both the upper and lower sides, and the upper opening is closed by the upper cover 51. The upper case 52 and the lower case 53 have substantially the same height, and divide the inner space of the case 50 into upper and lower portions substantially. Upper case 52 and lower case 53 are fastened by bolts 57. Arrow lines CL in FIGS. 4 and 5 indicate boundaries between the upper case 52 and the lower case 53.

  The control board 66, the laminated unit 20 and the capacitor 60 are fixed to the upper case 52. The reactor 70 is fixed to the lower case 53. The reactor 70 corresponds to the reactor 7 of FIG.

  The upper case 52 is provided with a middle partition 521 which divides the internal space 52s up and down, the control board 66 is fixed on the upper side of the middle partition 521, and the stacking unit 20 is fixed on the lower side. On the control board 66, circuits for controlling the switching elements embedded in the switching elements 9a to 9h and the power modules 8e to 8g of FIG. 1 are mounted. A control terminal 27 extending from each of the plurality of power modules 8 is connected to the control board 66. The stacking unit 20 is fixed to the lower side of the middle partition 521. The stacked unit 20 is sandwiched between a support wall 522 erected from the inner partition 521 and the inner wall of the upper case 52 together with a plate spring 67. The plurality of power modules 8 and the plurality of coolers 22 are accommodated in the upper case 52 by the plate spring 67 while receiving a load in the stacking direction. The load in the stacking direction brings the adjacent power modules 8 and the cooler 22 into close contact, and the cooling performance is improved.

  The capacitor 60 is disposed obliquely below the stacked unit 20. The capacitor 60 is fastened to the lower end of the protrusion 55 extending from the inner side surface of the upper case 52 by a bolt 56. The protrusion 55 extends from the inner side surface of the upper case 52, and is bent downward halfway. The protrusion 55 extends from the inner space 52s of the upper case 52 to the inner space 53s of the lower case 53, and the lower end thereof reaches the inner space 53s of the lower case 53. The capacitor 60 is supported by the upper case 52, but is accommodated in the internal space 53s of the lower case 53, and is fastened to the projection 55 of the upper case 52 in the internal space 53s of the lower case 53. The tab 62 on the side of the capacitor 60 is fastened to the lower end of the projection 55 with a bolt 56. Both ends in the longitudinal direction of the capacitor 60 are fastened to the projection 55 by bolts 56.

  The advantages of the above-described component layout in the case 50 of the power conversion device 2 will be described. As described above, the capacitor 60 is fastened to the projection 55 of the upper case 52, but is accommodated in the lower case 53. The stacked unit 20 is housed in the upper case 52. Since the stacked unit 20 and the capacitor 60 having a large physical size are separately accommodated in the upper case 52 and the lower case 53, the ratio of the height to the width (length in the Y-axis direction) of the case 50 can be reduced.

  In addition, the capacitor 60 is fastened to the lower end of the projection 55 with a bolt 56 in the internal space 53 s of the lower case 53. In the case 50, as shown in FIG. 4, the ratio of the height to the width (the length in the Y direction of the case 50) is close to one. Therefore, the stacked unit 20 and the capacitor 60 can not be arranged side by side in the horizontal direction. Further, since the stacked unit 20 and the capacitor 60 are connected by the positive electrode bus bar 30 and the negative electrode bus bar 40, assembling efficiency is degraded when the stacked unit 20 is fixed to the upper case 52 and the capacitor 60 is fixed to the lower case 53. It is desirable that both the stacked unit 20 and the capacitor 60 be fixed to the upper case 52 or both be fixed to the lower case 53. If the capacitor 60 is temporarily fixed to the upper case 52 at its upper end, the capacitor 60 is supported at its upper end in a cantilever manner. Then, the distance from the support point of the cantilever to the center of gravity G of the capacitor 60 becomes long. Since the power conversion device 2 is mounted on a vehicle, it receives strong vibration during traveling. When the distance from the fastening point of the capacitor 60 (the fastening point of the cantilever support) to the center of gravity G is long, the vibration resistance of the capacitor 60 is not good against the vibration in the Y direction in the figure.

  In the power converter 2 of the first embodiment, the tab 62 of the capacitor 60 is located approximately at the center of the capacitor 60 in the vertical direction. The fastening point (tab 62) of the capacitor 60 is close to the center of gravity G of the capacitor 60 in the vertical direction. The length dH in FIG. 4 indicates the distance in the height direction between the center of gravity G and the fastening point (tab 62). The distance dH is much shorter than the distance from the center of gravity G of the capacitor 60 to the upper end. Therefore, in the power conversion device 2 of the embodiment, the vibration resistance of the capacitor 60 is good with respect to the vibration in the Y direction in the drawing.

  A gap dL is secured between the package 108 of the power module 8 and the capacitor 60. In other words, the package 108 and the capacitor 60 are vertically separated from each other across the gap dL when viewed from the direction of the XY plane (that is, the horizontal direction) in the drawing. Therefore, the positive electrode bus bar 30 can be linear between the positive electrode terminal 25 a of the power module 8 and the capacitor 60. Similarly, the negative electrode bus bar 40 can be linear between the negative electrode terminal 25 b and the capacitor 60. The fact that the bus bars (positive bus bars 30 and negative bus bars 40) are linear between the power module 8 and the capacitor 60 also contributes to suppressing the parasitic inductance of the bus bars.

  (Modification) FIG. 6 shows a cross-sectional view of a power conversion device 2a of a modification. FIG. 6 is a cross-sectional view corresponding to FIG. 5, and is a cross-sectional view of the case 50a in which the side plate on the Y-axis negative side in the figure is cut. FIG. 6 is a view in which the lower case is removed, and the capacitor 60 is also removed from the upper case 52a.

  Inside the upper case 52a, a projection 55a whose lower end is located in the internal space 52s of the upper case 52a is provided. The capacitor 60 is fastened to the projection 55 a by the bolt 56 with the spacer 58 interposed therebetween. The spacer 58 is a cylinder through which a bolt 56 passes. The lower end of the spacer 58 is a fastening point of the capacitor 60, and the fastening point is located lower than the internal space 52s of the upper case 52a, as shown by a virtual line VL in FIG. That is, also in the case of this modification, the capacitor 60 is accommodated in the inner space of the lower case, and is fixed to the projection 55a extending from the upper case 52a via the spacer 58 in the inner space of the lower case. The component arrangement in the power conversion device 2a of the modification also has the same effect as the component arrangement of the power conversion device 2 described above.

  Second Embodiment A power converter 2b according to a second embodiment will be described with reference to FIGS. 7-9. The power conversion device 2b of the second embodiment differs from the power conversion device 2 of the first embodiment in the shapes of the positive electrode bus bar 130 and the negative electrode bus bar 140 and the structure of the capacitor element 161 (capacitor 160). The other structure is the same as that of the power conversion device 2 of the first embodiment, so the description will be omitted.

  FIG. 7 is an exploded perspective view of the bus bar, the capacitor element 161, and the stacked unit 20 of the power conversion device 2b. The lamination unit 20 is identical to that of FIG. The capacitor element 161 has a length W in the lateral direction shorter than a length L in the vertical direction when viewed in the X direction in the drawing. In other words, in the capacitor element 161, the lateral length W in the cross section intersecting the stacking direction (the X direction in the figure) of the power module 8 is shorter than the longitudinal length L. This point is the same as the capacitor element 61 of the power conversion device 2 of the first embodiment. However, in the capacitor element 161, the electrodes 161a and 161b are disposed on the side surface of the capacitor element 161 facing in the lateral direction. In the capacitor element 61 in the first embodiment, the electrodes 61 a and 61 b are disposed on the upper surface and the lower surface of the capacitor element 61. The electrode bonding portion 35 of the positive electrode bus bar 130 is bonded to the positive electrode 161 a of the capacitor element 161, and the electrode bonding portion 45 of the negative electrode bus bar 140 is bonded to the negative electrode 161 b.

  FIG. 9 is a side view of an assembly of the capacitor 160, the laminated unit 20, and the bus bar of the power conversion device 2b of the second embodiment. In FIG. 9, the case of capacitor 160 is shown in phantom and the internal structure of capacitor 160 is shown in cross section.

  A gap dL is secured between the package 108 of the power module 8 and the capacitor 160. That is, in other words, the package 108 and the capacitor 160 are vertically separated from each other across the gap dL when viewed from the direction of the XY plane (that is, the horizontal direction) in the drawing. Similar to the power converter 2 of the first embodiment, the positive electrode bus bar 130 can be linear between the positive electrode terminal 25a of the power module 8 and the capacitor 160. The negative electrode bus bar 140 can also be linear between the negative electrode terminal 25 b and the capacitor 160. The positive electrode bus bar 130 and the negative electrode bus bar 140 are in close proximity and run between the terminals 25 a and 25 b and the capacitor 160. This close parallel running reduces the inductance of the bus bar.

  The electrodes 161 a and 161 b of the capacitor element 161 are disposed on side surfaces of the capacitor element 161 facing in the lateral direction. As described above, the positive electrode bus bar and the negative electrode bus bar have a smaller inductance when they run close to each other. As shown in FIG. 9, in the case of the power conversion device 2 b of the second embodiment, the positive electrode bus bar 130 and the negative electrode bus bar 140 do not run parallel only on the upper side of the capacitor element 161 except for the electrode junctions 35 and 45. . That is, the bus bars 130 and 140 have non-parallel running sections of the distance W.

  FIG. 10 shows a side view of the assembly of the power converter of the modification. In the case of the modified example of FIG. 10, the capacitor element 261 has the electrodes 261a and 261b on the upper side and the lower side. In this case, the positive electrode bus bar 230 and the negative electrode bus bar 140 have non-parallel running sections on the sides of the capacitor element 261 except for the electrode junctions. That is, in the case of the modification of FIG. 10, it has the non-parallel running section of the distance L. On the other hand, in the power conversion device 2b shown in FIG. 9, in the capacitor elements 161 and 261, the length W in the lateral direction is shorter than the length L in the vertical direction. Therefore, the non-parallel running section of the bus bar can be shortened by adopting the structure of FIG. 9, that is, employing the capacitor element 161 in which the electrodes 161a and 161b are disposed on the upper side and the lower side. This point also contributes to reducing the inductance of the bus bar.

  Other features of the power conversion devices 2, 2a, 2b will be described. As shown in FIGS. 4 and 5, the upper case 52 and the lower case 53 are fixed by bolts 57. The bolt 57 is attached from the lower side. This feature contributes to increasing the volume of the space for housing the substrate 66 of the upper case 52 without increasing the volume of the entire case.

  Points to note regarding the technology described in the embodiment will be described. As shown in FIG. 1, main components constituting the inverter circuits 13 a and 13 b are accommodated in the stacked unit 20. Therefore, the stacked unit 20 can be called an "inverter". The upper case 52 of the case 50 fixes the inverters 13a, 13b (laminated unit 20) and the capacitor 60 connected by the bus bars 30, 40. The inverters 13 a and 13 b (laminated units 20) are accommodated in the upper case 52, and the capacitor 60 is accommodated in the lower case 53. The capacitor 60 extends from the upper case 52 and is fastened to the lower end of the protrusion 55 reaching the internal space 53s of the lower case 53.

  The power conversion device 2 of the embodiment includes a case 50 divided into an upper case 52 and a lower case 53 in the vertical direction. The stacked unit 20 and the capacitor 60 are fixed to the upper case 52. The capacitor 60 is fixed to the lower end of the projection 55 extending from the inner space 52s of the upper case 52 to the inner space 53s of the lower case 53 by a bolt 56. The capacitor 60 is fastened to the upper case 52, but is accommodated in the inner space 53 s of the lower case 53. The capacitor 60 is fastened in the inner space 53s of the lower case 53 substantially at the center (tab 62) in the vertical direction. Therefore, vibration resistance is good against lateral vibration.

  Even if the upper and lower sides of the case 50 (case 50a of FIG. 6) of FIGS. 4 and 5 are reversed, the same effect can be obtained as to the vibration resistance of the capacitor 60. When the case 50 in FIGS. 4 and 5 is turned upside down, the upper case 52 corresponds to the lower case, and the lower case 53 corresponds to the upper case. Therefore, the technique of the embodiment can be expressed as follows. The power converter includes a case divided into an upper case and a lower case. One of the upper case and the lower case is referred to as a first divided case, and the other is referred to as a second divided case. The stacked unit 20 and the capacitor 60 are connected by the positive electrode bus bar 30 and the negative electrode bus bar 40, and both are fixed to the first divided case. The stacked unit 20 is accommodated in the internal space of the first divided case, and the capacitor 60 is accommodated in the second divided case. The capacitor 60 is fastened to the protrusion 55 extending from the inner space of the first case in the inner space of the second case.

  In the power conversion device 2 (2b) of the embodiment, the stacked unit 20 is disposed on the upper side of the capacitor 60 (160), and the package 108 and the capacitor 60 (160) are separated by the gap dL. The positive electrode bus bar 30 (130) and the negative electrode bus bar 40 (140) run in parallel in a straight line between the power module 8 and the capacitor 60 (160). This feature contributes to reducing the inductance of the bus bar. The same effect can be obtained even if the stacked unit is disposed on the lower side of the capacitor and the package 108 and the capacitor are separated by the gap dL. The gap dL may be a small distance.

  As mentioned above, although the specific example of this invention was described in detail, these are only an illustration and do not limit a claim. The art set forth in the claims includes various variations and modifications of the specific examples illustrated above. The technical elements described in the present specification or the drawings exhibit technical usefulness singly or in various combinations, and are not limited to the combinations described in the claims at the time of application. In addition, the techniques exemplified in the present specification or the drawings can simultaneously achieve a plurality of purposes, and achieving one of the purposes itself has technical utility.

2, 2a, 2b: power converter 5: filter capacitor 6: smoothing capacitor 7, 70: reactor 8, 8a-8g: power module 9a-9h: switching element 12: voltage converter circuit 13a, 13b: inverter circuit (inverter)
20: Stacking unit (inverter)
22: cooler 23: connecting pipe 27: control terminal 30, 130: positive electrode bus bar 31, 41: flat plate portion 32, 44: positive electrode terminal hole 33, 43: branch 40, 140: negative electrode bus bar 42: negative electrode terminal hole 48: Insulating plate 49: through hole 50, 50a: case 51: upper cover 52, 52a: upper case 52s, 53s: internal space 53: lower case 55, 55a: projection 56, 57: bolt 58: spacer 60, 160: capacitor 62: Tab 66: Control board 67: Flat spring 100: Electric car

Claims (4)

Case divided into upper case and lower case,
An inverter housed in a first divided case, which is one of the upper case and the lower case, and fixed to the first divided case;
A capacitor which is connected to the inverter by a positive electrode bus bar and a negative electrode bus bar and which is disposed in an inner space of a second divided case which is the other of the upper case and the lower case;
Equipped with
The first divided case includes a fastening portion extending from the inner space thereof to the inner space of the second divided case.
The power conversion device, wherein the capacitor is fastened to the fastening portion in an internal space of the second divided case.   The power conversion device according to claim 1, wherein the positive electrode bus bar and the negative electrode bus bar extend in close parallel running toward the inverter from the capacitor. The inverter includes a stack of a plurality of power modules and a plurality of coolers,
Each of the power modules includes a package accommodating a switching element, and a plurality of terminals extending from the package and connected to the positive electrode bus bar or the negative electrode bus bar.
The power conversion device according to claim 1, wherein a gap is secured between the package and the capacitor when viewed in a horizontal direction.   In the cross section orthogonal to the stacking direction of the plurality of power modules, the capacitor has a length in the horizontal direction shorter than a length in the vertical direction, and electrodes connected to the positive bus bar and the negative bus bar are in the horizontal direction of the capacitor. The power converter according to any one of claims 1 to 3, which is disposed on the side facing the direction.

Images