JP2014042377A - Power supply bus bar and power converter using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize current flowing in respective DC terminals of power modules connected in parallel in a power converter.SOLUTION: A power supply bus bar 18 of a power converter comprises: a coupling part 22; a main bus bar 20 installed so as to extend in a first direction while being opposite to a plurality of power modules to be arranged in the first direction and be electrically connected in parallel; and a sub bus bar 30 for connecting the coupling part 22 and respective DC terminals of the plurality of power modules, when the power converter includes the plurality of power modules. The sub bus bar 30 includes: a first section 45 for transmitting power from the main bus bar 20 through the coupling part 22; a second section 40 which extends in parallel with the main bus bar 20 and transmits the power from the first section 45; and third sections 50a and 50b for dividing the power from the second section 40 and transmitting the divided power to the respective DC terminals of the plurality of power modules.

Description

  The present invention relates to a power bus bar of a power conversion device.

  In order to drive a load such as an AC motor, a power converter (inverter) may be used. In general, a power conversion device includes an upper arm transistor, a lower arm transistor, a controller that generates a control signal modulated according to the state of the load, an upper arm transistor, and a lower arm provided on each phase of the load. A gate driving circuit for driving the transistor.

  The upper arm transistor and the lower arm transistor may be configured by a power module including a switching element such as a field effect transistor (FET), an insulated gate bipolar transistor (IGBT), or a bipolar transistor. In a large-capacity power conversion device, a large current flows through the power module, so that a flat bus bar is often used to supply power to the power module.

JP 2002-34135 A

  In order to realize a large-capacity power conversion device, when a plurality of power modules are connected in parallel, it is common to select power modules having the same characteristics. At this time, in order to make maximum use of the capacity of each power module having the same characteristics, it is desirable that the current flowing from the power source to each power module is evenly distributed.

  However, there may be a case where an equal current is not distributed to each power module due to power supply arrangement, bus bar shape restrictions, and the like. If current does not flow evenly to each power module, a large current flows into some power modules, so it is necessary to use a power module with a larger capacity or increase the number of power modules connected in parallel as countermeasures. , Leading to increased costs.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and one exemplary object of one aspect thereof is a power conversion apparatus having a configuration in which a plurality of power modules are connected in parallel to each DC terminal of the power module. It is in equalization of the inflowing current.

  In order to solve the above problems, an aspect of the present invention relates to a power bus bar in a power conversion device. This power bus bar is a power bus bar connected to the arm of the power converter, and when the arm includes a plurality of power modules that are juxtaposed in the first direction and are to be electrically connected in parallel, the power bus bar is A main bus bar that has a connecting portion and extends in the first direction so as to face the plurality of power modules, and a sub bus bar that connects the connecting portion and each DC terminal of the plurality of power modules. . The sub bus bar includes a first section that transmits power from the main bus bar, a second section that runs parallel to the main bus bar and transmits power from the first section, and a plurality of power modules. And a third section for separately transmitting the power from the second section to the DC terminal.

  Another embodiment of the present invention relates to a power conversion device. The power conversion device includes an upper arm and a lower arm, an upper power bus bar connected to the upper arm, and a lower power bus bar connected to the lower arm. At least one of the upper arm and the lower arm includes a plurality of power modules to be juxtaposed in the first direction and electrically connected in parallel. At least one of the upper power bus bar and the lower power bus bar has a connecting portion, and extends in the first direction so as to face the plurality of power modules, the connecting portion, and each of the plurality of power modules. And a sub bus bar for connecting to the DC terminal. The sub bus bar includes a first section that transmits power from the main bus bar, a second section that runs parallel to the main bus bar and transmits power from the first section, and a plurality of power modules. And a third section for separately transmitting the power from the second section to the DC terminal.

  According to this aspect, an induced current is generated in the main bus bar due to the current flowing through the second section running parallel to the main bus bar. Due to the induced current, the current flowing through the main bus bar easily flows in the direction in which the second sections run side by side, and the current easily flows around the connecting portion so as to gather at the connecting portion. For this reason, the electric current which flows into each direct current terminal of a plurality of power modules through a sub bus bar is equalized.

  ADVANTAGE OF THE INVENTION According to this invention, the electric current which flows in into the DC terminal of each power module connected in parallel as a plurality of arms of each phase in a power converter is equalized.

It is a circuit diagram of a power converter concerning an embodiment of the present invention. It is a circuit diagram which shows the relationship between the U-phase arm of FIG. 1, and a power module. It is an external appearance perspective view of a power converter device. FIGS. 4A to 4C are schematic diagrams illustrating the connection relationship between the power supply bus bar, the rectifier diode, the smoothing capacitor, and the power module. It is an external appearance perspective view when a power supply bus bar is attached to the power converter device of FIG. 6A is a bottom view of the power supply bus bar shown in FIG. 5 as viewed from the bottom to the top (−z direction), and FIG. 6B is a side view. It is a figure which shows typically the effect of the electromagnetic induction by a power supply bus bar. It is a schematic diagram which shows the electric current which flows through the power supply bus bar which does not have a 2nd area. It is a schematic diagram which shows the electric current which flows through the power supply bus bar which concerns on 1st Embodiment. FIG. 10A is a bottom view of a power bus bar according to a modification of the first embodiment, and FIG. 10B is a side view thereof. FIGS. 11A and 11B are schematic diagrams showing currents flowing through the power supply bus bars of FIGS. 10A and 10B. FIG. 12A is a bottom view of the power bus bar according to the second embodiment, and FIG. 12B is a side view thereof. It is a schematic diagram which shows the flow of the electric current in the power supply bus bar which concerns on 2nd Embodiment. FIG. 14A is a bottom view of a power bus bar according to a modification of the second embodiment, and FIG. 14B is a side view thereof. FIGS. 15A and 15B are schematic diagrams illustrating the flow of current in a power bus bar according to a modification of the second embodiment. It is a schematic diagram which shows the power supply bus bar in the case of connecting three power modules in parallel. It is a schematic diagram which shows the electric current which flows through the sub bus bar shown in FIG. It is a schematic diagram which shows a sub bus bar in the case of connecting four power modules in parallel.

  The present invention will be described based on preferred embodiments with reference to the drawings. The same or equivalent components and members shown in the drawings are denoted by the same reference numerals, and repeated descriptions are appropriately omitted.

(First embodiment)
FIG. 1 is a circuit diagram of a power conversion device 1 according to an embodiment of the present invention. The power converter 1 converts a DC voltage from a power source 4 into an AC signal and drives a load 2 including a motor. The power supply 4 includes a rectifier diode 5 that rectifies the three-phase alternating current IN and a smoothing capacitor 6. The power source 4 may be a battery. In this embodiment, the case of three phases will be described, but the number of phases is not particularly limited.

  The upper arm 7P (U to W) is provided between the corresponding phase output terminal OUT (U, V, W) and the P-side power supply line LP, and is configured by a P-side semiconductor switch 8P which is an IGBT. The collector of the P-side semiconductor switch 8P is connected to the P-side power supply line LP, and the emitter thereof is connected to the output terminal OUT.

  The lower arm 7N (U to W) is provided between the corresponding phase output terminal OUT (U, V, W) and the N-side power supply line LN, and includes an N-side semiconductor switch 8N that is an IGBT. The collector of the N-side semiconductor switch 8N is connected to the output terminal OUT (U, V, W), and its emitter is connected to the N-side power supply line LN.

  FIG. 2 is a circuit diagram showing the relationship between the U-phase arm 7U and the power module 10 in FIG. Two power modules 10 are connected in parallel as the U-phase arm 7U. The same applies to the V-phase and W-phase arms.

  The power module 10 includes semiconductor switches 8P and 8N that are one or a plurality of IGBTs. The P-side semiconductor switch 8P constituting the upper arm 7P and the N-side semiconductor switch 8N constituting the lower arm 7N are included in one power module 10. The power module 10 includes a P-side DC terminal 12P to be connected to the P-side power line LP, an N-side DC terminal 12N to be connected to the N-side power line LN, and an AC terminal 14 to be connected to the load 2. Prepare.

  FIG. 3 is an external perspective view of the power conversion device 1. The power converter 1 includes a rectifier diode 5, a smoothing capacitor 6, a power module group 10 (U to W) constituting each arm 7 (U to W), a housing 70, a plurality of fans 72, and a heat sink 74 (U to W). ), 75.

  The power modules 10Ua and 10Ub constituting the U phase are juxtaposed in the first direction (x-axis direction) on the heat sink 74U. Similarly to the U phase, the power modules 10V (a, b) and 10W (a, b) constituting the V phase and the W phase are also juxtaposed in the x-axis direction on the heat sink 74 (V, W), respectively. The power module groups 10U, 10V, and 10W constituting each phase (U to W) are juxtaposed in a second direction (y-axis direction) perpendicular to the first direction (x-axis direction).

  The plurality of rectifier diodes 5 and the plurality of smoothing capacitors 6 constitute the power supply 4 of FIG. The plurality of rectifier diodes 5 are juxtaposed on the heat sink 75 in the y-axis direction. The plurality of smoothing capacitors 6 are inserted and fixed in mounting holes 76 provided in the housing 70. The rectifier diode 5, the smoothing capacitor 6, and the power module 10 are electrically and mechanically connected via a power bus bar described later.

  The intake fan 72a is provided in the vicinity of the smoothing capacitor 6, and a plane that forms the intake hole of the intake fan 72a is disposed perpendicular to the x-axis direction. The intake fan 72a blows air in the x-axis direction with respect to the smoothing capacitor 6 and the heat sinks 74 (U to W). The plurality of exhaust fans 72b are spaced apart from the intake fan 72a in the x-axis direction, and are arranged so that the plane forming the exhaust hole of the exhaust fan 72b is perpendicular to the x-axis direction. The air sucked from the outside of the housing 70 by the intake fan 72a is exhausted from the exhaust fan 72b through the smoothing capacitor 6, the heat sinks 74 (U to W), and the heat sink 75.

  FIG. 4A is a schematic diagram showing a connection relationship between the power supply bus bar 18, the rectifier diode 5, the smoothing capacitor 6, and the power module 10. The power bus bar 18 includes a P-side power bus bar 18P and an N-side power bus bar 18N, and functions as the P-side power line LP and the N-side power line LN in FIG. The power bus bar 18 is made of a metal plate having excellent conductivity such as copper (Cu) or aluminum (Al). The same applies to other bus bars described later.

  FIG. 4B is a schematic diagram showing the connection relationship of the P-side power bus bar 18P. The P-side power bus bar 18P includes a P-side main bus bar 20P and a P-side sub bus bar 30P. The P-side sub bus bar 30P is connected to the P-side DC terminal 12P of the power module 10 (a, b). P-side main bus bar 20P connects P-side sub bus bar 30P, P-side diode bus bar 66P connected to the P-side terminal of rectifier diode 5, and P-side capacitor bus bar 68P connected to the positive terminal of smoothing capacitor 6. .

  FIG. 4C is a schematic diagram showing the connection relationship of the N-side power bus bar 18N. Similar to the P-side power bus bar 18P, the N-side power bus bar 18N includes an N-side main bus bar 20N and an N-side sub bus bar 30N. The N-side sub bus bar 30N is connected to the N-side DC terminal 12N of the power module 10 (a, b). N-side main bus bar 20N connects N-side sub bus bar 30N, N-side diode bus bar 66N connected to the N-side terminal of rectifier diode 5, and N-side capacitor bus bar 68N connected to the negative terminal of smoothing capacitor 6.

  FIG. 5 is an external perspective view when the power bus bar 18 (P, N) is attached to the power conversion device 1 of FIG. 3. The power converter 1 of FIG. 5 is also provided with a capacitor bus bar 68 (P, N) and a diode bus bar 66 (P, N). The power bus bar 18 (P, N) includes a main bus bar 20 (U to W) provided for each corresponding phase (U to W) and a sub bus bar 30 (U to W).

  Each of the smoothing capacitors 6 includes a positive electrode terminal 6P and a negative electrode terminal 6N on the upper surface thereof. The positive terminal 6P is connected to the P-side capacitor bus bar 68P, and the negative terminal 6N is connected to the N-side capacitor bus bar 68N. The rectifier diode 5 not shown in FIG. 4 is connected to the diode bus bar 66 (P, N).

  From the capacitor bus bar 68, main bus bars 20 (U to W) of U phase, V phase, and W phase respectively extend in the x-axis direction. The U-phase main bus bar 20U includes a P-side main bus bar 20P and an N-side main bus bar 20N which are stacked while being insulated from each other. The same applies to the V phase and the W phase. Paying attention to the W phase, the main bus bar 20W and the DC terminals 12 of the power module 10W are connected by the sub bus bar 30W.

  Hereinafter, the shapes and functions of the main bus bar 20 and the sub bus bar 30 included in the power bus bar 18 will be described in detail. The N-side power bus bar 18N will be described, but it may be applied to the P-side power bus bar 18P, or may be applied to both the P-side power bus bar 18P and the N-side power bus bar 18N.

  In addition, when “A bus bar is connected to B”, “connection” means that physical and electrical connection is made, specifically, holes provided in A bus bar and B respectively. It is fixed by screwing on the same shaft. If necessary, the bus bars can be disassembled by removing the screws, and the bus bars can be assembled again using the screws.

  FIG. 6A is a bottom view of the power bus bar 18 shown in FIG. 5 as viewed from the bottom to the top (−z direction), and FIG. 6B is a side view. The main bus bar 20 extending in the x-axis direction has a connecting portion 22 connected to the sub bus bar 30.

The sub bus bar 30 includes a first section 45, a second section 40, and a third section 50 (a, b).
The first section 45 has a portion connected to the connecting portion 22 of the main bus bar 20, and extends from the connecting portion in a third direction (+ z direction) perpendicular to the main bus bar 20. The first section 45 has a predetermined width in the x-axis direction. For example, the width is about several times the thickness of the main bus bar 20 or the sub bus bar 30.

  The second section 40 extends in parallel with the main bus bar 20 from the end of the first section 45 extending in the + z direction. The second section 40 extends in parallel to the main bus bar 20 in the y-axis direction. An insulating material may be provided between the main bus bar 20 and the second section 40.

  The third section 50 (a, b) extends from the branch section 48 that is the end of the second section 40, and is connected to the DC terminal 12 (a, b) of the power module 10. One third section 50a is connected to one power module 10a constituting an in-phase arm, and the other third section 50b is connected to the other power module 10b.

The third section 50a connected to the DC terminal 12a of the power module 10a first extends in the + x direction from the branch portion 48, and bends and extends in the + y direction toward the DC terminal 12a at the same x coordinate position as the DC terminal 12a. . The third section 50a has a terminal portion 55a, and is connected to the DC terminal 12a at the terminal portion 55a.
On the other hand, the third section 50b connected to the DC terminal 12b of the power module 10b extends in the −x direction from the branch portion 48, and bends in the + y direction toward the DC terminal 12b at the same x coordinate position as the DC terminal 12b. Extend. The third section 50b has a terminal portion 55b, and is connected to the DC terminal 12b at the terminal portion 55b.

  With the above configuration, the sub bus bar 30 has a shape that is substantially plane-symmetric with respect to a plane that passes through the connecting portion and is perpendicular to the x-axis direction. “Substantially plane symmetry” includes not only the case where the shape of the bus bar is strictly plane symmetry, but also the case where the shape is symmetrical to the extent that the impedance is equal.

  FIG. 7 is a diagram schematically showing the effect of electromagnetic induction by the power supply bus bar 18. The main bus bar 20 and the sub bus bar 30, which are flat bus bars, face each other at a distance d. As shown in FIG. 4C, a rectifier diode 5 and a smoothing capacitor 6 serving as a power source are connected to the ends of the main bus bar 20 in the + x direction and the −x direction, respectively.

  A current flows through the main bus bar 20 in the x-axis direction (+ x direction or -x direction). The current applied to the direct current component is easily supplied from the rectifier diode 5, and the current applied to the high frequency alternating current component is easily supplied from the smoothing capacitor 6. The power conversion device according to the embodiment supplies power to the load by changing the frequency according to the operating state of the load. Therefore, the ratio between the current supplied from the rectifier diode 5 and the current value supplied from the smoothing capacitor 6 changes from time to time depending on the operating condition of the load.

respect to the main bus bar 20 in which a current flows in the x-axis direction, the opposite Sabubusuba 30, + y direction of the current I ₁ is to be flowing. According to the law of electromagnetic induction, a magnetic field caused by the current I ₁ is generated around the sub bus bar 30, and an induced current I ₂ is generated in the main bus bar 20 by the magnetic field. As a result, currents I ₂₁ and I ₂₂ having components in the y-axis direction flow through the main bus bar 20 in the vicinity of the sub bus bar 30. The present inventor has found that the current flowing into each DC terminal of a plurality of power modules can be equalized by using this induced current.

  FIG. 8 is a schematic diagram showing a current flowing through the power supply bus bar 18 that does not have the second section 40. First, current non-uniformity to be solved by the present invention will be described with reference to FIG. 8, and an embodiment of the present invention will be described with reference to FIG.

The sub bus bar 30 has a first section 45 connected to the connecting portion 22 and a third section 50 (a, b) connected to a DC terminal of a power module (not shown) at the terminal section 55 (a, b). . However, the second section that runs parallel to the main bus bar 20 is not provided. A power source (not shown) is connected to the main bus bar 20 as in FIG. 7, and currents I ₂₁ and I ₂₂ flow toward the sub bus bar 30. The current flowing through the main bus bar 20 becomes the current I ₀ flowing through the first section 45 via the connecting portion 22, and is divided by the branch section 48 to be divided into the current I ₁₁ flowing through the third section 50a and the I flowing through the third section 50b. ₁₂

The currents I ₁₁ and I ₁₂ separated by the branching part 48 are affected by the magnetic field generated by the current flowing around, and the ratio of the current values changes. Current _{I 11} flowing in the third section 50a is affected by the current _{I 21} flowing through the main bus bars 20 beneath it in the -x direction, the current easily flows in the + x direction. Similarly, the current I ₁₂ is affected by the current I ₂₂ and the current easily flows in the −x direction.

Depending on the characteristics of the power source connected to the main bus bar 20, the values of the currents I ₂₁ and I ₂₂ flowing into the connecting portion 22 may differ. Then, the induced current generated in the third section is different between the + x direction and the −x direction. The current I ₀ is not evenly distributed in the branching portion 48, and there is a difference between the magnitudes of I ₁₁ and I ₁₂ flowing into the DC terminals of the power module.

FIG. 9 is a schematic diagram showing a current flowing through the power supply bus bar 18 according to the first embodiment. Unlike the case of FIG. 8, the sub bus bar 30 has a second section 40 that runs parallel to the main bus bar 20, and has a first section S1, a second section S2, and a third section S3. Current _{I 21, I 22} flowing through the main bus bar 20 via the coupling portion 22, next to the current _{I 0} flowing through the first section 45, the current _{I 0} flows in the second section 40 running parallel with the main bus bar 20. The current I ₀ is divided by the branching portion 48 to become a current I ₁₁ flowing through the third section 50a and an I ₁₂ flowing through the third section 50b.

The second section 40 is run in parallel in close proximity to the main bus bar 20, the region located under the second section 40 of the main bus bar 20, the induced current caused by the current I ₀ occurring increases. Since the current I ₀ flows in the + y direction, the induced current is generated in the −y direction. Due to this induced current, a current flowing from the power source (not shown) in the x-axis direction is bent toward the connecting portion 22 in the y-axis direction. If the absolute values of the currents I ₂₁ and I ₂₂ flowing into the connecting portion 22 are the same as in the case of FIG. 8, the y component of the currents I ₂₁ and I ₂₂ increases, and the x component is the case of FIG. Smaller than As a result, the third section 50a, the induced current in the x-axis direction caused b becomes relatively small, even if there is a difference between the absolute value of the current I ₂₁ and I _22, ease of flow of the current in the branch section 48 The difference in the x-axis direction is less likely to occur. Thereby, the difference between the currents I ₁₁ and I ₁₂ is reduced, and the current flowing into the DC terminal of the power module is equalized.

Further, since the sub bus bar 30 has the second section 40, the distance between the main bus bar 20 and the third section 50 can be taken. As shown in FIG. 8, compared to the case where the main bus bar 20 and the third section 50 are close to each other, the value of the induced current generated in the third section 50 (a, b) by the currents I ₂₁ and I ₂₂ is Even when the absolute values of the currents I ₂₁ and I ₂₂ are different, the difference between the currents I ₁₁ and I ₁₂ can be further reduced.

  FIG. 10A is a bottom view of a power bus bar 18 according to a modification of the first embodiment, and FIG. 10B is a side view thereof. Hereinafter, a description will be given focusing on differences from the first embodiment.

  As shown in FIG. 10B, the main bus bar 20 has an L-shaped cross section, and includes a first main bus bar 26 provided on the xy plane and a second main bus bar 27 provided on the xz plane. Prepare. The connecting portion 22 is provided on the first main bus bar 26.

  The second section 40 of the sub bus bar 30 extends in parallel with the second main bus bar 27. The third section 50 extends from the branch section 48 that is the end of the second section 40, and is connected to the DC terminal 12 of the power module 10.

FIGS. 11A and 11B are schematic diagrams showing the current flowing through the power supply bus bar 18 of FIGS. 10A and 10B. FIG. 11A shows a part of the second main bus bar 27 cut out. As in the first embodiment, an induced current I ₂₀ is generated in the second main bus bar 27 adjacent to the second section 40 due to the current I ₀ flowing in the second section 40. The induced current _{I 20,} current _{I 21, I 22} flowing into the connecting part 22, so that the bend in the -z direction. As a result, the x components of the currents I ₂₁ and I ₂₂ are reduced, and the difference in the ease of current flow in the branch portion 48 is less likely to occur in the x-axis direction. Thereby, the currents I ₁₁ and I ₁₂ flowing into the DC terminal of the power module via the third section can be equalized.

(Second Embodiment)
FIG. 12A is a bottom view of the power bus bar according to the second embodiment, and FIG. 12B is a side view thereof. Hereinafter, a description will be given focusing on differences from the first embodiment.

  The power bus bar 18 includes a pair of side bus bars 31 and 32 as a sub bus bar 30. The main bus bar 20 has connecting portions 23 and 24. The connecting portion 23 is connected to one side bus bar 31, and the connecting portion 24 is connected to the other side bus bar 32.

  The side bus bar 31 has a first section 46, a second section 41, and a third section 51. Unlike the first embodiment, the side bus bar 31 is connected to the DC terminal 12a of one power module 10a. The third section 51 extends in the + x direction from the end of the second section 41 and extends in the + y direction toward the DC terminal 12a at the same x coordinate position as the DC terminal 12a. The third section 51 is connected to the DC terminal 12 a at the terminal portion 56.

  Similarly, the other side bus bar 32 has a first section 47, a second section 42, and a third section 52, and is connected to the DC terminal 12b of the other power module 10b. The third section 52 extends in the −x direction from the end of the second section 42 and extends in the + y direction toward the DC terminal 12b at the same x coordinate position as the DC terminal 12b. The third section 52 is connected to the DC terminal 12 b at the terminal portion 57.

  With the above configuration, the side bus bars 31 and 32 included in the sub bus bar 30 are substantially plane-symmetrical with respect to a plane perpendicular to the first direction (x-axis direction) passing through the centers of the connecting portions 23 and 24. Have

FIG. 13 is a schematic diagram showing a current flow in the power supply bus bar 18 according to the second embodiment. As in the first embodiment, currents I ₀₁ and I ₀₂ flow in the + y direction in the second sections 41 and 42. Due to the currents I ₀₁ and I ₀₂ , an induced current in the −y direction is generated in the main bus bar 20. Due to the induced current, the currents I ₂₁ and I ₂₂ flowing into the connecting portions 23 and 24 are bent in the −y direction. As a result, the x components of the currents I ₂₁ and I ₂₂ are reduced, and the difference in the ease of current flow between the side bus bars 31 and 32 is less likely to occur. Thus, it is possible to equalize the currents I ₁₁ and the current I ₁₂ flowing into the DC terminals of the power module via a side bus bar 31, 32.

  FIG. 14A is a bottom view of a power bus bar according to a modification of the second embodiment, and FIG. 14B is a side view thereof. Hereinafter, the difference from the second embodiment will be mainly described.

  Similar to the modification of the first embodiment, the main bus bar 20 has an L-shaped cross section, and includes a first main bus bar 26 provided on the xy plane, and a second main bus bar 27 provided on the xz plane. Is provided. The connecting portions 23 and 24 are provided on the first main bus bar 26.

  The second sections 41 and 42 of the side bus bars 31 and 32 extend in parallel with the second main bus bar 27. One third section 51 extends in the + x direction from the end of the second section 41 and extends in the + y direction toward the DC terminal 12a at the same x coordinate position as the DC terminal 12a. The other third section 52 extends in the −x direction from the end of the second section 42, and extends in the + y direction toward the DC terminal 12b at the same x coordinate position as the DC terminal 12b.

FIGS. 15A and 15B are schematic diagrams illustrating the flow of current in a power bus bar according to a modification of the second embodiment. Due to the currents I ₀₁ and I ₀₂ flowing in the second sections 41 and 42, an induced current I ₂₀ is generated in the second main bus bar 27 adjacent to the second sections 41 and 42. The induced current _{I 20,} current _{I 21, I 22} flowing in the connecting portion 23 and 24, so that the bend in the -z direction. As a result, the x components of the currents I ₂₁ and I ₂₂ are reduced, and the difference in the ease of current flow between the side bus bars 31 and 32 is less likely to occur. Thereby, the magnitudes of the currents I ₁₁ and I ₁₂ flowing into the DC terminals of the respective power modules via the side bus bars 31 and 32 can be equalized.

  In the above, this invention was demonstrated based on embodiment. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiment, and various design changes are possible, various modifications are possible, and such modifications are within the scope of the present invention. By the way. Hereinafter, such modifications will be described.

In the embodiment, the two power modules 10 are connected in parallel as the arms 7 (U to W) corresponding to the respective phases. However, the number of the power modules 10 used as the arms of each phase is two. Not limited.
FIG. 16 is a schematic diagram showing the power bus bar 18 when three power modules are connected in parallel. The sub bus bar 30 further includes a central third section 50c in addition to the third sections 50a and 50b at both ends extending from the branch portion 48 in the x direction.

  The central third section 50c has connection portions 60a and 60b, and the connection sections 60a and 60b are connected to the third sections 50a and 50b at both ends at positions where the distances in the x direction are equal to each other from the branch portion 48. . A portion 62a extending from one connecting portion 60a in the + y direction and extending in the -x direction and a portion 62b extending from the other connecting portion 60b in the + y direction and extending in the + x direction have the same x coordinate as the branch portion 48. Are joined at a junction 61 provided in A terminal portion 55c is provided at the end extending in the + y direction from the merging portion 61, and the DC terminal of the power module is connected to the terminal portion 55c. With the configuration described above, the sub bus bar 30 shown in FIG.

FIG. 17 is a schematic diagram showing a current flowing through the sub bus bar 30 shown in FIG. The current I ₀ flowing through the second section S2 becomes currents I ₀₁ and I ₀₂ distributed to the third sections 50a and 50b at both ends, and flows in the x direction to reach the connection portions 60a and 60b, respectively. Part of the currents I ₀₁ and I ₀₂ become currents I ₃₁ and I ₃₂ that flow by branching in the + y direction at the connection portions 60a and 60b, and become a current I ₁₃ that merges at the merge portion 61, and the central terminal portion 55c. Flow into. The rest of the currents I ₀₁ and I ₀₂ become currents I ₁₁ and I ₁₂ and flow into the terminal portions 55a and 55b at both ends, respectively.

At this time, the currents I ₀₁ and I ₀₂ distributed by the branching portion 48 are equalized by the sub bus bar 30 having the second section S2, as in the first embodiment, and flow in the x direction to flow through the connecting portions 60a, b is reached. Since the currents I ₀₁ and I ₀₂ reaching the connecting portions 60a and 60b flow in the x direction as they are through the connecting portions 60a and b, the currents I ₃₁ and I ₃₂ branching in the + y direction are It becomes smaller than each of the currents I ₁₁ and I _{12 that} flow and reach the terminal portions 55a and 55b at both ends. However, since the current I ₁₃ flowing through the central terminal portion 55c is the total value of the currents I ₃₁ and I ₃₂ branched in the + y direction, the currents I ₁₁ and I ₁₂ flowing through the terminal portions 55a and b at both ends are close to each other. Can be a value. Therefore, by using the sub bus bar 30 shown in FIGS. 16 and 17, it is possible to equalize the current flowing into the DC terminals of the three power modules connected in parallel.

  The central third section 50c shown in FIG. 16 is connected to the third sections 50a and 50b at both ends according to the second embodiment, thereby supplying power to three power modules connected in parallel. It may be used as Similarly, the third section 50c in the center may be connected to the third sections 51 and 52 according to the modification of the first and second embodiments.

  FIG. 18 is a schematic diagram showing the sub bus bar 30 when four power modules are connected in parallel. Two third sections S3b and S3c are further provided in the third section S3a extending from the second section S2. At this time, as in the first embodiment, a difference in the ease of current flow in the x-axis direction is unlikely to occur, so that the current flowing into the four power modules connected in parallel can be equalized. Further, by repeatedly providing the third section ahead of the two third sections S3b and S3c in FIG. 18, it can be used for a power conversion apparatus in which power-of-two power modules are connected in parallel.

  Furthermore, by combining the sub bus bar 30 shown in FIG. 16 and the third section S3b of FIG. 18, it can also be used in a power conversion apparatus in which other numbers of power modules are connected in parallel. For example, by providing the terminal sections 55a to 55c in FIG. 16 with the third section S3b in FIG. 18, six power modules can be connected in parallel, or to the terminal sections 55a to 55c in FIG. By providing three sections, nine power modules can be connected in parallel. It should be understood by those skilled in the art that the combination of the third sections used as the power busbar and the number of repetitions are not limited to these, and can be appropriately changed according to the number of power modules connected in parallel.

  In the embodiment, as shown in FIG. 2, the case where the P-side semiconductor switch 8P constituting the upper arm 7P and the N-side semiconductor switch 8N constituting the lower arm 7N are included in one power module 10 has been described. However, the present invention can also be applied to the case where the P-side semiconductor switch 8P and the N-side semiconductor switch 8N are included in separate power modules 10.

  In the embodiment, the semiconductor switch 8 included in the power module 10 is introduced using an IGBT. However, other semiconductor switches such as a field effect transistor (FET), a bipolar transistor, and a thyristor, and combinations thereof are used. It is possible to apply.

  In the embodiment, the case where the power bus bar is used in the power conversion device has been described. However, the application of the power bus bar according to the present invention is not limited thereto. It can also be used as a power bus bar for evenly distributing the current from the power source to the electronic components and the like provided in the electrical equipment.

DESCRIPTION OF SYMBOLS 1 ... Power converter device, 4 ... Power supply, 5 ... Rectifier diode, 6 ... Smoothing capacitor, 7 ... Arm, 10 ... Power module, 12 ... DC terminal, 18 ... Power bus bar, 20 ... Main bus bar, 30 ... Sub bus bar, 40 ... Second section, 45 ... first section, 50 ... third section.

Claims (5)

A power bus bar connected to an arm of a power converter, wherein the arm includes a plurality of power modules to be juxtaposed in a first direction and electrically connected in parallel;
The power bus bar is
A main bus bar having a connecting portion and extending in the first direction to face the plurality of power modules;
A sub bus bar for connecting the connecting portion and each DC terminal of the plurality of power modules;
With
The sub bus bar is
A first section for transmitting power from the main bus bar through the connecting portion;
A second section that runs parallel to the main bus bar and transmits power from the first section;
A third section for separately transmitting power from the second section to the DC terminals of the plurality of power modules;
A power bus bar characterized by comprising: The sub bus bar has a shape substantially plane-symmetric with a plane passing through the connecting portion and perpendicular to the first direction,
The power bus bar according to claim 1, wherein the second section extends in a direction perpendicular to the first direction.   3. The power bus bar according to claim 1, wherein the sub bus bar has a larger distance between the main bus bar and the third section than a distance between the main bus bar and the second section. The sub bus bar includes a set of side bus bars each having the first section and the second section;
One side bus bar has a third section for transmitting power from the second section of the side bus bar to the DC terminal of the corresponding power module,
The other side bus bar has a third section for transmitting electric power from a second section of the side bus bar to a DC terminal of a power module different from the corresponding power module. The power bus bar according to any one of the above. An upper arm and a lower arm,
An upper power bus bar connected to the upper arm;
A lower power bus bar connected to the lower arm;
With
At least one of the upper arm and the lower arm includes a plurality of power modules that are juxtaposed in a first direction and are to be electrically connected in parallel.
5. The power converter according to claim 1, wherein at least one of the upper power bus bar and the lower power bus bar is the power bus bar according to claim 1.

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