JP2014192936A - Power supply bus bar and power converter using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize a current flowing into each DC terminal of power modules to be connected in parallel, in a power converter.SOLUTION: In a power supply bus bar 18 to be connected with the arm of a power converter, when the arm includes a plurality of power modules 10a, 10b to be connected electrically in parallel, the power supply bus bar 18 includes a P side bus bar 18P to be connected with a P side power supply, an N side bus bar 18N running parallel to the P side bus bar 18P and to be connected with an N side power supply, and an intermediate magnetic shield 18C provided between the P side bus bar 18P and N side bus bar 18N, while being insulated therefrom, and to be connected with a frame ground.

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 to be electrically connected in parallel, each of the upper DC terminals of the plurality of power modules Between the first bus bar to be connected, the second bus bar that runs in parallel with the first bus bar and is connected to each of the lower DC terminals of the plurality of power modules, and the first bus bar and the second bus bar, An intermediate magnetic shield provided in an insulated state from the first bus bar and the second bus bar.

  Another embodiment of the present invention relates to a power conversion device. This power conversion device has an upper arm and a lower arm, and at least one of the upper arm and the lower arm is connected to an arm including a plurality of power modules to be electrically connected in parallel to the upper arm. The first bus bar, the second bus bar connected to the lower arm and running in parallel with the first bus bar, and the first bus bar and the second bus bar are provided in a state insulated from the first bus bar and the second bus bar. And an intermediate magnetic shield to be connected to the frame ground.

  According to this aspect, since the magnetic shield is provided between the first bus bar and the second bus bar, it is possible to prevent the current flowing through the second bus bar from being disturbed by the magnetic field generated by the current flowing through the first bus bar. It is also possible to prevent the current flowing through the first bus bar from being disturbed by the magnetic field generated by the current flowing through the second bus bar. As a result, the current flowing through each bus bar is prevented from becoming non-uniform under the influence of the current flowing through another bus bar, and the power supply current flowing into each of the plurality of power modules connected in parallel can be equalized. it can.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply current which flows in into each of several power module connected in parallel as an arm in a power converter device 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. (A)-(c) is a schematic diagram which shows the connection relation of a power supply bus bar, a rectifier diode, a smoothing capacitor, and a power module. It is an external appearance perspective view when a power supply bus bar is attached to the power converter device of FIG. It is an external appearance perspective view of a main bus bar and a sub bus bar. It is sectional drawing of a main bus bar and a sub bus bar. It is an external appearance perspective view of an N side sub bus bar. It is sectional drawing which shows arrangement | positioning of a sub bus bar. It is a figure which shows typically the electric current which flows into the sub bus bar which is not providing an intermediate magnetic shield. It is a figure which shows typically the electric current which flows into the sub bus bar which provided the intermediate magnetic shield. FIG. 10 is a plan view of a main bus bar and a sub bus bar according to Modification 1. It is sectional drawing of the main bus bar which concerns on the modification 1, and a sub bus bar. It is an external appearance perspective view of the power bus bar concerning the modification 2. It is sectional drawing of the power bus bar which concerns on the modification 3. FIG.

  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.

  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 power module group 10 (U to W) constituting each arm 7 (U to W), a housing 70, a fan module 72, a heat sink 74 (U to W), 75, a diode module 85, a capacitor. A module 86 is provided.

  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 diode module 85 is the rectifier diode 5 shown in FIG. 1, and the capacitor module 86 is the smoothing capacitor 6. The diode module 85 is provided on the heat sink 75. The capacitor module 86 is inserted into a mounting hole 76 provided in the housing 70 and fixed. The diode module 85, the capacitor module 86, and the power module 10 are electrically and mechanically connected via a power bus bar described later.

  The fan module 72 is provided in the vicinity of the capacitor module 86, and a plane that forms the air intake hole of the fan module 72 is arranged perpendicular to the x-axis direction. The fan module 72 blows air in the x-axis direction with respect to the capacitor module 86 and the heat sinks 74 (U to W).

  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 bus bar 18P, an intermediate magnetic shield 18C, and an N-side bus bar 18N.

  The P-side bus bar 18P functions as the P-side power line LP in FIG. 1, and the N-side bus bar 18N functions as the N-side power line LN. The P-side bus bar 18P and the N-side bus bar 18N are flat bus bars made of a metal plate having excellent conductivity including copper (Cu), aluminum (Al), and the like. The same applies to other bus bars described later.

  The intermediate magnetic shield 18C is a metal plate excellent in conductivity including copper (Cu), aluminum (Al), or the like, or a metal plate having ferromagnetism including iron (Fe), cobalt (Co), nickel (Ni), or the like. And is connected to a housing 70 serving as a frame ground. The intermediate magnetic shield 18C is provided between the P-side bus bar 18P and the N-side bus bar 18N, and absorbs magnetic flux generated by the current flowing through the P-side bus bar 18P and the current flowing through the N-side bus bar 18N.

  FIG. 4B is a schematic diagram showing the connection relationship of the P-side bus bar 18P. The P-side 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 bus bar 18N. Similar to the P-side bus bar 18P, the N-side 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 is attached to the power conversion device 1 of FIG. 3. A capacitor bus bar 68 and a diode bus bar 66 are also attached to the power converter 1 of FIG. The power bus bar 18 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).

  The capacitor module 86 includes a positive terminal 6P and a negative terminal 6N on the upper surface. The positive terminal 6P is connected to the P-side capacitor bus bar, and the negative terminal 6N is connected to the N-side capacitor bus bar 68N. The diode module 85 is connected to the diode bus bar 66.

  The P-side DC terminal 12P and the N-side DC terminal 12N of the power module 10 are provided adjacent to each other in the x direction, and the U-phase, V-phase, and W-phase main bus bars 20 (U to W) are capacitor bus bars. 68 extends in the x-axis direction. 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.

  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.

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.
6 is an external perspective view of the main bus bar 20 and the sub bus bar 30, and FIG. 7 is a cross-sectional view. The main bus bar 20 includes a P-side main bus bar 20P, a main magnetic shield 20C, and an N-side main bus bar 20N that are sequentially stacked. The P-side main bus bar 20P is connected to the P-side connection portion 35P of the P-side sub bus bar 30P. The N-side main bus bar 20N is connected to the N-side connection portion 35N of the N-side sub bus bar 30N.

  The main magnetic shield 20 </ b> C includes a magnetic layer 52 and an insulator layer 54, and the magnetic layer 52 is covered with the insulator layer 54. Therefore, the P-side main bus bar 20P, the main magnetic shield 20C, and the N-side main bus bar 20N are stacked in a state of being insulated from each other. The magnetic layer 52 is electrically connected to the housing 70 that serves as a frame ground.

  The sub bus bar 30 includes a P side sub bus bar 30P, a sub magnetic shield 30C, and an N side sub bus bar 30N. As with the main bus bar 20, the P-side sub bus bar 30P, the sub magnetic shield 30C, and the N-side sub bus bar 30N are sequentially stacked while being insulated from each other.

  The P-side sub bus bar 30P includes a P-side first terminal portion 31P, a P-side second terminal portion 32P, a P-side first side bar 33P, a P-side second side bar 34P, a P-side connection portion 35P, and a P-side branching portion 36P. Have.

  The P-side sub bus bar 30P extends in the + z direction from the P-side connection part 35P connected to the P-side main bus bar 20P toward the P-side branch part 36P. The P-side branch portion 36P branches into a P-side first side bar 33P extending in the −x direction and a P-side second side bar 34P extending in the + x direction. The P-side first side bar 33P extends in the −x direction, then bends in the + z direction, and travels toward the P-side first terminal portion 31P connected to the P-side DC terminal 12P of the first power module 10a. The P-side second side bar 34P extends in the + x direction, then bends in the + z direction, and travels toward the P-side second terminal portion 32P connected to the P-side DC terminal 12P of the second power module 10b. Thereby, P side sub bus bar 30P connects between P side main bus bar 20P and P side DC terminal 12P of a plurality of power modules 10a and 10b.

The P-side sub bus bar 30P functions as a P-side power line LP, and a current flows from the power source to the power module 10. Current _{I p} from P-side main bus bar 20P flows to the P-side Sabubusuba 30P, the current _{I p1} and the current _{I p2} divided into two parts at the P-side branch portion 36P. A current I _p1 flows toward the P-side DC terminal 12P of the first power module 10a, and a current I _p2 flows toward the P-side DC terminal 12P of the second power module 10b.

  FIG. 8 is an external perspective view of the N-side sub bus bar. The N-side sub bus bar 30N, like the P-side, has an N-side first terminal portion 31N, an N-side second terminal portion 32N, an N-side first side bar 33N, an N-side second side bar 34N, and an N-side connection portion 35N, N A side branch portion 36N is provided.

  The N-side sub bus bar 30N extends in the + z direction from the N-side connection portion 35N connected to the N-side main bus bar 20N toward the N-side branch portion 36N. The N-side branch portion 36N branches into an N-side first side bar 33N extending in the −x direction and an N-side second side bar 34N extending in the + x direction. The N-side first side bar 33N extends in the −x direction, then bends in the + z direction, and travels toward the N-side first terminal portion 31N connected to the N-side DC terminal 12N of the first power module 10a. The N-side second side bar 34N extends in the + x direction, then bends in the + z direction, and travels toward the N-side second terminal portion 32N connected to the N-side DC terminal 12N of the second power module 10b. Thereby, N side sub bus bar 30N connects between N side main bus bar 20N and N side DC terminal 12N of a plurality of power modules 10a and 10b.

The N-side sub bus bar 30N functions as an N-side power line LN, and a current drawn from the power module 10 to the power source flows. The current I _N1 from the N-side DC terminal 12N of the first power module 10a and the current I _N2 from the N-side DC terminal 12N of the second power module 10b are merged at the N-side branch portion 36N, and the N-side sub bus bar A current I _N flows from 30N to the N-side main bus bar 20N.

  9 is a cross-sectional view showing the arrangement of the sub bus bars 30, and shows a cross section of the sub bus bar 30 shown in FIG. 6 in the xy plane. The P-side sub bus bar 30P and the N-side sub bus bar 30N are provided so as to be shifted from each other in the x direction corresponding to the positions of the P side DC terminal 12P and the N side DC terminal 12N of the power module 10 provided adjacent to each other in the x direction. The P-side sub bus bar 30P and the N-side sub bus bar 30N are separated in the y direction, and a sub magnetic shield 30C is provided therebetween.

  Similar to the main magnetic shield 20C, the sub magnetic shield 30C includes a magnetic layer 52 and an insulator layer 54, and the magnetic layer 52 is covered with the insulator layer 54. Therefore, the P-side sub bus bar 30P, the sub magnetic shield 30C, and the N-side sub bus bar 30N are stacked in a state of being insulated from each other.

  The sub magnetic shield 30C is provided at a location where the P-side sub bus bar 30P and the N-side sub bus bar 30N are close to each other. Since the P-side sub bus bar 30P and the N-side sub bus bar 30N are arranged so as to be shifted in the x direction, the P-side branch portion 36P and the N-side first side bar 33N, or the N-side branch portion 36N are positioned as close to each other. And the P-side second side bar 34P.

  With the above configuration, the power bus bar 18 includes the intermediate magnetic shield 18C provided in an insulated state between the P-side bus bar 18P and the N-side bus bar 18N that are parallel to each other. Since the intermediate magnetic shield 18C is provided in contact with the P-side bus bar 18P and the N-side bus bar 18N, it absorbs magnetic flux generated by the current flowing through the P-side bus bar 18P and the N-side bus bar 18N. Therefore, the intermediate magnetic shield 18C prevents the magnetic field generated by the current flowing through the P-side bus bar 18P from acting on the current flowing through the N-side bus bar 18N. Similarly, the magnetic field generated by the current flowing through the N-side bus bar 18N is prevented from acting on the current flowing through the P-side bus bar 18P.

  FIG. 10 is a diagram schematically showing the current flowing through the sub bus bar not provided with the intermediate magnetic shield. Unlike FIG. 9, FIG. 10 shows a sub bus bar in which the sub magnetic shield 30C is not provided between the P side sub bus bar 30P and the N side sub bus bar 30N. First, current non-uniformity to be solved by the present invention will be described with reference to FIG. 10, and current equalization performed in the embodiment of the present invention will be described with reference to FIG.

Since the P-side branch portion 36P of the P-side sub bus bar 30P is close to the N-side first side bar 33N, it is affected by the current I _N1 flowing in the + x direction through the N-side first side bar 33N in the −x direction. It becomes easier for current to flow. Therefore, a difference occurs in the current _{I p1, I p2} branching in P-side branch portion 36P, who current _{I p1} flowing in the -x direction is larger than the current _{I p2.} As a result, the current flowing from the power source to the power modules connected in parallel becomes uneven.

Similarly, since the N-side branch portion 36N of the N-side sub bus bar 30N is close to the P-side second side bar 34P, it is affected by the current I _p2 flowing in the + x direction through the P-side second side bar 34P − A current easily flows in the x direction. Therefore, there is a difference between the currents I _p1 and I _p2 drawn into the N-side branch part 36N, and the current I _N2 flowing in the −x direction becomes larger than the current I _N1 . As a result, the current drawn from the power modules connected in parallel to the power source becomes uneven.

FIG. 11 is a diagram schematically showing the current flowing through the sub bus bar provided with the intermediate magnetic shield. The P-side branch portion 36P of the P-side sub bus bar 30P is close to the N-side first side bar 33N, but since the sub-magnetic shield 30C is provided therebetween, the current I flowing through the N-side first side bar 33N _Not easily affected by _N1 . As a result, the difference between the branching currents I _p1 and I _p2 that branches at the P-side branching part 36P hardly occurs, and the current flowing from the power source to the power modules connected in parallel can be equalized.

Similarly, the N-side branch portion 36N of the N-side sub bus bar 30N is close to the P-side second side bar 34P, but since the sub-magnetic shield 30C is provided therebetween, the P-side second side bar 34P is _{Insensitive to} the flowing current _Ip2 . As a result, the currents I _p1 and I _p2 drawn into the N-side branch part 36N are unlikely to differ, and the current drawn from the power modules connected in parallel to the power source 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.

(Modification 1)
12 is a plan view of the main bus bar 20 and the sub bus bar 30 according to the first modification, and FIG. 13 is a cross-sectional view thereof. The sub bus bar 30 according to the above-described embodiment is configured to extend in the z direction from the main bus bar 20 extending in the x direction. However, the sub bus bar 30 according to the modification 1 is configured in the y direction instead of extending from the main bus bar 20 in the z direction. It extends and is connected to the power module 10. Therefore, in the first modification, the P-side sub bus bar 30P, the sub magnetic shield 30C, and the N-side sub bus bar 30N all extend in the y direction and are sequentially stacked in a mutually insulated state. Hereinafter, differences from the embodiment will be mainly described.

  The P-side sub bus bar 30P extends in the + y direction from the P-side connection part 35P connected to the P-side main bus bar 20P toward the P-side branch part 36P. The P-side branch portion 36P branches into a P-side first side bar 33P extending in the −x direction and a P-side second side bar 34P extending in the + x direction. The P-side first side bar 33P extends in the −x direction, and then bends in the + y direction, toward the P-side first terminal portion 31P connected to the P-side DC terminal 12P of the first power module 10a. The P-side second side bar 34P extends in the + x direction, then bends in the + y direction, and travels toward the P-side second terminal portion 32P connected to the P-side DC terminal 12P of the second power module 10b. Thereby, P side sub bus bar 30P connects between P side main bus bar 20P and P side DC terminal 12P of a plurality of power modules 10a and 10b.

  The N-side sub bus bar 30N extends in the + y direction from the N-side connection portion 35N connected to the N-side main bus bar 20N toward the N-side branch portion. The N-side branch part branches into an N-side first side bar extending in the −x direction and an N-side second side bar extending in the + x direction. The N-side first sidebar extends in the −x direction and then bends in the + y direction and travels toward the N-side first terminal portion 31N connected to the N-side DC terminal 12N of the first power module 10a. The N-side second side bar extends in the + x direction, then bends in the + y direction, and travels toward the N-side second terminal portion 32N connected to the N-side DC terminal 12N of the second power module 10b. Thereby, N side sub bus bar 30N connects between N side main bus bar 20N and N side DC terminal 12N of a plurality of power modules 10a and 10b.

With the above configuration, the main bus bar 20 and the sub bus bar 30 having a branch structure are arranged on the same plane (xy plane). Even with such a configuration, an effect of equalizing the current flowing through the power modules 10 connected in parallel can be obtained, as in the above-described embodiment.
(Modification 2)
FIG. 14 is an external perspective view of the power bus bar 18 according to the second modification. The power bus bar 18 according to the above-described embodiment includes the sub bus bar 30 having a structure that branches to the DC terminal of each power module. However, in the second modification, the sub bus bar 30 is not provided, and the main bus bar 20 is branched. Have Hereinafter, differences from the embodiment will be mainly described.

  The power bus bar 18 according to Modification 2 includes a P-side main bus bar 20P, an N-side main bus bar 20N, and a main magnetic shield 20C. Similar to the embodiment, the P-side main bus bar 20P, the main magnetic shield 20C, and the N-side main bus bar 20N are sequentially stacked while being insulated from each other.

  The P-side main bus bar 20P includes a P-side first terminal portion 31P and a P-side second terminal portion 32P that extend in the x direction and project in the y direction. As a result, the P-side main bus bar 20P has a structure that branches into a P-side DC terminal 12P of the first power module 10a and a P-side DC terminal 12P of the second power module 10b. Connected to terminal 12P.

  Similarly, the N-side main bus bar 20N includes an N-side first terminal portion 31N and an N-side second terminal portion 32N that extend in the x direction and project in the y direction. Thus, the N-side main bus bar 20N has a structure that branches into an N-side DC terminal 12N of the first power module 10a and an N-side DC terminal 12N of the second power module 10b. Connected to terminal 12N.

Here, paying attention to the P-side main bus bar 20P, the current I _p1 flowing into the P-side first terminal portion 31P and the current I _p2 flowing into the P-side second terminal portion 32P are rectified connected to the P-side main bus bar 20P. Nonuniformity may occur due to the power supply arrangement such as the diode 5 and the smoothing capacitor 6. For example, the current Ip supplied from the power supply, when flowing through the P-side main busbar 20P in the + x direction, towards the current I _p1 flowing through P-side first terminal portion 31P near the current source, farther P side from the current source It becomes larger than the current _{I p2} flowing in the second terminal portion @ 32 P.

  Assuming that the intermediate magnetic shield 18C is not provided, the N-side main bus bar 20N disposed in a stack with the P-side main bus bar 20P is greatly affected by the current flowing through the P-side main bus bar 20P. Therefore, a relatively large current flows in the N-side first terminal portion 31N adjacent to the P-side first terminal portion 31P through which a relatively large current flows, as compared with the N-side second terminal portion 32N. As a result, a difference is generated in the current drawn from each N-side DC terminal 12N, resulting in uneven current.

  However, since the power bus bar 18 according to the modified example 2 includes the main magnetic shield 20C between the P-side main bus bar 20P and the N-side main bus bar 20N, the current flowing through the P-side main bus bar 20P becomes uneven. However, the influence is prevented from propagating to the N-side main bus bar 20N. Similarly, even when the current flowing through the N-side main bus bar 20N becomes non-uniform, the influence is prevented from propagating to the P-side main bus bar 20P. Thereby, the electric current which flows through the power module connected in parallel can be equalized.

(Modification 3)
FIG. 15 is a cross-sectional view of the power bus bar 18 according to the third modification. The power supply bus bar 18 according to the modification 3 is different from the embodiment in that in addition to the P-side bus bar 18P, the intermediate magnetic shield 18C, and the N-side bus bar 18N, an upper magnetic shield 18A and a lower magnetic shield 18B are further provided. Hereinafter, differences from the embodiment will be mainly described.

  As with the intermediate magnetic shield 18C, the upper magnetic shield 18A and the lower magnetic shield 18B are made of a metal plate excellent in conductivity including copper (Cu), aluminum (Al), etc., iron (Fe), cobalt (Co), It is made of a ferromagnetic metal plate containing nickel (Ni) or the like, and is connected to a housing 70 that serves as a frame ground.

  The upper magnetic shield 18A is provided on the P side bus bar 18P in parallel with the P side bus bar 18P, and is arranged so that the P side bus bar 18P is sandwiched between the upper magnetic shield 18A and the intermediate magnetic shield 18C. In other words, when the P-side bus bar 18P has the first main surface 41 opposed to the intermediate magnetic shield 18C, the upper magnetic shield 18A has the second main surface 42 of the P-side bus bar 18P facing away from the first main surface 41. Are provided opposite to each other.

  The lower magnetic shield 18B is provided in parallel with the N side bus bar 18N below the N side bus bar 18N, and is arranged so that the N side bus bar 18N is sandwiched between the lower magnetic shield 18B and the intermediate magnetic shield 18C. In other words, when the N-side bus bar 18N has the third main surface 43 facing the intermediate magnetic shield 18C, the lower magnetic shield 18B is the fourth main surface of the N-side bus bar 18N facing away from the third main surface 43. 44 is provided to face.

  A magnetic layer 52 is provided between the bus bar and the magnetic shield that are laminated in the order of the upper magnetic shield 18A, the P-side bus bar 18P, the intermediate magnetic shield 18C, the N-side bus bar 18N, and the lower magnetic shield 18B. Thereby, each bus bar and magnetic shield are laminated in a state of being insulated from each other.

  With the above configuration, the power bus bar 18 according to the modified example 3 not only absorbs the magnetic flux generated between the P-side bus bar 18P and the N-side bus bar 18N but also generates magnetic flux generated on the second main surface 42 side of the P-side bus bar 18P. The magnetic flux generated on the fourth main surface 44 side of the N-side bus bar 18N is also absorbed. This prevents the magnetic field generated on the second main surface 42 side of the P-side bus bar 18P from flowing around and affecting the N-side bus bar 18N, and the magnetic field generated on the fourth main surface 44 side of the N-side bus bar 18N This prevents the side bus bar 18P from being affected. Thereby, it is possible to prevent the currents flowing through the P-side bus bar 18P and the N-side bus bar 18N from becoming non-uniform, and to equalize the currents flowing through the plurality of power modules connected in parallel.

  In the above-described embodiment and Modification 1, the case where the sub bus bar 30 having the branch structure and the main bus bar 20 are configured as separate removable bus bars has been described, but the main bus bar 20 and the sub bus bar 30 are used as the power bus bar 18. Alternatively, a bus bar formed integrally with each other may be used. As shown in the embodiment or the first modification, the bus bar has a structure that branches toward each DC terminal of the plurality of power modules.

  In the embodiment, the intermediate magnetic shield is provided on the main bus bar 20 and the sub bus bar 30, but the intermediate magnetic shield may be provided on the diode bus bar 66 and the capacitor bus bar 68. Thereby, the power supply current supplied to each of the arms of each phase (U to W) can be equalized. Further, the upper magnetic shield 18A and the lower magnetic shield 18B may be provided on the diode bus bar 66 or the capacitor bus bar 68.

  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. The present invention is not limited, and may be applied when three or more are connected in parallel.

  In the embodiment, 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. The present invention can also be applied to a case where the N-side semiconductor switch 8N is included in a separate power module 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, 7, 7U, 7V, 7W ... Arm, 7N ... Lower arm, 7P ... Upper arm, 10 ... Power module, 12 ... DC terminal, 12N ... N side DC terminal, 12P ... P Side DC terminal, 18 ... Power bus bar, 18P ... P side bus bar, 18N ... N side bus bar, 18C ... Intermediate magnetic shield, 18A ... Upper magnetic shield, 18B ... Lower magnetic shield, 20P ... P side main bus bar, 20N ... N Side main bus bar, 20C ... main magnetic shield, 30 ... sub bus bar, 30P ... P side sub bus bar, 30N ... N side sub bus bar, 30C ... sub magnetic shield, 41 ... first main surface, 42 ... second main surface, 43 ... third Main surface, 44 ... 4th main surface.

Claims (8)

A power busbar connected to an arm of a power converter, wherein the arm includes a plurality of power modules to be electrically connected in parallel;
The power bus bar is
A first bus bar to be connected to each of the upper DC terminals of the plurality of power modules;
A second bus bar that runs in parallel with the first bus bar and is connected to each of the lower DC terminals of the plurality of power modules;
An intermediate magnetic shield provided between the first bus bar and the second bus bar in an insulated state from the first bus bar and the second bus bar;
A power bus bar characterized by comprising: The first bus bar has a structure branching toward the upper DC terminal,
The second bus bar has a structure that branches toward the lower DC terminal.
The power bus bar according to claim 1. The first bus bar has a first sub bus bar to be branched to each of the upper DC terminals of the plurality of power modules and to be connected to each of the upper DC terminals,
The second bus bar has a second sub bus bar that is branched toward the lower DC terminal of each of the plurality of power modules and to be connected to the lower DC terminal.
The power bus bar according to claim 1.   4. The power bus bar according to claim 3, wherein the intermediate magnetic shield is provided at least between the first sub bus bar and the second bus bar.   The power bus bar according to claim 1, wherein the intermediate magnetic shield is connected to a frame ground. The first bus bar has a first main surface facing the intermediate magnetic shield, and a second main surface facing away from the first main surface;
When the second bus bar has a third main surface facing the intermediate magnetic shield and a fourth main surface facing away from the third main surface,
An upper magnetic shield that runs parallel to the first bus bar and is provided to face the second main surface while being insulated from the first bus bar;
A lower magnetic shield that runs in parallel with the second bus bar and is opposed to the fourth main surface in a state of being insulated from the second bus bar;
The power supply bus bar according to claim 1, further comprising:   The power bus bar according to claim 6, wherein at least one of the upper magnetic shield and the lower magnetic shield is connected to a frame ground. An upper arm and a lower arm, wherein at least one of the upper arm and the lower arm includes a plurality of power modules to be electrically connected in parallel;
A first bus bar connected to the upper arm;
A second bus bar connected to the lower arm and running in parallel with the first bus bar;
An intermediate magnetic shield provided between the first bus bar and the second bus bar in a state of being insulated from the first bus bar and the second bus bar and to be connected to a frame ground;
A power conversion device comprising:

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