JPH08140363A - Power converter - Google Patents

Abstract

PURPOSE: To protect a switch element by reducing and making uniform the wiring inductance of a main circuit in a power converter and to reduce the cost and make compact by preventing the rating of the element and the capacitance of the snubber capacitor from increasing. CONSTITUTION: In a power converter, at least a plurality of semiconductor switch elements, a snubber capacitor connected to the switch elements, a smoothing capacitor which becomes a power supply, and the DC buses of positive and negative electrodes connected to the smoothing capacitor are arranged on a cooling body. A switch element 2, a snubber capacitor 3, DC buses 4 and 5, and a smoothing capacitor 6 are arranged in layers on the upper surface of a cooling body 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a semiconductor switch element,
The present invention relates to a power converter with an improved main circuit structure configured by connecting a snubber capacitor, a smoothing capacitor, a DC bus, and the like.

[0002]

2. Description of the Related Art FIGS. 13A and 13B show a conventional main circuit structure. FIG. 13A is a plan view and FIG. 13B is a front view.
In these figures, reference numeral 1 is a cooling body having fins 1a, and a semiconductor switch element 2 composed of two transistors connected in series which form upper and lower arms is provided on the upper surface thereof.
6 are arranged. Reference numerals 4'and 5'represent negative electrode and positive electrode direct current buses, respectively, and negative side terminals (E
2), connected to the positive terminal (C1) via the short-circuit bars 14 and 13. Here, the negative side terminal (E2) indicates the emitter of the lower arm transistor in the switch element 2, and the positive side terminal (C1) indicates the collector of the upper arm transistor.

A snubber capacitor 3'is connected between the negative terminal (E2) and the positive terminal (C1) of each switch element 2. Note that FIG. 13A shows a state in which the snubber capacitor 3 ′ is connected only to the three switching elements 2 on one side for the sake of convenience, but in reality, the three switching elements 2 on the other side are connected. It is also connected between the negative terminal and the positive terminal (see FIG. 13B).

Between the DC buses 4'and 5 ', four smoothing capacitors 6 serving as a DC power source are connected in parallel via shorting bars 7 and 8. Further, in FIG. 13A, 16 is an output terminal (E1C) of the adjacent switch element 2.
2) output wires of U, V, and W phases drawn from the short-circuit bar 15 connected to each other and connected to an output terminal block (not shown). Here, the output terminal (E1C2)
Shows the emitter of the upper arm transistor in the switch element 2 and the collector of the lower arm transistor connected to this emitter.

As is apparent from the above structure, the smoothing capacitor 6 is arranged on the side of the cooling body 1 on which the switch element 2 is arranged. Due to such arrangement, the DC busbars 4'and 5'and short circuits are formed. The wiring distance between the smoothing capacitor 6 and each switch element 2 via the bars 14 and 13 is not uniform between the switch element 2 that is far from the smoothing capacitor 6 and the switch element 2 that is close to it. .

[0006]

By the way, in recent years, with the increase in speed of switches, IGBTs have been added to semiconductor switch elements.
Power converters using (insulated gate bipolar transistors) are increasing. In such a power converter,
The time interval for switching on / off of the switch element becomes short, and the nonuniform wiring distance, that is, the nonuniform wiring inductance greatly affects the current load on the element.

If the current load of the switch element is unbalanced, the element breakdown due to overcurrent is promoted, which causes an increase in the rating of the switch element and a snubber circuit capacity, which in turn leads to an increase in cost and an increase in size of the device. It will be. Further, in the above-described conventional technique, the wiring inductance of the snubber capacitor 3 may cause a voltage jump at the time of switching, and an overvoltage may be applied to the switch element 2.

That is, conventionally, the above-mentioned various problems have occurred due to the wiring inductance and its nonuniformity. In addition, DC busbars 4 ', 5'and short-circuit bars 13, 14, 15
The number of wiring components such as the above is large, which has been a cause of increasing the number of manufacturing steps and the cost.

The present invention has been made to solve the above problems, and an object thereof is to make the wiring inductance uniform and reduce its value itself to increase the rating of the switch element and the snubber circuit capacity. It is an object of the present invention to provide a power conversion device that can prevent the above, reduce the cost, downsize the device, and reduce the number of parts.

[0010]

To achieve the above object, the present invention according to claim 1 provides a plurality of semiconductor switch elements, a snubber capacitor connected to these switch elements, on a cooling body. In a power converter in which at least a smoothing capacitor serving as a power source and positive and negative DC buses connected to the smoothing capacitor are arranged, a switch element, a snubber capacitor, a DC bus, and a smoothing capacitor are sequentially arranged on the upper surface of a cooling body. , Are arranged in a laminated manner.

In the present invention, as described in claim 2, the DC busbars of the positive electrode and the negative electrode are arranged in a laminated manner with the insulating material interposed therebetween, and the switch elements are substantially symmetrical below the DC busbars. It is desirable to place it in. Further, as described in claim 3, it is desirable that the output bars of the respective phases, which are connected to the output terminal block by short-circuiting the output terminals of the plurality of switch elements, be provided with the folded portions parallel to each other.

[0012]

In the present invention, by arranging the switch element, the snubber capacitor, the DC bus, and the smoothing capacitor in a laminated manner above the cooling body, the wiring distance between the smoothing capacitor and each switch element can be shortened to achieve a substantially uniform distribution. Can be In addition to this, by arranging symmetrically by a method such as connecting the switch element to both lower sides of the DC bus bar as necessary, by providing a folded portion in the output bar of each phase,
It is possible to reduce and uniformize the wiring inductance.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the first embodiment of the present invention.
1A is a plan view, FIG. 1B is a front view, and FIG.
FIG. 3 is a view in the direction of arrow A in FIG. Here, FIG.
In (a), the smoothing capacitor 6, which actually appears in the foremost position on the front side of the paper, is omitted for convenience sake.

In these figures, on the upper surface of the cooling body 1 having the fins 1a, six semiconductor switching elements 2 composed of two transistors connected in series, which form upper and lower arms, are arranged similarly to the above. 2 is a circuit diagram of the embodiment of FIG. 1, and will be described below with reference to FIG. 2 as necessary. As is apparent from FIG. 2, this embodiment is a case where the present invention is applied to a parallel three-phase double inverter.

As shown in FIG. 3, the output terminals (E1C2) of the two switch elements 2 adjacent to each other on the left and right sides in FIG. 1A are parallel to the folded portions 30a and 30b and the folded portion 3.
Connected by output bars 9, 10, 11 having a structure having a straight part 30c orthogonal to 0b.
10 and 11 are connected to an output terminal block (not shown). That is, the output terminals (E1C2) of the two switch elements 2 in the upper stage of FIG. 1A are output by the W-phase output bar 11 to the output terminals (E1C2) of the two switch elements 2 in the middle stage of FIG. 1A. Is shown in FIG. 1 (a) by the V-phase output bar 10.
Output terminals (E1C2) of the two lower switch elements 2
Are connected by U-phase output bars 9. In addition,
In FIG. 3, reference numeral 31 is a through hole for connecting to the output terminal (E1C2).

1A and 1B, a chip-shaped snubber capacitor 3 is connected between the positive side terminal (C1) and the negative side terminal (E2) of each switch element 2. The snubber capacitor 3 protects the switch element 2 by suppressing a voltage jump at the time of switching. Note that in FIG. 2, for convenience, only the snubber capacitor 3 connected to one switch element 2 is shown.

In FIGS. 1A and 1B, the negative and positive DC bus lines 4 and 5 made of a copper plate having the structure shown in FIG. 4 are connected so as to straddle two adjacent switch elements 2. ing. The negative DC bus 4 connects the negative terminal (E2) of each switch element 2 as shown in FIG. 2, and the positive DC bus 5 connects the positive terminal (C1) of each switch element 2. To do.

These DC buses 4 and 5 have almost the same width and length, and functionally, the DC buses 4'and 5'of FIG.
5'and short-circuit bars 13 and 14 are also used. FIG.
As shown in (a) and (b), the DC buses 4 and 5 are superposed with the insulating plate 12 interposed therebetween, and the negative side terminal (E
2) and the positive terminal (C1). The insulating plate 12 is not shown in FIG.

Further, as shown in FIG. 4, capacitor connecting portions 4a and 5a are attached to one side of each of the DC buses 4 and 5, and as shown in FIGS. 1 (b) and 1 (c). Four smoothing capacitors are connected in parallel between the DC buses 4 and 5 via the shorting bars 7 and 8 and the capacitor connecting portions 4a and 5a. In FIG. 2, for convenience, the smoothing capacitor 6
Are collectively shown as one. In FIG. 2, 3
2 shows an output terminal block.

In this embodiment, as shown in FIG. 1 (b), the cooling body 1, the switch element 2, the snubber capacitor 3, the DC bus lines 4, 5 and the smoothing capacitor 6 are stacked in this order from the bottom. With the above arrangement, the wiring distance from the short-circuit bars 7 and 8 of the smoothing capacitor 6 to the DC buses 4 and 5 can be made relatively short and have substantially the same length.
Therefore, it is possible to make the wiring inductance in the above wiring distance smaller than the conventional one and to make it substantially uniform.

Further, by making the DC buses 4 and 5 have substantially the same structure, the wiring inductances thereof can be made substantially equal, and the DC buses 4 and 5 are disposed above the center of the adjacent switch elements 2. By connecting the switching elements 2 to the substantially L-shaped connecting pieces of the DC buses 4 and 5 in a symmetrically hanging manner, the wiring distances between the DC buses 4 and 5 and the respective switching elements 2 are made equal. It is possible to make the wiring inductance uniform.
As a result, the wiring inductance from the smoothing capacitor 6 to each switch element 2 can be made uniform.

Furthermore, since the above-mentioned approximately L-shaped connecting piece is orthogonal to the main bodies of the DC buses 4 and 5, it is less susceptible to the magnetic field generated by the current. In the above embodiment, by providing the folded-back portions 30a and 30b on the output bars 9, 10 and 11, it is possible to cancel the wiring inductance corresponding to the extended wiring distance.

Next, FIGS. 5 to 7 show a second embodiment of the present invention, in which the same members as those in the first embodiment are designated by the same reference numerals. This embodiment is a case where two switch elements 2 cannot be vertically arranged in three stages due to restrictions on the element layout. As shown in FIG. 5, the directions of the two switch elements 2 are different. 4 are arranged orthogonally to each other. Note that FIG. 5 shows the configuration of the main part, and in reality, a DC bus, a snubber capacitor, a smoothing capacitor, etc., which will be described below, are further connected. In addition, in FIG.
A and 10A are U-phase and V-phase output bars, respectively.

In this embodiment, the negative DC bus 4A has the structure shown in FIG. 6 and the positive DC bus 5A has the structure shown in FIG. 7, and the positive DC bus 5A is on the upper side. Are laminated via an insulating plate (not shown). By attaching the short-circuit bar 13 to the DC bus 5A on the positive side, wiring can be performed by simple processing. Although not shown, the short-circuit bar 13 may be integrated to form the DC bus 5A.

Next, FIGS. 8 to 12 show a third embodiment of the present invention.
An example is shown. This embodiment is an example in which the switch elements 2 are arranged in three rows, as is apparent from FIG. 8 which is compared with FIG. In FIG. 8, the smoothing capacitor 6 is not shown.

In this embodiment, spacer bars 14 and 15 having the structure shown in FIGS. 9 and 10 are formed to support the central portions of the DC busbars 4B and 5B. Figure 11
Shows the output bars 9B, 10B, 11A of each phase,
Corresponding to the arrangement of three switch elements 2 in the lateral direction, three through holes 31 for terminal connection are provided. FIG. 12 shows the DC buses 4B and 5B, and a large square hole 33 is formed in a portion where the positive electrode and the negative electrode interfere with each other to ensure a sufficient insulation distance.

Although each of the above embodiments is the case where the present invention is applied to an inverter, the idea of the present invention can be applied to a rectifier circuit, a chopper, a cycloconverter and the like. The type of the semiconductor switch element is not limited to the IGBT, and may be an ordinary bipolar transistor, FET, various thyristors, etc., and the number thereof, the number of phases of the power converter, the number of snubber capacitors and smoothing capacitors are not limited. It's not the one.

[0028]

As described above, according to the present invention, the switch element, the snubber capacitor, the DC bus, and the smoothing capacitor are sequentially arranged in a laminated manner above the cooling body. The wiring distance can be shortened to be almost uniform. As a result, it is possible to reduce and equalize the wiring inductance, eliminate the risk of overcurrent or overvoltage destroying the switch element, etc., and increase the cost due to the rating of the element and the capacity of the snubber capacitor.
It is possible to prevent the size of the entire device from increasing. Furthermore, by arranging the switch elements symmetrically with respect to the DC busbar and devising the structure of the output bar, it is possible to further reduce the wiring inductance and make it uniform, and it is also possible to reduce the number of parts by improving the DC busbar. Becomes

[Brief description of drawings]

FIG. 1 shows a configuration of a first embodiment of the present invention,
(A) is a plan view, (b) is a front view, and (c) is A of (b).
FIG.

FIG. 2 is a perspective view of each phase output bar in the first embodiment.

FIG. 3 is a perspective view of positive and negative DC buses in the first embodiment.

FIG. 4 is a circuit diagram of the first embodiment.

FIG. 5 is a plan view showing the configuration of the main part of the second embodiment of the present invention.

FIG. 6 is a perspective view of a DC busbar of a negative electrode in the second embodiment.

FIG. 7 is a perspective view of a DC bus of a positive electrode in the second embodiment.

FIG. 8 is a front view showing the configuration of the main part of the third embodiment of the present invention.

FIG. 9 is a front view and a side view of a spacer bar according to a third embodiment.

FIG. 10 is a front view and a side view of a spacer bar according to a third embodiment.

FIG. 11 is a perspective view of an output bar in the third embodiment.

FIG. 12 is a perspective view of a DC bus bar in a third embodiment.

FIG. 13 shows a prior art, (a) is a plan view,
(B) is a front view.

[Explanation of symbols]

1 Cooling Body 1a Fin 2 Semiconductor Switching Element 3 Snubber Capacitor 4, 4A, 4B, 5, 5A, 5B DC Bus 4a, 5a Capacitor Connection Part 6 Smoothing Capacitor 7, 8, 13 Shorting Bar 9, 9A, 9B, 10, 10A , 10B, 11, 11A
Output bar 12 Insulation plate 14 and 15 Spacer bar 30a and 30b Folding part 30c Straight part 31 Through hole 32 Output terminal block 33 Square hole

Claims (3)

[Claims] 1. A plurality of semiconductor switch elements, a snubber capacitor connected to these switch elements, a smoothing capacitor as a power source, and positive and negative DC bus lines connected to the smoothing capacitor on a cooling body. In the power converter in which at least the above is arranged, a switch element, a snubber capacitor, a DC bus, and a smoothing capacitor are sequentially arranged in a laminated form on the upper surface of the cooling body. 2. The power converter according to claim 1, wherein the DC busbars of the positive electrode and the negative electrode are arranged in a laminated manner with an insulating material interposed therebetween, and the switch elements are arranged substantially symmetrically below the DC busbars. 3. The electric power according to claim 1 or 2, wherein the output bars of the respective phases, which are connected to the output terminal block by short-circuiting the output terminals of the plurality of switch elements, are provided with folded portions parallel to each other. Converter.