JPH0956169A - Inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformalize electrical burden on a pair of snubber capacitors by connecting the pair of the snubber capacitors with the same and small lead length on both sides of connecting members that connect conductors to a semiconductor switching element. SOLUTION: A pair of snubber capacitors 61, 62 with the same lead length are symmetrically installed on ends of conductors 2 on both sides of crimp terminals and mounting screws 51. An elevated electric wire securing portion 2a is formed at the middle part of the conductor 2, and an end of an electric wire 3 is installed at the electric wire securing portion 2a using a crimp terminal and a mounting screw 52 different from the crimp terminals and mounting screws 51. Since both capacitors 61, 62 are connected with the crimp terminals and mounting screws 51 with the same small lead length, their wiring resistances are almost equal to each other, which uniforms their respective lives. Since the range of the snubber capacitors 61, 62 movement is limited and the distance between them and a frame is increased, insulation to current-carrying parts is unnecessary, which leads to cost reduction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter in which a snubber capacitor forming a snubber circuit, an output current detector of each phase, and the like are mounted, and the mounting structure of these components is improved.

[0002]

2. Description of the Related Art FIG. 4 is a plan view showing an arrangement of main circuit components of a conventional three-phase inverter. In the figure, 1 is an IGBT (insulated gate bipolar transistor) as a semiconductor switching element, 2 is a conductor for connecting the IGBTs 1 to each other, 5 is a crimp terminal and a mounting screw as a connecting member, 6 is a crimp terminal and a mounting screw 5. A snubber capacitor connected to the conductor 2, 8 is a current detector such as a current transformer that detects the output current of each phase, 12 is a substrate to be a cooling body, 1
3 is a metal plate for mounting the current detector 8, 16 is an input / output terminal block,
17 is a rectifying diode, 18 is a smoothing capacitor, 19 is a fuse, 20 is a contactor, 21 is an internal fan for cooling,
Reference numeral 24 is a frame made of sheet metal.

In the above structure, the IGBT 1 of each phase has two built-in elements, and correspondingly, two snubber capacitors 6 are connected per phase. And
As shown in FIG. 5, the lead lengths of the snubber capacitor 6A and the snubber capacitor 6B (both described as snubber capacitor 6 in FIG. 4) are different, and the IGBT 1 It is connected to the. Here, one snubber capacitor 6A is not insulated, and the other snubber capacitor 6B having a long lead length is insulated on the conducting portion.

In FIG. 5, reference numeral 3 denotes an electric wire that passes through the inside of the current detector 8 and is connected to the input / output terminal block 16. The electric wire 3 is a crimp terminal for attaching the snubber capacitors 6A and 6B and Conductor 2 with mounting screw 5 also used
Attached to.

FIGS. 6 and 7 show the mounting state of the current detector 8. As shown in FIG. 6, the mounting piece 8 is fixed to the dedicated mounting metal plate 13 on the substrate 12 by the fixing screw 10.
a, or as shown in FIG. 7, a fixing screw 1
A method of fixing the attachment piece 8a with the fixing screw 10 to the exclusive mounting seat 14 fixed to the substrate 12 at 5 is adopted.

[0006]

In the conventional inverter described above, according to the snubber capacitor mounting structure shown in FIG. 5, the snubber capacitor 6A having a short lead length has a smaller wiring resistance than the snubber capacitor 6B having a long lead length. A large amount of current flows, increasing the electrical burden. Further, since the snubber capacitor 6B having a long lead has a wide movable range and is close to the frame 24,
Insulation is required for the energized parts. Therefore, there is a problem that the lifespans of the capacitors 6A and 6B are different from each other, and the cost is increased due to the insulation treatment.

Further, paying attention to the mounting structure of the current detector 8, it is necessary to prepare a dedicated mounting metal plate 13 and mounting seat 14, which not only causes a high cost but also these mounting metal plates. 13 and the positioning and fixing work of the mounting seat 14 were extremely complicated.

The present invention has been made in order to solve the above problems and is intended to eliminate various inconveniences associated with the mounting structure of the snubber capacitor and the current detector.

[0009]

In order to solve the above problems, the invention according to claim 1 is an inverter in which a snubber capacitor is connected to a conductor connecting semiconductor switching elements of respective phases to each other, and the conductor is a semiconductor. A pair of snubber capacitors having substantially the same short lead length are connected to both sides of a connecting member connected to the switching element. As a result, the electrical load on the pair of snubber capacitors is averaged, and the insulating process for the conducting parts of the capacitors is not required.

According to a second aspect of the invention, in an inverter in which a current detector for detecting an output current of each phase is arranged on a substrate, the current detector is fixed to a mounting seat integrally formed with the substrate. It was done. This eliminates the need for a dedicated mounting member for mounting the current detector and its positioning.

The invention according to claim 3 is the same as claims 1 and 2 above.
It has the components and actions of the described invention,
In an inverter in which a snubber capacitor is connected to the conductors that connect the semiconductor switching elements of each phase to each other and a current detector that detects the output current of each phase is arranged on the substrate, connect the conductors to the semiconductor switching elements. A pair of snubber capacitors having substantially the same short lead length are connected to both sides of the connecting member, and the current detector is fixed to a mounting seat integrally formed with the substrate.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing the arrangement of main circuit components of this embodiment, and the same components as those in FIG. 4 are designated by the same reference numerals. As is apparent from FIG. 1, the arrangement of each component is significantly different from that in FIG. 4, but the characteristic improvement in this embodiment is the mounting structure of the snubber capacitor and the current detector, and this point is The configuration will be mainly described.

In FIG. 1, 61 and 62 are 2 per phase.
These are snubber capacitors that are individually connected, and these capacitors 61 and 62 have the same and short leads on both sides thereof by a crimp terminal and a mounting screw 51 as a connecting member attached to the conductor 2 that connects the IGBT 1 to each other. Long connected.

FIG. 2 shows the mounting state of the snubber capacitors 61, 62 in detail. In the figure, a pair of snubber capacitors 61 and 62 having symmetrical lead lengths are symmetrically attached to both ends of the crimp terminal and the mounting screw 51 at the end of the conductor 2. Further, an electric wire fixing portion 2a which is bulged upward is provided in the middle of the conductor 2, and the electric wire 3 is attached to the electric wire fixing portion 2a by a crimp terminal and a mounting screw 52 which are separate from the crimp terminal and the mounting screw 51. The ends of are attached. As described above, this electric wire 3 passes through the inside of the current detector 8 and is connected to the input / output terminal block 16.

When the mounting structure of the snubber capacitors 61 and 62 is configured as described above, any of the capacitors 61 and 62 can be connected to the crimp terminal and the mounting screw 51 with the same short lead length, so that the wiring resistance becomes substantially the same and The life of each capacitor can be averaged without increasing the electrical load on the capacitor. In addition, the movement range of the snubber capacitors 61, 62 is limited, and the frame 24
Since the distance between and becomes long, it is not necessary to insulate the current-carrying part, and the cost can be reduced.

On the other hand, in FIG. 1, the current detector 8 is provided between the IGBT 1 and the input / output terminal block 16 for each phase.
Is arranged. FIG. 3 shows the mounting state of the current detector 8. The mounting seat 9 is erected integrally with the substrate 12 by die casting, and the mounting piece 8a of the current detector 8 is mounted in the recess 9a formed in the upper portion thereof. It is attached with the fixing screw 10.

In the mounting structure of the current detector 8, since the mounting seat 9 is integrated with the substrate 12, it is not necessary to prepare a dedicated mounting member, and the cost can be reduced by reducing the number of parts. . At the same time, there is no need to attach or position the mounting seat 9 itself to the substrate 12, and the assembly can be easily performed. Further, in the structure of FIGS. 6 and 7, the current detector 8 was easily rotated around the fixing screw 10, but if the mounting piece 8a is engaged with the recess 9a as shown in FIG.
It is possible to prevent rotation of the current detector 8 and obtain a stable fixed state.

As is well known, the snubber circuit has various electric configurations, but the invention according to claim 1 or 3 has a feature in the mounting structure of the snubber capacitor, so that various snubber circuits are configured. It is applicable to a pair of snubber capacitors. The semiconductor switching element used in the inverter is not limited to the IGBT, but is a general power transistor, GTO (gate turn-off thyristor).
And so on.

[0019]

As described above, according to the first aspect of the present invention, it is possible to equalize the electrical load of the pair of snubber capacitors and make their lifespan substantially equal. Further, since it is not necessary to insulate the energizing portion of the snubber capacitor, the cost can be reduced.

According to the second aspect of the present invention, the mounting member dedicated to the current detector is not required, so that the number of parts can be reduced, and the positioning work for fixing the mounting member to the substrate is also unnecessary. Therefore, the cost can be reduced and the assembling workability can be improved.

According to the invention described in claim 3, due to the effects of each of the above inventions, it is possible to reduce the cost and improve the assembling workability of the inverter in which both the snubber capacitor and the current detector are mounted.

[Brief description of drawings]

FIG. 1 is a plan view showing an arrangement of main circuit components according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a mounted state of the snubber capacitor in FIG.

FIG. 3 is a perspective view showing a mounting state of the current detector in FIG.

FIG. 4 is a plan view showing an arrangement of main circuit components of a conventional inverter.

5 is a perspective view showing a mounting state of the snubber capacitor in FIG. 4. FIG.

FIG. 6 is a perspective view showing a mounted state of the current detector in FIG.

FIG. 7 is a perspective view showing another attachment state of the current detector in FIG.

[Explanation of symbols]

 1 IGBT 2 conductor 2a electric wire fixing part 3 electric wire 8 current detector 8a mounting piece 9 mounting seat 9a recess 10 fixing screw 12 board 16 input / output terminal block 17 rectifying diode 18 smoothing capacitor 19 fuse 20 contactor 21 internal fan 24 frame 51, 52 Crimp terminals and mounting screws 61,62 Snubber capacitors

Claims (3)

[Claims] 1. An inverter in which a snubber capacitor is connected to conductors that connect semiconductor switching elements of each phase to each other, and a pair of substantially the same and short lead lengths are provided on both sides of a connecting member that connects the conductors to the semiconductor switching elements. An inverter characterized by connecting the snubber capacitor of. 2. An inverter in which a current detector for detecting an output current of each phase is arranged on a substrate, wherein the current detector is fixed to a mounting seat integrally formed with the substrate. Inverter. 3. An inverter in which a snubber capacitor is connected to conductors that mutually connect semiconductor switching elements of each phase, and a current detector for detecting an output current of each phase is arranged on a substrate, A pair of snubber capacitors having substantially the same short lead length are connected to both sides of a connecting member connected to the semiconductor switching element, and the current detector is fixed to a mounting seat integrally formed with the substrate. And an inverter.