JPH11275871A - Inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb switching overvoltage for cancellation by connecting DC positive electrode terminal and the DC negative electrode terminal of a pair of control element arms in common respectively, and arranging snubber capacitors between the terminals for each control element. SOLUTION: This inverter is provided with respective DC positive electrode terminals P1 , P2 , P3 and DC negative electrode terminals N1 , N2 , N3 of control elements 21-26 which are connected in series as the respective control elements, which are connected in common by the use of a positive electrode plate conductor PP and a negative electrode plate conductor NP. Snubber capacitors 1a, 2a, 1b, 2b, 1c, 2c divided into two between PP, NP plates are dividedly-connected for each control elements 21-26. Therefore, the snubber capacitors 1a, 2a, 1b, 2b, 1c, 2c dividedly-mounted with the shortest wiring is able to absorb the switching overvoltage of the control elements 21-26 induced by a DC circuit, by unit the control element arm. It is thus possible to suppress the generation of the switching overvoltage of the control element arms.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring structure of a large-capacity single-phase or three-phase bridge inverter applied to a reactive power device for power or an active filter.

[0002]

2. Description of the Related Art Hitherto, for a large-capacity bridge inverter using a high-speed control element, for example, an IGBT, an inverter main circuit wiring method as described in, for example, Japanese Patent Application Laid-Open No. 8-32020 has been adopted. That is, the DC charging capacitors are mounted collectively and collectively.

[0003] Further details will be described with reference to FIG. 3. 31, 32, 33, 34, 35, and 36 are transistors of a control element, 3 A is a DC charging capacitor, and 3 B is for absorbing a surge voltage of a circuit. The snubber capacitors 37, 38, and 39 connect the inverters to the system connection terminals U,
This was a reactor for connecting to V and W.

In such a bridge inverter configuration, wiring inductances l ₃₁ , l ₃₂ , l on the DC side due to wiring materials are provided.
₃₃ , l34, _l3A are present, and not only increase the wiring inductance, but also control elements 31, 32, ₃₃ , ₃₄ , ₃₅ , ₃₆ connected in series as transistor arms.
Have an unbalanced inductance for each of the.

For example, when the transistors 31 and 34 conduct to output a voltage from the capacitor 3A to the system connection terminals U and V, there is a wiring inductance of (l ₃₁ + l ₃₃ + l ₃₄ + l _3A ). , when outputting a voltage between 35 becomes conductive line connecting terminals V, W there is wiring inductance (l ₃₄ + l _3A).

[0006]

In the above-mentioned conventional configuration, since the DC charging capacitor 3A and the snubber capacitor 3B are centrally arranged, the larger the inverter capacity, the larger the shape of the DC charging capacitor 3A and the snubber capacitor 3B. The control elements 31, 32, 33,
The switching overvoltage due to the increase in the wiring inductance between the DC charging capacitors 3A, 34, 35, and 36 increases, and the effect of the snubber capacitor 3B decreases.

In severe cases, the control elements 31,
32, 33, 34, 35, and 36.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and reduces the wiring inductance of a DC circuit and the irregularity of the wiring inductance between control element arms.
The switching overvoltage of the control element arm is suppressed, the reliability of the inverter is increased, and the DC positive terminal and the DC negative electrode are provided by a snubber capacitor installed between the DC positive terminal and the DC negative terminal of each control element arm. An object of the present invention is to absorb and cancel a switching overvoltage between terminals.

[0009]

In order to achieve the above object, an inverter device of the present invention connects a DC positive terminal and a DC negative terminal of a pair of control element arms in common,
At least one or more DC charging capacitors are arranged for each control element arm.

Further, a snubber capacitor is arranged for each control element between the DC positive terminal and the DC negative terminal of the control element arm.

[0011]

According to the above-described configuration, it is possible to reduce the wiring inductance between the control element arm and the DC charging capacitor, thereby suppressing the occurrence of switching overvoltage of the control element arm. Reliability is improved.

Further, a switching overvoltage between the DC positive terminal and the DC negative terminal can be absorbed and canceled by a snubber capacitor provided between the DC positive terminal and the DC negative terminal of each control element arm. .

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. (Embodiment 1) In the inverter configuration of FIG.
1, 12, 13, 14, 15, 16 are control elements such as IGBTs, each of which has two control elements 11, 12, 13, 1;
A pair of control elements in which 4, 15 and 16 are connected in series is called a control element arm. 1A, 1B, 1C are DC charging capacitors divided into control element units, 17, 18,
Reference numeral 19 denotes a reactor for connecting the AC output of the control elements 11, 12, 13, 14, 15, 16 connected in series to the system connection terminals U, V, W, which are the control element arms.

In FIG. 1, the wiring inductances are three control element arms, that is, control elements 11, 12, connected in series.
13, 14, 15, 16 positive terminals P ₁ , P ₂ , P ₃ ,
The wiring inductances l ₁₁ , l ₁₂ , l ₁₃ , l ₁₄ existing in the respective wirings between the negative terminals N ₁ , N ₂ , N ₃ and the wiring inductances l _1A , l _1B , existing in the divided DC charging capacitor connection. It is divided into l _1C.

In the inverter unit constructed as described above, since the DC charging capacitors 1A, 1B and 1C are divided into three parts, the wiring inductances l _1A , l _1B and l _1C are controlled differently from the conventional example. Control elements connected in series as element arms, 11, 12, 13, 14, 1
5, 16 between the DC positive terminal and the DC negative terminal (P1, N1,
P2, N2, P3, N3).

For example, when the control elements 11 and 14 conduct and output to the system connection terminals U and V, the loop inductance of the DC charging capacitor 1A is (l _1A +
l ₁₂ ), the loop inductance of the DC charging capacitor 1B (l _1B + l ₁₁ ), and the loop inductance of the DC charging capacitor 1C (l _1C + l ₁₁ + l ₁₃ + l ₁₄ ).
Are present in parallel with the P1 and N2 of the conducting control elements 11 and 14.

Therefore, the wiring inductance viewed from the conductive element is a parallel connection value of the three loop inductances.

Further, DC charging capacitors lA, lB,
The wiring inductances l _1A , l _1B , and l _1C of the control elements 11, ₁₂ , ₁₃ , and ₁₄ are larger than the wiring inductances l ₁₁ , l ₁₂ , l ₁₃ , and l ₁₄ of the control elements 11, ₁₂ , ₁₃ , and ₁₄ . Since the condition that each of l _1A , l _1B and l _1C is equal is realized, the loop inductances (l _1A + l ₁₂ ), (l _1B + l ₁₁ ), (l _1C + l ₁₁ + l ₁₃₎
+ L ₁₄ ) is equivalent to one-third of the sum (l _1A + l _1B + l _1C ) of the wiring inductance of the DC charging capacitor.

That is, the loop inductance is reduced to １ ／, respectively, and at the same time, l _1A , l _1B and l _1C become equal, so that the control elements 11, 12, 13 which are control element arms connected in series. , 14,15,1
The inductance imbalance between 6 is eliminated.

On the other hand, the inverter output current output to the system connection terminals U, V, W is equal to three DC charging capacitors l.
A, IB, and IC are divided into three and output as i _A , i _B , and i _C. Since the electromagnetic energy stored in the loop inductance is proportional to the square of the current, the loop inductance is (i _A ² + i _B ² + i _C ² ), and the stored energy (i _A + i _B + i _C ) ² when not divided
Is smaller than that in proportion to
In this case, the switching surge voltage when the element is cut off is reduced.

The wiring inductance of the snubber capacitor according to the second embodiment of the present invention will be described below.
This will be described with reference to the drawings.

(Embodiment 2) In FIG.
2,23,24,25,26 are control elements, 27,28,
29 is a reactor, 2A, 2B and 2C are DC charging capacitors, which are the same as those in FIG.

What is different from FIG. 1 is that control elements 21, 22, 23, 24, 2
DC positive terminals P ₁ , P ₂ , and P ₃ and DC negative terminals N ₁ , N ₂ , and N ₃ are commonly connected using a positive plate conductor PP and a negative plate conductor NP. Snubber capacitors 1a, 2a, 1b, 2 divided into two parts between PN plates
b, 1c, and 2c are divided and connected for each control element 21, 22, 23, 24, 25, and 26 connected in series as a control element arm.

In the inverter device configured as described above, the switching overvoltage caused by the control elements 21, 22, 23, 24, 25, and 26 connected in series, which are control element arms induced in the DC circuit, is controlled by the control element arm unit. so,
Snubber capacitors 1a, 2 divided and installed with the shortest wiring
a, 1b, 2b, 1c, and 2c, the wiring inductances l _1a , l _2a , l _1b , l _2b ,
l _1c and l _2c are small, and the snubber capacitors 1a, 2a, 1
The switching overvoltage absorbing functions of b, 2b, 1c, and 2c are large.

On the other hand, snubber capacitors 1a, 2a, 1
b, 2b, 1c, 2c, surge currents i _1a , i _2a ,
i _1b , i _2b , i _1c , i _2c are divided snubber capacitors 1
Since the current flows to a, 2a, 1b, 2b, 1c, and 2c, the withstand current capacity of each snubber capacitor is reduced, and the heat load of the snubber capacitor is reduced.

[0026]

As is apparent from the above description, the inverter device of the present invention reduces the wiring inductance of the DC circuit and the wiring inductance unbalance between the control element arms to reduce the occurrence of switching overvoltage of the control element arm. Can be reduced.

Further, a switching overvoltage between the DC positive terminal and the DC negative terminal can be absorbed and canceled by a snubber capacitor provided between the DC positive terminal and the DC negative terminal of each control element arm.

Further, since the absorbed surge current flows through the snubber capacitor in a divided manner, the heat generated by the snubber capacitor can be dispersed.

[Brief description of the drawings]

FIG. 1 is a connection configuration diagram for explaining an operation of a three-phase inverter bridge according to a first embodiment of the present invention;

FIG. 2 is a connection configuration diagram for explaining an operation of the three-phase inverter bridge according to the second embodiment;

FIG. 3 is a connection configuration diagram for explaining the operation of a conventional three-phase inverter bridge.

[Explanation of symbols]

11, 12, 13, 14, 15, 16, 21, 22, 2
3, 24, 25, 26 control elements P ₁ , P ₂ , P ₃ DC positive terminal N ₁ , N ₂ , N ₃ DC negative terminal PP positive plate conductor NP negative plate conductor l ₁₁ , l ₁₂ , l ₁₃ , l ₁₄ , l _1A , l _1B , l _1C Wiring inductance 17, 18, 19, 27, 28, 29 Reactors 1A, 1B, 1C, 2A, 2B, 2C DC charging capacitors 1a, 2a, 1b, 2b, 1c, 2c Snubber capacitor U, V, W system connection terminal

Claims (2)

[Claims] 1. A DC positive electrode terminal and a DC negative electrode terminal of a pair of control element arms constituting a single-phase or three-phase bridge are commonly connected, and at least one DC charging capacitor is provided for each control element arm. An inverter device characterized by the following. 2. The inverter device according to claim 1, wherein a snubber capacitor is arranged between the DC positive terminal and the DC negative terminal of the control element arm for each of the control element arms.