JPH01122370A - Transistor inverter - Google Patents

Abstract

PURPOSE:To effectively prevent a transistor from breaking down by connecting a plurality of sets of 3-phase bridges of transistors in parallel, and providing current detectors in the respective 3-phase bridges. CONSTITUTION:A transistor inverter is composed by connecting 3-phase bridges 7-1-7-N to DC power sources 1, 2 and bridge-connecting 6 transistors QU-QW. Further, U--W-phase output lines 17-19 are respectively connected in parallel with output lines 4A-6A. In this case, overcurrent detectors 20-1-20-N are respectively provided at the DC sides of the respective bridges 7-1-7-N. Thus, the currents which flow to the bridges 7 are for one parallel connection of the transistors, the detectors 20 can be easily provided in the respective bridges, thereby inexpensively and effectively protecting them.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transistor inverter device formed by bridge-connecting a plurality of transistors.

[Prior art] Figure 3 shows, for example, Fuji Jiho Vo1.57. No, 7.19
84, in which (IL (2) is an input terminal connected to a DC power supply, (3A), (3B), (3C
) is a group of transistors connected to input terminals (1) and (2) and outputting three-phase alternating current (U phase, ■ phase, W phase).

Here, the transistor group (3A) is configured by connecting N sets of transistor arms (transistor arms) in parallel, each consisting of a pair of upper and lower transistors QL]t, QXi(it, 2.-, N). Both ends of the upper and lower arms of are connected to input terminals (1) and (2), respectively.

Similarly, the transistor group (3B) is also QVi.

QYi (i・1.2...,N) is connected to the input terminals (1), (2), and the transistor group (3C) is also connected to QWi, QZi (i=1,2...,N). ”
, N) and are connected to input terminals (1) and (2).

On the other hand, in Figure 3, (4), (5), and (6) are 3
These are output terminals for phase alternating current (U phase, ■ phase, and W phase, respectively), and these output terminals (4), (5), and (6) are connected to output lines (4a), (5a), and (6a), respectively. It is connected. And output lines (4a), (5a), (6
a) are transistor groups (3A) and (38
), (3C:) N sets of arms are connected in parallel.

In addition, (10) is a smoothing capacitor inserted in the input terminals (1) and (2), and (11) to (16) are transistors QL]i, QVi, QWI, QXi, QYi, Q, respectively.
Zi, (i=1.2....,N) (This is a terminal that supplies base current (base drive signal) to the D base.

In this way, the conventional transistor inverter device has three
It is configured separately into three transistor groups (3A), (3B), and (3C) for each phase alternating current (U phase, ■ phase, W phase).

Next, the operation will be explained. The DC current input from the input terminals (1) and (2) is applied to each transistor group (3A),
(3B), (3G), and after AC conversion is performed in each transistor group (3A), (3B), (3G), from output terminals (4), (5), (6) to 3
Phase alternating current (U phase, ■ phase, W phase) is output.

In the conventional transistor inverter device, the current value flowing through each transistor group (3A), (3B), and (3C) is equal to the output current value, making it difficult to detect current imbalance within each group.

[Problem that the invention seeks to solve]

Since the conventional transistor inverter device is configured as described above, it is difficult to protect the transistors when an unbalance in the currents of the transistors in each arm occurs, and there is a problem that the transistors may be destroyed.

This invention was made to solve the above-mentioned problems, and provides a transistor inverter that can protect transistors from destruction by making it possible to protect transistors in the case of current imbalance of each transistor regardless of the number of parallel transistor arms. The purpose is to obtain equipment.

(Means for Solving the Problems) A transistor inverter device according to the present invention includes a plurality of sets of three-phase bridge circuits formed by bridge-connecting transistors connected in parallel, and each of the three-phase bridge circuits described above. The in-phase output lines of the three-phase bridge circuit are connected in parallel, and an overcurrent detection circuit is provided for each three-phase bridge circuit.

[Effect]

In the transistor inverter device according to the present invention, 3
Since the phase bridge circuits are connected in parallel to each other, the current flowing through each three-phase bridge circuit is equivalent to one parallel transistor, and an overcurrent detection circuit can be easily provided for each three-phase bridge circuit. This results in a transistor inverter device that is inexpensive and has reliable protection.

〔Example) An embodiment of the present invention will be described below.

FIG. 1 is a circuit diagram showing a transistor inverter device according to an embodiment of the present invention.
1), (2) are input terminals connected to the DC power supply, (4)
, (5), and (6) are three-phase AC (U phase, ■ phase, and W phase, respectively).
Output terminals (4A), (5A), and (6A) of the phase) are output lines connected to output terminals (4), (5), and (6), respectively.

Also, (7-1), (7-2), ..., (7-N)
are three-phase bridge circuits, and each three-phase bridge circuit 7-i (i=1°2, . . . , N) includes six transistors QU i , QV i , l i .

It is configured by bridge-connecting QXi, QYt, and QZi (i=1.2...,N). In other words, transistors QUi, QXi, and transistors qvi, qyi
and transistor QWi.

QZi are paired to form three arms, and these arms are connected in parallel to input terminals (1) and (2).

Furthermore, (10) is a smoothing capacitor inserted in the input terminals (1) and (2), and (11) to (16) are transistors QUi, QVi, QWi, QXi, QYi, and Q, respectively.
Zi (i-1, 2, . . . , N) tf) This is a terminal that supplies a base current (base drive signal) to the base.

On the other hand, (17-1), (17-2), ..., (17
-N) are three-phase bridge circuits (7-1) and (7
-2), ..., (7-N), and these U phase ratio lines (17-1), (17-2), ..., (17 -N)
are connected in parallel to the output line (4A). Also, (1
8-1), (18-2), ..., (18-N) are three-phase bridge circuits (7-1), (7-2), ..., respectively.
・, (7-N) are the V phase ratio lines as in-phase output lines, and these V phase ratio lines (18-1)
, (18-21, . . . , (18-N)) are connected in parallel to the output line (5A).

Similarly, (19-1), (19-2), ..., (1
9-N) are three-phase bridge circuits (7-1) and (7
-2), ..., (7-N) are W phase ratio lines as in-phase output lines, and these W phase ratio lines (19-1), (19-2), ..., (19-N
) are connected in parallel to the output line (6A).

Therefore, (2(1-1), (20-2), -,
(20-N) is each three-phase bridge circuit (7-1), (7-
2), ..., (7-N) is an overcurrent detection circuit provided on the DC side.

Next, the operation will be explained. The DC current input from input terminals (1) and (2) is connected to each three-phase bridge circuit (7-1
+, (7-, 2L..., (7-N)), each 3
Phase bridge circuit (7-1), (7-2), ..., (7
-N), an AC conversion takes place. Then, the converted three-phase AC (U phase,
-1,2,...,N) to output lines (4A), (5
A) and (6^) are respectively output.

By the way, in the embodiment of the present invention, the current value flowing through a set of three-phase bridge circuits (7-i) (i=1.2...,N) is determined by the output terminals (4), (5), ( The output current value is 1/N times the output current value in 6), and only one transistor flows in parallel. Therefore, by providing an overcurrent detection circuit on the DC side or AC side for each set of three-phase bridge circuits, one transistor in parallel can be This enables protection for each (every three-phase bridge circuit).

In the conventional circuit, the upper and lower arms form a parallel circuit,
It is difficult to provide a current detection circuit for each parallel transistor, and it is impossible to detect when current imbalance occurs in the parallel transistors, resulting in destruction of the transistors. In the circuit of this embodiment, since a detection circuit is provided for each three-phase bridge, it is possible to reliably protect the transistors even if current imbalance occurs in the parallel transistors.

Note that the embodiment in FIG. 1 includes a three-phase bridge circuit (7-1),
Overcurrent detection circuit (20-1), (2G-2), ..., (2G-
N), but the overcurrent detection circuit (21-1) in Figure 2
, (21-2), ..., (21-N), (22-1
), (22-2), . . . , (22-N) may of course be provided on the AC side.

(Effects of the Invention) As described above, according to the present invention, a plurality of sets of three-phase bridge circuits formed by bridge-connecting transistors are connected in parallel to each other, and a current detection circuit is provided for each of the three-phase bridge circuits. This has the effect of reliably preventing transistor breakdown.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a transistor inverter device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing another embodiment of the invention, and FIG. 3 is a circuit diagram showing a conventional transistor inverter device. . In the figure, (7-1), (7-2), ..., (7-N),
3-phase bridge circuit, (17-1), (17-21,...
・, (17-N); U phase ratio line as in-phase output line, (18-1), (18-2), ..., (18-N)
; V phase ratio line as common-mode output line, (19-1), (19-2), ..., (19-N)
; W phase ratio line as common mode output line, QUI, Q [I2, ・QUN, QVI, QV2, ・, Q
VN, QWI, QW2, ・QWN. QXI, QX2, -, QXN, QYI, QY2, ., Q
YN, QZI, QZ2,... QzN: Transistor. (20-1), <2O-2), ., (20-N);
DC side overcurrent detection port (21-1), (21-2),...
・, (21-N), (22-1), (22-2),
..., (22-N); AC side overcurrent detection circuit. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Masuo Oiwa Figure 1 Figure 2

Claims (1)

[Claims] A plurality of sets of 3-phase bridge circuits formed by bridge-connecting transistors are connected in parallel to form a transistor inverter device, and in-phase output lines of each of the 3-phase bridge circuits are connected in parallel to form each 3-phase bridge circuit. 1. A transistor inverter device characterized in that an overcurrent detection circuit is provided for each of the transistors, thereby making it possible to detect current imbalance.