JPH0884482A - Inverter - Google Patents

Abstract

PURPOSE: To reduce the size of an inverter by forming the inverter section from a power semiconductor module for three-phase circuit incorporating a power semiconductor element using a predetermined element and forming the converter section of other elements in the same module and an external power semiconductor element. CONSTITUTION: Four elements 1a-1d are selected from six power semiconductor elements built in a power semiconductor module 7 for three-phase circuit and the series circuits of two elements are connected in parallel into a single phase circuit constituting an inverter section 1 wherein a load 3 is connected with each series joint through an output transformer 5. Two switching elements 11a, 11b, other than the four elements at the inverter section 1, are connected in series and the series circuit is connected in parallel with an external power semiconductor module 12 connected in series with the semiconductor elements 11c, 11d to obtain a single phase circuit for constituting a converter section 11 where a power supply 4 is connected with each series joint through an input transformer 6. The converter section 11 is connected, on the output side thereof, with the input side of the inverter section 1 through a smoothing capacitor C connected in parallel therewith.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device,
More specifically, the present invention relates to a single-phase circuit inverter device formed by using a three-phase circuit power semiconductor module.

[0002]

2. Description of the Related Art Inverter devices are used, for example, as active filters for compensating harmonics. For example, when compensating for the voltage of a household outlet, when changing from a three-phase three-wire system to a single-phase system and compensating on the single-phase side, or , When changing from a three-phase three-wire system to a three-phase four-wire system through a delta star transformer and compensating for the voltage between the neutral point and each phase on the three-phase four-wire side, an inverter device for a single-phase circuit is used, An example thereof will be described below with reference to FIG. First, in FIG. 2A, (1) is an inverter section, (2) is a converter section, (3) is a load, and (4).
Is a power supply, (5) is an output transformer, (6) is an input transformer,
(C) is a smoothing capacitor. The inverter section (1) is composed of four power semiconductor elements (1a) (1b) (1c) (1
It is for a single-phase circuit in which two d) are connected in series, and a load (3) is connected to each series connection point via an output transformer (5), and pulse width modulation (PWM) control is used. DC-AC conversion. In addition, each element is a transistor (Qa) (Q
b) (Qc) (Qd) and diode (Da) (Db) (Dc) (D
d) is a switching element in which they are connected in parallel, and the transistors are bipolar transistors (BT),
Insulated gate bipolar transistors (IGBT), MOS field effect transistors (MOSFET), etc. are available.

At this time, the module structure of the power semiconductor element is a module containing one element for large capacity, a module containing two elements for medium capacity, and a module containing six elements for small capacity. In particular, a power semiconductor module for a single-phase circuit incorporating four power semiconductor elements is in low demand and is not marketed alone. On the other hand, a power semiconductor module for a three-phase circuit, in which six power semiconductor elements (1a) (1b) ... Are incorporated, has a great demand for motor control and is generally popular. Therefore, since the single-phase circuit has almost a small capacity, the above-mentioned four elements use a commercially available power semiconductor module for three-phase circuit (7) as shown by the dotted line in the figure, and four elements from there. With
The other two in the module (7) are left unused, as shown in the double focus line (7a). Alternatively,
Although not shown, the single-phase circuit inverter unit (1) may use two modules having the smallest capacity among the modules having two elements.

The converter section (2) is a diode converter for a single-phase circuit in which four diodes (De), (Df), (Dg), and (Dh) are connected in series, and two diodes are connected in parallel. The power supply (4) is connected via the input transformer (6), and the output side is connected to the input side of the inverter section (1) via the three-phase circuit smoothing capacitor (C) connected in parallel to it. Here, the four elements are three-phase circuit diode modules (8) in which six diodes (De) (Df) ... Are incorporated, as shown in the dotted line, as in the inverter section (1). To 4 diodes (De) (Df)
(Dg) (Dh) is used. For the other two, 2
Leave unused, as shown in the focus line (8a).

Since the inverter section (1) and the converter section (2) serve as heat sources, although not shown, the inverter section (1) is mounted on a cylindrical heat sink that absorbs and cools heat by the air blown by a cooling fan. Also, each module of the converter section (2) is directly mounted and cooled together with each power supply transformer for applying the gate voltage. However, since the size and the heat capacity of the heat sink are set so as to correspond to the power semiconductors and the diode modules (7) and (8) for the three-phase circuit, the single-phase circuit actually has a margin in heat capacity. .
Further, in order to disperse the heat generating region, of the six elements of each of the power semiconductors and diodes for the three-phase circuit (7) and (8), the two elements located in the central portion may not be used. .

In the above structure, the power supply voltage (E) is transformed through the input transformer (6) and is subjected to direct full-wave rectification in the converter section (2), which is smoothed by the smoothing capacitor (C) and is converted into the inverter section (1). ). Therefore, the predetermined period of ON
-The element (1a) (1d) is turned on by the OFF control and the element (1a)
b) Breaking off (1c), the discharge current of the capacitor (C) changes from the element (1a) to the terminal (U) of the transformer (5) and the load (3).
When passing through (V), passing through the element (1d) and returning to the capacitor (C), a positive half-wave discharge pulse waveform appears at the terminals (U) and (V). Next, the elements (1b) and (1c) are turned on to cut off the elements (1a) and (1d), and the discharge current of the capacitor (C) changes from the element (1b) to the terminals of the transformer (5) and the load (3). When passing through (V) and (U) and again through the element (1c) and returning to the capacitor (C), a negative half-wave discharge pulse waveform appears at the terminals (U) and (V). Therefore, by ON-OFF control
By controlling each pulse width in the ON region and the OFF region and further shaping the waveform into a sine wave through a filter, direct current is converted into alternating current having a predetermined frequency. At this time, although not shown, the smoothing capacitor (C) is divided into two and provided in the vicinity of the converter unit side and the inverter unit side respectively, and the smoothing capacitor (C), the converter unit (2) and the inverter unit (1) are provided. Shorten each distance. As a result, when a pulse waveform is generated by switching control, the surge distortion that occurs in the flat portion of the ON waveform is suppressed, and the suppression prevents the ON waveform from exceeding the overvoltage withstand capability of the element.

Also, another conventional inverter device is shown in FIG.
It shows with reference to (b). The difference is that four switching elements (9a) (9b) (9c) (9) in which a transistor and a diode are connected in parallel instead of a diode converter as a converter unit (9) for converting AC to DC are used.
d)) PWM (pulse width modulation) converter
A single-phase full-bridge inverter device is formed by controlling the voltage by M control. Also in this case, as shown in the dotted line in the figure, four elements are used from the commercially available power semiconductor module for three-phase circuit (10), and the other two in the module (10) are double-focused. Leave unused as shown in (10a).

[0008]

The problem to be solved by the present invention is that no power semiconductor module for a single-phase circuit is currently on the market, and when an inverter device for a single-phase circuit is formed,
Since the power semiconductor modules for three-phase circuits (7), (8) and (10) are used, some of the elements shown within the dotted lines (7a), (8a) and (10a) in the modules (7), (8) and (10) However, the cooling device such as a heat sink has a wasteful portion in terms of heat capacity and size, which is wasteful in terms of cost and is large in size.

[0009]

SUMMARY OF THE INVENTION According to the present invention, six power semiconductor elements incorporated in a commercially available power semiconductor module for a three-phase circuit are connected in parallel by connecting two of four elements each in series. In addition, the inverter part for a single-phase circuit, in which a load is connected to each series connection point via an output transformer, and the other two elements in the module are connected in series, and an external 2 Power semiconductor elements are connected in parallel, a power supply is connected to each series connection point via an input transformer, and the output side is connected to the input side of the inverter section via a smoothing capacitor connected in parallel to it. And a converter section for a single-phase circuit as described above.

[0010]

According to the above technical means, when forming an inverter device for a single-phase circuit, an inverter is formed by using four elements from a commercially available power semiconductor module for a three-phase circuit in which six power semiconductor elements are incorporated. And the other two elements in the same module and the two external power semiconductor elements form a converter section. This reduces the number of commercially available power semiconductor modules for three-phase circuits from two to one.

[0011]

Embodiment FIG. 1 shows an embodiment of an inverter device according to the present invention.
This will be described below with reference to (a) and (b). The same parts as those shown in FIG. 2 are designated by the same reference numerals. First, Fig. 1 (a)
In (1) is the inverter section, (3) is the load, and (4)
Is a power supply, (5) is an output transformer, (6) is an input transformer,
(C) is a smoothing capacitor, and (11) is a converter section. As in the conventional case, the inverter part (1) has four elements (1a) out of six power semiconductor elements incorporated in a commercially available power semiconductor module for three-phase circuit (7) as shown in the dotted line. Select (1b) (1c) (1d) and set them to 2
For single-phase circuits that are connected in series and connected in parallel,
A load (3) is connected to each series connection point via an output transformer (5), and DC-AC conversion is performed by pulse width modulation (PWM) control.

The converter section (11) is made up of the commercially available three-phase circuit power semiconductor module (7) to the inverter section (1).
An external element in which two power semiconductor elements (11c) (11d) are connected in series to two unused switching elements (11a) (11b) other than the four elements used in It is for a single-phase circuit in which two power semiconductor modules (12) are connected in parallel, and a power supply (4) is connected to each series connection point via an input transformer (6). Then, the output side is connected to the input side of the inverter unit (1) via the smoothing capacitor (C) connected in parallel with it. The external power semiconductor module (12) is a diode module using two diodes (Di) (Dj) as power semiconductor elements (11c) (11d) to form a half-bridge inverter device.

Next, another embodiment of the present invention will be described with reference to FIG. 1 (b). The difference is that a power semiconductor module (14) containing two external elements of the converter section (13). Replace the diode module (12) with a diode (D
A full bridge inverter device is formed by using a transistor module including switching elements (11e) and (11f) in which m) (Dn) and transistors (Qe) and (Qf) are connected in parallel.

According to the above construction, it is possible to reduce the number of power semiconductor modules for three-phase circuits from one in the conventional case to one,
And there is no unused part. Furthermore, the number of power supply transformers for applying gate voltage and the smoothing capacitors of the module can be reduced from two in the conventional case to one. However, the number of secondary windings of the power transformer is increased by the number of external elements as necessary. Further, the heat capacity and size of the cooling heat sink can be set to be about half as small as the conventional one.

[0015]

According to the present invention, when forming an inverter device for a single-phase circuit using a power semiconductor module for a three-phase circuit, an unused element and an external attachment of the power semiconductor module for a three-phase circuit in an inverter section are externally attached. Since the converter part is formed with the element of 3), only one power semiconductor module for three-phase circuit is required, the power transformer and smoothing capacitor of that module are reduced, the number of components is reduced, and the cooling heat sink is also reduced. It is possible to realize cost reduction and device miniaturization. Also, the unused portion of the power semiconductor module for a three-phase circuit is eliminated and it can be effectively used.

[Brief description of drawings]

FIG. 1A is a circuit diagram showing an embodiment of an inverter device according to the present invention. (B) is a circuit diagram showing another embodiment of the inverter device according to the present invention.

FIG. 2A is a circuit diagram showing an example of a conventional inverter device. (B) is a circuit diagram showing another example of the conventional inverter device.

[Explanation of symbols]

 1 Inverter section 1a, 1b, 1c, 1d Power semiconductor element 3 Load 4 Power supply 5 Output transformer 6 Input transformer 7 Power semiconductor module for three-phase circuit 11, 13 Converter section 11a, 11b Power semiconductor element 11c, 11d, 11e, 11f External power semiconductor element C smoothing capacitor

Claims (1)

[Claims] 1. A power semiconductor module for a three-phase circuit, which is incorporated in a commercially available power semiconductor module, is composed of six power semiconductor elements, each of which has four elements connected in series, and two elements are connected in series. Two external power semiconductor devices connected in series are connected in parallel to a single-phase circuit inverter part connected to a load via an output transformer and two other devices in the module connected in series. A single-phase circuit converter unit in which a power supply is connected to each series connection point via an input transformer, and the output side is connected to the input side of the inverter unit via a smoothing capacitor connected in parallel to it. An inverter device comprising: