JPH0318285A - Inverter device - Google Patents

Abstract

PURPOSE:To decrease the number of components required and to make an inverter device small-sized and inexpensive by suitably selecting either a braking circuit or a boosting chopper circuit to form each circuit between a voltage type inverter. CONSTITUTION:When an induction motor 6 is operated in a regenerative mode and the voltage EDC at a DC capacitor 4 is raised by regenerative power, a thyristor 18 is turned ON and a braking circuit 9 is formed by a resistance 7, the thyristor 18 and a transistor 16. When an converter 1 goes wrong, a thyristor 17 gets 'ON' stage, while the thyristor 18 'OFF' state. A boosting chopper circuit 10 is formed by the thyristor 17, transistor 16 and further a capacitor 12, a reactor 13 and a diode 15, which controls voltage EDC. Both braking circuit and boosting chopper circuit can thereby be suitably selectively used, so that the number of components can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inverter device, and particularly to an inverter device equipped with a brake circuit and a step-up chopper circuit for keeping the DC voltage constant.

[Conventional technology]

FIG. 2 is a circuit diagram showing a general circuit configuration of a voltage source inverter. In the figure, (1) is the converter as the first DC power supply connected to the AC power supply (2), (3) the beam actor, f4) is the DC capacitor, (the phrase is the voltage connected to the DC capacitor (4) A type inverter converts the DC power from the converter (1) into AC power and outputs it to the induction motor (6), which is an AC load.

By the way, when the operation of the induction motor (6) becomes the regeneration mode, the regenerated power reaches the DC side of the voltage source inverter (5) and increases the voltage EDC of the DC capacitor (4).

In order to keep the usage conditions of each device within a certain range, it is necessary to suppress the above voltage increase within a predetermined range.

Figure 3 shows the circuit configuration in this case, where:
A brake circuit (9) consisting of a series body of a resistor (7) and a self-extinguishing transistor (8) as a first switch.
is connected between both terminals of the DC capacitor (4). Then, when the voltage EDC rises above a predetermined value, 1
・The induction motor (6) is controlled by turning on/off the transistor (8).
) is consumed by the resistor (sword) to suppress the rise in voltage EDC.

Conversely, FIG. 4 shows a circuit configuration for performing voltage compensation when the voltage EDC drops below a predetermined value. That is, a step-up chopper circuit QOI, which will be described below, is connected between both terminals of the DC capacitor (4). (l1) and (12) are a converter connected to an AC power source (2) and a capacitor connected to this converter (11), respectively, and correspond to a second DC power source. (13) Hari Aku 1 Hell, (
14) Output measurement of the beam actor (13) ↓A self-extinguishing transistor as a second switch connected to the
5) is a diode connected to the output f-law of 1 to transistor (14). And the above (II) to (15)
The above-mentioned boost chopper circuit QOI is configured.

In FIG. 4, for example, when the converter (1) fails and causes a momentary power outage, the voltage EDC immediately begins to drop. When this becomes less than a predetermined value, the transistor (14) of the boost chopper circuit 00) is controlled to turn on and off, and the capacitor (14) is turned on and off.
The energy stored in 2) is transferred to the DC capacitor (4) via the reactor (l3) and diode (15).
and suppresses a drop in the voltage EDC.

In addition, in FIGS. 3 and 4, the DC capacitor (4) and the brake circuit {9} or the boost chopper circuit 0
0) and means for switching are not shown in the drawings, but appropriate connection means such as a thyristor or a transistor is provided in consideration of the capacity, switching frequency, etc.

[Problem to be solved by the invention]

Since the conventional inverter device is configured as described above, the voltage source inverter (the brake circuit (9) for keeping the DC voltage constant and the step-up chopper circuit 00)
) is set up independently? -J, and the problem was that the overall number of parts was large, making the device large and expensive (3).

The present invention has been made to solve the above-mentioned problems, and aims to provide an inverter device that reduces the number of required parts, is smaller in size, and is less expensive.

[Means to solve the problem]

In the inverter device according to the present invention, a single switch is used in common as the first switch and the second switch, and further, the inverter device is connected to the single switch to appropriately select one of the brake circuit and the step-up chopper circuit. A circuit selection means for forming each of the above circuits is provided between the voltage source inverter and the voltage source inverter.

[For production]

When the DC voltage of the voltage source inverter exceeds a predetermined value, the circuit selection means first operates to form a brake circuit including a shared switch. Next, the shared switch is controlled to turn on and off, causing the resistance that controls the brake circuit to consume the regenerative power from the AC load, thereby suppressing the rise in DC voltage.

When the DC voltage falls below a predetermined value, the circuit selection (4) means operates again to eliminate the step-up chipper concave path including the shared switch. Subsequently, the shared switch is controlled on and off, and power is supplied from the second DC power supply forming the boost chopper circuit to suppress a drop in the DC voltage.

〔Example〕

FIG. 1 is a circuit diagram showing the circuit configuration of an inverter device according to an embodiment of the present invention. In the figure, (1) to (7
), (9) to (13) and (15) are the same as the conventional ones.

(l6) Self-extinguishing type 1 transistor as a shared single switch connected to the output side of the beam actor (l3), (17) Beam actuator (l3) and diode (
The thyristor (l8) is connected between the intermediate connection point between the resistor (7) and the transistor (l6), and the thyristor (17) and the thyristor (l8) constitute a circuit selection means (19).(20) is a brake chopper circuit, and by operating the circuit selection means (l9),
A brake circuit (9) or a boost chopper circuit (101) is selectively formed between the DC capacitor (4) and the DC capacitor (4).

Next, the operation will be explained. First, the conductive motor (6) is operated in regenerative mode, and when the voltage EDC of the DC capacitor [4J] rises and reaches a predetermined value or more due to the regenerated power, the circuit selector (19) turns on the circuit selector (l8). . As a result, a brake circuit (9) is formed by the resistor (71.Sirisk (18)) and 1.Ransisk (16), and as in the past, the 1.Ransistor (16) is controlled on/off to control the induction motor (6). The regenerative power from the brake is consumed by the resistor to suppress the rise in voltage EDC.In other words, in this case, the brake chopper circuit (20) is connected to the brake circuit (9).
).

Next, when the voltage EDC of the DC capacitor (4) drops below a predetermined value due to a failure of the converter (1) or the like, the thyristor (17) of the circuit selection means (19) is turned on. Of course, in this case, the Sairisk (18) is in an off state. As a result, cyrisk (17), transistor (1
6) Furthermore, a capacitor (step-up chopper circuit α0 by 12L reactor (13) and diode (15)) is formed, and turns on/off the transistor (16) to transfer the energy stored in the capacitor (l2) to the reactor. (13) and the diode (15) to the DC capacitor (4) to suppress a drop in the voltage EDC.

That is, here, the brake chopper circuit (20) functions as a boost chopper circuit 00).

As mentioned above, since the transistors, which are the main components of both circuits f91 00) and require high-frequency switching operation, are shared by a single transistor (16), the main components are reduced accordingly. As a result, the device becomes smaller and cheaper, and reliability also improves.

In the above embodiment, a transistor is used as the switch (16), but other types of self-extinguishing elements may be used. In addition, the circuit selection means (
19> is made of Cyrisk, but other types of self-extinguishing elements may be used.

Furthermore, a single switch (16) may be composed of a plurality of switching elements.

〔Effect of the invention〕

As described above, in this invention, the switches necessary for both the brake circuit and the boost chopper circuit are shared by a single switch, and one of the two circuits is selected and formed as appropriate (7). Since the means is provided, the number of necessary switches is reduced compared to the conventional case, and the device becomes smaller and cheaper accordingly.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing the circuit configuration of an inverter device according to an embodiment of the present invention, Fig. 2 is a circuit diagram showing a general circuit configuration of a voltage source inverter, and Fig. 3 is a conventional circuit diagram showing a conventional circuit forming a brake circuit. FIG. 4 is a circuit diagram showing a conventional circuit structure in the form of a boost chopper circuit. In the figure, (1) is a converter as the first DC power source, (4) is a DC capacitor, (5) is a voltage source inverter, (6) is an induction motor as an AC load, (7) is a resistor, and (9) is a voltage source inverter. ) is a brake circuit, 00) is a step-up chopper circuit, <l1) and (12) are a converter and a capacitor as a second DC power source, respectively, (l6) is a 1 transistor as a shared single switch, (19) ) is a circuit selection means, and (20) is a brake/shipper circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts (8).

Claims (1)

[Claims] a voltage source inverter that is connected to a first DC power source and converts the DC power into predetermined AC power and outputs it to an AC load;
Comprised of a first switch and a resistor, when the DC voltage of the voltage source inverter rises above a predetermined value due to the regenerated power from the AC load, the first switch is controlled on and off, and the regenerated power is consumed by the resistor. a brake circuit that suppresses the increase in the DC voltage by controlling the DC voltage; a second switch; and a second DC power source; A step-up chopper circuit that suppresses a drop in the DC voltage by supplying power from a second DC power source, wherein the first switch and the second switch are shared by a single switch, An inverter device comprising circuit selection means connected to the single switch to select and form one of the two circuits as appropriate.