JPH0349567A - Current type inverter device - Google Patents

Abstract

PURPOSE:To shorten charge time by performing the charge to an energy absorbing element by the specified circuits on the converter side and on the inverter side. CONSTITUTION:A current type inverter device consists of a three-phase AC power source 1, a safety breaker 2, an AC reactor 3, a converter main circuit 4, an inverter main circuit 5, etc., and drives an AC motor 10 by the generated AC power. Moreover, these both main circuits 4, 5 are controlled by an operation control part 27 through a current control circuit 26 and base driving circuits 22, 23. And an enegy absorbing element (capacitor) 20 for the converter main circuit 4 is provided, and this os charged with electricity by an auxiliary contactor 11 for charge and a charge limiting resistance 12. Moreover, an energy absorbing element (capacitor) 21 for the invertor main circuit 5 is charged with electricity by the operation of the inverter main circuit 5.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a main circuit structure of a current source inverter, and in particular,
This invention relates to a current source inverter device that is equipped with a high voltage suppression circuit and has excellent economic efficiency and reliability.

[Conventional technology]

In a current source inverter device, when the current loop of the circuit is interrupted due to a transistor becoming non-conductive, high voltage is generated due to the inductance of a DC reactor, etc. A conventional device for suppressing high voltage is disclosed in Japanese Patent Application No. 62-97359.
As proposed in the issue, a rectifier is provided on the AC side of the converter main circuit and the inverter main circuit, and an energy absorption element and a rectifying element are connected to the DC end of the rectifier. A DC circulation circuit was installed that connected both sides, and the high voltage was absorbed by energy absorbing elements.

If the energy absorption element is not charged in advance, an excessive charging current will flow when the device is started, damaging the rectifying element etc.
The voltage drop will lead to malfunction of the control device. Therefore, a charging circuit was provided to initially charge the energy absorbing element in advance.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, in order to charge the energy absorbing element of the DC circulation circuit, a certain charging circuit is provided from a transformer or a rectifier, and therefore the cost of manufacturing and maintaining the charging circuit becomes expensive.

An object of the present invention is to construct a current source inverter device without providing a separate charging circuit.

[Means to solve the problem]

In order to achieve the above object, the present invention charges the energy absorbing element on the main circuit side of the converter using a certain circuit from an auxiliary contact and a current limiting resistor, and charges the energy absorbing element on the main circuit side of the inverter using a certain circuit. This is done by the operation of the converter main circuit.

[Effect]

Initial charging of the energy absorbing element on the main circuit side of the converter is performed through the path of the current limiting resistor and rectifier by closing the auxiliary contact. In addition, for the initial charging of the energy absorbing elements on the inverter main circuit side, as soon as the charging of the energy absorbing elements on the converter main circuit side is completed, the main contactor is closed and the converter main circuit operates to generate DC current, and the DC current circulates. It is carried out through the rectifying element on the inverter main circuit side of the circuit.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

Figure 1 is a diagram of the current source inverter device in this example. 1 is a three-phase AC power supply, 2 is a safety circuit breaker that cuts off the power supply l, 3 is an AC reactor, and 4 is a converter main circuit that converts AC power into DC power, which is composed of elements with a self-extinguishing function (transistors, etc.) , 5 is an inverter main circuit that converts DC power into AC power, which is also constructed of elements (such as transistors) having a self-extinguishing function, 9 is a current detector that detects the output current of the converter main circuit 4, and 11 is a converter. An auxiliary contact for charging the energy absorption element 20 on the main circuit 4 side, 12 a limiting resistor for limiting the charging current of the energy absorption element 20'' on the converter main circuit 4 side, 13 from the power supply L to the converter main circuit 4 Main contacts for supplying power, 14 and 15 are rectifiers connected to the AC terminals of the converter main circuit 4 and the inverter main circuit 5, 16, 17, 1
8.19 is a rectifier element connecting the DC end of the rectifier 14.15 to the converter main circuit 4 and the DC end of the inverter main circuit 5; 20.21 is an energy absorption element provided at the DC end of the rectifier 14.15. A certain capacitor, 22.23 is a base drive circuit for driving the converter main circuit 5, 24.25 is a base drive circuit, a PWM pulse generator that controls 22.23, and 26 is a PWM pulse generator on the converter main circuit 4 side. a current control circuit that controls the section 24;
7 is an operation control unit that controls the current control circuit 26 on the converter main circuit 4 side and the PWM pulse generation unit 25 on the inverter main circuit 5 side, and gives commands to open and close the main contact 13 and the auxiliary contact 11. .

FIG. 2 shows the initial charging operation of the capacitor, which is the energy absorbing element 20, 21.

This embodiment will be explained with reference to FIG. 1 and FIG. In FIG. 1, it is assumed that the safety circuit breaker 2 has already been closed at time Tl.

In the initial charging operation of the energy absorbing element (capacitor) 20 on the converter main circuit 4 side, when a device start signal is generated in the operation control section 27 at time T2, a command A to deceive the auxiliary contact 11 is generated, and the auxiliary contact 11 is activated. is closed, and by closing the auxiliary contact 11, the power supply 1, the auxiliary contact 11, and the current limiting resistor 1 are connected.
2, AC reactor 3, rectifier 14, and energy absorbing element (capacitor) 20, and the initial charging operation is completed after time t'.

Next, the initial charging operation of the energy absorbing element (capacitor) 21 on the inverter main circuit 5 side will be described. After the time t' required for initial charging of the energy absorbing element (capacitor) 20 on the converter main circuit 4 side, a command A to close the auxiliary contact 11 and a command B to close the main contact 13 are simultaneously issued by the operation control unit at time T3. 27, and the main contactor 13 closes.

At the same time as the main contact l3 closes, a command C for operating the converter main circuit 4 is output from the operation control section 27. In response to this command, the current control system consisting of the current control section 2 6 , PWM pulse generation section 24, base drive circuit 22, and current detector 9 operates, and controls the converter main circuit 4, so that the converter main circuit 4 receives DC current. Occur. The generated DC current charges the energy absorption element (capacitor) 21 through the path of the DC reactor 8, the II current element 18, the energy absorption element (capacitor) 21, the current element 19, and the converter main circuit 4, and is charged at time T4. complete. At this time, the inverter main circuit 5 stops operating (all transistors are off) for the time t required to charge the energy absorbing element (capacitor) 21. Upon completion of these charging operations, the operation control section 27 that operates the inverter main circuit 5, the PWM pulse generation section 25, and the base drive circuit 23 are operated to generate AC power and drive the AC electric filo.
to drive.

By operating the current source inverter device as in this embodiment, the initial charging circuit dedicated to charging the energy absorbing elements (capacitors) 20 and 21 can be removed, which not only improves economic efficiency but also improves the current source inverter device. The reliability of the inverter device can be improved. Another embodiment of the present invention will be explained with reference to FIG.

In FIG. 3, 28.29 is a voltage detector 30 that detects the voltage of the energy absorption element (capacitor) 20.21.
is a fault diagnosis unit that diagnoses a fault based on the voltage detectors 28 and 29 and the charging target voltage.

As shown in FIG. 4, in the fault diagnosis of the current source inverter device, the charging voltage of the energy absorbing elements (capacitors) 20 and 21 is detected by the voltage detectors 28 and 29 after the charging completion time t' and the fault diagnosis section 3o is detected. The voltage is compared with the charging target voltage, and if a failure is diagnosed, a signal is sent to the operation control unit 27 to stop the device.

If voltage remains in the energy absorbing element (capacitor) 20 or 21, such as when a current source inverter is operated intermittently, the voltage detector 2
8.29, the initial voltage (Eκ) of the energy absorption element (capacitor) 20.21 can be detected and the initial voltage (
The time required to reach the charging target voltage D:e) from Eκ) is calculated.

For example, consider the charging time for the energy absorbing element (capacitor) 21 on the inverter side. The converter main circuit 4 is controlled to output a constant current. Therefore, the initial voltage Eκ, the charging point 11ffi pressure Ee, the converter main circuit output current d, and the capacitor capacitance value c4 of the energy absorbing element (capacitor) 21 are determined by the relationship shown in equation (1), and the charging time T
Find s.

i When this charging time Ts deviates from the time range shown by equation (2), a failure diagnosis of the power converter is performed and an abnormality signal is sent to the operation control unit to stop the power converter.

Ts<Ts<T2
- (2) That is, the time Ts calculated by equation (1)
If the time Ts is very short, it indicates that the output current of the converter main circuit 4 is large, and if the time Ts is very long, it indicates that the output current is small. This makes it possible to diagnose failures in the converter main circuit 4 and other current control systems. This has the effect of making it possible to diagnose the inverter device before operation, and providing a highly reliable power conversion device.

Furthermore, by calculating the charging time from the initial voltage of the energy absorbing element and the charging target voltage, there is an effect that the time required for charging can be shortened.

〔Effect of the invention〕

According to the present invention, since the energy absorption element can be charged by the operation of the current source inverter device, the separately installed charging circuit can be removed, and the cost of manufacturing and maintenance of the initial charging circuit can be improved. Get better. Furthermore, since the number of components in the initial charging circuit is reduced, the reliability of the device is further improved.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of FIG. 1, and FIG. 3 is a diagram showing another embodiment of the present invention.
FIG. 4 is an explanatory diagram of the operation of the failure diagnosis section, and FIG. 5 is an explanatory diagram related to shortening the charging time. FIG. 6 is an explanatory diagram of the operation of the failure diagnosis section. 3... AC reactor, 4... converter main circuit,
5... Inverter main circuit, 8... DC reactor, 9
... Current detector, 11... Auxiliary contact, 12... Current limiting resistor, 13... Main contact, 14.15... Rectifier, 16-17... Rectifying element, 27... Operation control unit,
28, 1st A Fig. 3 Fig. 4 Voltage conversion visit 28 Two fault diagnosis sections 30 Fig. 5 Charging time

Claims (1)

[Claims] 1. A converter main circuit that converts AC power to DC power, an inverter main circuit that converts DC power to AC power,
a DC reactor connecting the converter main circuit and the inverter main circuit, an AC motor is connected to an AC end of the inverter main circuit, the converter main circuit;
and a rectifier at the AC end of the inverter main circuit,
In a current source inverter device, an energy absorbing element and a rectifying element are connected to the DC end of the rectifier, and the rectifying element is connected to the DC sides of the converter main circuit and the inverter main circuit, respectively, to form a DC circulation circuit. , initial charging of the energy absorbing element of the converter main circuit is performed by a circuit consisting of an auxiliary contact and a current limiting resistor, and initial charging of the energy absorbing element of the inverter main circuit is performed by the converter main circuit section. A current source inverter device characterized by: 2. A converter main circuit that converts AC power to DC power, an inverter main circuit that converts DC power to AC power,
a DC reactor connecting the converter main circuit and the inverter main circuit, an AC motor is connected to an AC end of the inverter main circuit, the converter main circuit;
and a rectifier at the AC end of the inverter main circuit,
An energy absorbing element and a rectifying element are connected to a DC end of the rectifier, and the rectifying element and the converter main circuit, and
In a current source inverter device in which the DC side of the inverter main circuit is connected to each other to form a DC circulation circuit, initial charging of the energy absorption element of the converter main circuit is performed by a circuit comprising an auxiliary contact and a current limiting resistor. , a current source inverter device characterized in that initial charging of the energy absorbing element of the inverter main circuit is performed by the converter main circuit, and further comprising a fault diagnosis section comprising a charging voltage of the energy absorbing element and a charging target voltage. . 3. The current source inverter device according to claim 1, wherein the fault diagnosis section calculates the charging time from the initial value of the charging voltage and the charging target voltage.