JPS6244064A - Overvoltage suppressor - Google Patents

Abstract

PURPOSE:To increase the efficiency and to reduce the weight and the size of an inverter by constructing an overvoltage suppressor of an element of a small capacity capacitor and a charging/discharging circuit to reduce the charging/ discharging voltage smaller than that of a snubber circuit. CONSTITUTION:When a U-phase gate turn-OFF thyristor (GTO) 8 is conducted, a current I flows as shown in the drawing, and a voltage suppressing capacitor 3 is stored to a voltage EFC. When an OFF pulse is input to the GTO8 in this state, an energy stored in a leakage inductance of a motor flows to a snubber capacitor 12. When the voltage of the capacitor 12 becomes equal to the input voltage EFC of an inverter, diodes 5, 11, 6, 18 are conducted, and energies stored in anode reactances 7, 10 and a wiring leakage inductance flow to the capacitors 12 and 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to suppressing overvoltage of main circuit switching elements of an inverter device.

BACKGROUND ART FIG. 6 shows a conventional overvoltage suppression device. In the figure, (
1) is a filter capacitor, (7) αQ is an anode reactor, and (8) and (9) are main circuit switching elements, such as a gate turn-off thyristor CGT.

Q circle is a snubber diode, (2) mouth is a snubber capacitor, and Q5 (lη is a freewheeling diode).

Next, the operation will be explained. When the GTO (8) is turned off, the current flowing through the GTO (8) flows through the diode aυ and the capacitor @ due to the load and the induced energy of the anode reactor (7). The capacitor (2) is charged by this current, and the inductive energy is transferred to the capacitor (2).
b) It is converted into electrostatic energy. Therefore G.T.O.
The voltage applied across (8) is equal to 1 voltage charged in the capacitor @. When GTO (8) becomes conductive again,
The charge on the capacitor (b) is discharged through the resistor (to), and the voltage on the capacitor (4) becomes equal to the voltage drop in the singing direction of the GTO (8).

In this way, the conventional ones are Q1103Q5 and 03α4
A snubber circuit consisting of +1171 suppresses overvoltage of the main circuit switch element (8) (91).

(Problem to be solved by the invention) Since the conventional overvoltage suppression circuit is configured as described above, the capacitor is repeatedly charged and discharged from the peak voltage to the forward drop voltage of the switching elements connected in parallel, and when discharging Therefore, increasing the capacitance of the capacitor to suppress the peak voltage applied to the switching elements leads to the problem of lower efficiency and increased external weight of the inverter device. Dots or hot.

This invention was made with the aim of solving the above-mentioned problems.In order to avoid increasing the capacitance of the capacitor connected in parallel to the switching element, and thereby increasing the energy loss of the inverter, An object of the present invention is to obtain an overvoltage suppressing device that can suppress the peak voltage of.

Means for Solving Problems] The overvoltage suppressing device according to the present invention is composed of a capacitor and a circuit for charging and discharging the capacitor charge, and the capacitor is initially charged to a predetermined voltage by charging from a DC power source. I am forced to do so.

When the voltage applied to the element to be protected reaches this predetermined voltage, a current flows into the capacitor, thereby suppressing the surge of the voltage applied to the element.

[Effect]

The overvoltage suppressor in this invention is used together with a snubber circuit, and when the snubber capacitor voltage rises after the switching element is cut off and becomes equal to the capacitor voltage of the overvoltage suppressor, a current flows through the snubber circuit. flows through the overvoltage suppression circuit for 0 minutes, so the voltage generated in the snubber circuit and the overvoltage suppression device is shunted and increases due to the current, so it is suppressed to a low value and suppresses the voltage splash of the element.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. @1
In the figure, (2) to (6) are main circuit devices to which the present invention is applied. (3) is a capacitor for suppressing the rising voltage, (2) and (4) are resistors for discharging the overcharged charge of capacitor (3), and (5) and (6) are the initial stage of capacitor (3). This is a diode for blocking the discharge of charged charges. (1) and (7) to (to) are similar to the conventional device. α-threat and (E) have the same structure as the U-phase composed of (2) to (G). In the overvoltage suppression device configured in this way, when the U-phase GTO (8) is conducting, the current I flows as shown in Figure 2, and the voltage suppression capacitor (3) is charged up to RFC. There is. GTO in this condition
When an off pulse is input to (8), as shown in FIG. 8, the leakage inductance of the motor, the anode reactor (7) of the circuit, and the energy stored in the leakage inductance flow to the snubber capacitor 4.

Snubber capacitor Q2 [voltage is inverter input voltage (E
Fc), each diode (5) αυ (6) Q19 becomes conductive as shown in Fig. 4, and the energy stored in the leakage inductance of the wiring (7) C1O and the wiring is Snubber capacitor (6
) and voltage suppression capacitor (3).

In the mode shown in Fig. 4, when the inductive energy of the circuit is transferred to the snubber capacitor □□□ and the voltage suppression capacitor (3), the mode shown in Fig. 4 ends and the freewheeling mode shown in Fig. 5 is entered, and the U phase arc extinction is completed.

In the above embodiment, the case where the main circuit switch element is a GTO has been described, but even if the main circuit switch element is a thyristor and a commutation circuit is used, the same operation as in the above embodiment can be expected.

〔Effect of the invention〕

As described above, according to the present invention, the device overvoltage suppression device is configured by a small capacitor and a charging/discharging circuit so that the charging/discharging voltage width is smaller than that of the snubber circuit. The effects of higher efficiency, lighter weight, and smaller size of the equipment can be obtained.

[Brief explanation of drawings]

FIG. 1 is a main circuit diagram of an inverter device according to an embodiment of the present invention, FIGS. 2 to 5 are main circuit diagrams explaining the operation of an embodiment of the present invention, and FIG. 6 is a conventional inverter device. FIG. In the figure, (2) and (4) are resistors, (3) is a capacitor, (5) and (6) are diodes, and (8) and (9) are switchable semiconductor elements. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (3)

[Claims] (1) In a device that uses a switchable semiconductor element and has a reactor connected in series to the anode of the switchable semiconductor element in order to conduct or cut off current in a circuit, the switchable semiconductor element a diode with an anode connected to the anode; a resistor connected to the cathode of the diode and a reactor end on the side not connected to the switchable semiconductor element;
An overvoltage suppression device comprising a capacitor connected to a cathode of the diode and a cathode of the switchable semiconductor. (2) In a device having a switchable semiconductor element and a reactor connected in series to the cathode of the element,
a diode whose cathode is connected to the cathode of the switchable semiconductor element; a resistor connected to the anode of the diode and a reactor end not connected to the switchable semiconductor element; The overvoltage suppression device according to claim 1, further comprising a capacitor connected to the switchable semiconductor anode. (3) In claim 2, the switchable semiconductor element and reactor shown in claim 1 are connected to the anode of a DC power source, and the reactor is connected to the cathode of the DC power source. In one phase of the inverter device having the switchable semiconductor elements and reactor shown,
a diode whose anode is connected to the anode of the switchable semiconductor element on the anode side; a resistor connected to the cathode of the diode and the anode of the DC power supply; and a switchable semiconductor element on the cathode side of the DC power supply. A diode whose cathode is connected to the cathode, a resistor whose anode is connected to the cathode of the DC power supply, and a resistor which is connected to the cathode of the diode on the anode side of the DC power supply and the anode of the diode on the cathode side of the DC power supply. The overvoltage suppression device according to claim 1, further comprising a capacitor.