JPH0456490B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gate circuit that controls on/off of a gate turn-off thyristor.

[Conventional technology]

FIG. 3 is a circuit diagram showing a gate circuit of a conventional gate turn-off thyristor disclosed in Utility Application No. 59-15009, and in the figure, 1 is a gate turn-off thyristor (hereinafter abbreviated as GTO); is a gate electrode, and K is a cathode electrode.
2 is a chopper circuit, and the on-gate power supply 3
The current detecting means 22 detects the output current of the chopper circuit 2, and a freewheeling diode 23.

30 is a reactor, which is composed of a primary winding 30a and a secondary winding 30b. 31 is a second capacitor, and 32 is a diode. 5 is a resistor, and 6 is a first capacitor. 7 is an on-gate switch, which supplies the output current of the chopper circuit 2 and capacitor 6 to the GTO 1 as an on-gate current. A charging circuit 8 charges the capacitor 6. 9 is an off-gate circuit,
Supply off-gate current to GTO1.

Next, the operation will be explained. During the off period of GTO1, the on-gate switch 7 is turned off,
The first and second capacitors 6 and 31 are charged by the charging circuit 8 to the illustrated polarity, and this charging voltage is set to a value higher than the voltage of the on-gate power supply 3. At time _t1 , when the on-gate switch 7 and the tip switch 21 are turned on,
The gate current Ig is the discharge current Ic of the first capacitor 6
and the second capacitor 31 and the reactor 30.
The sum of the oscillating current Ic ₂ with the next winding 30b flows. At time _t2 , when the voltage of the second capacitor 31 decreases and becomes lower than the voltage of the on-gate power supply 3, the current in the secondary winding 30b of the reactor 30 is transferred to the primary winding 30a of the reactor 30. . Primary and secondary windings 30a, 3 of this reactor 30
Assuming that the turns ratio of 0b is 8:1, the output current I _CH of the chopper circuit ₂ is I CH = I _CH =
It starts to flow as I _C2 /8. Actually, it is desirable to determine the winding ratio of the reactor 30 so that the initial value of the primary winding 30a of the reactor matches the constant current control value of the chopper circuit 2. time
After _t2 , the gate current Ig flows as a substantially constant current due to the constant current control function of the chopper circuit 2.

At time _t3 , the on-gate switch 7 and the chopper switch 21 are turned off and the off-gate circuit 9 is turned on, thereby supplying a negative off-gate current to the GTO 1 as shown. on the other hand,
The excitation energy of the primary winding 30a of the reactor 30 is released through the path of the resistor 5, the capacitor 6, and the chopper circuit 2, and the capacitor 6 is charged. The shortfall in the charging voltage of the capacitor 6 is handled by the charging circuit 8 through the diode 32 and the secondary winding 30 of the reactor 30.
b, charged via resistor 5;

[Problem that the invention seeks to solve]

Since the conventional gate circuit is configured as described above, it is necessary to provide a charging circuit 8 to charge the first capacitor 6 that supplies the on-gate current, which makes the circuit complicated and expensive. Since the resistor 5 is inserted in series with the first capacitor 6, there are problems such as unavoidable current loss during charging.

This invention was made to solve the above problems, and aims to provide a gate circuit for a gate turn-off thyristor that can eliminate the need for a charging circuit and reduce current loss during charging. .

[Means for solving problems]

A gate circuit of a gate turn-off thyristor according to the present invention has an on-gate circuit and an off-gate circuit of the gate turn-off thyristor, and in the on-gate circuit, a primary winding and 2
A secondary winding is provided, a first DC output terminal of the on-gate power supply is connected to the input terminal of the primary winding, and a second DC output terminal of the on-gate power supply is connected to the input terminal of the primary winding and the secondary winding. A series connection body consisting of a parallel circuit of a first capacitor, a resistor, and a diode is connected between the common output terminal and the second DC output terminal of the on-gate power supply and the input terminal of the secondary winding. In between, a second capacitor and a diode are connected in series, a diode is connected between the common output terminal and the connection midpoint of the series connection, and an on-gate switch is configured to output on-gate power to the gate turn-off thyristor. It is configured to be connected to the common output terminal.

[Effect]

The chopper circuit of the present invention turns the chopper section switch on and off even after the on-gate switch is turned off, and charges the first capacitor and the second capacitor through each diode that bypasses the resistor circuit. It acts to prepare for activation of the gate turn-off thyristor by the next on-gate.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 42 is a diode, which connects the common output terminal of the primary winding 30a and the secondary winding 30b, the second capacitor 31, and the diode 32.
It is used to charge the second capacitor 31. Further, 43 is a charging diode, which is connected in parallel to the resistor 5. Note that other circuit parts that are the same as those shown in FIG. 3 are designated by the same reference numerals, and redundant explanation thereof will be omitted.

Next, the operation will be explained. The chopper circuit 2, which constitutes the on-gate power supply in combination with the on-gate power supply 3, has a constant current control function and controls the gate current.
By detecting Ig by the current detection means 22 and adjusting the conduction ratio of the chopper section switch 21, the value of the on-gate current is made constant. The freewheeling diode 23 is conductive when the chopper switch 21 is off, and functions to continue the gate current via the reactor 30a. On-gate switch 7
When is off, the off gate circuit 9
GTO1 is supplied with an off-gate current.

Next, the operation of turning on and off the on-gate switch 7 will be described with reference to FIG.

Before time _t1 , the on-gate switch 7 is off, and the chopper section switch 21 is turned on and off, so that the first capacitor 6 and the second capacitor 31 are connected through the primary winding 30a of the reactor 30 and the diode 42, 43, respectively, and are charged to the polarity shown. Next, at time _t1 , when the on-gate switch 7 is turned on, the gate current Ig becomes equal to the discharge current Ic of the first capacitor 6,
The sum of the oscillating current I _C2 of the second capacitor 31 and the secondary winding 30b of the reactor 30 flows. At time _t2 , when the voltage of the second capacitor 31 decreases and the voltage generated at the primary winding 30a (opposite polarity to the power supply) becomes lower than the voltage of the on-gate power supply 3, the secondary winding of the reactor 30 The current in line 30b is transferred to primary winding 30a of reactor 30.

Primary and secondary windings 30 of this reactor 30
Assuming that the turns ratio of a and 30b is 8:1, the output current I _CH of the chopper circuit 2 is as follows at time t ₂ .
I _CH = I _C2 /8 and it starts to flow. Also in this case,
It is desirable to determine the winding ratio of the reactor 30 so that the initial value of the primary winding 30a of the reactor matches the constant current control value of the chopper circuit 2. After time _t2 , the gate current Ig flows as a substantially constant current due to the constant current control function of the chopper circuit 2.

At time _t3 , by turning off the on-gate switch 7 and turning on the off-gate circuit 9,
The negative polarity off-gate current as shown in the figure is GTO1
is supplied to On the other hand, a charging current flows through the primary winding 30a of the reactor 30, the diode 43 to the first capacitor 6, and the diode 42 to the second capacitor 31, charging these to the on-gate power supply voltage. When this charging ends, the output current ICH does not flow after time _t4 .

In the above embodiment, a converter method is used in which the on-gate power supply 3 and the chopper circuit 2 are combined as a DC power supply having the function of constant current control of the on-gate current. The constant on-gate current generation source may have a constant current control function by controlling the phase of the AC power supply with a mag-amp, and the constant on-gate current generation source has a constant current control function and converts the DC output. Any container is fine.

[Effects of the Invention] As described above, according to the present invention, the chopper section switch is constantly turned on and off to charge the first capacitor and the second capacitor from the reactor output terminal through the diode. This has the effect of not only being able to prepare for activation of the gate turn-off thyristor due to on-gate without using a special charging circuit, but also being able to suppress current loss due to resistance during charging.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a GTO gate circuit according to an embodiment of the present invention, FIG. 2 is an operation waveform diagram showing the operation of FIG. 1, and FIG. 3 is a circuit diagram showing a conventional GTO gate circuit. FIG. 4 is an operation waveform diagram showing the operation of FIG. 3. 1... Gate turn-off thyristor (GTO),
2... Chopper circuit, 3... On-gate power supply,
5... Resistor, 6... First capacitor, 7... On-gate switch, 9... Off-gate circuit, 3
0...Reactor, 30a...Primary winding, 30b
...Secondary winding, 31...Second capacitor, 3
2, 42, 43...diode. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. An on-gate circuit that supplies an on-gate current to the gate turn-off thyristor, an off-gate circuit that supplies an off-gate current to the gate turn-off thyristor, and the on-gate circuit,
A reactor consisting of a primary winding and a secondary winding, the output ends of these windings are connected to each other, and the reactor is configured such that a coupling action occurs between the windings, and a constant current control an on-gate power supply having a first DC output terminal connected to the input terminal of the primary winding of the reactor; and a second DC output terminal of the on-gate power supply and the two windings of the reactor. a series connection body consisting of a parallel circuit of a first capacitor, a resistor, and a diode, connected between a common output end of the line, and a second DC output end of the on-gate power supply and two of the reactor.
a series connection body consisting of a second capacitor and a diode connected between the input end of the next winding;
A diode is connected between the common output terminal of the reactor and the connection midpoint of the series connection body consisting of the second capacitor and the diode, and one end is connected to the common output terminal of the reactor, and the on-gate current is connected to the common output terminal of the reactor. A gate circuit for a gate turn-off thyristor equipped with an on-gate switch that outputs to the turn-off thyristor.