JPS5845271B2 - Thyristor valve gate tensioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gate ignition device for a thyristor valve having a large number of thyristors connected in series, and particularly to a ignition device for a thyristor valve for direct current power transmission.

Conventionally, as a gate pulse for a thyristor valve (hereinafter simply referred to as a valve) in which a large number of thyristors are connected in series, a gate pulse that exists during the period when the valve is to be conductive, that is, a wide pulse, has been used as the ignition pulse for the valve.

In the stiff ignition method, a gate pulse exists during the period when the valve should conduct, so it is easy to deal with abnormal phenomena such as intermittent current during this period without destroying the thyristor, and the converter (e.g. Considering the operation of a bridge consisting of six valves, there are various advantages such as not having to use a special starting method.

However, it is unnecessary to apply a signal to the gate even when it is energized, the power consumption of the gate circuit is large, and it is difficult to transmit wide pulses to each thyristor both in terms of circuit and insulation. There are many points, the circuit configuration is generally complicated, and therefore it is expensive.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to generate a gate pulse having a pulse width necessary to fire the valve only when necessary, thereby providing a gate for a thyristor valve that operates stably. Provides an ignition device.

The present invention relates to a narrow pulse system that generates a gate pulse when a valve is to fire.

If the current is intermittent even during the period when the valve should be conducting because the load is light and a reverse voltage is applied to the valve, or if the valve stops conducting and a reverse voltage is applied, the reverse voltage period is the thyristor turn-off time. A gate pulse is generated even when the voltage is equal to or lower than that, to prevent the thyristor from being destroyed due to partial turn-off failure of the thyristor.

If this reverse voltage period is sufficient, the gate pulse will not be issued in the case where the next ignition command is issued.

This makes it possible to generate a gate pulse only when necessary, prevent damage to the thyristor due to partial turn-off failure, and provide a gate pulse that can stably control the ignition of the valve.

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 shows a block diagram of a gate firing circuit according to the present invention. -11 is a flip-flop, 1-1 is a set signal input terminal, 1-2 is a reset signal input terminal, and 1-3 is a set signal input terminal. This is an output terminal that outputs a signal.

2 is a timer, 2-1 is an input terminal, and 22 is an output terminal from which an output pulse is output after a time T after a positive input signal is received.

3 is a voltage detector, 31 is an input terminal, and 3-2 is an output terminal, which outputs a positive output when the input voltage becomes negative, and outputs a negative output when the input changes from negative to O or positive. It is configured.

4 is an inverter that outputs a positive output when there is a negative input, 5 is an AND circuit, and 6 is an input signal when there is an input signal.
This is a pulse conversion circuit that produces pulse output.

T1 is a terminal connected to terminal 1-1, T2 is connected to terminal 31, and T3 is a terminal connected to output terminal 6.

The output terminal 3-2 of the voltage detection circuit 3 is connected to the input terminal 2-1 of the timer 2 and to the input terminal of the inverter 4.

The output terminal 2-2 of the timer 2 is connected to the reset input terminal 1-2 of the flip-flop 1.

The output terminals 1-3 of the flip-flop 1 and the output terminal of the inverter 4 are connected to the input of the AND circuit 5.

The output terminal of the AND circuit 5 is connected to the input terminal of the pulse conversion circuit 6.

In such a configuration, if an ignition command signal is input to the terminal T1 and a valve voltage is input to the terminal T2, the operation will be as shown in FIGS. 2 and 3.

In Figures 2 and 3, a is the valve voltage, b is the ignition command signal, C is the timer output, d is the flip 70 knob output, and e
is the inverter output and f is the firing signal.

First, in FIG. 2, the valve reverse voltage period t is longer than the operating time T of the timer 2.

Therefore, the ignition signal f is output only when the ignition command signal is present.

In FIG. 3, since t<T, the output of timer 2 is output, and therefore the 7 lip flop is not reset.

Therefore, when the valve voltage becomes positive, the AND condition of the AND circuit 5 is satisfied, and an ignition signal is obtained at the terminal T3.

It goes without saying that an ignition signal can also be obtained when an ignition command signal is input.

FIG. 4 shows an embodiment in which the gate circuit of FIG. 1 is applied to a valve.

This is a case where the series thyristors to be fired are divided into several groups and each group is provided with a gate firing circuit.
This is a part of it.

Let the thyristor in the groove be Th1°Th2, and its voltage divider be V D 1 * V D2 .

A is the gate ignition circuit in Figure 1, B is the pulse amplification circuit, and C
is an optical-electric conversion circuit, and D is an ignition command signal.

As shown in the figure, circuits A, B, and C are connected by a conductive wire l so that the potential is the same as that of point P1.

Generally, the ignition control device that issues the ignition command is at ground potential, and the point P1 is at a high potential, so the ignition command is transmitted by light.

C converts the optical signal into an electrical signal and applies it to terminal T1.

The output of the gate firing circuit A is applied to the pulse amplifier circuit B via the terminal T3, and the output is applied to the main thyristor Th1. Added to Th2.

The voltage across Th1 is applied to terminal T2 as the equivalent voltage of the bulb.

In this embodiment, since these gate circuits are not at ground potential, the ignition command signal is an electrically isolated signal, such as by converting it into light as described above or via an insulated pulse transformer. However, the pulse transformer that applies the ignition pulse only needs to withstand the voltage between point P1 and each thyristor.

Further, as shown in the figure, the valve voltage can be taken directly from the thyristor without insulation.

In this case, it is necessary to select the thyristor to which the voltage should be applied, taking into account the variation in reverse recovery characteristics of the thyristors within the group.

For example, if you take the voltage of the one with the largest reverse recovery charge, the reverse voltage period will be the smallest, so if you issue a firing pulse when that voltage reaches O, the other thyristors will change to the forward voltage. Therefore, the thyristor will not be destroyed by forward overvoltage.

It is also necessary to consider variations in thyristor characteristics between the housing groups.

If there are variations in the reverse recovery characteristics of the thyristors that detect the voltage in each group, depending on the relationship with the operating time T of the timer 2, some groups may or may not issue an ignition signal.

Therefore, it is necessary to match the reverse recovery characteristics of the thyristors that detect voltage.

FIG. 5 shows another embodiment.

This is the case when the gate ignition circuit A is set to the ground potential.

The ignition command signal to the gate ignition circuit A is directly applied from the control device, but since there is a high potential difference between each thyristor and the gate ignition circuit A, the ignition signal and valve voltage are electrically transmitted by light, etc. It is necessary to use one that is insulated.

Therefore, E converts the ignition signal into an optical ignition signal G using an electro-optical conversion circuit, and transmits it to each of the thyristors Th1 to Thn or to each group when divided into several groups.

The optical ignition signal is converted back into an electrical signal by the optical-electrical conversion circuits F1 to Fn and applied to the thyristors Th1 to Thn:.

The bulb voltage is represented by the voltage of the thyristor Th1, which is applied to the terminal T2 via the electric-to-optical conversion circuit H1 and the optical-to-electrical conversion circuit (2).

FIG. 6 shows another embodiment.

This is the case when the gate ignition circuit A is set to the same potential as the potential at point P2 of the valve.

The same reference numerals as in FIGS. 4 and 5 indicate the same parts.

The operation is the same as in the previous embodiment, so a description thereof will be omitted.

As is clear from the above description, the effects of such an embodiment can be summarized as follows.

(1) Generate a gate firing pulse with the necessary pulse width only when the valve is to be fired.

Unlike the wide pulse method, pulses are not emitted even when unnecessary, so the power consumption of the gate circuit can be reduced.

(2) Just issue a single VC pulse when necessary.

Since there is no need for intermittent oscillation unlike wide pulses, the circuit configuration is greatly simplified.

(3) When the reverse voltage period becomes about the same as the turn-off time, an ignition pulse is generated to prevent damage caused by forward overvoltage.

(4) Since the gate circuit can be installed at various positions with respect to the potential of the main thyristor, there is a degree of freedom in circuit configuration.

As explained above, the present invention is configured to generate a gate pulse having the width necessary for ignition of the thyristor, and when the reverse voltage range of the thyristor valve is less than a predetermined time, the gate pulse is generated to the thyristor. This gate ignition method for thyristor valves can prevent the thyristor from being destroyed due to partial valve turn-off failure and can stably control the ignition of the valve.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a gate ignition circuit showing an embodiment of the present invention, Figs. 2 and 3 are explanatory diagrams of the operation of Fig. 1, and Fig. 4 is an application of the gate ignition circuit of the present invention. FIGS. 5 and 6 are block diagrams showing other embodiments to which the gate ignition circuit of the present invention is applied. Explanation of symbols, 1...Flip-flop, 2...
...Timer, 3...Voltage detection circuit, 4...
...Inverter, 5...AND circuit, 6.
...Pulse conversion circuit, A...Gate ignition circuit, B...Pulse amplification circuit, C2...
・・Optical-electrical conversion circuit, D・・・・Ignition signal, Th
1~Thn...Thyristor, E, H...
- Electrical-optical conversion circuit, F1 to Fn... Optical-electrical conversion circuit, G... Optical ignition signal.

Claims (1)

[Claims] 1 Generates a gate pulse with a pulse width necessary to fire the thyristor valve in response to a firing command signal from the firing control device, and also generates a gate pulse when the reverse voltage period of the thyristor valve is less than a predetermined time. In the gate ignition device for a thyristor valve, the gate ignition circuit includes a flip-flop that is set to a set state by the ignition command signal, and a voltage detection circuit that detects the voltage of the thyristor valve. , a timer that outputs an output after a predetermined period of time after this voltage detection circuit detects the reverse voltage of the thyristor valve and resets the flip-flop with the output; an AND circuit operated by the output of the flip-flop and the voltage detection circuit; A gate ignition device for a thyristor valve, comprising a pulse conversion circuit that converts the output of the AND circuit into a pulse.