JPS5995731A - Thyristor valve - Google Patents

Abstract

PURPOSE:To prevent a thyristor from being destroyed by a too small gate pulse, by monitoring a gate circuit power supply voltage, and stopping a gate pulse when the power supply voltage of the gate circuit is not sufficiently charged. CONSTITUTION:A voltage divider 20 is set so as to turn on an AND logical circuit 21 when there exists an output of an operational amplifier 19 in response to a voltage being a prescribed value or over of a capacitor 6. When the voltage of an AC power supply is reduced and the charging voltage of the capacitor 6 is decreased, an output voltage of the amplifier 19 is reduced accordingly and the circuit 21 is not turned on, then a signal applied to a trigger signal input terminal 12 does not reach a transistor 13 and no current flows from the gate circuit 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gate circuit 18 for supplying gate current to the gate of each thyristor in thyrisk pulp used in AC/DC converters for DC power transmission, etc.
In particular, gate circuits that obtain power for supplying gate current from the thyristor voltage! This applies to

This type of Silisk pulp is used in circuits with a much higher voltage than the withstand voltage of Silisk alone, so as shown in Figure 1, a large number of Silisks are connected in series, a voltage divider circuit, and a gate circuit. It is composed of etc.

In FIG. 1, (1) is a thyristor, (2) is a voltage dividing circuit, and (3) is a gate circuit.

By the way, the total number of sires in the 1-jo Iristabulp is 1
The gate currents of each thyristor (1) need to be supplied at the same time, since they must operate in unison for the two ignition signals. On the other hand, since each of the thyristors (1) connected thereto is at a high potential and the potential of each thyristor <1) is the same, the gate circuits (3) of each thyristor must be insulated from each other. In order to satisfy such conditions, it has been conventionally practiced to transmit gate signals as optical signals using optical fibers, which are electrical insulators. However, the potential energy transmitted through the optical fiber alone cannot send the energy that causes the gate current of the thyrisk to flow, so the power source for the gate circuit is generated from the voltage divider circuit (2) at the potential of each thyrisk. An example of such a circuit (!--shown in FIG. 2).

In Figure 2, (1) is Cyrisk, (2) is a voltage dividing circuit consisting of a capacitor and resistor, (3) is a gate circuit, (4) is a phototransistor that turns on when receiving an optical signal, and (5) is Resistor, (6) is the capacitor charged by the gate power supply, (7) is the diode, (8) is the Zener diode, (10 is the optical fiber, αυ is the ignition circuit, @
is an ignition signal input terminal, Q is a transistor, and 0.41 is a light emitting diode.

The operation of the conventional gate circuit will be explained below based on FIG. The voltage applied to the SIRISK (1) causes current to flow through the voltage divider circuit (2) to the capacitor (6), which becomes the power source for the gate circuit (3). The charging voltage of the capacitor (6) is limited by the Zener diode (8) Vz
It rises with i. An example of the voltage applied to Cyrisk (1) is shown in Figure 3a. This is the waveform when the converter is in converter operation. When an ignition signal is input to the ignition signal input terminal (2) in this state, the transistor αa is turned on, current flows through the light emitting diode αa, and a light signal is emitted. When this optical signal is applied to the phototransistor (4) through the entire optical fiber 00, the phototransistor (4) turns on and the charge stored in the capacitor (6) is transferred to the resistor (5) and the cyrisk (1). is discharged through the gate of , and a gate current flows through the cyrisk (1).

The gate current of Cyrisk is given at the timing shown in Figure 3. At this time, the charging voltage of the capacitor (6), that is, the waveform of the gate circuit power supply voltage is as shown in FIG. 3C. When the gate current flows, the charging voltage is discharged, and when the thyrisk is turned off and a voltage is applied to the thyrisk, the charging voltage rises to the Zener limit voltage Vz.

By the way, when the converter is operating normally, it operates as described above, but if an accident occurs in the AC system to which the converter is connected, for example, the voltage applied to the SI risk may It is conceivable that it will be considerably lower than when driving. In this case, Condens! The current for charging /-(6) also becomes small, and in extreme cases, a half-full charge occurs where charging to the Zener limit voltage is no longer possible. However, in conventional gate circuits, the optical signal is not applied regardless of the buoy risk voltage.
When the gate current is turned on, the gate current tries to flow, so if the gate circuit power supply voltage is insufficient, a too small gate pulse of less than the rated current will be applied to the sirisk, which is a big disadvantage of destroying the sirisk in the cursion process. sometimes occurred.

Also, if the current of Cyrisk is small and intermittent,
Normally, control is performed to flow the gate current when a forward voltage is detected during the period when the Cyrisk should be fired, but if you try to flow the gate current more times than the charge charged in the capacitor (6), , as above, the pulse may be too small, leading to destruction of the cyrisk.

The present invention eliminates the drawbacks of the conventional gate circuit as described above, monitors the gate circuit power supply voltage, and stops the gate pulse when the gate circuit power supply voltage is not sufficiently charged, thereby reducing the risk of si-risk or under-charging. The purpose is to prevent damage caused by gate pulses.

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

In addition, parts with the same reference numerals in the drawings indicate the same or equivalent parts.

In FIG. 4, αQ is a light emitting diode Q5, which is connected to both ends of the capacitor (6) through the resistor u. a''7) One end of I is an optical fiber facing the light emitting diode αG, and o is the light receiving diode facing the other end of the optical fiber αη.
O and nine light-receiving diodes are optically coupled. 4 is an operational amplifier that amplifies the photocurrent of the photodetector diode (G), and (21) is an AND logic circuit, one input of which is connected to the output of the operational amplifier 0.1 through a voltage divider (A).
The other input is connected to the ignition signal input terminal @, and the output is connected to the pace of transistor CL3.

Now, assuming that the converter is operating normally and the normal voltage is being applied to the thyrisk valve, the gate circuit (3
) of Conchin? (6) is also charged to the limited voltage of Zener diode (8). The light emitting diode (QQ) generates an optical signal corresponding to the charging voltage of the capacitor (6), and the optical signal is converted into a current by the light receiving diode (α) via the optical fiber.
6) Outputs a voltage according to the charging voltage. Here, if the settings of the voltage divider () are set so that the AND logic circuit The signal applied to the signal input terminal (6) is applied to the transistor Ua on the condition that the capacitor (6) is charged to a predetermined voltage.
is reached, the light emitting diode a< is made to emit light, and the gate circuit (
3) causes the gate current to flow and ignites the cyrisk (1).

Here, for example, assume that the voltage of the AC power supply to which Cyrisk Pulp is connected decreases, and the charging voltage of the capacitor (6) decreases. Then, the output voltage of the arithmetic amplifier 11m (1) decreases accordingly, and the AND logic circuit c1.υ is not turned on, so the signal applied to the ignition signal input terminal (6) does not reach the transistor α@, Therefore, the gate circuit (3
) does not cause gate current to flow.

That is, according to the present invention, when the gate circuit power supply voltage drops, the ignition signal is stopped and the gate current is not allowed to flow, thereby preventing the tool risk from being destroyed due to an insufficient gate pulse. I can do it.

Further, another embodiment of the invention will be described with reference to FIG.

In Figure 5, 4 is the si risk (1
) K light emitting diodes connected in parallel, (A) optical fiber, (C) light receiving diode, 4 operational amplifier, (7
) is a gate circuit simulation circuit, @ is a capacitor, ) is a transistor, and 4 is a diode that simulates the gate of Cyrisk.

The light emitting diode (a) outputs an optical signal according to the voltage applied to the builisk (1). The optical signal is sent to a light receiving diode (c) through an optical fiber (), and is converted back into a voltage signal by an operational amplifier ().

The gate circuit simulation circuit (c) simulates the constitution of the voltage dividing circuit (2) and the gate circuit (3) according to the voltage ratio. In addition, the transistor and diode 4 simulate the gates of the phototransistor (4) and the transistor (1).
A voltage similar to the voltage of Contin+j (6) is output to the capacitor at all times. The output 'dt pressure is connected to the output of the AND logic circuit ■υ of the ignition circuit αυ through the voltage divider (A), as in the example of FIG.

Now, assuming that the converter is operating normally and the gate Ml source voltage of the capacitor (6) is being charged normally, the voltage of the capacitor (6) is also being charged accordingly. If the voltage divider () is set so that the AND logic circuit (01) turns on when the voltage on the capacitor wire exceeds a predetermined value, the gate circuit (3) will cause the gate current to flow as in the previous example, and the (1) is ignited.

Here again, if the voltage of the AC power supply to which the Cyrisk Pulp is connected drops and the charging voltage of the capacitor (6) also drops, the charging voltage of the capacitor (b) of the gate circuit simulation circuit (c) will also change accordingly. descend.

Therefore, the AND logic circuit (IV) is no longer turned on, and as in the example of FIG. 4, the gate circuit (3) no longer allows gate current to flow.

That is, in the example shown in FIG. 5, by simulating the gate circuit power supply voltage, an excessively small gate pulse is prevented from flowing into the sirisk, thereby preventing destruction of the sirisk.

In addition, although the optical fiber t of Oη and c13 increases the size of the parts, it actually increases the size of the optical fiber (4), optical fiber (17), light receiving diode (0), and operational amplifier ( , 1g1 (7) is usually installed in a silice valve, so in the example of FIG. 5, it is only necessary to add a gate circuit simulating circuit @ and an AND logic circuit υ.

As described above, according to the present invention, the gate circuit voltage of the cylisk pulp is monitored or simulated to prevent the cylisk from being destroyed by an insufficient gate pulse when the gate circuit power supply voltage drops. This has the effect of producing highly reliable twillisk pulp.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing the configuration of Cyrisk pulp, Figure 2 is a detailed circuit diagram of one element of Cyrisk of conventional Cyrisk pulp, Figure 3 is a waveform diagram explaining the operation, and Figure 4 is this FIG. 5 is a detailed circuit diagram of one thyristor element of thyristor pulp according to an embodiment of the present invention. FIG. 5 is a detailed circuit diagram of one thyristor element of thyristor pulp according to another embodiment of the invention. In the figure, (1)...Sirisk, (2)...Voltage divider circuit, (3)...Gate circuit, (4)...Phototransistor, (5)...Resistor, (6 )...Capacitor, (7)...Diode, (8)...Zener diode, C...Optical fiber, αυ...
Ignition circuit, (6)... Ignition signal input terminal, α4...
Transistor, 4 us n... light emitting diode,
QQ...Resistor, (To) (Foundation)...Light receiving diode,
uI4...Operation amplifier, (4)...Voltage divider, Qυ・
AND logic circuit, (a)...gate circuit simulation circuit, e7
′)...Capacitor, (C)...Transistor, (A)
··diode. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno - Figure 1, Figure 31/1 L-J 1 Wa 1 Commissioner of the Japan Patent Office 1, case display frame L'la 1983-207075 P)
2. Title of the invention: Sairisk Valve 3. Representative Hitoshi Katayama of the person making the amendment Part 6: Detailed explanation of the invention in the statement subject to the amendment 6. Contents of the amendment (1) Section 4 of the description In the 7th line of the page, the word ``daroode'' is corrected to ``diode.'' (2) On page 7, lines 16 and 17, “Capacitor (6
) is corrected to read ``a voltage greater than a predetermined voltage of the capacitor (6), which is equal to the limiting voltage of the Zener diode (8), for example.'' (3) On page 7, line 20, the word "predetermined" is corrected to "the above predetermined". that's all

Claims (1)

[Claims] (1) In a builisk pulp configured to obtain a power source for flowing a gate current of the sirisk by a voltage applied to the sirisk, the gate circuit power supply of the sirisk or a voltage corresponding to and a device that stops the firing signal to the thyristor when the power supply voltage from this monitoring device is below a predetermined value. (The two-in monitoring device is connected to both ends of the gate power supply. The cyrisk pulp according to claim 1, comprising a device for converting a power supply voltage into an optical signal, a device for transmitting the optical signal, and a device for converting the transmitted optical signal into a voltage. (3) The monitoring device includes a device that is connected to both ends of the cyrisk and converts the voltage applied to the cyrisk into an optical signal, a device that transmits the optical signal, and a device that converts the transmitted optical signal into a voltage. , a device for simulating a dirt circuit of Cyrisk, and a device for applying voltage from the voltage conversion device to the simulating device.