JPH0770978B2 - Power supply device for gate drive circuit of GTO thyristor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a power supply device for a gate drive circuit for driving a GTO thyristor in an inverter device or the like using a gate turn-off thyristor (hereinafter referred to as “GTO thyristor”). .

[Conventional technology]

As a gate drive circuit for switching a current using a GTO thyristor, one having a configuration as shown in FIG. 3 is generally known. Further, the GTO thyristor is provided with a snubber circuit as shown in FIG. 3 for the purpose of reducing switching loss. In FIG. 3, reference numeral 10 indicates a GTO thyristor. As a gate drive circuit of this GTO thyristor 10, a gate drive unit 12 is provided.
And a power supply circuit 14 are provided. In this case, the power circuit
Electric power is supplied to 14 through an insulating transformer 16 to form positive and negative DC power supplies necessary for supplying an on-gate pulse and an off-gate pulse in this power supply circuit 14. A free wheel diode 18 is connected between the anode and cathode terminals of the GTO thyristor 10, and a series connection circuit of a snubber diode 20 and a snubber capacitor 22 in parallel with the free wheel diode 18 and the snubber diode 20. Snubber resistor connected in parallel with
A snubber circuit consisting of 24 is connected and arranged.

[Problems to be Solved by the Invention]

However, according to the power supply circuit method for the gate drive unit 12 described above, particularly in the case of a high-voltage device configured by connecting a plurality of GTO thyristors 10 in series, the size is very large in order to increase the withstand voltage of the insulating transformer 16. There is a problem that it becomes expensive and expensive. Further, when the voltage changes due to the switching operation of the GTO thyristor 10, a noise current flows through the stray capacitance of the insulating transformer 16 and the like, which causes a problem that the gate drive unit 12 is likely to malfunction.

Therefore, in the gate drive circuit of the GTO thyristor, an object of the present invention is to obtain a power source from a snubber circuit provided for the GTO thyristor, thereby omitting a large and expensive insulating transformer and improving reliability such as noise resistance. (EN) Provided is a power supply device for a gate drive circuit of a GTO thyristor capable of improving the power consumption.

[Means for Solving the Problems]

A power supply device for a gate drive circuit of a GTO thyristor according to the present invention is a GTO thyristor in which a snubber circuit in which a diode and a capacitor are connected in series are connected in parallel, and the snubber capacitor is charged through an impedance element and the thyristor. A second capacitor is connected in series with the impedance element and the thyristor and is connected and arranged in parallel between the terminals of the snubber capacitor, and an ignition pulse is supplied to the gate of the thyristor in synchronization with the ON command signal of the GTO thyristor. And a discharge circuit that holds the charging voltage of the capacitor at a constant voltage in parallel with the second capacitor to configure an operating power supply for the gate drive circuit of the GTO thyristor. And

In the above-mentioned power supply device for gate drive circuit, the gate pulse generation circuit can be composed of a monostable for inputting an ON command signal of the GTO thyristor and generating a predetermined gate pulse, a pulse amplifier and a pulse transformer.

Further, the discharge circuit has a discharge capacitor connected in parallel with the second capacitor via a transistor, and a Zener diode is connected to the base of the transistor so that the charging voltage of the second capacitor exceeds a set voltage. In addition, the transistor can be turned on.

Further, it is preferable to connect the second capacitor to the GTO thyristor through a charging resistor and a diode so as to perform initial charging and supplementary charging by the voltage between the anode and the cathode.

[Action]

According to the power supply device for the gate drive circuit of the GTO thyristor according to the present invention, with respect to the snubber capacitor forming the snubber circuit connected in parallel to the GTO thyristor, via the thyristor and the impedance element that fires when the GTO thyristor is in the ON state. By providing a capacitor to charge,
The charging voltage of this capacitor is used as the operating power supply of the gate drive circuit of the GTO thyristor, and the stable gate drive circuit that is not affected by switching noise is used without using an insulating transformer that has a high breakdown voltage and is large and expensive. A power supply device for use can be provided. Further, in the power supply device of the present invention, by providing the capacitor with a discharge circuit that operates at the time of overcharging, or by attaching a charging circuit that can perform initial charging and auxiliary charging by the voltage between the anode and cathode of the GTO thyristor. It is possible to improve the stability and reliability of the power supply device.

〔Example〕

Next, an embodiment of a power supply device for a gate drive circuit of a GTO thyristor according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a circuit diagram of a power supply device for a gate drive circuit showing an embodiment of the present invention. For convenience of explanation, the same components as those of the conventional circuit shown in FIG. 3 are designated by the same reference numerals. That is, in FIG. 1, a charging resistor 26, a diode 28, and a second capacitor 30 are connected in parallel with a series connection circuit of a snubber diode 20 and a snubber capacitor 22 which form the snubber circuit of the GTO thyristor 10.
Connected in series, and between the connection point of the snubber diode 20 and the snubber capacitor 22 and the connection point of the diode 28 and the second capacitor 30, an impedance element 32 such as a resistor and a reactor and a thyristor 34. Connect through. Also, the second capacitor
With respect to 30, the emitter of the transistor 36 is connected to one end thereof, and the collector of the transistor 36 is connected to the other end of the second capacitor 30 via the discharge resistor 38. The base of the transistor 36 and the second capacitor 30
Zener diode 42 via resistor 40 to the other end of
Connect. However, the second circuit configured in this way
Both ends of the capacitor 30 are connected to the power supply circuit 14. The monostable 44, which operates by branching in the ON command signal input to the gate drive unit 12 of the GTO thyristor 10, the pulse amplifier 46 and the pulse transformer 48 are sequentially connected and arranged, and the output signal of the pulse transformer 48 is The circuit is configured to supply the gate of the thyristor 34.

In this way, in the circuit of this embodiment, the power supply circuit 14 is connected as the power supply for the gate drive unit 12, the monostable 44 and the pulse amplifier 46.

Next, the operation of the circuit of this embodiment configured as described above will be described.

In the circuit of this embodiment, the second capacitor 30 is configured to be charged from the snubber capacitor 22 constituting the snubber circuit via the impedance element 32 and the thyristor 34. When the ON command signal is input to the monostable 44 at the same time as the gate drive unit 12 of the GTO thyristor 10, the thyristor 34 outputs a signal whose waveform is shaped into a predetermined pulse width from the monostable 44, and the output signal is pulsed. It is input as a gate pulse of thyristor 34 via amplifier 46 and pulse transformer 48,
Is fired and the second capacitor 30 is charged. In this case, the capacity of the second capacitor 30 is the snubber capacitor.
Select sufficiently larger than the capacity of 22. As a result, the charging voltage of the second capacitor 30 per charge is changed to the GTO thyristor 10
It can be made sufficiently smaller than the element voltage. Further, when the charging voltage of the second capacitor 30 exceeds a voltage value (Ve) substantially determined by the Zener voltage of the Zener diode 42, the base current is supplied to the transistor 36 via the Zener diode 42 and the resistor 40. When the transistor 36 is turned on, the discharge resistor 38 is connected in parallel with the second capacitor 30, and the second capacitor 30 is discharged when it is overcharged. In this way, by stabilizing the charging voltage of the second capacitor 30,
The power supply circuit 14 can be operated properly.

Further, the operating state of the power supply device according to the present embodiment described above will be described in detail with reference to the operating waveform of FIG. 2 which shows the current and voltage characteristics of the second capacitor 30, in particular. Now, when an ON command signal is input to the gate drive unit 12 to the GTO thyristor 10 [Fig. 2 (1)], at the same time, the gate of the thyristor 34 is passed through the monostable 44, the pulse amplifier 46 and the pulse transformer 48. A firing pulse is supplied to [[2] in FIG. 2], and the thyristor 34 is turned on. At this time, snubber capacitor 22
Is discharged through the impedance element 32, and the current I flows through the path shown by the solid line in FIG. 1 to charge the second capacitor 30 [FIG. 2 (3)]. In this way, when the voltages of the snubber capacitor 22 and the second capacitor 30 become substantially equal, the current II flows through the path shown by the broken line in FIG. 1 due to the anode-cathode voltage of the GTO thyristor 10, and the second capacitor Charge 30 [Fig. 2 (3)]. afterwards,
When the voltage of the snubber capacitor 22 becomes zero, the charging current II
Gradually decreases, and when the current II becomes zero, the thyristor 34
Is turned off, and the charging of the second capacitor 30 is completed [Fig. 2 (4)]. At this time, when the charging voltage of the second capacitor 30 exceeds the limit voltage Ve defined by the Zener diode 42, the transistor 36 is turned on, the discharge resistor 38 is connected to the capacitor 30, and the voltage is the limit voltage Ve. Is discharged until the temperature reaches (4), (5) in FIG. 2, and then the voltage of the capacitor 30 is stabilized at a constant voltage Ve.

In this way, the second capacitor 30 charged to a constant voltage is connected to the power supply circuit 14, and this power supply circuit 14 can create positive and negative DC power supplies and supply this to the gate drive unit 12. In the circuit of this embodiment, the second
The charging resistor 26 and the diode 28 connected to the capacitor 30 of the second capacitor 30 precharge the second capacitor 30 before starting the device using the GTO thyristor 10 and the second capacitor 30 during operation of the device. It functions as a circuit for supplementary charging.

〔The invention's effect〕

As is apparent from the above-mentioned embodiments, according to the present invention,
This is required especially in the case of a device configured by connecting GTO thyristors in series by configuring it to obtain the power supply necessary for the operation of the gate drive circuit from the snubber circuit provided to reduce the switching loss of the GTO thyristor. Not only does the use of a high-voltage, large-sized, and expensive insulating transformer need not be used, but the effect on switching noise and the like can be effectively prevented.

Therefore, according to the present invention, when a large number of GTO thyristors are connected in series according to the device voltage, it is not necessary to prepare an insulating transformer having different withstand voltage each time, and it becomes possible to standardize the power supply device for this kind of gate drive circuit. The effect of improving the reliability of the device and reducing the manufacturing cost thereof is extremely large.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the GTO thyristor in the above embodiment, but can be widely applied as a power supply device for a gate drive circuit of a similar switching element, and the like. It goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a power supply device for a gate drive circuit of a GTO thyristor according to the present invention, FIG. 2 is an operation waveform diagram of the circuit shown in FIG. 1, and FIG. 3 is a conventional GTO thyristor. It is a schematic circuit diagram which shows the structure of a gate drive circuit and a snubber circuit. 10 …… GTO thyristor 12 …… Gate drive unit 14 …… Power supply circuit, 16 …… Isolation transformer 18 …… Free wheel diode 20 …… Snubber diode 22 …… Snubber capacitor 24 …… Snubber resistor, 26 …… Charging resistance Unit 28 …… Diode, 30 …… Second capacitor 32 …… Impedance element 34 …… Thyristor, 36 …… Transistor 38 …… Discharge resistor, 40 …… Resistor 42 …… Zener diode 44 …… Monostable, 46 …… Pulse amplifier 48 …… Pulse transformer

Claims (4)

[Claims] 1. A GTO thyristor in which a snubber circuit in which a diode and a capacitor are connected in series are connected in parallel, wherein a second capacitor charged to the snubber capacitor via an impedance element and the thyristor is connected to the impedance element and the thyristor. It is connected in series with and is connected in parallel between the terminals of the snubber capacitor, and a gate pulse generator circuit is connected to the gate of the thyristor, which supplies an ignition pulse in synchronization with the ON command signal of the GTO thyristor, and A power supply for a gate drive circuit of a GTO thyristor, characterized in that a discharge circuit for holding the charging voltage of the capacitor at a constant voltage is connected in parallel with the second capacitor to constitute an operating power supply of the gate drive circuit of the GTO thyristor. apparatus. 2. The GTO thyristor according to claim 1, wherein the gate pulse generating circuit comprises a monostable for inputting an ON command signal of the GTO thyristor and generating a predetermined gate pulse, a pulse amplifier and a pulse transformer. Power supply for gate drive circuit. 3. A discharging circuit, wherein a discharging resistor is connected in parallel with a second capacitor through a transistor, and a Zener diode is connected to the base of the transistor to connect the second capacitor.
The power supply device for a gate drive circuit of a GTO thyristor according to claim 1, wherein the transistor is turned on when the charging voltage of the capacitor exceeds a set voltage. 4. The GTO thyristor according to claim 1, wherein the second capacitor is connected to the GTO thyristor via a charging resistor and a diode so as to perform initial charging and supplementary charging by the voltage between the anode and the cathode. Power supply for gate drive circuit.