JPH041581B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device having a control function, particularly a special turn-off function, for a self-extinguishing thyristor such as a gate turn-off thyristor or an electrostatic induction thyristor.

Gate turn-off thyristor (hereinafter referred to as GTO thyristor) is a conventional self-extinguishing thyristor.
The electrostatic induction thyristor (hereinafter referred to as SI thyristor) is known as a new type. This SI thyristor is
Similar to GTO thyristors, the device can be turned off by applying a reverse bias voltage between the cathode and gate of the current-carrying device. Regarding turn-off, there are two types: normally-off type, which requires forward bias to be applied between the gate and cathode like GTO thyristors, and normally-on type, which turns on simply by removing reverse bias between gate and cathode. There is. All of them are characterized by extremely fast switching times, and combined with the fact that they can easily be made to withstand high voltages, they are viewed as promising switching elements for high frequency and high power applications.

Next, FIG. 1 shows a typical example of a DC switch circuit using a GTO thyristor or SI thyristor.

Figure 1 shows an example of the configuration of a DC switch circuit using a normally-off type SI thyristor, where 1 is the SI thyristor, 2 is the main power supply, 3 is the resistor,
4 is a switch, 5 and 12 are capacitors, 6 is a resistor, 7 and 13 are diodes, 8 is a turn-on switch, 9 is a turn-off switch, 10 and 11
is the power source.

That is, when operating a circuit configuration using such an SI thyristor, it is performed as follows. To facilitate understanding, time charts showing the state of waveforms at various parts of the circuit shown in FIG. 1 are shown in FIGS. 2a and 2b. Note that _T1 is the time when the turn-on switch 8 is turned on, and _T2 is the time when the turn-off switch 9 is turned on.

Now, in FIG. 1, the turn-on switch 8 is turned off, the turn-off switch 9 is closed, and the voltage E ₂ of the power supply 11 is applied between the cathode and gate of the SI thyristor 1 through the diode 13. When the capacitor 5 is closed, the voltage E _S of the main power supply 2 is applied between the anode and cathode of the SI thyristor 1 through the resistor 3.
is charged through the diode 7 and becomes equal to the main power supply 2 voltage. Here, when turning on the SI thyristor 1, the turn-off switch 9 is turned off and the turn-on switch 8 is turned on. Then, a closed circuit is formed in the path of power supply 10 → turn-on switch 8 → capacitor 12 → SI thyristor 1 (gate electrode - cathode electrode) → power supply 10,
The charging current of the capacitor 12 flows to make the SI thyristor 1 conductive. At this time, the capacitor 12 is charged to the voltage E ₁ of the power supply 10 with the polarity shown. When the SI thyristor 1 turns on, the electric charge stored in the capacitor 5 is discharged via the resistor 6, and the energy is transferred to the resistor 6.
is consumed and converted into heat.

Further, in order to turn off the SI thyristor 1 while it is energized, the turn-on switch 8 is turned off and the turn-off switch 9 is turned on. At this time, the voltage E _{2 of the power supply 11 and the voltage V of the capacitor 12 are applied to the gate of the SI thyristor 1 through the path of the power supply 11 → SI thyristor 1 (cathode electrode to gate electrode) → capacitor 12 → turn-off switch 9} → power supply 11. _C is added and applied, SI thyristor 1
Excess carriers inside the SI thyristor 1 are swept out from the gate electrode as a gate reverse current, and the SI thyristor 1 is suddenly turned off. As a result, the capacitor 5 is charged again to the voltage E _S of the main power supply 2, and the SI thyristor 1 is maintained in a non-conducting circuit state.

In this way, self-extinguishing thyristors are useful because they can turn on and off the main current I _T by controlling the gate current, but the method of circuit configuration of the gate circuit section, especially The drawback was that it was difficult to extract the gate current at turn-off. This means that in order to cut off a certain value of main current I _T , it is necessary to flow a gate reverse current of more than a certain amount, for example, about (I _T /5) in a GTO thyristor, and more than that in an SI thyristor. This is because a fast rise characteristic is required to reduce the influence of internally generated hot spots. and,
This problem becomes more difficult to solve as the capacity of devices increases. There is also a problem with the discharge of the capacitor 5 that occurs at turn-on, and as mentioned above, the energy stored in the capacitor 5 becomes thermal energy and is dissipated by the resistor 6. As the resistance becomes higher, the capacitance of the resistor part must also be increased.

The present invention has been made to solve the above-mentioned problems, and provides a control device that effectively transfers the charge accumulated in the capacitor and utilizes it to sweep out excess carrier at turn-off. It is something. The present invention will be explained below based on the drawings.

3 and 4 are diagrams for explaining the operating principle shown to explain the technical idea of the present invention and time charts showing the state of waveforms of each part, and are 14, 15, 17.
is a capacitor, 16 is a diode, and 18 is a resistor. In the figure, the same reference numerals as in FIG. 1 indicate parts having the same function. Here, FIG. 4 shows the temporal transition of the waveform due to the turn-on of the turn-on switch 8 and the turn-on switch 9 based on FIG. 2.

That is, in the circuit configuration shown in FIG. 3a, by first turning off the turn-on switch 8 and the turn-off switch 9 and turning on the switch 4, the voltage E _S of the main power supply 2 is applied between the anode and cathode of the SI thyristor 1. , capacitor 14 is charged through diode 16 to voltage E _S . Next, when the turn-on switch 8 is turned on, the capacitor 17 is charged via the resistor 18, the voltage of the capacitor 17 increases, and the voltage V _GK between the gate and cathode of the SI thyristor 1 becomes positively biased. The SI thyristor 1 can be made conductive. As a result, a closed circuit consisting of capacitor 14 -> SI thyristor 1 (anode electrode to cathode electrode) -> capacitor 15 -> capacitor 14 is formed, and the discharge current of capacitor 14 is passed through. This is as shown in Figure 3b. Therefore,
The capacitor 15 is charged with the polarity shown, and the voltage V _SC1 of the capacitor 14 after discharge is equal to the voltage V _SC2 of the capacitor 15, and its value is expressed by equation (1). However, C ₁ and C ₂ are the capacitances (μF) of the capacitors 14 and 15.

V _SC2 = E _S ·(C ₁ /C ₁ +C ₂ )...(1) The waveforms of each part of this relationship are shown as shown in FIG. 4a.

Furthermore, when the turn-on switch 8 is turned off and the turn-off switch 9 is turned on, as shown in FIG.
As shown by the dashed line, a closed circuit of capacitor 15 → SI thyristor 1 (cathode electrode to gate electrode) → turn-off switch 9 → capacitor 15 is formed, and a reverse current flows to the gate of SI thyristor 1, and SI thyristor 1 Begin turn-off. At this time, when the excess carrier of the SI thyristor 1 is swept out and the reverse voltage between the cathode and the gate of the SI thyristor 1 is restored, the capacitor 17 has the polarity shown by the two-dot chain line in Figure 3c. It is charged until the voltage reaches the same voltage as that of the capacitor 15. Then, as the SI thyristor 1 turns off and the voltage between the anode and cathode begins to recover,
As shown in Figure 3d, current flows through the path of main power supply 2 -> resistor 3 -> switch 4 -> capacitor 14 -> capacitor 15 -> main power supply 2, so if turn-off switch 9 is turned off at this time, capacitor 14 will be turned off (as shown in the figure). Since the capacitor 17 is charged with the polarity shown in the figure, the SI thyristor 1
The gate and cathode of the transistor are reverse biased. Further, when the capacitor 15 is discharged and its charging voltage is reversed, the voltage V _SC1 of the capacitor 14 is charged to the voltage _S due to conduction to the diode 16, and returns to the original state. The waveforms of each part of these relationships are as shown in FIG. 4b.

Therefore, in the technology based on this technical idea, the charge stored in the snubber capacitor 14 at turn-off is used to sweep out excess carriers of the element at the next turn-off, and compared to the conventional method, the charge stored in the snubber capacitor 14 at turn-off is used to sweep away excess carriers from the element, and the amount of charge required in the gate control circuit section at turn-off is reduced compared to the conventional method. In addition, by effectively transferring the capacitor charge consumed in the snubber resistor at turn-off to another location, heat generation in the snubber circuit can be effectively reduced. Next, the present invention will be described in detail with reference to specific embodiment drawings.

FIG. 5 is a circuit diagram showing an embodiment of the present invention similar to FIG. 3a, in which 19 and 20 are conventional thyristors. In the figure, the same reference numerals as in FIG. 3a indicate the same components. That is, in the circuit shown in FIG. 5, the turn-on switch 8 and turn-off switch 9 of the circuit configuration of FIG. 3a are replaced by thyristors 19 and 20.
It consists of: and has the following functions:

In FIG. 5, when turning on, the thyristor 19 is made conductive by an on signal (not shown) to charge the capacitor 17, but when the SI thyristor 1 becomes conductive, the forward voltage of the thyristor 19 becomes zero, so the thyristor 19 is turned off. be able to. Also, at turn-off, the thyristor 20 is turned on by an off signal (not shown) and a reverse current flows through the gate of the SI thyristor 1.
SI thyristor 1 turns off and capacitor 1
A charging current flows through the capacitors 4 and 15, and when the charge in the capacitor 15 is discharged, a reverse bias is applied to the thyristor 20, so that it can be turned off.

Further, the circuit configuration of the embodiment as described above is
In order to limit the discharge current of the snubber capacitor flowing at the moment when the SI thyristor is turned on, it may be configured as shown in FIG. 6 or FIG. 7.
That is, FIGS. 6 and 7 are partial connection diagrams showing modifications of the capacitor circuit shown in FIG. 5, in which 23 and 23' are resistors, 24 is a diode, and
5 and 25' are reactors. In the figure, the same reference numerals as in FIG. 5 indicate parts having the same functions. In this way, for example, as shown in FIGS. 6a and 6b, a current suppressing circuit is added such as connecting a parallel circuit consisting of a resistor 23 or a reactor 25 and a diode 24 in series with the capacitor 14, or the capacitor 15 side It is added to. In addition, in the embodiment drawing, a diode 1 is connected in parallel to the capacitor 15.
However, it is clear that even if the diode 16 is removed, the present invention can be effectively used without impairing the function of the present invention.
It should be added that the effect will be further improved by adding the above.

As described above, according to the present invention, it is possible to provide an exceptional control device in which gate power is supplied from the main circuit, especially during turn-off.

[Brief explanation of drawings]

Figures 1 and 2 are circuit diagrams showing a configuration example of a DC switch circuit using SI thyristors, time charts showing waveform states of each part, and Figures 3 and 4 are for explaining the technical idea of the present invention. FIG. 5 is a circuit diagram showing an embodiment of the present invention; FIG.
FIG. 7 is a partial connection diagram showing a modification of the capacitor circuit portion. 1... Electrostatic induction thyristor (SI thyristor),
2... Main power supply, 5, 12, 14, 15, 17...
Capacitor, 7, 13, 16...Diode, 8
... Turn-on switch, 9... Turn-off switch, 19,20... Thyristor.

Claims (1)

[Claims] 1 Connect one end of the first capacitor to the anode terminal of a self-extinguishing thyristor with a capacitor connected in parallel between the gate terminal and cathode terminal, and connect one end of the second capacitor and the cathode terminal of the diode to the cathode terminal. At the same time, one end of the turn-off switch and one end of the turn-off switch are commonly connected to the gate terminal, and the other end of the first capacitor, the other end of the second capacitor, the anode terminal of the diode, and the turn-off switch are connected in common. and the other end of the turn-on switch is connected to the anode terminal of the self-arc-extinguishing thyristor via a resistor.