JPH0342732B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in gate circuits for self-extinguishing thyristors such as gate turn-off thyristors and electrostatic induction thyristors, and aims to unify gate power supplies and reduce power consumption. It is an object of the present invention to provide a gate circuit device with improved performance, and to realize a self-extinguishing thyristor device that is useful for high frequency switching.

In general, a self-extinguishing thyristor (hereinafter referred to as SCTH) can be turned on by passing a forward current through its gate electrode, and extinguished by passing a reverse current through the gate electrode. Also,
There are some types of SCTH that require a continuous gate forward current to be supplied during the on-state period.
A mode that only requires supply for a short period of time during ignition is attracting attention. In any of these embodiments, the power required for the gate power supply to supply the gate forward current is trivial, but compared to the gate forward current, the value of the gate reverse current at the time of extinction is comparable to the anode current of SCTH. The power supply for the reverse current supply was also extremely large. Note that the gate reverse current only needs to flow for a very short time during arc extinction, so it is not a big problem in low frequency switching operations, but in high frequency operations there is a marked tendency for higher power consumption.

On the other hand, as a method for supplying the bidirectional gate forward current and gate reverse current necessary to perform the SCTH switching operation, a forward current supply power supply and a reverse current supply power supply are provided separately.
There is a so-called two-power supply system in which the respective currents are turned on and off by each supply switching element, and a single-power supply system in which bidirectional current is controlled by one shared power supply and four bridge-connected control switching elements. There is.

Although the dual power supply system allows relatively simple control operations, it is cumbersome to prepare two independent power supplies, whereas the single power supply system requires a large number of switching elements for control, making it difficult to control these openings and closings. The command circuit used to do this was also becoming more complex.

The present invention has been made in view of the above points, and the technical idea can be summarized as follows. In other words, the power of the gate reverse current supply power source is regenerated from the absorber capacitor to reduce the external power supply, and since the power required for gate forward current supply is small, the gate reverse current charge is reduced. Based on the principle that the data is stored in a separately provided storage means, the present invention provides an exceptional device that apparently uses two power sources even though it uses one power source. Hereinafter, the present invention will be explained in detail with reference to the drawings.

Figures 1 and 2 show the main part configuration and waveforms of each part of an embodiment of the present invention, where 1 is an SCTH, 2 is an absorber capacitor, 3 is a diode, and 4 is a gate reverse current supply power supply ( 5 is a switching element for supplying reverse current, 6 is a capacitor which is an example of storage means as a power supply for gate forward current supply, 7 is a Zener diode, 8
1 is a forward current supply switching element, 9 and 10 are resistors, and 11 is a reactor. Also, _I.G.
The gate current of SCTH, V _AK is the voltage between the anode and cathode of SCTH 1, V _CS is the voltage of absorber capacitor 2, I _L is the current of reactor 11, and V _C is the voltage of capacitor 6.

The operations shown in FIGS. 1 and 2 are as follows.
The details of the connection configuration shown in FIG. 1 will be explained as follows.

Here, before time T ₀ shown in Figure 2,
It is assumed that SCTH1 is in a conductive state. Therefore, the voltages V _AK and V _CS are zero, and the current I _G is the voltage
A current of an appropriate value is passed through the forward current supply switching element 8 and the resistor 9 due to V _C .

Now, at time T ₀ , when the forward current supply switching element 8 opens and the reverse current supply switching element 5 closes due to the arc extinguishing command, the DC power supply 4
Therefore, a gate reverse current is applied from the Kaleido of SCTH1 to the gate electrode direction through the capacitor 6. Here, as shown in the figure, the current I _G is at time T ₀
During this _period , the capacitor 6 is charged by its gate reverse current, and the voltage V _C
increases as shown in the example. Further, if the voltage V _C exceeds the Zener potential of the Zener diode 7 before time T ₁ , a gate reverse current flows through the Zener diode 7 and the rise of the voltage V _C is stopped. What should be noted about such an action is that the capacitor 6 is charged by the gate reverse current when the arc is extinguished. It can be removed.

In addition, SCTH1 completes arc extinguishing near time _T1 when the gate reverse current becomes zero, and the main current that has been flowing through SCTH1 is transferred to the series circuit of absorber capacitor 2 and diode 3, and the current flows through the absorber capacitor. Charge 2. Therefore, voltages V _AK and V _CS begin to rise simultaneously near time T ₁ , and at time T ₂
The voltage reaches the voltage value of the main circuit power supply (not shown). From then on, SCTH remains off.

Further, at time _T3 , when the switching element 5 for reverse current supply is opened and the switching element 8 for forward current supply is closed by the ignition command, the gate forward current is supplied by the voltage V _C of the capacitor 6, and the SCTH
1 becomes the ignition state, and the voltage V _AK drops to near zero in a short time. Then, the gate forward current will decrease with a time constant determined by the values of capacitor 6 and resistor 9, but it is difficult to decide whether to continue it during the on period or to flow it only for a short time at the time of ignition at time _T3 . It is determined by the aspect of the SCTH 1 as described above, and the capacitance of the capacitor 6, the resistance value of the resistor 9, the voltage of the Zener diode, etc. may be appropriately selected.

Now, when SCTH1 is ignited at time _T3 , the charge of absorber capacitor 2, which had been charged to the polarity shown in FIG. 1 during the off period, is discharged through SCTH1, DC power supply 4, and reactor 11.
Here, absorber capacitor 2 and reactor 1
Due to the resonance effect of 1, the current I _L due to this discharge increases in a sine wave manner, and the voltage V _CS decreases in a cosine wave manner.

Furthermore, assuming that the voltage V _CS becomes zero at time T ₄ , the current I _L flows through the diode 3 and the DC power supply 4 from then on, so the slope determined by the inductance L of the reactor 11 and the voltage V of the DC power supply 4 ( -V/L) and decreases linearly to zero at time _T5 .

The discharge current of the absorber capacitor 2 from time T ₃ to time T ₄ and from time T ₄ to time T ₅ are as follows.
It is clear that the return current of the reactor 11 up to this point flows from the anode to the cathode of the DC power supply 4 to perform the power regeneration operation. Therefore, by providing the illustrated DC power supply 4 with an energy storage ability, the power required for extinguishing the arc can depend on this regenerated power, and externally supplied power is almost unnecessary. Of course, depending on the magnitude of the regenerated power and the arc-extinguishing power, external power may be required.On the other hand, if the regenerated power is larger, it may be necessary to consume it with a resistor, etc., but it goes without saying that this can be easily handled. .

Although the example is shown in which the current I _L becomes zero during the on period, this is not necessarily necessary and no problem will occur if the current I L becomes zero before the next ignition.
In addition, it is assumed that the capacitor 6 is not charged when the switching operation is started for the first time, but this can be done by closing the reverse current supply switching element 5 for a predetermined period of time before starting the switching operation. Can be charged via

Next, in the device shown in FIG. 1, as the gate reverse current becomes larger than the gate forward current, the current flowing through the Zener diode 7 increases and the loss generated therein increases. Figure 3 shows an example in which such problems have been improved.

FIG. 3 is a partial circuit diagram showing a main part configuration of a modified example of the device shown in FIG. 1, in which 12 is a diode and 13 is an avalanche diode. In the figure, the same reference numerals as in FIG. 2 indicate the same components.

That is, in FIG. 3, the Zener diode 7 connected in parallel to the capacitor 6 shown in FIG. 2 is replaced with a diode 12 and an avalanche diode 13 as shown. As is well known, the avalanche diode 13 has good blocking characteristics when the applied voltage is below a certain value.
When this value exceeds a certain value, the device enters an on state and its forward voltage becomes insignificant. Therefore, in FIG. 3, the gate reverse current flows through the capacitor 6 and the diode 12 at the beginning of arc extinction, and the gate reverse current flows through the capacitor 6 and the diode 12.
It is possible to cause the voltage to flow through the avalanche diode 13 when the voltage exceeds a predetermined value. At this time, the voltage of the avalanche diode 13 is not as large as that of the Zener diode 7, and the loss that occurs is not so large. Note that instead of such an avalanche diode, an electrostatic induction thyristor having a large current capacity can be used. That is, similar characteristics can be achieved by applying an appropriate gate bias to the electrostatic induction thyristor.

As described above, according to the present invention, it is possible to provide a device with a simple configuration that is particularly useful for SCTH that performs high frequency switching.

[Brief explanation of drawings]

1 and 2 are circuit diagrams and waveform diagrams of the main parts of an embodiment of the present invention, and FIG. 3 is a partial circuit diagram showing a modification of the apparatus shown in FIG. 1. 1... Self-extinguishing thyristor (SCTH), 2...
...absorber capacitor, 4... power source for gate reverse current supply (DC power supply), 5... switching element for reverse current supply, 6... capacitor, 7... Zener diode, 8... switching element for forward current supply, 11...Reactor, 13...Avalanche diode.

Claims (1)

[Claims] 1. A series connection body of an absorber capacitor and a diode arranged between the anode and cathode of a self-arc-extinguishing thyristor, and a Zener diode and a switching element for reverse current supply arranged between the gate and cathode of the self-arc-extinguishing thyristor. and a reverse current supply power source, a series connection body of a capacitor, a forward current supply switching element, and a resistor between the gate and cathode of the self-extinguishing thyristor, and a series connection body of the absorber capacitor and the diode. A self-extinguishing thyristor comprising a reactor disposed between a connection point and a connection point of the reverse current supply switching element and the reverse current supply power supply, the capacitor and a Zener diode being connected in parallel. gate circuit.