JPH05175489A - Self-arc extinguishing type thyristor - Google Patents

Abstract

PURPOSE:To perform triggering by one signal. CONSTITUTION:A normal OFF type switching element M1 is connected between a second N-type region and a fourth N-type region of a P-N-P-N junction type thyristor 1. A normal ON type switching element M2 is connected between a third P-type region and a fourth N-type region of the thyristor 1. A photovoltaic element PV for turning ON the element M1 and turning OFF the element M2 at the time of arc firing is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-extinguishing thyristor which can be extinguished by controlling a gate voltage.

[0002]

2. Description of the Related Art Equivalent circuit of a PNPN junction type thyristor
Is shown in FIG. Here, the thyristor 1 is a typical n⁺p
n^-p⁺In case of structure, transistor Tr in the figure₁Is
p⁺n ^-p part, transistor Tr₂Is n⁺pn^-Department
Min, gate resistance R_GKIs the lateral resistance of the p-base (p-well).
Each represents a resistance.

In this type of thyristor 1, a high-sensitivity type having no short-emitter structure generally has a voltage (dv / d) having a sharp potential change such as noise.
When t) is applied between the anode and the cathode, a displacement current flows through the electrostatic capacity of the junction, and when it exceeds the allowable value, the thyristor 1 is ignited, so-called false ignition occurs.

Therefore, in order to improve the noise resistance,
Attempts have been made to bypass the displacement current by providing a low impedance between the gate and the cathode. In this way, when the impedance between the gate and the cathode is low, a transistor or a low resistance is connected between the gate and the cathode. However, if a low resistance is connected as described above, there is a problem that the sensitivity itself of the thyristor 1 is lowered. Further, when a transistor is used, since it is driven by current, there is a problem that the switching characteristics are deteriorated due to the carrier accumulation effect and the lateral base effect. Further, the transistor is not preferable in that the collector-emitter voltage does not drop below a certain value.

Therefore, as a method for improving this point,
As shown in FIG. 6, a switching element (for example, MOSFET) M ₂ 'having excellent switching characteristics is connected between the gate and the cathode (between the third P region and the fourth N region) in parallel with the gate resistance R _GK. Can be considered. If such a switching element M ₂ 'is used, erroneous firing can be prevented, the sensitivity is not lowered, and the switching characteristics are improved.

By the way, in the case of the thyristor 1 shown in FIG. 6, a normally-off type switching element (enhancement type MOSFE) is provided between the second N region and the fourth N region.
T) M ₁ is connected. The switching element M ₁ is for turning on the thyristor 1 by triggering the transistors Tr ₁ and Tr ₂ . That is, FIG.
(A), the at the turn on the thyristor 1 As shown in the biased transistor Tr ₁ FIG (c) by turning on the switching element M _1.

Further, in the thyristor 1 shown in FIG. 6, a normally-on type switching element (enhancement type MOSFET) is used as the switching element M ₂ 'to provide a self-extinguishing type thyristor 1. That is, in the case of the general thyristor 1, it is possible to turn on by applying a trigger, but this on state cannot be forcibly turned off unless another switch or the like is provided. However, as described above, the normally-on type switching element M
'If and a, as shown in FIG. 7 (b), the switching element M _{2' 2} by turning on a gate
By connecting the cathodes with low impedance so that the transistor Tr ₂ is not biased, the same figure (c)
The thyristor 1 can be forcibly turned off as shown in FIG. It should be noted that the switching elements M ₁ and M ₂ ′ may be triggered by pulse waves.

[0008]

However, in FIG.
The self-extinguishing thyristor shown has two gates G₁, G
₂The drawback is that you have to trigger each
It was The present invention has been made in view of the above points.
The purpose of is to trigger with one signal.
The purpose is to provide a self-extinguishing thyristor.

[0009]

In order to achieve the above object, the present invention provides a PNPN junction type thyristor and a normally-off type switching element connected between the second N region and the fourth N region of the thyristor. And a normally-on switching element connected between the third P region and the fourth N region, and a bias element for turning on the normally-off switching device at the time of ignition and turning off the normally-on switching device. Is equipped with.

A photoelectric element, for example, can be used as the bias element. In the case of AC control, the self-extinguishing thyristors may be connected in antiparallel.

[0011]

According to the present invention, the thyristor can be turned on and off by controlling the bias element having the above-described structure, and the control of one bias element is sufficient. It is made possible to call.

[0012]

(Embodiment 1) FIG. 1 shows an embodiment of the present invention. The self-arc-extinguishing thyristor 1 of the present embodiment has a normally-on switching element (depletion-type MOSFET) instead of the normally-off switching element (enhancement-type MOSFET) M ₂ 'of the self-extinguishing thyristor in FIG. ) M ₂ is used. That is, the normally-on type switching element M is provided between the third P region and the fourth N region of the PNPN junction type thyristor 1.
₂ are connected. The gate of the switching element M ₂ is commonly connected to the gate of the normally-off type switching element M ₁ (enhancement type MOSFET). Then, between the gate and the cathode, the turns on the switching element M ₁ of the normally-off during firing, is connected a biasing element to turn off the switching element M ₂ of normally-. Here, in this embodiment, a photovoltaic element PV such as a photodiode or a solar cell is used as the bias element, and the photovoltaic element PV is irradiated with light from the light emitting element LD to apply an optical trigger. Is done. Thus, the photovoltaic element PV
By turning on and off both switching elements M ₁ and M ₂ with, a self-extinguishing thyristor can be turned on and off with one signal.

Now, when light is not emitted from the light emitting element LD to the photovoltaic element PV, the photovoltaic element PV is in a state where no electromotive force is generated. At this time, the switching element M ₁ is on and the switching element M ₂ is off. When the switching element M ₂ is thus turned on, the impedance between the gate and the cathode of the thyristor 1 becomes low, and the voltage (dv / dt) having the abrupt potential change is applied between the anode and the cathode as described above. By displacing the displacement current at this time, false ignition is prevented. Therefore, the self-arc-extinguishing thyristor of this embodiment also has improved noise resistance. The gate resistance R _GK of the thyristor 1 is several 100 kΩ or more, and the thyristor 1 itself has high sensitivity.

The light from the light emitting element LD is the photovoltaic element PV.
When irradiated with, a predetermined electromotive force is generated. Where
Of the transistor Tr of the thyristor 1₁, Tr
₂Above the threshold voltage of, and maximum of thyristor 1
The gate voltage is set to be lower than that. At this time
Is the switching element M₂Turns off and switches
Element M₁Turns on. Thus, the switching element M
₂When is off, the sensitivity of thyristor 1 is gate resistance R_GK
It becomes a high sensitivity state. Therefore, the
Touching element M₁Turning on the transistor Tr₁But
Turns on. At this time, flow between the anode and cathode
Gate resistance R due to current_GKThe voltage generated across the
Register Tr₂Base current flows to the transistor Tr
₂Turns on. In this way, the transistor Tr₂But
When turned on, the transistor Tr ₂Through Transis
Ta Tr₁The base current is applied to the
Langista Tr₁, Tr₂Both supply their base currents.
Will be supplied and the thyristor 1 will be kept in the ON state.
It

However, the latched state of the thyristor 1 is continued only while the light emitting element LD emits light. That is,
In the self-arc-extinguishing thyristor of this embodiment, when light is not emitted from the light emitting element LD to the photovoltaic element PV, the electromotive force of the photovoltaic element PV does not occur at this time, and the switching element M ₁ is turned off. , The switching element M ₂ is turned on.

In this way, the switching element M₂Is o
Gate resistance R_GKBoth ends have low impedance
Becomes, transistor Tr₁The current from the switching element
Child M ₂Bypassed by. Therefore, the transistor Tr
₂Turns off, and at this time the switching element M₁Also off
Therefore, the transistor Tr₁The base current of
And transistor Tr₁Will also be off. This
Thyristor 1 is turned off.

In other words, the self-arc-extinguishing thyristor of this embodiment is turned on only when the light emitting element LD is emitting light, and is turned off when the light emitting element LD stops emitting light. Here, it is desirable that the switching element M ₂ has a switching speed as fast as possible. (Embodiment 2) FIG. 2 shows another embodiment of the present invention. In this embodiment, a phototransistor PT and a resistor R are used instead of the photovoltaic element PV as the bias element. Here, the phototransistor PT includes a base of the transistor Tr ₁ and switching elements M ₁ and M ₂
Connected to the commonly connected gates of
Are connected between the commonly connected gates and cathodes of the switching elements M ₁ and M ₂ . Here, the phototransistor PT is connected so that a current flows from the base of the transistor Tr ₁ to the resistor R.

Now, when light is emitted from the light emitting element LD to the phototransistor PT with a voltage of a certain level or more applied between the anode and the cathode, the anode of the thyristor 1 and the emitter-base of the transistor Tr ₁ are A current flows through the path of the phototransistor PT, the resistor R, and the cathode of the thyristor 1, thereby generating a voltage in the resistor R. This voltage is the same as the above-mentioned photovoltaic element PV of Example 1.
Since the resistance value of the resistor R and the like are set so as to be the same voltage as the above, the thyristor 1 is turned on in the same manner as in the first embodiment.
Can be turned off.

This embodiment and the first embodiment can be used, for example, as a semiconductor DC latching relay. (Embodiment 3) FIGS. 3 and 4 show still another embodiment of the present invention. The self-arc-extinguishing thyristor of each of the above-mentioned embodiments was unidirectional, but as shown in FIG.
If the self-extinguishing thyristors of are connected in antiparallel, they can be made bidirectional. The self-extinguishing thyristor of FIG. 2 may be connected in anti-parallel to be bidirectional.

Now, when the AC power source V _L and the load R _L are connected in series at both ends of the self-extinguishing thyristor of this embodiment, and the light emitting element LD is caused to emit light as shown in FIG. The power shown in FIG. 7C is supplied to the load R _L during the light emission period of the element LD. Note that FIG. 4B shows an AC power waveform. The self-extinguishing thyristor of this embodiment can be used as a non-zero-cross type semiconductor relay or the like.

[0021]

As described above, the present invention provides a PNPN junction type thyristor, a second N region and a fourth N region of this thyristor.
A normally-off switching element connected to the region, a normally-on switching element connected to the third P region and the fourth N region, and turning on the normally-off switching device at the time of ignition. , And a bias element for turning off the normally-on type switching element, the thyristor can be turned on and off by controlling the bias element, and the thyristor can be turned on and off by controlling one bias element. Therefore, it is possible to trigger with one signal.

If the self-arc-extinguishing thyristors are connected in antiparallel, a self-arc-extinguishing bidirectional thyristor can be constructed, and can therefore be used for AC control.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a circuit diagram of another embodiment.

FIG. 3 is a circuit diagram of still another embodiment.

FIG. 4 is an explanatory diagram of an operation of the above.

FIG. 5 is an equivalent circuit diagram of a PNPN type thyristor.

FIG. 6 is a circuit diagram of a conventional self-extinguishing thyristor.

FIG. 7 is an operation explanatory diagram of the above.

[Explanation of symbols]

1 Thyristor M ₁ , M ₂ Switching element PV Photovoltaic element PT Phototransistor R Resistance

Claims (3)

[Claims] 1. A PNPN junction type thyristor, a normally-off type switching element connected between the second N region and the fourth N region of this thyristor, and a third P region and a fourth N region. A self-extinguishing thyristor comprising a normally-on type switching element and a bias element for turning on the normally-off type switching element at the time of ignition and for turning off the normally-on type switching element. 2. The self-extinguishing thyristor according to claim 1, wherein a photoelectric element is used as the bias element. 3. The self-extinguishing thyristor according to claim 1, wherein the self-extinguishing thyristor is connected in antiparallel.