JPH01261921A - Semiconductor switching circuit - Google Patents

Abstract

PURPOSE:To protect all semiconductor switching elements by constituting a snubber circuit by means of a resistance element and a capacity element and connecting the capacity element to both ends of a second resistance element with the other switching element. CONSTITUTION:The resistance element 10 and the capacity element 14 are connected serial and they are connected between two terminals except for a gate terminal in a three terminals-semiconductor switching element 2, whereby they constitute the conventionally similar snubber circuit. Consequently, the element 2 is protected from a surge. Since the element 14 is connected to both ends of the other semiconductor switching element and the resistance element 12, the surge with respect to the element 4 bypasses the element 10 and the element 14. Consequently, the element 4 is protected from the surge. Namely, the surge for the element 2 and the element 4 arranged in the gate terminal bypasses the snubber circuit consisting of the element 10 and the element 14, and the elements 2 and 4 are protected from the surge.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor switching circuit equipped with a surge absorption circuit.

[Prior Art] In a conventional semiconductor switching circuit having a semiconductor switching element such as a thyristor or triac used in a power control circuit, a snubber circuit consisting of a series circuit of a capacitor and a resistor is connected to both ends of the semiconductor switching element. A snubber circuit is used to absorb surges generated during commutation of the switching element to prevent erroneous triggering of the semiconductor switching element and to protect the element from destruction.

FIG. 2 is a circuit diagram of a conventional semiconductor switching circuit.

Reference numeral 2 indicates a triac which is a bidirectional three-terminal semiconductor switching element. A triac section 6 of a phototriac 4, which is another semiconductor switching element, is arranged in the gate circuit of the triac 2. That is, a resistor 10, a triac section 6, and another resistor 12 connected in series are connected between two terminals other than the gate terminal of the triac 2, and the gate terminal of the triac 2 is connected to the triac section 6 of the phototriac 4. and the connection point between the resistor 12 and the resistor 12.

A light emitting diode section 8 optically coupled to the triac section 6 inside the phototriac 4 has trigger signal input terminals 8a at both ends.

8b. On the other hand, both ends of triac 1 and triac 2 are connected to AC input terminals 2a and 2b, respectively.

Furthermore, a snubber circuit consisting of a series circuit of a capacitor 16 and a resistor 18 is connected to both ends of the triac 2.

The conventional semiconductor switching circuit described above is used by applying an AC voltage between the AC input terminals 2a and 2b. Only while a DC trigger signal is applied between the trigger signal input terminals 8a and 8b, the light emitting diode section 8 of the phototriac 4 emits light, and the phototriac 4 emits light.
The triac section 6 becomes conductive. Triac 2 is
The conduction is triggered by the conduction of the triac section 6 of the phototriac 4. That is, this semiconductor switching circuit allows phase control of the AC power passing through the triac 2 between the AC input terminals 2a and 2b.

Now, surges generated during commutation of the triac 2 become a particular problem when the triac 2 interrupts an inductive load current. capacitor 16 and resistor 18
The snubber circuit consisting of a series circuit with triac 2
The rate of increase in applied voltage is the critical off-voltage increase rate dv of this element.
/dt to prevent false triggering and destruction of the triac 2.

[Problems to be Solved by the Invention] In the conventional semiconductor switching circuit described above, the surge applied to the triac 2 is absorbed by the snubber circuit consisting of the series circuit of the capacitor 16 and the resistor 18, and the triac 2 is protected. You can do it. However, the triac portion 6 of the phototriac 4 provided for triggering the triac 2 was not protected. Therefore, in the conventional circuit, the triac section 6 may be erroneously triggered or destroyed by the surge.

The present invention has been made in view of the above points, and includes three
To provide a semiconductor switching circuit in which a gate circuit of a terminal semiconductor switching element is arranged with another semiconductor switching element, and is equipped with a surge absorption circuit capable of protecting both semiconductor switching elements.

[Means for Solving the Problems] A semiconductor switching circuit according to the present invention is a circuit in which another semiconductor switching element 4 is arranged in a gate circuit of a three-terminal semiconductor switching element 2, and the first resistive element 1
0, semiconductor switching element 4, and second resistive element 12
are sequentially connected in series between two terminals other than the gate terminal of the three-terminal semiconductor switching element 2, and the gate terminal of the three-terminal semiconductor switching element 2 is connected to the semiconductor switching element 4 and the second resistive element 12. is connected to the connection point of the semiconductor switching element 4 and the second resistive element 12.
A capacitive element 14 is connected to both ends of the .

[Function] In the semiconductor switching circuit according to the present invention, the first resistive element 12 and the capacitive element 14 are connected in series.
The first resistive element 12 and the capacitive element 14 are connected between two terminals other than the gate terminal of the terminal semiconductor switching element 2, and constitute a conventional snubber circuit for the three-terminal semiconductor switching element 2. Therefore, this semiconductor switching element 2 is protected from surges.

Furthermore, unlike the conventional case, since the capacitive element 14 is connected across the other semiconductor switching element 4 and the second resistive element 12, the surge to the semiconductor switching element 4 is caused by the first resistive element 12. Element 12 and capacitive element 14 are bypassed.

Therefore, this switching element 4 is also protected from surges.

That is, all surges to the three-terminal semiconductor switching element 2 and other switching elements 4 disposed in the gate circuit of this element bypass the snubber circuit consisting of the first resistive element 12 and the capacitive element 14, These bidirectional conductor switching elements 2.4 are protected from surges.

Embodiment FIG. 1 is a circuit diagram of a semiconductor switching circuit according to an embodiment of the present invention.

The reference numeral 2 indicates a triac which is a two-way three-terminal semiconductor switching element, as in FIG. A triac section 6 of a phototriac 4, which is another semiconductor switching element, is arranged in the gate circuit of the triac 2. That is, a resistor IO, a triac section 6, and another resistor 12 connected in series are connected between two terminals other than the gate terminal of the triac 2, and the gate terminal of the triac 2 is connected to the triac section 6 of the phototriac 4. and the connection point between the resistor 12 and the resistor 12.

Both ends of the light emitting diode section 8 of the phototriac 4 are connected to trigger signal input terminals 8a and 8b, respectively.
Both ends of triac 2 are AC input terminals 2a,
2b.

Furthermore, unlike the conventional method, a capacitor 14 is connected to both ends of the triac section 8 of the phototriac 4 and the resistor 12 connected in series.

The semiconductor switching circuit according to the embodiment of the present invention described above is also used by applying an AC voltage between the AC input terminals 2a and 2b, and the trigger signal input terminal 8a, similar to the conventional one,
By applying a DC trigger signal between G and B, the phase of AC power passing through the triac 2 can be controlled.

For example, a surge generated during commutation in the triac section 6 of the phototriac 4 bypasses the snubber circuit composed of the resistor 10 and the capacitor 14. Therefore, erroneous triggering and destruction of the triac section 6 are prevented. In other words, all surges from triac 2 and phototriac 4 to triac section 6 are caused by resistor 1.
Bypassing the snubber circuit consisting of 0 and capacitor 14, these bidirectional conductor switching elements 2.4 are protected from surges.

In particular, in the embodiment described above, since the phototriac 4 is used as another semiconductor switching element disposed in the gate circuit of the triac 2, the trigger signal input terminals 8a, 8b and the AC input terminals 2a, 2b are It is possible to insulate between.

In the above description, a bidirectional triac 2 is used as the three-terminal semiconductor switching element, but a unidirectional thyristor may be used instead. Further, although the phototriac 4 is used as another semiconductor switching element disposed in the gate circuit of the three-terminal semiconductor switching element, other types of semiconductor switching elements may be used instead.

[Effects of the Invention] As explained above, the semiconductor switching circuit according to the present invention includes another semiconductor switching element 4 in the gate circuit of the three-terminal semiconductor switching element 2, and the first resistive element 10 and the semiconductor switching element 2. A switching element 4 and a second resistive element 12 connected in series are connected between two terminals other than the gate terminal of the three-terminal semiconductor switching element 2, and the gate terminal of the three-terminal semiconductor switching element 2 is connected to the semiconductor switching element 2. Since it is connected to the connection point between the element 4 and the second resistive element 12, and the capacitive element 14 is connected to both ends of the semiconductor switching element 4 and the second resistive element 12, it is a three-terminal semiconductor switching. Both the element 2 and the other semiconductor switching element 4 arranged in the gate circuit of this element can be protected from surges.

Furthermore, one of the two resistive elements 10 and 12 connected in series to one of the semiconductor switching elements 4 is also used as a resistive element constituting a snubber circuit together with the capacitive element 14, so that the resistive element Another effect is that the number can be reduced.

−１〇　−

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a semiconductor switching circuit according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional semiconductor switching circuit. Explanation of symbols 2...triac, 4...phototriac,
6...triac part, butt...light emitting diode part, 1
0, 12...Resistor, 14...Capacitor.

Claims (1)

[Claims] A semiconductor switching circuit in which another semiconductor switching element is arranged in a gate circuit of a one- and three-terminal semiconductor switching element, the first resistive element, the other semiconductor switching element, and the second resistive element being connected in series. , and the gate terminal of the three-terminal semiconductor switching element is connected to the other semiconductor switching element and the second resistive element. 1. A semiconductor switching circuit characterized in that a capacitive element is connected to both ends of the other semiconductor switching element and the second resistive element.