JPH0678538A - Ac switching circuit apparatus - Google Patents

Abstract

PURPOSE:To prevent a break-through of a thyristor, by providing a self-arc- extinguishing type semiconductor element connected in parallel with the thyristor, and by making the semiconductor element turn on in the lower dV/dt value than the dV/dt-withstanding quantity of the thyristor. CONSTITUTION:In the state wherein the voltage-time-varying rate dV/dt of the voltage applied to a MOS FET (SE4) is lower than the dV/dt-withstanding quantity of a thyristor, a voltage drop (Vr) of a resistor 5, which is caused by a displacement current (Ic) flowing through the resistor 5, becomes the voltage value exceeding the ignition voltage (Vth) of the FET SE4, and a drain 4a of the FET SE4 is connected with its source 4b in a conducting way. Therefore, the bypass of a thyristor 2 is generated between an anode 2b and cathode 2a of the thyristor 2 by the FET SE4, and the potential difference between the anode 2b and cathode 2a is reduced to a small value violently. Thereby, the varying ratio of a reverse recovery current (Irr) of a thyristor 1 is decreased, and the dV/dt value applied to the thyristor 2 between its anode 2b and its cathode 2a is reduced, and in its turn, the break-through of the thyristor 2 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch circuit device used for switching an AC circuit.

[0002]

2. Description of the Related Art FIG. 4 is a circuit diagram of an AC switch circuit device used for switching an AC circuit according to the prior art. In FIG. 4, 1 and 2 are cathodes 1a and 2a, anodes 1b and 2b, and gates 1c and 2, respectively.
c, which are connected in antiparallel with each other,
The AC load 3 is connected to the AC power supply 15 and the AC load 3 in series and alternately performs a switching operation in response to a command signal from a gate circuit (not shown) connected to each of the gates 1c and 2c. It is a thyristor that applies AC power according to the power supply 15. 3a is a resistance component (R) of the AC load 3, and 3b
Is the inductance of the AC load 3 (including stray inductance) (L). The thyristor is a semiconductor element having a property of continuing the current flow until the current becomes equal to or less than the holding current once it is ignited, and is not a so-called self-extinguishing type semiconductor element. When the above-mentioned thyristors 1 and 2 having such a property are applied to an AC circuit including an AC load 3 and an AC power supply 15, the thyristor 1 or the thyristor 2 starts from a half wave of the AC power supply 15 and goes in the opposite direction. When switching to the next half-wave, the current flowing through a certain thyristor, for example, the thyristor 1 is reduced and becomes equal to or less than the holding current, so that it is turned off.

However, immediately after being turned off, a large number of excess carriers generated by conductivity modulation during conduction of the thyristor 1 still remain. When a voltage in the opposite direction of the next half wave is applied to the thyristor 1 in this state, a reverse recovery current (Irr) due to excess carriers flows. This reverse recovery current (Irr) rapidly decreases as the thyristor 1 is reversely recovered, but its rate of change [d (Ir
rr) / dt)] is orders of magnitude greater than the rate of change due to the alternating current flowing during normal conduction. The rate of change of this large reverse recovery current (Irr) [d (Irr)
/ Dt)], a large jump voltage [V = L × d (Irr) / dt] is generated in the inductance (L) of the AC load 3.

This jump voltage (V) is applied to the other thyristor 2 in the forward direction, and the time change of the jump voltage (V) is applied to the thyristor 2 through the junction capacitance between the anode 2b and the gate 2c thereof. A displacement current according to the rate (dV / dt) flows, and this serves as a gate trigger current, causing the thyristor 2 to misfire. Once ignited, the thyristor has the property of allowing current to continue flowing, so even if the AC circuit is going to be cut off, it cannot be cut off.

If the jump-up voltage (V) increases and exceeds the withstand voltage of the thyristor 2, the thyristor 2 will be destroyed in this case. What has been described above naturally occurs in the thyristor 1. The protection circuit 20 in FIG. 4 is installed to deal with these problems. The protection circuit 20 includes a snubber capacitor 2
1 and a snubber circuit formed by a series circuit of a snubber resistor 22 and a surge absorber 23 connected in parallel to the snubber circuit. The snubber circuit causes the jump voltage (V) to change with time. (DV / dt) is reduced, and the surge absorber 23 absorbs and reduces an excessive jumping voltage (V).

[0006]

In the above-mentioned conventional AC switch circuit device, the jump voltage (V) and the rate of change of the jump voltage (V) with time (dV /
Although the problem due to dt) can be solved,
The value of the inductance component (L) of the AC load 3 is more uncertain than that of the resistance component (R), or the value of the inductance component (L) of the AC load 3 is large when the AC load 3 is changed. In order to prepare for the value, etc., the protection circuit needs to have a large capacity snubber circuit element and surge absorber 23, and the snubber capacitor 21 and surge absorber 23 need high withstand voltage values. Therefore, downsizing of the AC switch circuit device has been hindered.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide a miniaturized AC switch circuit device.

[0008]

According to the present invention, the above-mentioned objects are as follows: 1) In an AC switch circuit device equipped with a thyristor and a protection circuit connected in parallel with the thyristor, the protection circuit comprising: A self-arc-extinguishing semiconductor element connected in parallel to the thyristor is provided, and the self-arc-extinguishing semiconductor element is configured to conduct at a dV / dt value lower than the dV / dt withstand capability of the thyristor. And 2) in the means described in 1 above, the self-extinguishing type semiconductor element included in the protection circuit is a voltage-driven semiconductor element, and 3) in the means described in 2 above, the protection circuit Is a self-extinguishing voltage-driven semiconductor device having two main electrodes and a gate,
A resistor connected between the main electrode and the gate of one of the voltage-driven semiconductor elements is provided, and the main electrode to which the resistor of the voltage-driven semiconductor element is connected is connected to the cathode of the thyristor. A circuit configuration in which the other main electrode that is connected and is not connected to the resistor of the voltage-driven semiconductor element is connected to the anode of the thyristor,
Moreover, the electrical resistance value of the resistor is set to a value that allows the voltage-driven semiconductor element to conduct at a dV / dt value lower than the allowable dV / dt value of the thyristor, and 4) the thyristor. And a protection circuit for protecting the thyristor connected in parallel to the thyristor, the protection circuit comprising a self-extinguishing type semiconductor element connected in parallel to the thyristor. The arc-extinguishing semiconductor element is configured to conduct at a voltage value lower than the withstand voltage value of the thyristor, and 5) the self-arc-extinguishing semiconductor element included in the protection circuit according to the above item 4. Is a voltage-driven semiconductor element, and 6) in the means described in 5 above, the protection circuit has two main electrodes and a gate. Self-extinguishing voltage driven semiconductor element, a resistor connected between the one main electrode and the gate of the voltage driven semiconductor element, and the other main electrode of the voltage driven semiconductor element A constant voltage diode having a cathode connected to the gate and an anode connected to the gate, the main electrode connected to the resistor of the voltage-driven semiconductor element is connected to the cathode of the thyristor, and the voltage drive -Type semiconductor element has a circuit configuration in which the other main electrode connected to the cathode of the constant voltage diode is connected to the anode of the thyristor, and the Zener voltage value of the constant voltage diode is
And a protection circuit for protecting the thyristor and a protection circuit for protecting the thyristor connected in parallel with the thyristor. The circuit includes a self-arc-extinguishing semiconductor element connected in parallel to the thyristor, the self-arc-extinguishing semiconductor element having a dV / d lower than a dV / dt withstand capability of the thyristor.
The t-value and the voltage which is lower than the withstand voltage of the thyristor are used for conduction, and 8) the self-extinguishing type semiconductor element included in the protection circuit is a voltage-driven type. 9) In the means described in the above item 8, the protection circuit is a self-turn-off type voltage driving type semiconductor element having two main electrodes and a gate, and this voltage driving type. A resistor connected between the one main electrode of the semiconductor element and the gate, a cathode connected to the other main electrode of the voltage driven semiconductor element, and an anode connected to the gate. The main electrode, which is provided with a voltage diode and to which the resistor of the voltage-driven semiconductor element is connected, is connected to the cathode of the thyristor, and the constant current of the voltage-driven semiconductor element is connected. Allowable d the main electrode other having a cathode connected diodes and connected to the circuit arrangement to the anode of the thyristor, the electric resistance value of the resistor, having a voltage-driven semiconductor element is a thyristor
The voltage is selected to be conductive at a dV / dt value lower than the V / dt value, and the Zener voltage value of the constant voltage diode is selected to be lower than the withstand voltage value of the thyristor. Is achieved by.

[0009]

In the present invention, the protection circuit includes a self-arc-extinguishing type semiconductor element such as a voltage drive type semiconductor element connected in parallel to the thyristor. In the case of a voltage-driven semiconductor element having a main electrode and a gate, a resistor is connected between one of the main electrodes and the gate, and the main electrode to which this resistor is connected is connected to the cathode of the thyristor. However, the circuit configuration is such that the other main electrode to which the resistor is not connected is connected to the anode of the thyristor, and the electrical resistance value of the resistor has an allowable dV / d that the thyristor has a voltage-driven semiconductor element.
The thyristor is configured so that the self-extinguishing type semiconductor element is made conductive at a dV / dt value lower than the t value and a dV / dt value lower than the dV / dt withstanding capability of the thyristor. DV applied to
A dV / dt value equivalent to the / dt value is also applied to the voltage-driven semiconductor element which is a self-arc-extinguishing semiconductor element. When dV / dt is applied to the voltage-driven semiconductor element, a displacement current is generated in the junction capacitance between the main electrode and the gate of the voltage-driven semiconductor element, and this displacement current flows through the resistor and the resistor A voltage drop occurs in the. Since the value of this resistor is selected according to the above relationship, the voltage-driven semiconductor element is ignited at a dV / dt value lower than the allowable dV / dt value of the thyristor due to the voltage drop generated in the resistor. To be done. When the voltage-driven semiconductor element is turned on, the bypass path that bypasses between the anode and the cathode of the thyristor by the voltage-driven semiconductor element is closed, so that dV /
Further increase of the dt value is suppressed, and false firing of the thyristor is prevented.

Further, the protection circuit includes a self-arc-extinguishing type semiconductor element such as a voltage drive type semiconductor element connected in parallel to the thyristor. For example, this self-extinguishing type semiconductor element has two main electrodes. In the case of a voltage drive type semiconductor element having a gate, a resistor is provided between one main electrode and the gate of this voltage drive type semiconductor element, and the other main electrode and gate of the voltage drive type semiconductor element Constant voltage diodes are connected to each other so that the gate side becomes an anode, and the main electrode to which the resistor of the voltage driven semiconductor element is connected is connected to the cathode of the thyristor, and the constant voltage diode of the voltage driven semiconductor element is connected. Has a circuit configuration in which the main electrode connected to the cathode of the thyristor is connected to the anode of the thyristor, and the zener voltage value of the constant voltage diode is set to the withstand voltage of the thyristor. A voltage value equivalent to the voltage value applied to the thyristor can be obtained by selecting a lower value and setting the circuit configuration to conduct the self-extinguishing type semiconductor element at a voltage value lower than the withstand voltage value of the thyristor. , It is also applied to the constant voltage diode. When a voltage exceeding the Zener voltage is applied to this constant voltage diode, a current flows through the resistor and a voltage exceeding the Zener voltage is applied to this resistor, whereby the voltage-driven semiconductor element is It is fired. Since the Zener voltage of the constant voltage diode is selected in the above relationship, the voltage-driven semiconductor element turns on at a voltage value lower than the withstand voltage value of the thyristor. When the voltage-driven semiconductor element is turned on, the voltage-controlled semiconductor element closes the bypass path that bypasses the anode and cathode of the thyristor, thereby suppressing the voltage value and preventing the thyristor from being damaged by overvoltage. It

Furthermore, the protection circuit comprises a self-extinguishing semiconductor element such as a voltage-driven semiconductor element connected in parallel with a thyristor. For example, the self-extinguishing semiconductor element has two main electrodes. In the case of a voltage drive type semiconductor device having a gate and a gate, a resistor is provided between one main electrode and the gate of this voltage drive type semiconductor device, and the other main electrode and gate of the voltage drive type semiconductor device. Constant voltage diodes are connected so that the gate side serves as an anode between them, and the main electrode to which the resistor of the voltage driven semiconductor element is connected is connected to the cathode of the thyristor, and the constant voltage of the voltage driven semiconductor element is connected. The circuit configuration is such that the main electrode, to which the cathode of the diode is connected, is connected to the anode of the thyristor, and the electrical resistance value of the resistor is set to the voltage drive type semiconductor device. The thyristor has a thyristor having a value that allows conduction at a dV / dt value lower than the allowable dV / dt value that the thyristor has, and a zener voltage value of the constant voltage diode that is lower than a withstand voltage value of the thyristor. The dV / dt value applied to the thyristor is set to have a circuit configuration that conducts the self-extinguishing type semiconductor element at a dV / dt value lower than the dV / dt withstand voltage and a voltage value lower than the withstand voltage value of the thyristor. DV equivalent to
The / dt value is also applied to the voltage-driven semiconductor element that is a self-extinguishing semiconductor element, and the voltage value equivalent to the voltage value applied to the thyristor is also applied to the constant voltage diode.

When dV / dt is applied to the voltage-driven semiconductor element, a displacement current is generated in the junction capacitance between the main electrode and the gate of the voltage-driven semiconductor element, and this displacement current flows through the resistor. A voltage drop is generated across this resistor. Since the value of this resistor is selected according to the above relationship, the voltage drop generated in the resistor causes the voltage-driven semiconductor element to have dV / d lower than the allowable dV / dt value of the thyristor.
Fired at the t value. When the voltage-driven semiconductor element is turned on, a bypass path that bypasses between the anode and the cathode of the thyristor by the voltage-driven semiconductor element is formed, so that a further increase in dV / dt value is suppressed, and the thyristor is suppressed. The false ignition of is prevented.

At the same time, when a voltage having a value exceeding the Zener voltage is applied to the constant voltage diode, a current flows through the resistor to cause a voltage drop and the voltage-driven semiconductor element is ignited. Since the Zener voltage of the constant voltage diode is selected in the above relationship, the voltage-driven semiconductor element turns on at a voltage value lower than the withstand voltage value of the thyristor. When the voltage-driven semiconductor element is turned on, a voltage-controlled semiconductor element forms a bypass path that bypasses between the anode and cathode of the thyristor, suppressing the voltage value and preventing the thyristor from being damaged by overvoltage. It

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. Embodiment 1; FIG. 2 is a circuit configuration diagram of an AC switch circuit device according to an embodiment corresponding to claims 1 to 3 of the present invention. In FIG. 2, the same parts as those of the conventional AC switch circuit device of FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 2, reference numeral 4 denotes a MOSFET which is a self-extinguishing type semiconductor element and is also a voltage drive type semiconductor element.
And has a drain 4a which is the other main electrode, a source 4b which is the one main electrode, and a gate 4c, and the junction capacitance 4d (Cg ) Has been formed. MOSFET4 is
Between the drain 4a and the source 4b, the gate 4c has a threshold value which is a characteristic value peculiar to the MOSFET 4 (sufficient in comparison with a withstand voltage value which is a voltage allowed to be applied to the thyristors 1 and 2). When the ignition voltage (Vth), which is a small value, is applied, the drain 4a and the source 4
This is a semiconductor device having a property of being electrically connected to the gate electrode b, and being in a non-conductive state by self-extinguishing the arc between the drain 4a and the source 4b when the potential of the gate 4c disappears.

Reference numeral 5 is a resistor as a gate resistance connected between the gate 4c and the source 4b of the MOSFET 4 and having a dV / dt lower than the dV / dt withstand capability of the thyristor 2.
The ignition voltage (Vth) of the MOSFET 4 at the dt value
It is selected as a resistance value (Rg) capable of generating a voltage exceeding the above value. Reference numeral 8 is a constant voltage diode whose cathode is connected to the gate 4c of the MOSFET 4 in parallel with the resistor 5, and is a protective element for preventing an overvoltage from being applied to the gate 4c.
Between the drain 4a of the OSFET 4 and the anode 2b of the thyristor 2, the cathode is the drain 4 of the MOSFET 4.
It is a diode connected to a,
This is a protective element that blocks the flow of current in the opposite direction when a voltage is applied from the source 4b to the drain 4a. Reference numeral 10 is a protection circuit for the thyristor 2, which is composed of the MOSFET 4, the resistor 5, the constant voltage diode 8 and the diode 9 and protects the excessive dV / dt value.
The anodes of are connected to the cathode 2a and the anode 2b of the thyristor 2, respectively.

Since the present invention has the above-mentioned configuration, the MOS
When a voltage having a certain dV / dt value from the drain 4a to the source 4b is applied to the FET 4, the junction capacitance 4
Displacement current [Ic = Cg × (dV /
dt)] flows and a voltage drop (Vr = Rg ×
Ic) is generated. Since the resistance value (Rg) of the resistor 5 is as described above, the dV / dt value of the voltage applied to the MOSFET 4 is equal to the dV of the MOSFET 4
When the dV / dt value is lower than the / dt tolerance, the resistor 5
Voltage drop (Vr) caused by displacement current (Ic)
Becomes a voltage value exceeding the ignition voltage (Vth) of the MOSFET 4, and the drain 4a and the source 4b of the MOSFET 4 are
Conduction is established between and. As a result, MOSFET4
By forming a bypass path that bypasses between the anode 2b and the cathode 2a of the thyristor 2, the potential difference between the anode 2b and the cathode 2a of the thyristor 2 is drastically reduced to an extremely small value, and the reverse recovery current in the thyristor 1 is reduced. The rate of change of (Irr) [d (Irr) / dt)] is reduced, and the dV / dt value applied between the anode 2b and the cathode 2a of the thyristor 2 is reduced, so that the thyristor 2 is erroneously ignited. Prevent.

When the excessive dV / dt applied state to the MOSFET 4 and the thyristor 2 disappears due to the disappearance of the remaining excess carriers in the thyristor 1, the voltage drop (Vr) generated in the resistor 5 by the displacement current (Ic). ) Is M
Since it becomes lower than the ignition voltage (Vth) of the OSFET 4, the MOSFET 4 which is a self-extinguishing semiconductor element.
The drain 4a and the source 4b are immediately brought into a non-conductive state, and the AC switch circuit device returns from the protection state against the excessive dV / dt value of the thyristor 2 to the normal operation state. The protection circuit 10 is connected to each of the thyristors 1 and 2, and operates for the thyristor 1 in exactly the same manner as the operation for the thyristor 2. Further, although protection against overvoltage to the thyristors 1 and 2 is not shown, for example,
The surge absorbers 23 shown in the conventional example of FIG. 4 described above are connected in parallel with the respective protection circuits 10.

Embodiment 2; FIG. 3 is a circuit configuration diagram of an AC switch circuit device according to an embodiment corresponding to claims 4 to 6 of the present invention. 3, the same parts as those of the AC switch circuit device according to claims 1 to 3 of the present invention shown in FIG. 2 and the AC switch circuit device according to the prior art shown in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 3, 6 is
The zener voltage value of the constant voltage diode 6 is lower than the withstand voltage value of the thyristor 2, which is a constant voltage diode whose cathode is connected to the drain 4a of the MOSFET 4 and whose anode is connected to the gate 4c of the MOSFET 4. It has been selected as a value.

Reference numeral 7 is a resistor as a gate resistance connected between the gate 4c and the source 4b of the MOSFET 4, and a voltage having a value exceeding the Zener voltage value of the constant voltage diode 6 is connected to the drain 4a of the MOSFET 4. When applied between the source 4b and the source 4b, the amount exceeding the Zener voltage value of the constant voltage diode 6 is applied to the resistor 7. Reference numeral 11 is a protection circuit for the thyristor 2, which is composed of the MOSFET 4, the constant voltage diode 6, the resistor 7, the constant voltage diode 8 and the diode 9 described above, and the source 4b of the MOSFET 4 and the anode of the diode 9 are It is connected to the cathode 2a and the anode 2b of the thyristor 2, respectively.

Since the present invention has the above-mentioned structure, when the voltage from the cathode to the anode is applied to the constant voltage diode 6 and the voltage value exceeds the Zener voltage value of the constant voltage diode 6, the constant voltage diode 6 is driven. Current (Id) flowing from the cathode to the anode flows, and a voltage drop (Vr ′ = Rg ′ ×) occurs in the resistor 7 having a resistance value (Rg ′).
Id) is generated. The voltage drop (V
When r ') becomes a voltage value exceeding the ignition voltage (Vth) of the MOSFET 4, the drain 4a and the source 4b of the MOSFET 4 become conductive. This allows the MOSF
Anode 2b and cathode 2 of thyristor 2 by ET4
By forming a bypass path that bypasses between a and a, the potential difference between the anode 2b and the cathode 2a of the thyristor 2 is drastically reduced to a very small value, and the rate of change [drr] of the reverse recovery current (Irr) in the thyristor 1 is reduced. (Irr) / dt)]
Is reduced to prevent the thyristor 2 from being destroyed by overvoltage. In the case of the present embodiment, the sum of the Zener voltage value of the constant voltage diode 6 and the voltage drop (Vr ′) generated in the resistor 7 is set to a value lower than the withstand voltage value of the thyristor 2. To do.

When the excessive voltage applied state to the MOSFET 4 and the thyristor 2 disappears due to disappearance of the remaining excess carriers in the thyristor 1, the constant voltage diode 6 is released.
Since the voltage applied to the voltage is below the Zener voltage of the constant voltage diode 6 and the voltage drop (Vr ′) generated in the resistor 7 disappears, it is a self-extinguishing semiconductor element. The drain 4a and the source 4b of the MOSFET 4 become non-conductive, and the AC switch circuit device returns from the protection state against the excessive voltage value of the thyristor 2 to the normal operation state. The protection circuit 1
1 is connected to each of the thyristor 1 and the thyristor 2, and operates for the thyristor 1 in exactly the same manner as the operation for the thyristor 2. Further, although protection against excessive dV / dt values to the thyristors 1 and 2 is not shown, for example, a series circuit of the snubber capacitor 21 and the snubber resistor 22 shown in the conventional example of FIG. 4 described above is used. A snubber circuit is connected in parallel with each protection circuit 11 to correspond thereto.

Embodiment 3; FIG. 1 is a circuit configuration diagram of an AC switch circuit device according to an embodiment corresponding to claims 7 to 9 of the present invention. 1, an AC switch circuit device according to claims 1 to 3 of the present invention shown in FIG. 2, an AC switch circuit device according to claims 4 to 6 of the present invention shown in FIG. 3, and an AC switch circuit device according to the prior art shown in FIG. The same reference numerals are given to the same portions as, and the description thereof will be omitted. In FIG. 1, reference numeral 12 is a protection circuit for the thyristor 2, which is composed of the MOSFET 4, the resistor 5, the constant voltage diode 6, the constant voltage diode 8 and the diode 9, and which protects both the excessive dV / dt value and the excessive voltage. MOSFE
The source 4b of T4 and the anode of the diode 9 are connected to the cathode 2a and the anode 2b of the thyristor 2, respectively.

Since the present invention has the above-mentioned configuration, the protection circuit 12 performs the combined operation of the protection circuit 10 of the first embodiment and the operation of the protection circuit 11 of the second embodiment, and is excessive. A single protection circuit prevents false firing of the thyristor 2 due to the dV / dt value and destruction of the thyristor 2 due to overvoltage. The protection circuit 12 is
The thyristor 1 and the thyristor 2 are connected to each other, and the thyristor 1 operates in exactly the same manner as the thyristor 2.

In the above description, the voltage-driven semiconductor element is assumed to be a MOSFET, but the invention is not limited to this, and may be an IGBT, for example. Further, in the description so far, the thyristors used are those connected in anti-parallel, but bidirectional thyristors may be used.

[0025]

According to the present invention, the protection circuit is provided with a self-arc-extinguishing semiconductor element such as a voltage-driven semiconductor element connected in parallel with a thyristor. In the case of a voltage-driven semiconductor device having a plurality of main electrodes and a gate, a resistor is connected between one of the main electrodes and the gate, and the main electrode to which the resistor is connected is connected to the cathode of the thyristor. To the anode of the thyristor and the other main electrode to which the resistor is not connected is connected to the anode of the thyristor, and the electrical resistance value of the resistor is the allowable d
By selecting a value that conducts at a dV / dt value lower than the V / dt value, and making the self-extinguishing type semiconductor element conduct at a dV / dt value lower than the dV / dt withstand capability of the thyristor. , A dV / dt value equivalent to the dV / dt value applied to the thyristor is also applied to the voltage drive type semiconductor element which is a self-extinguishing type semiconductor element, and the dV / dt value applied to the voltage drive type semiconductor element is applied. A displacement current according to the dt value is generated in the junction capacitance between the main electrode and the gate of the voltage-driven semiconductor element, and the value of the voltage drop generated by the displacement current flowing through the resistor is the voltage-driven semiconductor element. Is designed to exceed the ignition voltage (Vth) of the voltage-driven semiconductor element at a dV / dt value lower than the allowable dV / dt value of the thyristor. When the voltage-driven semiconductor element is turned on, a bypass path that bypasses between the anode and the cathode of the thyristor by the voltage-driven semiconductor element is formed, so that a further increase in dV / dt value is suppressed, and the thyristor is suppressed. The false ignition of is prevented.

The elements constituting the protection circuit may be selected in accordance with the allowable dV / dt value specified in the thyristor to be protected, and it is not necessary to depend on the value of the inductance of the AC load. Even for thyristors applied to AC loads with large inductance,
The protection circuit for dV / dt can be downsized, and thus a small AC switch circuit device can be obtained.

Further, the protection circuit is provided with a self-arc-extinguishing type semiconductor element such as a voltage driving type semiconductor element connected in parallel with the thyristor. For example, this self-extinguishing type semiconductor element has two main electrodes. In the case of a voltage drive type semiconductor element having a gate, a resistor is provided between one main electrode and the gate of this voltage drive type semiconductor element, and the other main electrode and gate of the voltage drive type semiconductor element Constant voltage diodes are connected to each other so that the gate side becomes an anode, and the main electrode to which the resistor of the voltage driven semiconductor element is connected is connected to the cathode of the thyristor, and the constant voltage diode of the voltage driven semiconductor element is connected. Has a circuit configuration in which the main electrode to which the cathode of is connected to the anode of the thyristor, and the Zener voltage of the constant voltage diode is set to the withstand voltage value of the thyristor. By selecting a value that is lower than that of the thyristor, and by using a circuit configuration that conducts the self-extinguishing type semiconductor element at a voltage value lower than the withstand voltage value of the thyristor, a voltage value equivalent to the voltage value applied to the thyristor can be obtained. , When the voltage exceeding the Zener voltage is applied to the constant voltage diode and the voltage exceeding the Zener voltage is applied to the constant voltage diode, the current flows through the resistor and the voltage exceeding the Zener voltage is applied to this resistor. When the voltage exceeds the ignition voltage (Vth) of the voltage-driven semiconductor element, the voltage-driven semiconductor element is turned on. When the voltage-driven semiconductor element is turned on, the voltage value applied between the anode and the cathode of the thyristor is suppressed by forming a bypass path that bypasses the anode and the cathode of the thyristor by the voltage-driven semiconductor element. Therefore, destruction of the thyristor due to overvoltage is prevented.

The elements forming the protection circuit may be selected in accordance with the withstand voltage value specified in the thyristor to be protected, and it is not necessary to depend on the value of the inductance of the AC load. Even if it is for a thyristor applied to an AC load having a large value, the protection circuit for the withstand voltage value can be downsized, and thus a small AC switch circuit device can be obtained.

Furthermore, the protection circuit is provided with a self-arc-extinguishing type semiconductor element such as a voltage-driven type semiconductor element connected in parallel with a thyristor. For example, this self-arc-extinguishing type semiconductor element has two main electrodes. In the case of a voltage drive type semiconductor device having a gate and a gate, a resistor is provided between one main electrode and the gate of this voltage drive type semiconductor device, and the other main electrode and gate of the voltage drive type semiconductor device. Constant voltage diodes are connected so that the gate side serves as an anode between them, and the main electrode to which the resistor of the voltage driven semiconductor element is connected is connected to the cathode of the thyristor, and the constant voltage of the voltage driven semiconductor element is connected. The circuit configuration is such that the main electrode, to which the cathode of the diode is connected, is connected to the anode of the thyristor, and the electrical resistance value of the resistor is set to the voltage drive type semiconductor device. DV / dt of the thyristor is selected by selecting a value for conducting at a dV / dt value lower than the allowable dV / dt value of the thyristor, and selecting the zener voltage of the constant voltage diode lower than the withstand voltage value of the thyristor. / Dt resistance dV / dt value lower than the withstand voltage value, and a voltage value lower than the withstand voltage value of the thyristor, by providing a circuit configuration that conducts the self-extinguishing type semiconductor element, this protection circuit, the above-mentioned two types of Since the protection operation for the thyristor in which the operations of the protection circuits of the embodiments are combined can be performed by the single protection circuit, it is possible to obtain a smaller AC switch circuit device.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an AC switch circuit device according to an embodiment corresponding to claims 7 to 9 of the present invention.

FIG. 2 is a circuit configuration diagram of an AC switch circuit device according to an embodiment corresponding to claims 1 to 3 of the present invention.

FIG. 3 is a circuit configuration diagram of an AC switch circuit device according to an embodiment corresponding to claims 4 to 6 of the present invention.

FIG. 4 is a circuit configuration diagram of an AC switch circuit device according to a conventional example.

[Explanation of symbols]

1 Thyristor 1a Cathode 1b Anode 2 Thyristor 2a Cathode 2b Anode 4 Self-extinguishing type (voltage drive type) semiconductor element (MOSF
ET) 4a Other main electrode (drain) 4b One main electrode (source) 4c Gate 4d Junction capacitance 5 Resistor 6 Constant voltage diode 7 Resistor 10 Protection circuit 11 Protection circuit 12 Protection circuit Ic Displacement current

Claims (9)

[Claims] 1. An AC switch circuit device comprising a thyristor and a protection circuit connected in parallel with the thyristor for protecting the thyristor, wherein the protection circuit is a self-arc-extinguishing semiconductor connected in parallel with the thyristor. An AC switch circuit device comprising an element, wherein the self-extinguishing type semiconductor element conducts at a dV / dt value lower than a dV / dt withstand capability of the thyristor. 2. The AC switch circuit device according to claim 1, wherein the self-extinguishing type semiconductor element provided in the protection circuit is a voltage drive type semiconductor element. 3. The AC switch circuit device according to claim 2, wherein the protection circuit includes a self-extinguishing voltage-driven semiconductor element having two main electrodes and a gate, and one of the voltage-driven semiconductor elements. A resistor connected between the main electrode and the gate, the main electrode connected to the resistor of the voltage-driven semiconductor element is connected to the cathode of the thyristor, the voltage-driven semiconductor element The other main electrode to which the resistor is not connected is connected to the anode of the thyristor, and the electric resistance value of the resistor has an allowable dV / dt that the thyristor has the voltage-driven semiconductor element. An AC switch circuit device characterized by being selected as a value for conducting at a dV / dt value lower than the value. 4. An AC switch circuit device comprising a thyristor and a protection circuit connected in parallel with the thyristor for protecting the thyristor, wherein the protection circuit is a self-extinguishing semiconductor connected in parallel with the thyristor. An AC switch circuit device comprising an element, wherein the self-extinguishing type semiconductor element conducts at a voltage value lower than a withstand voltage value of the thyristor. 5. The AC switch circuit device according to claim 4, wherein the self-extinguishing type semiconductor element provided in the protection circuit is a voltage drive type semiconductor element. 6. The AC switch circuit device according to claim 5, wherein the protection circuit includes a self-extinguishing voltage-driven semiconductor element having two main electrodes and a gate, and one of the voltage-driven semiconductor elements. A resistor connected between the main electrode and the gate, and a constant voltage diode whose cathode is connected to the other main electrode of the voltage-driven semiconductor element and whose anode is connected to the gate, The main electrode to which the resistor of the voltage driven semiconductor element is connected is connected to the cathode of the thyristor, and the other main electrode to which the cathode of the constant voltage diode of the voltage driven semiconductor element is connected is the A circuit configuration connected to the anode of the thyristor, and the zener voltage value of the constant voltage diode is lower than the withstand voltage value of the thyristor. AC switch circuit device which is characterized in that which has been selected. 7. An AC switch circuit device comprising a thyristor and a protection circuit connected in parallel with the thyristor for protecting the thyristor, wherein the protection circuit is a self-extinguishing semiconductor connected in parallel with the thyristor. This self-extinguishing type semiconductor element is characterized in that it conducts at a dV / dt value lower than the dV / dt withstand capability of the thyristor and at a voltage value lower than the withstand voltage value of the thyristor. AC switch circuit device. 8. The AC switch circuit device according to claim 7, wherein the self-extinguishing type semiconductor element included in the protection circuit is a voltage-driven semiconductor element. 9. The AC switch circuit device according to claim 8, wherein the protection circuit includes a self-extinguishing voltage-driven semiconductor element having two main electrodes and a gate, and one of the voltage-driven semiconductor elements. A resistor connected between the main electrode and the gate, and a constant voltage diode whose cathode is connected to the other main electrode of the voltage-driven semiconductor element and whose anode is connected to the gate, The main electrode to which the resistor of the voltage driven semiconductor element is connected is connected to the cathode of the thyristor, and the other main electrode to which the cathode of the constant voltage diode of the voltage driven semiconductor element is connected is the A circuit configuration connected to the anode of the thyristor, wherein the electrical resistance value of the resistor is greater than the allowable dV / dt value of the voltage-driven semiconductor element included in the thyristor. An AC switch characterized in that it is selected as a value for conducting at a low dV / dt value, and that the zener voltage value of the constant voltage diode is selected to be lower than the withstand voltage value of the thyristor. Circuit device.