JPH11285237A - Optical thyristor converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect an optical thyristor from breaking by overvoltage impression by firing the optical thyristor by a light emitted from a laser diode which is connected in series to a voltage-dividing resistor connected in parallel to each optical thyristor. SOLUTION: In this thyristor converter, a laser diode 21 is used as a light source where Ith , a current flowing in a voltage-dividing resistor 4 connected in parallel with an optical thyristor 1 and being the threshold of light emission satisfies the relation Ith >=VBO/RD to VBO, the protecting voltage of the optical thyristor and RD, the resistance of a voltage-dividing resistor connected in parallel with the optical thyristor, and the laser diode 21 is caused to emit light to fire the optical thyristor. Accordingly, it becomes possible to quickly fire the optical thyristor, since a gate controller is not used to transmit an optical gate signal when overvoltage is impressed. Consequently, it becomes possible to protect the optical thyristor from overvoltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical thyristor converter including an optical thyristor.

[0002]

2. Description of the Related Art An optical thyristor converter is shown in FIG. Each of the optical thyristors 1 connected in series has a snubber capacitor 3 and a voltage dividing resistor 4 connected in series to a snubber resistor 2, respectively, connected in parallel. A pair of light emitting diodes 5a and 5a connected in anti-parallel
b are connected in series. The light emitting diode 5a or 5b emits light of an amount corresponding to the current flowing through the voltage dividing resistor 4 by the voltage applied to the optical thyristor 1, and the voltage detector 7 detects the voltage applied to the optical thyristor by the amount of the light. Is detected. If the detected voltage of the optical thyristor is determined to be an overvoltage equal to or lower than a predetermined voltage of the optical thyristor, a signal for transmitting an optical trigger signal to the gate control device 8 is sent, and the gate control device 8 allows a current to flow to the light emitting diode 9, The optical thyristor 1 emits light and transmits the light as an optical gate signal to the optical thyristor 1 through the optical fiber 10.
To protect the optical thyristor from destruction due to overvoltage.

[0003]

When the voltage applied to the optical thyristor is detected from the light emitted by the light emitting diode 5a or 5b, and the detected voltage is judged as an overvoltage equal to or higher than a predetermined voltage of the optical thyristor, In order to protect the optical thyristor from destruction by applying an overvoltage, to send an optical gate signal to fire the optical thyristor,
Further, a delay by the gate control device 8 occurred. The delay of the optical gate signal by the gate control device due to overvoltage application is
The optical thyristor will be destroyed.

Accordingly, an object of the present invention is to provide an apparatus which, when an overvoltage is applied to an optical thyristor, ignites the optical thyristor without delay by a gate control device and protects the optical thyristor from being damaged by the application of an overvoltage. It is in.

[0005]

In order to achieve the above object, an optical thyristor converter according to the present invention is an optical thyristor converter comprising an arm constituted by a plurality of serially connected optical thyristors. When a device that detects a voltage applied to the optical thyristor connected to the optical thyristor flows a current proportional to the applied voltage, a voltage equal to or higher than a predetermined voltage of the optical thyristor is applied to the optical thyristor In addition to the light source for transmitting the optical gate signal during the normal operation, the protection voltage V _{BO of} the optical thyristor and the voltage _dividing resistor _RD connected in parallel with the optical thyristor supply a current I _th which becomes a light emission threshold value. _Causes a light source having a relationship of I _th ≧ V _BO / _RD to emit light, and the light is used as an optical gate signal to fire the optical thyristor, thereby destroying the optical thyristor by applying an overvoltage. It is characterized by being protected from.

An optical thyristor converter according to the present invention is an optical thyristor converter comprising an arm composed of a plurality of serially connected optical thyristors, wherein a voltage higher than a predetermined voltage of the optical thyristor is applied to the optical thyristor. When applied, the leakage current flowing through the voltage-dividing resistor connected in parallel to each optical thyristor causes the protection voltage V _BO of the optical thyristor other than the light source that sends the optical gate signal during normal operation, and the optical thyristor to The current I _{th, which} is the light emission threshold, is applied to the voltage _dividing resistor R _D connected in parallel by I
Light is emitted from a light source having a relationship of _th ≧ V _BO / _RD , and the light is used as an optical gate signal to fire the optical thyristor, whereby the optical thyristor is protected from destruction due to application of an overvoltage.

According to the optical thyristor converter according to the present invention, in an optical thyristor converter comprising an arm constituted by a plurality of serially connected optical thyristors, the voltage is applied to the optical thyristor connected to each optical thyristor. When a device that detects the voltage that is applied flows a current proportional to the applied voltage, when a voltage equal to or higher than a predetermined voltage is applied to the optical thyristor, other than a light source that transmits an optical gate signal during normal operation , Protection voltage V of optical thyristor
_{For the BO} and the voltage-dividing resistor R _D connected in parallel to the optical thyristor, the current I _{th serving as the} light emission threshold is I _th ≧
A light source having a relationship of V _BO / _RD is emitted, and the light is used as an optical gate signal to cause the optical thyristor to be fired. The optical thyristor can be protected from destruction due to overvoltage application more quickly than the optical thyristor.

Further, according to the optical thyristor converter according to the present invention, in the optical thyristor converter including the arm composed of a plurality of serially connected optical thyristors, a voltage equal to or higher than a predetermined voltage of the optical thyristor is applied to the optical thyristor. When applied to the thyristor, the leakage current flowing through the voltage-dividing resistor connected in parallel to each optical thyristor causes the protection voltage V _BO of the optical thyristor other than the light source that sends the optical gate signal during normal operation, and the light A current I, which is a light emission threshold, is applied to a voltage dividing resistor R _D connected in parallel with the thyristor.
_th causes a light source having a relation of I _th ≧ V _BO / _RD to emit light,
By firing the optical thyristor using the light as an optical gate signal, the optical thyristor is fired without delay by the gate control device, and the optical thyristor is protected from destruction due to overvoltage application more quickly than a conventional optical thyristor converter. be able to.

Further, according to the optical thyristor converter of the present invention, the light emitting threshold is set for the protection voltage V _{BO of} the optical thyristor and the voltage _dividing resistor _RD connected in parallel to the optical thyristor. A target optical thyristor converter can be manufactured by using a laser diode as a light source having a current I _{th in} a relationship of I _th ≧ V _BO / _RD .

Further, according to the optical thyristor converter of the present invention, the threshold voltage of light emission is provided for the protection voltage V _{BO of} the optical thyristor and the voltage _dividing resistor _RD connected in parallel to the optical thyristor. By using a light source having a relationship of ΔI _th ≦ ΔV _BO × _RD with respect to a threshold current variation ΔI _th and a protection current variation ΔV _BO of a light source having a current I _th of I _th ≧ V _BO / _RD. In addition, it is possible to manufacture a target optical thyristor converter having no variation in ignition delay of the optical thyristor with respect to application of an overvoltage.

[0011]

FIG. 1 shows an embodiment of an optical thyristor converter according to the present invention. The current flowing through the voltage dividing resistor 4 connected in parallel to the optical thyristor 1 causes a light emission threshold for the protection voltage V _{BO of} the optical thyristor and the voltage _dividing resistor _RD connected in parallel to the optical thyristor. Current I
_The light thyristor is fired by causing the laser diode 21 to emit light as a light source having a relation of _th where I _th ≧ V _BO / _RD , thereby protecting the optical thyristor from destruction due to overvoltage application. As described above, since an optical gate signal is not transmitted through the gate control device when an overvoltage is applied, the optical thyristor can be fired more quickly than a conventional converter, thereby protecting the optical thyristor against overvoltage.

FIG. 5 shows the relationship between the amount of light emitted from the light emitting diode and the light source having a threshold value for the current to emit light and the minimum light gate signal light required for firing the optical thyristor. . In a light emitting diode, light emission starts to emit light with a current smaller than that of a light source that has a threshold value.However, when this light is used as a gate signal, light emission due to current flowing through a voltage dividing resistor at a voltage equal to or less than an overvoltage causes Since the optical thyristor is fired, a device for determining whether the voltage applied to the optical thyristor is equal to or higher than a predetermined voltage of the optical thyristor is required. On the other hand, in the case of using a light source having a threshold value for the current to emit light for light emission, the current I _{thr serving} as the light emission threshold value is determined by the voltage V _BO and the resistance R _D of the voltage- _dividing resistor, where I _thr ≧ If V _BO / _RD is selected, an overvoltage is determined by the light emission of the light source having a threshold value in the current to be emitted for the light emission. Therefore, a device for determining the overvoltage is unnecessary, and the light emission for this emission is eliminated. An optical thyristor can be fired as an optical gate signal by light from a light source having a threshold value in the current to be applied.

FIG. 2 shows another embodiment of the optical thyristor converter according to the present invention. Device 3 for detecting the voltage applied to the optical thyristor connected to each optical thyristor
1, when a current proportional to the applied voltage is applied, when a voltage higher than a predetermined voltage is applied to the optical thyristor, when the optical thyristor is applied to the optical thyristor, the protection voltage V of the optical thyristor other than the light source that transmits the optical gate signal during normal operation _BO, and to the voltage dividing resistors R _D which is connected in parallel to the optical thyristor, a current I _th as an emission threshold values causes light sources 32 are in a relationship of I _th ≧ V _BO / R _D. The optical gate signal generated by the light emitted from the light source 32 is transmitted through the optical fiber 33 and is transmitted to the optical coupler 2.
3, the light is transmitted to the light introducing portion of the optical thyristor together with the optical fiber 10 for transmitting the optical gate signal in the normal operation. By firing the optical thyristor 1 using the light as an optical gate signal, the optical thyristor is protected from destruction due to application of an overvoltage. As described above, since an optical gate signal is not transmitted through the gate control device when an overvoltage is applied, the optical thyristor can be fired more quickly than a conventional converter, thereby protecting the optical thyristor against overvoltage.

FIG. 3 shows still another embodiment of the optical thyristor converter according to the present invention. The voltage flowing through the voltage-dividing resistor 4 connected in parallel to the optical thyristor 1 causes a light emission threshold for the protection voltage V _{BO of} the optical thyristor and the voltage- _dividing resistor _RD connected in parallel to the optical thyristor. Current I
_The light thyristor 1 is ignited by emitting light from the light source 24 having a relation of I _th ≧ V _BO / _RD , thereby protecting the optical thyristor from destruction due to application of an overvoltage. As described above, since an optical gate signal is not transmitted through the gate control device when an overvoltage is applied, the optical thyristor can be fired more quickly than a conventional converter, thereby protecting the optical thyristor against overvoltage.

[0015]

According to the present invention, the optical thyristor can be protected from destruction by igniting the optical thyristor without time delay when an overvoltage is applied.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of an optical thyristor converter according to the present invention.

FIG. 2 is a diagram showing another embodiment of the optical thyristor converter according to the present invention.

FIG. 3 is a diagram showing still another embodiment of the optical thyristor converter according to the present invention.

FIG. 4 is a diagram showing an example of an optical thyristor converter using a conventional overvoltage protection device.

FIG. 5 is a diagram for comparing a relationship between a light emitting diode and a light emitting current of a light source having a threshold value for a light emitting current for light emission and a light amount;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical thyristor, 2 ... Snubber resistor, 3 ... Snubber capacitor, 4 ... Voltage divider resistor, 5a, 5b ... Light emitting diode, 6a, 6b, 10 ... Optical fiber, 7 ... Voltage detector,
8. Gate control device.

Claims (4)

[Claims] An optical thyristor converter comprising a plurality of serially connected optical thyristors and an arm composed of a snubber resistor and a snubber capacitor connected in parallel to each optical thyristor. When the device that detects the voltage applied to the connected optical thyristor flows a current proportional to the applied voltage, when a voltage equal to or higher than the predetermined voltage of the optical thyristor is applied to the optical thyristor, during normal operation For the protection voltage V _BO of the optical thyristor other than the light source that transmits the optical gate signal and the voltage _dividing resistor _RD connected in parallel to the optical thyristor, the current I _{th serving as the} light emission threshold is I _th ≧ A light source having a relationship of V _BO / _RD is emitted, and the light is used as an optical gate signal to fire the optical thyristor, so that the optical thyristor is protected from destruction due to overvoltage application. An optical thyristor converter characterized by protection. 2. An optical thyristor converter comprising a plurality of serially connected optical thyristors and an arm composed of a snubber resistor and a snubber capacitor connected in parallel with each optical thyristor, wherein a predetermined number of optical thyristors are provided. When a voltage higher than the voltage is applied to the optical thyristor, the leakage current flowing through the voltage-dividing resistor connected in parallel with each optical thyristor protects the optical thyristor other than the light source that sends the optical gate signal during normal operation. to voltage dividing resistors R _D which is connected in parallel to the voltage V _BO, and optical thyristor causes current I _th as an emission thresholds to emit light in a relation of I _th ≧ V _BO / R _D An optical thyristor converter characterized in that the optical thyristor is protected from destruction by applying an overvoltage by firing the optical thyristor using the light as an optical gate signal. 3. The light-emitting device according to claim 1, wherein a current Ith serving as a light-emitting threshold value is I.sub.0 with respect to a protection voltage _{V.sub.BO of} the optical thyristor and a voltage _dividing resistor _RD connected in parallel with the optical thyristor. An optical thyristor converter, wherein a laser diode is used as a light source having a relationship of _th ≧ V _BO / _RD . 4. The method according to claim 1, wherein the current Ith, which is a light emission threshold, is equal to the protection voltage V _{BO of} the optical thyristor and the voltage _dividing resistor _RD connected in parallel with the optical thyristor. The threshold current variation ΔI _th and the protection current variation ΔV _BO of the light source in the relationship of _th ≧ V _BO / _RD are Δ
An optical thyristor converter characterized by a relation of I _th ≦ ΔV _BO × _RD .