JPH05103486A - High voltage pulse generator - Google Patents

Abstract

PURPOSE:To protect a semiconductor switch device against an overcurrent by providing an overvoltage protecting circuit and a malfunction detector. CONSTITUTION:When a voltage becomes higher than a breakover voltage, a silicon breakover diode (BOD) falls in a breakdown region, its resistance value is abruptly decreased, and a high current flows. Since the current flows to the gate of a healthy thyristor Thy, the thyristor Thy is turned ON. Thus, the healthy thyristor Thy in which the overvoltage is applied is turned ON by itself to be protected. On the other hand, since a breakdown current of the BOD flows to a light emitting element LED, an optical signal is sent to a malfunction detector 50 through an optical fiber cable LG. When a malfunction is detected, the detector 50 sends a stop signal to a high voltage DC charger 10 and a control signal transmitter 20 to stop the operation of a device. Thus, it can protect a semiconductor switch device against the overcurrent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for generating a high voltage having a high rise rate and a high repetition rate, which has a high repetition rate. The present invention relates to a high voltage path generator that generates a high voltage path.

[0002]

2. Description of the Related Art In recent years, there has been an increasing industrial demand for a so-called pulse power technique for exciting a gas laser or forming a pulse magnetic field by utilizing a large pulse current. As a method of obtaining a pulse current, a method of switching a circuit such as a capacitor charged to a high voltage is generally used, and a thyratron filled with low-pressure hydrogen gas or the like has been often used as a switching element.
However, since thyratron involves discharge during switching, the consumption of electrodes cannot be avoided, and the short life of the element makes it difficult to apply it to a pulse generator with high repetition rate. Therefore, recently, an attempt has been made to perform a switching operation by using a semiconductor element. The pulse power switch is required to have a high voltage and high current rating of several tens of kilovolts and several kiloamperes, but at present, there is no single semiconductor switch that satisfies this rating, and the withstand voltage is high. Is no more than a few kilovolts. Therefore, it becomes necessary to connect a plurality of semiconductor switches in series. However, if a failure occurs in one or several of the elements connected to the plurality for some reason, and a short circuit occurs, it is possible to prevent failure without failure when a specified voltage is applied to the entire switch. Also, an overvoltage of n / (n-1) times is applied (n is the total number of elements in series), and there is a disadvantage that all elements including sound elements are destroyed. As a method of eliminating this, it is possible to judge the abnormality by monitoring the voltage of the elements of each stage connected in series.

FIG. 4 shows a block diagram of a conventional high voltage pulse generator using a MOSFET as such an example. The capacitor C1 is charged by the DC power supply 10.
The semiconductor switch device has m · n connected in m parallel n series.
The gate is composed of individual FETs, and each FET operates by receiving an optical signal from the control signal transmitter 20.

It is turned on by a gate drive signal from the drive circuit GU. When all the FETs are turned on, the electric charge of the capacitor C1 is discharged to be transferred to the capacitor C2, and the basic operation of injecting energy into the discharge load 30 is a well-known technique and will not be described in detail here. In this high voltage pulse generator, the semiconductor switch is protected as follows. That is, the overvoltage protection circuit 40 is connected in parallel to each stage of the FETs connected in series. This overvoltage protection circuit 40 is a Zener diode.
It is composed of a protection FET and a protection FET, and protects the FET, which is a switching element, from overvoltage by the constant voltage property of the Zener diode. Further, the overvoltage detection circuit 41 transmits an abnormal signal to the control signal transmission device 20 which detects the overvoltage of each stage and generates the switch trigger signal.

[0005]

In such a conventional high voltage pulse generator, the semiconductor switches connected in series can be protected from overvoltage, but they have the following drawbacks. That is, since an overvoltage protection circuit for protecting the semiconductor switch from the overvoltage and an overvoltage detection circuit for detecting the overvoltage and stopping the operation of the apparatus are connected to each stage, the connection of the overvoltage detection circuit becomes complicated.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional high voltage pulse generator, and it is possible to easily detect that the semiconductor switch overvoltage is applied.
An object of the present invention is to provide a high voltage pulse generator capable of protecting a semiconductor switch device from overvoltage and taking protective measures such as stopping of the device.

[0007]

In order to achieve the above object, the present invention provides an overvoltage in which a non-linear resistance and a light emitting element are connected in series between the anode terminal and the gate terminal of each of a plurality of semiconductor switches. A protection circuit and an abnormality detection device for detecting an optical signal of the light emitting element and transmitting a stop signal to the high voltage DC charging device and the control signal transmission device are provided.

[0008]

With the configuration described above, when an overvoltage is applied to the semiconductor switch, the resistance value of the non-linear resistance changes and the voltage applied to the semiconductor switch is limited, and the current flowing in the non-linear resistance is The semiconductor switch is turned on automatically to flow into the gate, and the shared voltage is set to zero, so that it is protected from overvoltage. Further, since a current flows through the light emitting element, an optical signal is transmitted to the abnormality detecting device. When an abnormality is detected, the abnormality detecting device immediately sends a stop signal to the high voltage DC charging device and the control signal transmitting device to stop the operation of the device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 1, in which the same parts as those of the conventional one are designated by the same reference numerals.

According to the present invention, as shown in FIG. 1, a semiconductor switch device is constituted by connecting n power thyristors Thy in series, and a resistor is provided between the anode terminal and the gate terminal of each thyristor. R1 and diode D1 and silicon blade
The quad diode BOD, the light emitting element LED, the Zener diode D4 and the diode D3 are connected. The breakover voltage of the silicon breakover diode BOD is higher than the steady voltage between the anode and cathode of the thyristor and lower than the allowable voltage of the thyristor.

A resistor R2 and a capacitor C2 are connected in parallel between the cathode terminal of the light emitting element LED and the cathode terminal of the thyristor Thy, and a resistor R3 and a capacitor C3 are connected to the anode terminal and the cathode terminal of the thyristor Thy. .. The optical output of the light emitting element LED is guided to the abnormality detection device 50 by the optical fiber cable LG. In the inside of the abnormality detection device 50, the optical signals from the light emitting elements LED of each stage are converted into electric signals by the photoelectric converters 51 and then input to the OR circuit 52. The output of the OR circuit 52 becomes the output of the abnormality detection device 50. Anomaly detection device 50
Output is high-voltage DC charger 10 and control signal transmitter 2
It becomes a 0 emergency stop signal.

Next, the operation of the present invention having the above configuration will be described. Now, it is assumed that a failure occurs in one or more elements of the thyristors connected in series for some reason and a short circuit is caused, and an overvoltage is applied to the remaining healthy elements. When the value of the overvoltage exceeds the breakover voltage (hereinafter referred to as BOV) of a silicon breakover diode (hereinafter simply referred to as BOD) connected in parallel, BO
D is in the nonlinear region. A typical voltage-current characteristic of BOD is shown in FIG. BOD when the voltage becomes larger than BOV
Enters the breakdown region, the resistance value decreases sharply, and a large current flows. This current flows into the gate of a healthy thyristor, which turns it on.

In this way, the sound thyristor to which the overvoltage is applied is protected by turning on itself. on the other hand,
Since the breakdown current of BOD flows through the light emitting element LED, the optical signal is transmitted through the optical fiber cable LG and the abnormality detection device 50
Sent to. When an abnormality is detected, the abnormality detection device 50 immediately sends a stop signal to the high voltage DC charging device 10 and the control signal transmission device 20 to stop the operation of the device.

As described above, in the embodiment of FIG. 1, the case where the silicon breaker diode having the thyristor characteristic is used as the nonlinear resistance connected between the gate nodes of the semiconductor switch has been described. For example, a diode with avalanche characteristics will not cause any problems. The voltage-current characteristic of the diode having the avalanche characteristic is shown in FIG. In the avalanche diode, when the reverse voltage of the diode exceeds the avalanche voltage VA, the current enters a non-linear region and the current rapidly increases. Therefore, like the silicon breakover diode, a current is passed through the gate of the thyristor connected in parallel to turn it on. The other functions are exactly the same and will not be described.

[0015]

As described above, according to the present invention, it is possible to easily detect that a semiconductor switch overvoltage is applied,
It is possible to provide a high-voltage pulse generator capable of protecting the semiconductor switch device from overvoltage and taking protective measures such as stopping the device.

[Brief description of drawings]

FIG. 1 is a block diagram of a high voltage pulse generator showing an embodiment of the present invention.

FIG. 2 is an operating characteristic diagram of a silicon breakover diode.

FIG. 3 is an operating characteristic diagram of the avalanche diode.

FIG. 4 is a configuration diagram of a conventional high voltage pulse generator.

[Explanation of symbols]

10 ... High-voltage DC charging power source 20 ... Control signal transmission device 30 ... Discharge load 50 ... Failure detection device

Claims (1)

[Claims] 1. A semiconductor switch device comprising a plurality of semiconductor switches connected in series, a gate drive circuit for driving the semiconductor switch, and a control signal transmission device for transmitting a control signal to the gate drive circuit. A high-voltage pulse generator including a high-voltage direct current charging device for charging the semiconductor switch device to a high voltage, wherein a non-linear resistance is provided between an anode terminal and a gate terminal of each of the plurality of semiconductor switches. An overvoltage protection circuit in which light emitting elements are connected in series, and an abnormality detection device that detects an optical signal of the light emitting element and transmits a stop signal to the high voltage DC charging device and the control signal transmission device, High voltage pulse generator.