JPS6126305B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conversion device operated at a high potential,
In particular, the present invention relates to a conversion device that enhances the protection of devices that are prone to discharge, such as a DC power transmission device or a power source for a neutral particle injection device for a nuclear fusion device.

Although it is also related to a DC power transmission device, the conventional technology of a conversion device for a power supply system of a neutral particle injection device for a nuclear fusion device will be explained in particular.

The power supply system of the neutral particle injection device for nuclear fusion devices supplies power to the ion source, which is a type of discharge tube.
A thyristor converter is normally used for the power supply. On the other hand, conversion devices using thyristor converters connect multiple conversion devices in cascade due to the need to apply voltage to various electrodes of the ion source.
I am trying to apply the appropriate voltage. In such a converter, a certain converter is operated at a high potential, and in that case, the phase control device equipped with a pulse generator, etc., is also operated at a high potential from the viewpoint of reliability and economy. It is desirable that only operation commands be issued using signals insulated from the ground.

On the other hand, ion sources that serve as loads often generate discharges between the electrodes or from the electrodes to the ground. If such a discharge or ground fault occurs, the stray capacitance to ground of the transformer and thyristor converter in the converter will undergo a sudden change in potential, so the output voltage of other converters will be at a certain value. The electric charge that had been charged in the controller will be discharged, and in some cases, it is conceivable that a part of the discharge current will flow into the control device that is operated at a high potential.

The electronic components of the control device are housed in a case, which is connected to either the converter output terminal or the lead wire to fix the potential.

Normally, in order to fix the potential of a control circuit composed of electronic components, one end thereof is connected to the case directly or via a low impedance.

When the discharge current flows into the control device as described above, it is conceivable that the discharge current flows to the ground via the control circuit and the case. If a sudden current flows through the control circuit, it is highly conceivable that it will not only cause the control circuit to malfunction, but also generate abnormal voltage and damage it.

Conventionally, there were not many power supply systems of this type, and even when there were, they were often low voltage, and the effects of various stray capacitances could be ignored, but 100KV
In the above power supply system, this kind of phenomenon occurs and becomes a big problem.

Below, the above explanation will be supplemented using circuit examples regarding the current technology.

FIG. 1 shows a circuit example of a conventional conversion device in order to clarify the problem.

In FIG. 1, 1 is a converter transformer, and 2 is a converter using a thyristor element. 3 is a synchronization transformer connected to the DC winding side of converter transformer 1 to obtain a synchronization signal for the control system; 4 is a load; 5
is the other converter replaced with the battery symbol, 6
7 shows the case of the control device, and 7 shows the case of the control device 6. 8
is an isolation transformer for supplying power to the control device 6. Reference numeral 9 denotes a control operating device at ground potential, which has the role of sending various control signals to the control device 6 via an insulator such as the light guide 10. 11 is the inductance of the lead wire 11a from the thyristor converter 2 to the load 4 replaced by a lumped constant, and 12, 13, and 14 are the inductance of the converter transformer 1, the synchronizing transformer 3, and the isolation transformer 8. Stray capacitance is expressed as a concentrated capacitor.

In the circuit configuration shown in FIG. 1, if a ground fault occurs at point "A" between the loads 4, the stray capacitances 12, 13 and 14 will be charged by the voltage of the other converter 5. Therefore, the discharge currents i ₁ and i ₂ flow through the converter 2 and the inductance 11 of the lead wire, and some of them flow through the synchronous transformer 3,
It flows through the control device 6 and the case 7. The magnitude of both currents depends on the impedance of the circuit and the charging voltage value, but the synchronous transformer 3,
The current flowing through the control device 6 and the case 7 will cause the control device 6 to malfunction, and if the control device 6 and the case 7 are connected with low impedance, an abnormal voltage will occur between them. . On the other hand, it is thought that the current i ₃ flows from the stray capacitance of 14 through the control device 6 and the case 7, causing the same problem as described above.

In cascade-connected converters, the present invention prevents discharge current from stray capacitance in the converter from flowing into the control device as much as possible in the event of a ground fault on the load side, and also uses other low impedance It is an object of the present invention to provide a converter which prevents malfunction and damage to a control device by bypassing the current by connecting the circuit.

An embodiment of the present invention will be described below with reference to FIG. Note that the same parts as in FIG. 1 are given the same reference numerals and their explanations will be omitted.

The circuit configuration of this embodiment suppresses the entry of high-frequency current into the lead wire 15a between the secondary winding of the synchronizing transformer 3 for obtaining a synchronizing signal and the input terminal of the control device 6. Connecting a high frequency current ingress prevention member 15, such as a block core, which has a characteristic of acting as a high impedance to high frequencies,
On the other hand, in order to bypass the current flowing into the control device 6, connect the middle point 16 of the Y-connection on the primary side (or secondary side) of the synchronous transformer 3 and the lead wire 11a of the thyristor converter 2. A high frequency bypass member 17, such as a series circuit of a capacitor and a resistor, which has a low impedance to high frequencies, is connected between the connecting point "B" to fix the potential of the case 7.

On the other hand, regarding the isolation transformer 8 of the control power source, a high-frequency current ingress prevention member 18 is similarly attached to the lead wire 18a.
is installed to alleviate the influence of stray capacitance 14, and a high frequency current bypass member 19 is connected between isolation transformer 8 and point "B" of lead wire 11a.

Next, the effect will be explained.

When the surge block core is used as the high-frequency current intrusion prevention member 15, the through-type iron core (not shown) has the same effect as a normal core-containing reactor, so that current with high-frequency components will flow through the lead wire 15a passing through the iron core. In this case, that part becomes a large impedance, and as a result, it is suppressed. Note that since the normal detection waveform is a commercial frequency component, this does not pose a major hindrance.

On the other hand, in order to actively pass the discharge current from the capacitor 12 or 13, the high frequency current bypass member 17 is designed to have an impedance much lower than the impedance between the high frequency current intrusion prevention member 15, the control device 6, and the case 7. The high frequency current bypass member 17 absorbs most of the current by setting the current to be proportionally divided according to the impedance ratio. Further, a high frequency current entry prevention member 18,
The high frequency current bypass member 19 also has a similar effect,
Control system malfunctions are prevented and the safety of the control system is maintained.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can of course be implemented with various modifications without changing the gist thereof.

As explained above, according to the present invention, high frequency discharge current such as noise current is prevented from entering the control device 6, so malfunction of the control system is prevented and abnormal voltage is applied to the low voltage circuit of the control system. It is possible to provide a reliable conversion device that prevents the occurrence and damage thereof.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional conversion device, and FIG. 2 is a circuit diagram showing an embodiment of the conversion device of the present invention. 1...Transformer for converter, 2...Thyristor converter,
3... Synchronous transformer, 4... Load, 5... Other conversion device, 6... Control device, 7... Case, 8... Isolation transformer, 11a, 15a, 18a... Lead wire, 15,
18... High frequency current entry prevention member, 17, 19... High frequency current bypass member.

Claims (1)

[Claims] 1 A control device that inputs the input from the converter transformer to the thyristor converter, connects the thyristor converter to the load with a lead wire, extracts the synchronization signal from the converter transformer with the synchronization transformer, and obtains power from the isolation transformer. controlling said thyristor converter via;
Connecting this control device together with its case to the load lead wire of the thyristor converter or its terminal,
In a converter that connects other converters similar to this one in cascade and is operated at high potential and in an ungrounded system, lead wires connect the synchronizing transformer and the control device, and leads connect the isolation transformer and the control device. A conversion device characterized in that each line is provided with a high-frequency current ingress prevention member, and a high-frequency current bypass member is connected between a synchronous transformer, an insulating transformer, and a load lead wire of the thyristor converter or its terminal. .