JP2555401B2 - Pulse power generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pulse power generator, for example, for large power used for a power source of a klystron for a particle accelerator, a power source of a fusion device, or the like.

[Conventional technology]

In general, a pulse power generator generates high-voltage pulse power by a pulse shaping circuit that connects a capacitor and a reactor in a ladder shape and supplies it to a load device such as a klystron via a switching element such as a thyratron. Has become.

In the pulse power generation device having such a configuration, when a short circuit accident occurs in the load device, the switching element cannot be turned off unless the energy of the pulse shaping circuit is absorbed.

This energy absorbing circuit (hereinafter referred to as EOL clipper. EOL: End of Line) has been used as a document in the past (The Stanford University Two Mile Accelerator: The STANFORD TWO).
-MILE ACCELERATOR-RB Neal,
1968, W, A, Benjamin Inc,: WABenjamin
Inc.) pages 425-427 have been proposed. That is, according to the technique of the above-mentioned document, an EOL clipper formed by connecting in series a non-linear resistance element having a characteristic similar to the Zener characteristic, a resistor, and a diode is provided at the power supply side end (anti-load end) of the pulse shaping circuit. The connection can be made, and the characteristic of the non-linear resistance element can be used to absorb the energy, thereby making it possible to turn off the switch element.

[Problems to be Solved by the Invention]

However, according to the above-mentioned conventional technique, when the pulse shaping circuit has a large capacity, the energy absorption amount imposed on the non-linear resistance element increases accordingly. Then, there is a possibility that the same element will not be able to withstand capacity or the life thereof will be shortened due to this, so there is a problem that periodical replacement is required, and there is a restriction on increasing the capacity of the pulse power generation device. there were.

It is possible to increase the capacity by connecting a plurality of non-linear resistance elements in parallel, but in this case, the non-linear resistance elements must have exactly the same characteristics, which is extremely difficult in practice. Further, since it is necessary to divide the series resistor according to the number of parallels, there is a problem that the device becomes large.

An object of the present invention is to provide a pulsed power generation device equipped with an energy absorption circuit capable of increasing the capacity.

[Means for solving the problem]

In order to achieve the above object, a pulse power generation device of the present invention is formed by connecting a plurality of capacitors and a reactor in a ladder shape, and supplies pulse power to a load via a switch element connected in series to the load. Pulse shaping circuit,
A series circuit of a thyristor and a resistance element connected in parallel to the capacitor at the power supply side end of the pulse shaping circuit in a polarity opposite to the polarity of the capacitor during normal operation, and a forward voltage applied to the thyristor is a predetermined value or more. Has an overvoltage detection circuit that outputs an ignition signal to the thyristor at
As the switch element, a switch element such as a thyratron that applies a reverse voltage to turn off is used, and the resistance value of the resistance element is set to be equal to or higher than the characteristic impedance of the pulse shaping circuit.

Further, the predetermined forward voltage related to the ignition of the thyristor is
It is desirable to set the voltage higher than the parasitic oscillation voltage when the pulse shaping circuit is normal. This is to prevent energy absorption during normal times.

Further, it is desirable that the pulse width of the firing signal be set to be larger than the output pulse width of the pulse shaping circuit. This is to prevent the thyristor from being damaged for the reason described below.

[Action]

According to the present invention thus configured, the object is achieved by the following actions.

When an accident such as a short circuit occurs in the load device, the energy of the pulse shaping circuit that was not consumed by the load is transmitted in the pulse shaping circuit in the opposite direction to the normal state, and is normally transmitted to the series circuit consisting of the thyristor and the resistance element. It is applied as a reverse voltage (forward for a thyristor). At this time, the overvoltage detection circuit detects the forward voltage applied to the thyristor, and if it is a predetermined value or more, triggers the thyristor to turn on. In this case, the current of the thyristor that was turned on once is interrupted by the oscillating current of the pulse shaping circuit,
If this causes the thyristor to turn off, the forward voltage applied next may damage the thyristor. Therefore, the width of the ignition pulse given to the thyristor should be set sufficiently longer than the output pulse width of the pulse shaping circuit. Is desirable. After the thyristor turns on, the resistance element absorbs the energy. At this time, by selecting its resistance value larger than the characteristic impedance of the pulse shaping circuit, a reflected wave is generated due to impedance mismatch, a reverse voltage is applied to the switch element connected to the load end, and the switch element is turned off. , The load is disconnected. As described above, the EOL clipper including the thyristor and the resistance element can reliably protect the high-power pulse generator including the pulse shaping circuit. Further, it is possible to realize a highly reliable large-capacity pulse power generation device without fear of life deterioration due to energy absorption operation.

〔Example〕

The present invention will be described below based on the embodiment shown in FIG.

As shown in FIG. 1, the pulse shaping circuit 1 is configured by connecting n capacitors C ₁ , C ₂ ..., Cn and reactors L ₁ , L ₂ ..., Ln in a ladder shape. The connection point between the capacitor Cn and the reactor Ln at the left end in the drawing of the pulse shaping circuit 1 is a power source terminal, and the charging circuit 2 supplies DC power thereto. On the other hand, the right end of the pulse shaping circuit 1 is a load end, and the load device 4 is connected thereto via the switch element 3. For the switch element 3, for example, Saratron is applied.

Further, a series circuit of a diode 6, a resistor 7 and a thyristor 8 is connected in parallel with the capacitor Cn located at the power source end of the pulse shaping circuit 1. This diode 6
And thyristor 8 are connected so that the polarity of the charging voltage of the capacitor Cn in the normal operation is opposite to that of the capacitor Cn. This thyristor 8 is triggered by an overvoltage detection circuit 9, and the overvoltage detection circuit 9 outputs an ignition pulse to the gate of the thyristor 8 when the forward voltage applied to the thyristor 8 is a predetermined value or more. It is like this.
That is, the series circuit and the overvoltage detection circuit 9 cause EO
An L clipper 5 is formed.

With such a configuration, the DC power supplied from the charging circuit 2 is charged and accumulated in the capacitors C _{1 to} Cn,
A high-voltage pulse having a width determined by the LC constant is supplied to the load device 4 via the switch element 3.

Here, the charging voltage of the pulse shaping circuit 1 is limited by the withstand voltage of the switch element 3 which is normally available. The load device 4 is composed of a combination of a pulse transformer and a klystron. When the resistance value of the load device 4 is R _L , the characteristic impedance of the pulse shaping circuit 1 is adjusted to this. The values of L and C are selected so that At this time, the width of the output pulse power is Given as. Therefore, during normal operation of the device, the energy stored in the pulse shaping circuit 1 is consumed by the load device 4 with impedance matching. At this time, due to the finite number of constituent elements of the pulse shaping circuit 1, the reverse voltage due to some parasitic oscillation voltage is
It may be applied as a forward voltage to the thyristor 8 of the L clipper 5. Therefore, by setting the predetermined voltage related to the voltage detection of the overvoltage detection circuit 9 higher than this, the EOL clipper 5 normally does not operate.

Here, a case where an abnormality occurs in the load device 4 and a short circuit occurs will be described. In this case, the energy that should originally be consumed by the load device 4 is transmitted to the opposite side (power supply end) of the pulse shaping circuit 1 without being consumed, and a reverse voltage is applied to both ends of the EOL clipper 5. When the overvoltage detection circuit 9 detects an increase in the forward voltage of the thyristor 8 due to this reverse voltage and triggers the thyristor 8, a current flows through the EOL clipper 5, and the resistor 7 consumes the energy. The diode 6 is attached for the purpose of preventing the charging voltage of the pulse shaping circuit 1 from discharging through the EOL clipper 5. That is, since the reverse blocking voltage of the thyristor 8 is generally low, the diode 6 compensates for this.

Here, if the resistance value of the resistor 7 is R _cl and the charging voltage of the pulse shaping circuit 1 is Vo, the current i _EOCl flowing through the EOL clipper 5 is _given by the following equation (1).

And If, reflection occurs in the energy due to impedance mismatching, reverse voltage V _R shown by the following formula (2) is applied to the switching element. This voltage becomes a reverse voltage (several KV) required to turn off the switch element 3, which turns off and cuts off the short-circuit current.

FIG. 2 shows an example of simulating the operation of the above embodiment. Here, the ladder type circuit of the pulse shaping circuit 1 and the number of stages n are selected as 17 stages, and the characteristic impedance is selected. Output pulse width The operation waveform when the load device is short-circuited when the charging voltage Vo is set to 40 KV. Also, R _cl = 34Ω is set. FIG. 2A shows the voltage waveform of the capacitor C ₁ closest to the load device 4. Although not shown here, the load device 4
The short-circuit current flowing through the device ends at t = about 300 μs, and a reverse voltage of −5 KV is secured at this point, indicating that the switch element 3 can be reliably turned off.

FIG. 2B shows the voltage Vc ₁₇ of the capacitor C ₁₇ at the power source end (termination) of the pulse shaping circuit 1, and this voltage is applied to the EOL clipper 5. After the thyristor 8 is triggered, this reverse voltage is borne by the EOL clipper resistor 7.

FIG. _2C shows the current i _EOCl flowing through the EOL clipper 5. After the pulse current of about 200 μs width flows, the current once decreases to near 0, and then the component due to impedance mismatch continues. If the pulse width that triggers the thyristor is not long enough, the thyristor will be damaged by the voltage applied next if the current is interrupted. Therefore, if the ignition pulse width is set larger than the output pulse width of the pulse shaping circuit 1, such a problem can be prevented.

〔The invention's effect〕

As described above, according to the present invention, an EOL clipper is a series circuit of a thyristor and a resistance element, and an overvoltage detection circuit that fires the thyristor when the forward voltage applied to the thyristor is a predetermined value or more. Since it is configured by, by simply increasing the capacitance of the thyristor and the resistance element,
The energy of the pulse shaping circuit at the time of load short circuit that requires a large amount of power can be sufficiently absorbed, and a large capacity can be easily realized. Moreover, since the Zener characteristic such as that of the non-linear resistance element is not used, there is no possibility of deterioration of life and reliability can be improved. Since the resistance value of the resistance element is set to be equal to or higher than the characteristic impedance of the pulse shaping circuit, the reverse voltage necessary to turn off the switch element such as a thyratron that applies a reverse voltage to turn off is reliably obtained. The short-circuit load can be reliably cut off.

Further, the predetermined value of the forward voltage related to the thyristor ignition,
Since it is set above the parasitic oscillation voltage, the EOL clipper will not operate by mistake during normal operation of the pulse shaping circuit.

Further, since the width of the firing pulse of the thyristor is set to be equal to or larger than the output pulse width of the pulse shaping circuit, the thyristor will not be repeatedly turned on / off by the parasitic oscillating current, and damage to the thyristor can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 (a),
(B) and (c) are waveform diagrams of voltage and current of each part simulated by the embodiment of FIG. 1 ... Pulse shaping circuit, 2 ... Charging circuit, 3 ... Switch element, 4 ... Load device, 5 ... Energy absorbing circuit (EOL clipper), 6 ... Diode, 7 ... Resistor, 8 ... Thyristor, 9 ... Overvoltage detection circuit.

Claims (3)

(57) [Claims] 1. A pulse shaping circuit, which is formed by connecting a plurality of capacitors and a reactor in a ladder shape and supplies pulse power to a load, and the load connected to one end of the pulse shaping circuit. A switching element connected in series, a series circuit of a thyristor and a resistance element connected in parallel to the capacitor at the power source side end of the pulse shaping circuit in the opposite polarity to the polarity of the capacitor during normal operation, and applied to the thyristor. The forward voltage is provided with an overvoltage detection circuit that outputs an ignition signal to the thyristor when the forward voltage is a predetermined value or more,
A pulse power generation device in which a switch element such as a thyratron that applies a reverse voltage to turn off is used as the switch element, and the resistance value of the resistance element is set to be equal to or higher than the characteristic impedance of the pulse shaping circuit. 2. The pulse power generation device according to claim 1, wherein the predetermined value related to the overvoltage detection circuit is set to be equal to or higher than a parasitic oscillation voltage during normal operation of the pulse shaping circuit. 3. The pulse power generation according to claim 1, wherein the pulse width of the ignition signal related to the overvoltage detection circuit is set to be larger than the output pulse width of the pulse shaping circuit. apparatus.