JP3574340B2 - Square wave voltage generator - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a square wave voltage generator used for, for example, applying a high voltage square wave voltage to a load such as a high voltage gap or a high voltage device and testing a breakdown voltage of the load. . More specifically, in order to test the breakdown voltage in consideration of the Vt characteristic (dielectric breakdown voltage-time characteristic) from a very short time in the ns region to the μs region of the load, the rise is steep. Generates a square wave voltage (for example, a rise time of 100 ns or less), a long pulse width (for example, 5 μs or more), a good flat top flatness (for example, a droop of 10% or less), and a high voltage (for example, a peak value of 100 kV or more). To a square wave voltage generator. In this specification, a square wave voltage is a voltage having a square, rectangular, or similar waveform.
[0002]
[Prior art]
The Vt characteristics of a high-voltage gap, high-voltage equipment, and the like are significantly affected by the applied voltage waveform, and therefore, the selection of the applied voltage waveform is important for testing these breakdown voltages.
[0003]
Conventionally, as an applied voltage waveform, a standard waveform such as a lightning impulse voltage has been used for reasons such as easy voltage generation.
[0004]
However, an overvoltage waveform due to a lightning surge or a switching surge of a disconnector or the like generated in an actual power system is significantly different from a standard waveform, and has a steep rise time of, for example, several tens ns to several hundred ns, and The duration is long, for example, several μs to several tens μs or more.
[0005]
Therefore, in order to accurately test the breakdown voltage of a high voltage gap or a high voltage device, etc., the applied voltage has a sharp rise (for example, a rise time of 100 ns or less) and a long pulse width (for example, 5 μs or more). ), Using a high-voltage (for example, a peak value of 100 kV or more) square wave voltage with a good flat top flatness (for example, a droop of 10% or less), preferably a rise time of 50 ns or less, a pulse width of 10 μs or more, and a flat top. It is very effective to use a square wave voltage having a droop of 5% or less and a peak value of 300 kV or more, since the waveform is more realistic.
[0006]
Conventional examples of a square wave voltage generator capable of generating a high voltage square wave voltage RV are shown in FIGS.
[0007]
The square-wave voltage generator of FIG. 3 has a configuration in which a pulse shaping network 10 in which a plurality of capacitors 12 and inductors 14 are combined in a ladder-like configuration and an output switch 16 are combined to generate a high-voltage square-wave voltage RV. are doing. This square wave voltage RV is applied to a load 20 composed of, for example, a high voltage gap or a high voltage device.
[0008]
The square wave voltage generator shown in FIG. 4 combines a pulse forming line 30 filled with a dielectric 36 between a coaxial outer electrode 32 and an inner electrode 34 and an output switch 38 to form a high voltage square wave voltage. It is configured to generate RV.
[0009]
The square-wave voltage generator of FIG. 5 combines a Marx circuit 40 that generates a high-voltage pulse voltage PV and a voltage cutting gap 50 that cuts the tail of the pulse voltage PV to form a high-voltage square-wave voltage RV. Is generated.
[0010]
As is well known, the Marx circuit 40 generates a high-voltage pulse voltage PV by switching a number of capacitors charged in parallel in series by a gap switch. FIG. 6 shows an example of the circuit diagram. C ₁ -C _n capacitors, G is the gap switch, R represents charging resistor, r is braking resistor for high-frequency vibration suppression, _{G S} is the start gap, 42 and 44 is an output terminal.
[0011]
FIG. 7 shows an example of the waveform of the square wave voltage RV applied to the load 20. This specification defines as follows. That is, a line connecting the 30% of point b and the 90% point c the peak value _{V P} as 100%, 0% line and 100% line and a point of intersection, respectively, the time between d is the rise time _{T R} . From the peak value point e to the cutting point f is flat-top (flat portion) FT, it is during which time the pulse width T _P. Ratio peak value _{V P} of the differential voltage _{V 1} of the voltage peak value _{V P} and the cutting point f, i.e. _{(V 1 / V P) ×} 100 is a loop _D R [%] of the flat top FT. That is, droop _{D R} of the pulse width _{T P.}
[0012]
[Problems to be solved by the invention]
Square-wave voltage generator shown in Figure 3, although the pulse width T _P It is possible to generate a square wave voltage RV of μs order, in which case it is impossible to shorten the rising time T _R. For example, in a device having a pulse width T _P generates the square wave voltage RV of 10μs is to the rising time T _R to a sub .mu.s (i.e. about 1/10 of .mu.s) is practically the limit. This is in order to shorten the pulse width T _P long and rising time T _R is necessary number of capacitors 12 and an inductor 14 described above becomes very large, because becomes impractical. For example, when the pulse width _{T P} 10 [mu] s and rising time _{T R} to 10ns is also required about 1000 steps. This is unrealistic.
[0013]
Square-wave voltage generator shown in FIG. 4, although it is possible to make the rising time T _R of the square wave voltage RV to about 10 ns, it is impossible to increase the pulse width T _P.
[0014]
That is, if the relative permittivity of the dielectric 36 of the pulse forming line 30 is ε _r , the relative magnetic permeability is μ _r , and C is the speed of light (3 × 10 ⁸ m / s), per unit length of the pulse forming line 30 Is expressed by the following equation.
[0015]
(Equation 1)
τ = 2 × (ε _r × μ _r ) ^1/2 / C
[0016]
The only thing that can be used as the dielectric 36 of the pulse forming line 30 is water (pure water) that has a large relative dielectric constant ε _{r and} is practical for a voltage of several hundred kV to MV class. When the dielectric 36 is water, epsilon _r ≒ 80, because it is mu _r ≒ 1, in order to obtain a pulse width _{T P} of 10μs, the length of the pulse forming line 30 is also about 17m. This is unrealistic.
[0017]
Furthermore, to increase the specific resistance of water since 1~2MΩ · m is a limit, constant 7~14μs next time the pulse forming line 30 if the dielectric 36 is water, if the pulse width _{T P} is 10μs can not be realized 5-10% droop _{D R} to.
[0018]
If the square wave voltage generator shown in FIG. 5, the capacitance of the Marx circuit 40 is generally large, although it is possible to make the pulse width T _P of the square wave voltage RV than 5~10μs , it is impossible to increase the rising time T _R. That hundreds stray inductance Marx circuit 40 for generating a kV~MV grade pulse voltage PV is increased, typically because some degree 10 .mu.H, the rising time T _R is a limit μs order is reduced.
[0019]
Accordingly, the present invention provides a square wave voltage generator capable of generating a square wave voltage having a rise time of 100 ns or less, a pulse width of 5 μs or more, a flat-top droop of 10% or less, and a peak value of 100 kV or more. The main purpose is.
[0020]
A second object of the present invention is to provide a square wave voltage generator capable of generating a square wave voltage having a rise time of 50 ns or less, a pulse width of 10 μs or more, a flat-top droop of 5% or less, and a peak value of 300 kV or more. The purpose is.
[0021]
[Means for Solving the Problems]
A square wave voltage generator according to the present invention includes a Marx circuit that generates a high-voltage pulse voltage, a voltage cutting gap connected in parallel to an output of the Marx circuit, and a parallel connection to an output of the Marx circuit. Having a capacitance not more than 1/10 of the equivalent capacitance of the Marx circuit and not less than 10 times the stray capacitance of the load, and having a stray inductance of not more than 1/10 of the equivalent inductance of the Marx circuit. And an output gap switch, which is connected in series between the output of the Marx circuit and the output of the square-wave voltage generator and comprises a laser trigger gap using a laser as a trigger. It is characterized by comprising (claim 1).
[0022]
According to the above configuration, when a pulse voltage is generated from the Marx circuit, the intermediate storage capacitor is charged in a very short time because the capacitance of the intermediate storage capacitor is as small as 1/10 or less of the equivalent capacitance of the Marx circuit. You. When the output gap switch is turned on when the charging of the intermediate storage capacitor is completed, a steep rising voltage is generated at the output section. Although the output voltage may slightly decrease immediately after the output gap switch is turned on, the voltage is supplied from the Marx circuit immediately thereafter, so that the output voltage of the long wave tail is maintained. Thereafter, when the voltage cutting gap is turned on, voltage cutting occurs at the tail of the output voltage, and a square wave voltage having a predetermined pulse width is generated at the output section.
[0023]
In that case, the output gap switch consists of a laser trigger gap with a very short turn-on time, and the stray inductance of the intermediate storage capacitor, which first applies a voltage to the load, is less than 1/10 of the equivalent inductance of the Marx circuit. Therefore, a sharp rising square wave voltage having a short rising time can be generated. Moreover, since the equivalent capacitance of the Marx circuit is generally large, it is possible to maintain the voltage for a long time, and thus it is possible to generate a square wave voltage having a long pulse width and a small droop.
[0024]
As a result, it is possible to generate a square wave voltage having a rise time of 100 ns or less, a pulse width of 5 μs or more, a flat-top droop of 10% or less, and a peak value of 100 kV or more.
[0025]
Further, it has a capacitance of 1/50 or less of the equivalent capacitance of the Marx circuit and 50 times or more of the stray capacitance of the load, and has a stray inductance of 1/50 or less of the equivalent inductance of the Marx circuit. If an intermediate storage capacitor and an output gap switch comprising a laser trigger gap using an excimer laser as a trigger are used (claim 2), the charge and discharge of the intermediate storage capacitor can be performed more quickly. Since the turn-on time is extremely short in the laser trigger gap using, a square wave voltage having a rise time of 50 ns or less, a pulse width of 10 μs or more, a flat-top droop of 5% or less, and a peak value of 300 kV or more can be generated. .
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a circuit diagram showing an example of a square wave voltage generator according to the present invention. FIG. 2 is an equivalent circuit diagram of the square wave voltage generator of FIG. Parts that are the same as or correspond to those in the conventional example in FIG. 5 are denoted by the same reference numerals, and differences from the conventional example will be mainly described below.
[0027]
The square-wave voltage generator 100 is connected in parallel to the above-described Marx circuit 40 for generating a high-voltage pulse voltage PV and to an output of the Marx circuit 40 (that is, between its output terminals 42 and 44). The voltage cutting gap 50 as described above, the intermediate storage capacitor 60 connected in parallel to the output of the Marx circuit 40 (that is, between its output terminals 42 and 44), and the output of the Marx circuit 40 (that is, An output gap switch 80 connected in series to the output side of the square-wave voltage generator 100 (that is, the output end 102 of the non-grounded side) is provided. Reference numeral 104 denotes an output terminal on the ground side of the square wave voltage generator 100.
[0028]
The load 20 as described above is connected to the output of the square wave voltage RV of the square wave voltage generator 100, that is, between the output terminals 102 and 104. The load 20 is, in this example a high-voltage gap example, as shown in FIG. 2, it can be equivalently represented by the stray capacitance C ₂₀ and the stray inductance L ₂₀ connected in series with each other.
[0029]
The Marx circuit 40 generates a high-voltage pulse voltage PV by switching a number of capacitors charged in parallel in series by a gap switch as described above, and an example of a circuit diagram thereof is shown in FIG. It is as follows. When a pulse voltage is generated, the Marx circuit 40 is equivalently represented by an equivalent capacitance C ₄₀ , an equivalent inductance L ₄₀ , an equivalent resistance R _40, and a gap G ₄₀ connected in series as shown in FIG. Can be. Equivalent capacitance C ₄₀ is a representation of the capacitance of the capacitor C ₁ -C _n of each stage of the series switching of FIG. 6 equivalently, the equivalent inductance L _40, each stage of the series switching Are equivalently expressed as the inductances existing in. The equivalent resistance R ₄₀ is an equivalent representation of the braking resistance r of each stage at the time of series switching in FIG. 6, and also has an effect of suppressing the generation of vibration between the Marx circuit 40 and the intermediate storage capacitor 60. I do. The Marx circuit 40 is, for example, an oil-filled type, so that downsizing can be achieved.
[0030]
The Marx circuit 40 can easily generate a high-voltage pulse voltage PV as is well known. In addition, since the equivalent capacitance C ₄₀ is generally large, in other words, it is easy to increase the equivalent capacitance C ₄₀ , so that the voltage of the wave tail is maintained long, that is, the pulse having a long wave tail is maintained. It is possible to generate a voltage PV.
[0031]
The voltage cutting gap 50 cuts the tail of the pulse voltage PV output from the Marx circuit 40. Usually, a series resistor is inserted into the voltage cutting gap 50. These can be equivalently represented by a gap G ₅₀ , a series resistance R _50, and a stray inductance L ₅₀ connected in series, as shown in FIG. In the laser trigger gap using a laser as a trigger, the switching time (time from when a trigger pulse is turned on to when it is turned on) and turn-on time (the time from when it is turned on until it is completely turned on) are short, and jitter (time variation) ) Is small, it is preferable to use a laser trigger gap as the voltage cutting gap 50. Among them, it is more preferable to use a laser trigger gap using an excimer laser as a trigger, so that switching time and turn-on time can be shortened and jitter can be further reduced.
[0032]
The intermediate storage capacitor 60 can be equivalently represented by a capacitance C ₆₀ , a leakage resistance R ₆₀ and a stray inductance L _{60 as} shown in FIG. The intermediate storage capacitor 60 is sufficiently smaller than the equivalent capacitance _{C 40} of the Marx circuit 40, and has a stray capacitance _{C 20} from a sufficiently large capacitance _{C 60} of the load 20, and the very small stray inductance _{L 60} Have. Specifically, the intermediate storage capacitor 60 is equal to or less than 1/10 (preferably 1/50 or less) of the equivalent capacitance C ₄₀ of the Marx circuit 40 and is equal to or more than 10 times the stray capacitance C ₂₀ of the load 20 ( preferably those with stray inductance _{L 60} have the capacitance _{C 60} of more than 50-fold), and 1/10 of the equivalent inductance _{L 40} Marx circuit 40 (preferably 1/50 or less).
[0033]
As such an intermediate storage capacitor 60, it is preferable to use a water capacitor filled with pure water as a dielectric between coaxial cylindrical electrodes. By doing so, high withstand voltage and ultra-low inductance can be realized relatively easily.
[0034]
Since the intermediate storage capacitor 60 has an ultra-low inductance as described above, when it is combined with an output gap switch 80 described later, which has an extremely short turn-on time, an effect of generating a square wave voltage RV having a steep rise is obtained. .
[0035]
It is preferable to insert a braking resistor 70 in series on the output side of the intermediate storage capacitor 60 as in this example. By doing so, local voltage oscillation generated by the stray inductance and the stray capacitance existing in the discharge circuit can be suppressed. As shown in FIG. 2, the braking resistor 70 can be equivalently represented by a resistor R ₇₀ , a stray inductance L ₇₀ and a stray capacitance C ₇₀ .
[0036]
The output gap switch 80 includes a laser trigger gap using a laser as a trigger. As described above, the laser trigger gap has features that the switching time and the turn-on time are short and the jitter is small, and has a function of generating a sharp rising square wave voltage RV. This output gap switch 80 can be equivalently represented by a gap G ₈₀ , a stray inductance L ₈₀ and a stray capacitance C _{80 as} shown in FIG.
[0037]
It is preferable to use a laser trigger gap using an excimer laser as a trigger for the output gap switch 80. In such a case, the switching time and the turn-on time can be shortened, and the jitter can be further reduced. More specifically, it is preferable to use an excimer laser using an unstable resonator having good light-collecting characteristics.
[0038]
To explain the overall operation of the square wave voltage generator 100, when the pulse voltage PV is generated from the Marx circuit 40, the capacitance of the intermediate storage capacitor 60 is sufficiently larger than the equivalent capacitance of the Marx circuit 40. Since it is small, the intermediate storage capacitor 60 is charged in a very short time. When the output gap switch 80 is turned on when the charging of the intermediate storage capacitor 60 is completed, a steep rising voltage is generated at the output section. The output voltage may drop slightly immediately after the output gap switch 80 is turned on, but since the voltage is supplied from the Marx circuit 40 immediately thereafter, the output voltage of the long wave tail is maintained. Thereafter, when turning on the voltage cutting gap 50, occurs the voltage cut in the wave tail part of the output voltage, square-wave voltage RV with a predetermined pulse width T _P is generated in the output section.
[0039]
In that case, the output gap switch 80 comprises a laser trigger gap with a very short turn-on time, and the stray inductance of the intermediate storage capacitor 60, which will first apply a voltage to the load 20, is compared to the equivalent inductance of the Marx circuit 40. because Te sufficiently small, it is possible to generate a short rise time T _R steep rise of the square wave voltage RV. Moreover, the equivalent capacitance of the Marx circuit 40 is generally large, it is possible to maintain a long time the voltage, thus the pulse width T _P generates a small square-wave voltage RV of long and droop D _R Can be.
[0040]
As a result, less rise time _{T R} is 100 ns, the pulse width _{T P} is 5μs or more, can droop _{D R} is 10% or less and the peak value _{V P} of the flat top FT generates a more square-wave voltage RV 100 kV.
[0041]
Further, it has a capacitance C ₆₀ that is 1/50 or less of the equivalent capacitance C ₄₀ of the Marx circuit 40 and 50 times or more of the stray capacitance C ₂₀ of the load 20, and has an equivalent inductance L ₄₀ of the Marx circuit ₄₀ . an intermediate storage capacitor 60 having a 1/50 stray inductance L _60, by using the output gap switch 80 consisting of a laser trigger gap using an excimer laser to trigger, charging and discharging of the intermediate storage capacitor 60 more quickly it is possible, moreover the laser trigger gap using an excimer laser so very short turn-on time as described above (for example, several ns), following the rising time T _R is 50 ns, the pulse width T _P is 10μs or more, flattop FT droop _{D R} than 5% and the peak value _{V P} is more square-wave voltage 300kV of It is possible to generate a V.
[0042]
Therefore, if such a square wave voltage generator 100 is used, for example, when testing the breakdown voltage of a high voltage gap, a high voltage device, or the like, it is possible to test with a voltage having a waveform closer to reality. Can be tested more accurately.
[0043]
It is preferable that the braking resistor 70 is provided at a stage before the output gap switch 80 (ie, at the Marx circuit 40 side) as in this example, rather than at a stage following the output gap switch 80 (ie, at the load 20 side). By doing so, the floating capacitance C ₇₀ of the braking resistor 70 can be charged before the output gap switch 80 is turned on, which is advantageous for the steep rise of the square wave voltage RV.
[0044]
Incidentally, the droop of the flat top FT To D _{R [%]} or less at a predetermined pulse width T _{P [s],} the equivalent leakage resistance against the ground of the square-wave voltage generator 100 (which is almost intermediate storage When the leakage resistance R ₆₀ of the capacitor 60 is R _E [Ω], the equivalent capacitance C ₄₀ [F] of the Marx circuit 40 may satisfy the following equation.
[0045]
(Equation 2)
_{D R <[1-exp {} -T P / (C 40 × R E)}] × 100
[0046]
Further, as described above, immediately after on of the output gap switch 80, i.e. a wave head of the square-wave voltage RV, for example, as shown enlarged in FIG. 8, slightly only the output voltage V ₂ albeit drops . The ratio of the voltage _{V 2} to the peak value _{V P} of the square-wave voltage RV is is (i.e. _{V 2 / V P) × 100} , a wave decline rate _V D [%] of the head. The decline rate to V _{D [%]} or less, the sum of the capacitance between the ground (which most are stray capacitance C ₂₀ of the load 20 including the output gap switch 80 after the load 20 ) Is C _E [F], the capacitance C ₆₀ [F] of the intermediate storage capacitor 60 may satisfy the following expression.
[0047]
(Equation 3)
V _D <{1-C ₆₀ / (C ₆₀ + C _E )} × 100
[0048]
【The invention's effect】
The present invention is configured as described above, and has the following effects.
[0049]
According to the first aspect of the present invention, since a Marx circuit and a voltage cutting gap are provided, it is possible to generate a square wave voltage having a high voltage, a long pulse width and a small droop, and a very small floating inductance. With an output gap switch consisting of a small intermediate storage capacitor and a laser trigger gap with a very short turn-on time, a square wave voltage with a sharp rise can be generated. As a result, it is possible to generate a square wave voltage having a rise time of 100 ns or less, a pulse width of 5 μs or more, a flat-top droop of 10% or less, and a peak value of 100 kV or more.
[0050]
According to the second aspect of the present invention, the intermediate storage capacitor can be charged and discharged more quickly, and the turn-on time of the laser trigger gap using an excimer laser is extremely short, so that the rise time is 50 ns or less, A square wave voltage having a width of 10 μs or more, a flat-top droop of 5% or less, and a peak value of 300 kV or more can be generated.
[0051]
According to the third aspect of the present invention, it is possible to suppress local voltage oscillation generated by the stray inductance and the stray capacitance existing in the discharge circuit. In addition, the floating capacitance of the braking resistor can be charged before the output gap switch is turned on, which is advantageous for steep rise of the square wave voltage.
[0052]
According to the invention described in claim 4, it is possible to realize a predetermined droop D _R in a predetermined pulse width T _P.
[0053]
According to the invention described in claim 5, it is possible to realize a predetermined decline rate V _D at wave front portions of the square-wave voltage.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an example of a square-wave voltage generator according to the present invention.
FIG. 2 is an equivalent circuit diagram of the square-wave voltage generator of FIG.
FIG. 3 is a circuit diagram showing an example of a conventional square wave voltage generator using a pulse shaping network.
FIG. 4 is a circuit diagram showing an example of a conventional square-wave voltage generator using a pulse shaping line.
FIG. 5 is a circuit diagram showing an example of a conventional square wave voltage generator using a Marx circuit and a voltage cutting gap.
FIG. 6 is a circuit diagram illustrating an example of a Marx circuit.
FIG. 7 is a diagram illustrating an example of a waveform of a square wave voltage applied to a load.
FIG. 8 is an enlarged view showing an example of a crest of the square wave voltage in FIG. 7;
[Explanation of symbols]
Reference Signs List 20 load 40 Marx circuit 50 voltage cutting gap 60 intermediate storage capacitor 70 braking resistor 80 output gap switch 100 square wave voltage generator PV pulse voltage RV square wave voltage

Claims (5)

A square wave voltage generator that generates a high voltage square wave voltage and applies it to a load. And is connected in parallel to the output of the Marx circuit, has a capacitance of 1/10 or less of the equivalent capacitance of the Marx circuit and 10 times or more of the floating capacitance of the load, and An intermediate storage capacitor having a stray inductance of 1/10 or less of the equivalent inductance of the Marx circuit, and a series connection between the output of the Marx circuit and the output of the square-wave voltage generator to trigger the laser; And an output gap switch comprising a laser trigger gap used in (1). The intermediate storage capacitor has a capacitance of 1/50 or less of the equivalent capacitance of the Marx circuit and 50 or more times the stray capacitance of the load, and 1/50 or less of an equivalent inductance of the Marx circuit. 2. The square-wave voltage generator according to claim 1, wherein the output gap switch comprises a laser trigger gap using an excimer laser as a trigger. 3. The square wave voltage generator according to claim 1, wherein a braking resistor is connected in series to the Marx circuit side of the output gap switch. When the target droop at the pulse width _TP [s] of the square wave voltage is D _R [%], and the equivalent leakage resistance between the ground of the square wave voltage generation circuit is R _E [Ω], 4. The square-wave voltage generator according to claim 1, wherein the equivalent capacitance C ₄₀ [F] of the Marx circuit satisfies the following expression.
_{D R <[1-exp {} -T P / (C 40 × R E)}] × 100 A case where a target drop rate of the wave front of the square wave voltage is V _D [%], and a total capacitance between the ground including the load after the output gap switch is _CE [F]. 5. The square wave voltage generator according to claim 1, wherein the capacitance C ₆₀ [F] of the intermediate storage capacitor satisfies the following expression.
V _D <{1-C ₆₀ / (C ₆₀ + C _E )} × 100

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