JP2828107B2 - High voltage pulse generation circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage pulse generation circuit used in a high-repetition-rate discharge-excitation laser such as a copper vapor laser and an excimer laser.

[Related Art] In a discharge excitation laser such as a copper vapor laser or an excimer laser, an increase in average output due to high repetition rate is strongly required. For example, in a copper vapor laser used as an atomic method laser for enriching uranium, which is one of the isotope separation methods for uranium 235 used in nuclear power plants, an average output of 100 W at a high repetition rate of 4 to 10 kHz.
More than a degree is required. In this case, a command charging method using the inverter 1 as shown in FIG. 10 may be used as a high-voltage pulse generating circuit for oscillating the laser. In the figure, 1 is an inverter, 2 and 3 are output terminals of the inverter 1, 4 is a transformer, 5 is a primary winding of the transformer 4, 6 is a secondary winding of the transformer 4, 8 is a diode, and 9 is a diode. Thyratron, 10 is a main capacitor, 11 is a peaking capacitor, 12 is a laser main discharge electrode, and 13 is a charging inductance or resistance. FIG. 13 shows a circuit configuration example of the inverter 1 in FIG. Here, 22 is a DC power supply, 23 is a charging resistance of a capacitor 27, 24 is a thyristor, 25
Is a diode, 26 is a resistor, and 27 is a capacitor. Eleventh
Figure shows the charging voltage v ₁ of the waveform of the current i ₁ and the main capacitor 10 through the diode 8 in the high-voltage pulse generating circuit of Figure 10. I ₁ m in the figure peak value of the current i ₁ flowing through the diode 8, V ₁ m is the peak value of the voltage v ₁ of the main capacitor 10, V ₁ 'm is the voltage of the main capacitor 10 immediately before the thyratron 9 is turned on v ₁ value, a period from t ₁ is the current i ₁ starts to flow until the power v ₁ of the main capacitor 10 reaches the peak value, a thyratron and t ₂ is the same 9
There period until the turn-on, t ₃ is a repetition period. Here the period from t ₂ to t ₃ is selected to be a period of time sufficient to thyratron 9 is turned off.

By providing a sufficient period for the thyratron 9 to turn off in this manner, a high repetition operation can be performed while preventing runaway of the thyratron.

Regarding laser uranium enrichment, see, for example, Yasukazu Izawa: “Laser isotope separation”, Laser Research, Vol. 15, No. 6,
pp.101-106, June 1987, and the excitation circuit using the command charging method by the inverter, Tatsuhiko Yamanaka, Chihiro Yamanaka, Norio Fujiwara, Chiyomi Yamanaka: "Buffer gas effect of copper vapor laser", Refer to the Institute of Electrical Engineers of Japan, Optical and Quantum Device Workshop, OQD-87-3, 1987.

In high-voltage pulse generating circuit using the inverter 1 according to [invention will to a problem to solve] The above prior art, by the internal capacitance of the diode 8, the current i ₁ flowing through the diode 8 shown in FIG. 11 in broken lines Such a reverse current called a reverse recovery current is generated. FIG. 12 is an enlarged view of the broken line i ₁ in Figure 11. In the figure, I ₁ r is the peak value of the reverse recovery current. The voltage v ₁ of the main capacitor 10 by the reverse recovery current decreases with time from the peak value V ₁ m at time t ₁ which i ₁ is zero, V ₁ is immediately before t ₂ which thyratron 9 is turned 'm Will be.

Therefore, there is a problem that the energy transfer efficiency from the inverter 1 to the main capacitor 10 (the ratio of the output energy of the inverter 1 to the input energy of the main capacitor 10 immediately before the thyratron 9 is turned on) is reduced.

Further, the reverse recovery current causes a reverse recovery loss in the diode 8, which causes a problem that the junction temperature of the diode 8 rises and, in an extreme case, the diode 8 is destroyed.

Since the reverse recovery current has a characteristic of increasing with temperature, the reverse recovery current further increases due to the temperature rise caused by the reverse recovery loss, and the voltage V ₁ ′ m of the main capacitor immediately before the thyratron 9 turns on becomes Decreases over time. For this reason, there is also a problem that the output of the high voltage pulse generation circuit, in this example, the energy input to the laser main discharge electrode changes over time. For this reason, when used for a discharge-excited laser as in this example, it causes a change in the laser output,
The life time of the laser (generally, the time until the laser output is reduced by half) is also greatly reduced.

In particular, in a discharge pump laser such as the copper vapor laser or the excimer laser, a reverse breakdown voltage of the diode is required to be at least about 40 kV or more. Good recovery characteristics are also required. It is difficult to realize these conditions with a single diode, and it is generally used to connect a plurality of diodes in series and parallel as shown in FIG. In this case, a capacitor is added to the outside as shown in the figure to prevent the distribution of the reverse voltage due to the characteristic variation of each diode from becoming unbalanced.
As a result, it is known that the reverse recovery characteristic is greatly deteriorated because the capacitance of the capacitor is added to the junction capacitance of the diode, and the problem caused by the reverse recovery current becomes more and more problematic.

An object of the present invention is to reduce the charging voltage of the main capacitor due to the reverse recovery current of the diode, to reverse recovery loss, and to destroy the diode due to the reverse recovery loss or to change the output of the high voltage pulse generating circuit. It is an object of the present invention to provide a high-voltage pulse generating circuit which addresses the above problem.

Means for Solving the Problem The present invention uses an inverter connected to the primary side of a transformer to charge a capacitor via a diode connected in series with a secondary winding of the transformer, A high-voltage pulse generating circuit for generating a high-voltage pulse by discharging a charge of the capacitor using a switching element, comprising an amorphous magnetic core in series with a diode connected in series with the secondary winding. A high-voltage pulse generating circuit characterized by inserting a saturable reactor.

By inserting a saturable reactor composed of an amorphous magnetic core in series with a diode connected in series with the secondary winding of the transformer, the peak value I ₁ r of the reverse recovery current of the diode is reduced. With the reduction, the reverse recovery loss of the diode can be reduced, and the reduction of the charging voltage of the main capacitor can be suppressed. Further, it is possible to suppress the fluctuation of the output of the high voltage pulse generating circuit caused by the rise of the junction temperature of the diode due to the reverse recovery loss of the diode.

By using an amorphous core for the saturable reactor connected in series with the diode, the core loss is smaller than that of a conventionally used ferrite core or permalloy core, and the reverse recovery current peak value can be suppressed. This is also preferable because the magnetic core can be downsized.

In addition, a polymer film such as a polyimide film, a polyethylene terephthalate film, or MgO, SiO ₂
Wound magnetic core insulated by ceramic particles etc.
Alternatively, by using a laminated magnetic core, an increase in eddy current loss can be suppressed, which is preferable.

As the amorphous magnetic core, the composition of the amorphous magnetic material is (Co _{1−αM α} ) _{100− βXβ} where M is Fe, Mn, Ni, Cr, Nd, Mo, V, Ta, W One or more elements selected from the group consisting of, X is B, or B and Si, and by defining so as to satisfy 0 <α ≦ 0.24 and 12 ≦ β ≦ 26, the squareness is good, and A magnetic core with a small core loss can be obtained, which is preferable in terms of suppressing the peak value of the reverse recovery current. Also, by selecting the same composition range, the magnetostriction can be reduced to the order of 10 ⁻⁶ or less, so that the deterioration of the magnetic properties due to the stress applied to the magnetic core when the pulse current flows through the saturable reactor is also reduced. This is preferable.

In addition to the main winding for charging the main capacitor to the saturable reactor, a second winding is provided so that the saturable reactor can be magnetized in the same direction as the direction in which the saturable reactor is magnetized by the charging current of the main capacitor. By applying the magnetizing force to the winding, it is possible to reduce the delay of the main capacitor charging current caused by resetting the saturable reactor due to the reverse recovery current flowing through the main winding.

Further, by supplying a direct current to the second winding of the saturable reactor at all times, the reverse current flowing through the main winding is reduced.
The dead band of the main capacitor charging current caused by resetting the saturable reactor with the recovery current can be reduced.

Copper vapor lasers load of the high-voltage pulse generating circuit, an excimer laser, TEA (T ransversely E xcited A tmosph
eric P ressure) -CO ₂ laser, TEMA (T ransversely
E xcited M ulti- A tmospheric P ressure ) case of the discharge excitation laser of -CO ₂ laser or the like, can be with high repetition operation without impairing the reliability becomes possible, achieve high efficiency. Further, since the high-voltage pulse output fluctuation can be reduced, it is easy to prevent the laser output fluctuation.

 Hereinafter, the present invention will be described with reference to the drawings.

Embodiment (Embodiment 1) FIG. 1 shows a circuit configuration in a case where the present invention is used in a capacity transfer type copper vapor laser using a thyratron 9 by a command charging system using an inverter 1. In the figure, 1 is an inverter, 2 and 3 are output terminals of the inverter 1, 4 is a step-up transformer, 5 is a primary winding of the transformer 4, 6 is a secondary winding of the transformer 4, and 7 is an amorphous. Reference numeral 8 denotes a diode, 9 denotes a thyratron, 9 denotes a main capacitor, 11 denotes a peaking capacitor, 12 denotes a laser main discharge electrode, and 13 denotes a charging inductance of the main capacitor 10. FIG. 2 shows the waveforms of the current i ₁ flowing through the saturable reactor 7 and the diode 8 and the main capacitor voltage v ₁ in the circuit of FIG. 1, and FIG. 3 shows the current i ₁ shown in FIG. FIG. 4 is an enlarged view of the waveform, and FIG. 4 is an operation magnetization curve of the saturable reactor 7.

Hereinafter, the operation of this circuit will be described with reference to FIGS.
This will be described with reference to the drawings.

Immediately before the thyristor 24 (see FIG. 13) in the inverter 1 is turned on, that is, when t = 0, the magnetic flux density of the saturable reactor 7 is at point a. When the thyristor 24 is turned on, a voltage having a polarity opposite to that of the black circle in the drawing is induced in the secondary winding 6 of the transformer 4, and the same voltage is applied to the saturable reactor 7. For this reason, the magnetic flux density of the saturable reactor 7 changes from the point a as shown in the figure, and after saturation at the point b, the wave of the gate magnetizing force determined by the peak value I ₁ m of the current i ₁ flowing through the diode 8 by the following equation: Via the point c of the magnetic flux density Bs corresponding to the high value H ₁ m, it changes by ΔB ′ to the point d at time t = t ₁ + td.

N: winding of the saturable reactor 7 le: Mean magnetic path length of the saturable reactor 7 (m) In this case, the time td determined by the following equation, to prevent the charging current i ₁ of the main capacitor 10.

Np: winding of the primary winding 5 of the transformer 4 Ns: winding of the secondary winding 6 of the transformer 4 E: voltage (V) of the DC power supply 22 of the inverter 1 Ae: effective core of the saturable reactor 7 Cross-sectional area (m ² ) As a result, the time when the voltage v ₁ of the main capacitor 10 reaches the peak value V ₁ m, that is, the time when the current i ₁ = 0 is t ₁ + td.

During the period from t ₁ + td to t ₂ , the saturable reactor 7 is moved from the point d to the point e by the reverse recovery current of the diode 7.
The point is reset by ΔB. At this time, the peak value I ₁ r of the reverse recovery current of the diode 7 is determined by the dynamic characteristics of the amorphous core constituting the saturable reactor 7 (for example, Nakajima, Yamauchi, Matsumoto: “Amorphous saturable Magnetic core loss evaluation (I) ", see IEEJ, Magnetics Research Group fund MAG88-71), and the magnetizing force Hr determines the value of the following equation.

At this time, the effective sectional area Ae of the amorphous core constituting the saturable reactor 7 needs to be determined so as to satisfy the following equation.

ΔBmax = Bs - (- Br) : The operating magnetic flux density maximum value of the amount (T) magnetic flux density of the saturable reactor 7 in the period from t ₂ to t ₃ is self-set from the point e to a point (self set For example, Kiwaki and Onda: "Experimental design of magnetic core operation of high frequency magnetic amplifier for DC-DC converter", IEE of Japan,
(See Magnetics Research Group Material MAG-88-223).

In t _3, operation is repeated as described above.

As is clear from the above operating principle, the saturable reactor 7 can reduce the peak value of the reverse recovery current of the diode 8. Therefore, the reverse recovery loss of the diode is reduced, the safe operation of the diode can be achieved, and the charging voltage of the main capacitor 10 is increased by the reverse recovery current of the diode as shown in FIG. It is possible to suppress the decrease from ₁ m. Further, the fluctuation of the energy input to the capacitor 11 caused by the heat generated by the diode can be suppressed, and the output stability of the laser can be improved. Further, the rise of the current when the thyristor 24 in the inverter 1 is turned on can be delayed, and the turn-on loss of the thyristor can be reduced.

In FIG. 1, the terminal voltage peak value of the secondary winding 6 of the transformer 4 is 23 kV, and the diode 8 has a withstand voltage of 1.5 kV per element.
As shown in FIG. 14, 60 fast recovery diodes are connected in series and 3 in parallel, and the external
Capacitors 10 and 11 were 12 nF and 6 nF, respectively, with the addition of a pF film capacitor.
Further, t ₁ = 60 μs, t ₂ = 70 μs, and t ₃ = 20 in FIG.
It was set to 0 μs.

As the core of the saturable reactor 7, ten kinds of amorphous wound cores shown in Table 1 were used, and the windings were set so as to satisfy the design conditions under the above-mentioned operating conditions, and forcibly cooled with silicon oil. Used. In each case, the peak value of the reverse recovery current could be reduced as compared to before the saturable reactor 7 was inserted, but the effect is better when the magnetic core of any composition has been subjected to interlayer insulation. Met. In addition, capacitors for long-term operation
From the viewpoint of the energy fluctuation input to 11, the case where the interlayer insulation was performed was better. Further, in terms of the stability over time of the magnetic core when the operation is repeatedly performed after the operation is stopped, it is # 5.
To # 10, especially # 6, # 8, and # 10 were excellent. Furthermore, the same examination was carried out for amorphous cores having different compositions. As a result, the composition of the amorphous core was (Co _1−α M _α ) _100−β X _β where M is Fe, Mn, Ni, Cr , Nd, Mo, V, Ta, W, at least one element selected from the group consisting of: X is B, or B and Si, and 0 <
In the case of using the one satisfying α ≦ 0.24 and 12 ≦ β ≦ 26, after taking out the laser output continuously for 3 hours,
After the operation is stopped and the laser tube is cooled down to room temperature, the energy input to the condenser 11 when the test for restarting is performed five times is preferably 3% or less of the initial operation. Results were obtained.

(Embodiment 2) FIG. 5 shows a circuit configuration in the case where the present invention is applied to a capacity transfer type copper vapor laser using a thyratron 9 by a command charging method using an inverter 1. In this embodiment, in FIG. 1 showing the circuit configuration of the first embodiment,
The saturable reactor 7 is provided with a second winding 15 in addition to the main winding 14. Further, a bias power supply 16 is connected to the winding ends 17 and 18 of the second winding 15 of the saturable reactor 7, so that a DC current Ic having the illustrated polarity flows. The bias power supply 16 is configured as shown in FIG. 6. In FIG. 6, reference numerals 17 and 18 denote output terminals, reference numeral 19 denotes a DC power supply, reference numeral 20 denotes a resistor for determining the value of the bias current Ic, and reference numeral 21 denotes a saturable reactor 7. This is a choke coil for preventing a surge induced in the second winding 15.

The operation of this circuit is shown by the circuit configuration in FIG. 5, the current flowing through the main winding 14 and the diode 8 of the saturable reactor 7 in FIG.
i ₁ and main capacitor voltage v ₁ waveform, FIG. 8 i ₁ waveform enlarged view,
The operation will be described using the operating magnetization curve of the saturable reactor 7 in FIG.

In this circuit, the saturable reactor 7 is connected to the bias power supply 16 via the second winding 15 of the saturable reactor 7.
The bias magnetizing force Hr given by the following equation is always given to the polarity of the black circle in the figure, so that not only the self-setting but also the forced setting can be performed.

Therefore, immediately before the thyristor 24 (see FIG. 13) of the inverter 1 is turned on, that is, at the time of t = 0, the magnetic flux density of the saturable reactor 7 is at the point a '.
As compared with the case of (1), the transmission td 'of the charging current rise time of the main capacitor 10 can be reduced.

Therefore, as compared with the case of the first embodiment, the variation in the time until the voltage of the main capacitor 10 reaches the peak value (the variation which is considered to be caused by the self-setting action occurs in the first embodiment) is significantly reduced. Can be done.

In this embodiment, an operation test was performed under the same conditions as in the first embodiment. In the case where is used, the voltage fluctuation input to the capacitor 11 can be reduced by about 30% as compared with the case of the first embodiment.

In the above embodiment, an example of application to a copper vapor laser is shown, but an excimer laser, a TEA-CO ₂ laser, a TEMA-CO
Needless to say, the present invention can be applied to other discharge excitation lasers such as _two lasers, or accelerators such as induction accelerators.

[Effects of the Invention] According to the present invention as described above, a capacitor is connected via a diode connected in series with a secondary winding of the transformer using an inverter connected to the primary side of the transformer. In a high-voltage pulse generation circuit that generates a high-voltage pulse by charging and discharging a charge of the capacitor using a switch element, a reverse voltage of the diode caused by a reverse recovery current of the diode is generated.
Recovery loss and a reduction in the capacitor charging voltage can be prevented. The reverse diode of the diode
The output fluctuation of the high voltage pulse generation circuit due to the recovery loss can be prevented, and the diode can operate safely. In addition, since it is possible to prevent output fluctuation, in the parallel operation of loads using the present high-voltage generating circuit (for example, the parallel operation of copper vapor laser using the present high-voltage generating circuit), the synchronous operation of each load is performed. Can be easily performed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a high-voltage pulse generating circuit according to the present invention, and FIG. 2 is a saturable reactor of the circuit shown in FIG. 1, a current i ₁ flowing through a diode and a main capacitor voltage v _1. shows the waveform Figure 3 is an enlarged view of the current i ₁ in FIG. 2, FIG. Fig. 4 shows the operation magnetization curve of the saturable reactor in the circuit of FIG. 1, Fig. 5 present invention FIG. 6 is a diagram showing a bias power supply circuit for biasing the saturable reactor used in FIG. 5, and FIG. 7 is a saturable circuit of the circuit shown in FIG. Waveforms of the current i ₁ flowing through the main winding of the reactor and the main capacitor voltage v ₁ , FIG. 8 is an enlarged view of the current i ₁ in FIG. 7,
9 is an operating magnetization curve of the saturable reactor in the circuit of FIG. 5, FIG. 10 is a configuration diagram of a conventional high-voltage pulse generating circuit, and FIG. 11 is a saturable reactor and a diode of the circuit shown in FIG. waveform of the current i ₁ and the main capacitor voltage v ₁ flowing, FIG. 12 is an enlarged view of the current i ₁ in FIG. 11, FIG. 13 is an inverter 1 used in Figure 1, Figure 5, and Figure 10 FIG. 14 is a block diagram of the diode 8 used in FIG. 1, FIG. 5, and FIG.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-3290 (JP, A) JP-A-59-179751 (JP, A) JP-A-62-226602 (JP, A) JP-A-1- 98206 (JP, A) Shokai Sho 63-194587 (JP, U) Institute of Electrical Engineers of Japan Opto-Quantum Device Research Group OQD-87-3 (1987) p13-21 (58) Fields investigated (Int. Cl. ⁶⁾ , DB name) H01S 3/097-3/0979

Claims (7)

(57) [Claims] A high voltage pulse is generated by charging a capacitor through a diode connected in series with a secondary winding of the transformer using an inverter connected to the primary side of the transformer. In a high voltage pulse generating circuit, a saturable reactor constituted by using an amorphous magnetic core is inserted between the secondary winding and a diode connected in series to the secondary winding. Generator circuit. 2. The high-voltage pulse generating circuit according to claim 1, wherein a high-voltage pulse is generated by discharging a charge charged in said capacitor using a switching element. circuit. 3. A high-voltage pulse generating circuit according to claim 1, wherein said amorphous magnetic core is formed by using an amorphous magnetic ribbon and applying interlayer insulation with a polymer film or an insulating coating or the like. A high-voltage pulse generation circuit characterized by a magnetic core or a laminated magnetic core. In high-voltage pulse generating circuit according to 4. The method of claim 1, wherein the composition of the amorphous magnetic core _{(Co 1-α M α)} 100-β X β where M is Fe, Mn, Ni, Cr , Nb, Mo, V, Ta, W, at least one element selected from the group consisting of: X is B or Si, and 0 <α
A high-voltage pulse generation circuit that satisfies ≦ 0.24 and 12 ≦ β ≦ 26. 5. The high-voltage pulse generating circuit according to claim 1, wherein the saturable reactor is magnetized by a charging current of the main capacitor in addition to a main winding for charging a main capacitor. A high-voltage pulse generating circuit, wherein a second winding is provided so as to be able to be magnetized in the same direction as the direction of the high voltage pulse. 6. The high-voltage pulse generating circuit according to claim 5, wherein a DC current always flows through said second winding. 7. The high-voltage pulse generating circuit according to claim 1, wherein the load is a discharge excitation laser.