JPH06237153A - Pulse power supply - Google Patents

Abstract

PURPOSE:To simplify the configuration of the device for the power supply by reducing a switching loss of a semiconductor switch and increasing a rate of rise of current so as to reduce a voltage load onto the circuit. CONSTITUTION:A saturable reactor SI1 is provided in series with a semiconductor switch SW to execute magnetic assist, a discharge pulse current of an energy storage capacitor C0 is used for a primary current of a saturable transformer ST, which boosts the voltage to charge up capacitors C1, C2, the capacitor C1 is charged inversely by the magnetic switch operation of the saturable transformer ST, a double voltage is obtained by using the capacitors C1, C2 and a current subjected to pulse compression is fed to a laser head LH.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse power source for generating high voltage / high current pulses as a power source for pulse lasers, pulse plasma generators, pulse denitration devices and the like.

[0002]

2. Description of the Related Art As a pulse power source for pulse laser excitation or pulse plasma generation, there is a structure shown in FIG. 4 which uses a saturable reactor which serves as a semiconductor switch and a magnetic switch. In the figure, a plurality of thyristors TH connected in series are high voltage semiconductor switches, and the transformer TR is short-circuited by short-circuiting the series circuit of the capacitor C ₀ charged to a high voltage by the power source PS and the temporary winding of the step-up transformer TR. High-voltage pulse is generated in the secondary circuit of.

From the generated voltage, pulse-compressed currents are respectively obtained in the series circuit of the three-stage saturable reactors SR ₁ , SR ₂ , SR ₃ and the capacitors C ₁ , C ₂ , C ₃ to obtain the final stage saturable reactor. High-voltage, large-current pulse is obtained by pulse-compressing SR ₃ and the laser head LH which becomes the discharge tube.

[0004]

In the conventional configuration,
The first stage semiconductor switch (thyristor TH) bears the control of the output voltage required for laser oscillation, and performs the pulse compression by the magnetic switch action of the saturable reactor to obtain the required pulse width and the saturable reactor and capacitor. The ladder is provided in multiple stages.

Here, while discharge pumping of a general pulse laser (for example, excimer laser, lateral pumping CO ₂ laser, etc.) requires several KV as the output voltage of the power supply, current semiconductor devices use several KV. Since only the withstand voltage of is obtained, a large number of semiconductor elements are connected in series, and a drive circuit and a snubber circuit are provided to obtain a desired withstand voltage. Considering the power loss of the semiconductor element,
It will be a large capacity first stage switch configuration.

The step-up transformer TR reduces the number of semiconductor elements, but this increases the number of magnetic pulse compression stages and increases the load on the saturable reactor for pulse compression.

The volume (number) of saturable reactors
Is proportional to the product of voltage and energization time (voltage-time product V × t), so a large number of saturable reactors are required for the first-stage magnetic compression, and the circuit of saturable reactor and capacitor is required. The configuration in which a plurality of stages are provided in a ladder shape makes the device configuration large and expensive.

As another conventional pulse power source, as shown in FIG. 5, a gas entering / exiting switch element S (thyratron or the like) having a large current rise rate (di / dt) is used, and the pulse generated by the switching is directly used for the laser head LH. However, the life of the gas-introduced discharge switching element S is as short as about 10 ⁸ pulses, and it cannot be adopted as a power source for obtaining a high repetitive output.

It is an object of the present invention to provide a pulse power supply with a simplified device configuration.

[0010]

In order to solve the above problems, the present invention relates to a semiconductor switch, a saturable reactor connected in series with the semiconductor switch for magnetic assist, and a first DC voltage charged. A primary winding is connected in series to the capacitor, the capacitor, the semiconductor switch and the saturable reactor, and a primary current is supplied by turning on the semiconductor switch to obtain a boosted output and a magnetic switch operation. A second capacitor connected in parallel to the secondary winding of the saturable transformer and charged with a secondary output current during the transformer operation of the saturable transformer and inversely charged by a magnetic switch operation after the transformer operation of the saturable transformer; The second capacitor is connected in series and is charged by the secondary output current during the transformer operation of the saturable transformer. Characterized in that a third capacitor is supplied to the discharge tube a pulse discharge current in the series circuit of the capacitor.

[0011]

[Function] The semiconductor switch is magnetically assisted by the saturable reactor to perform the switching operation to reduce the switching loss and increase the rate of current rise, and the pulse current boosted by the transformer operation of the saturable transformer is used for the pulse current. The second and third capacitors are charged with high voltage, and then the second capacitor is reversely charged by the magnetic switch operation of the saturable transformer, and the doubled high voltage is obtained in the series circuit of the second and third capacitors. To supply pulse-compressed current to the discharge tube.

[0012]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. The semiconductor switch SW is a first-stage switch configured by connecting a plurality of semiconductor elements such as GTO thyristor, SI thyristor, and IGBT in series.

The saturable reactor SI ₁ , the first stage energy storage capacitor C ₀ and the primary winding of the saturable transformer ST are connected in series to the semiconductor switch SW.

The saturable transformer ST has a magnetic core material having a high squareness ratio, such as an iron-based amorphous alloy magnetic core material, an iron-based ultrafine crystalline alloy magnetic core material, or a cobalt-based amorphous alloy magnetic core material. 1
It has a winding ratio of n (for example, n = 3).

A capacitor C ₁ is connected in parallel to the secondary winding of the saturable transformer ST, a capacitor C ₂ is connected in series to this capacitor C ₁ , and a laser head is provided at both ends of a series connection circuit of the capacitors C ₁ C _2. A parallel circuit of LH and saturable reactor SI ₂ is connected.

Further, the laser head LH and the condenser C
_In addition to electrodes A and B, ₁ and C ₂ are connected to mesh B
The C electrode is arranged on the back surface of the electrode through the dielectric D, and is set to the same potential as the A electrode.

The operation of this embodiment will be described. First, the capacitor C ₀ is charged at a high voltage by the high voltage DC power supply HV via the charging resistor R ₀ . After that, by turning on the semiconductor switch SW, the capacitor C ₀ → saturable reactor SI ₁ → semiconductor switch SW → saturable transformer ST
A primary current I _{0 is made} to flow in the path of the primary winding.

Here, the saturable reactor SI ₁ is reset by applying a bias current opposite to the initial stage pulse current so as to obtain a magnetic assist operation for reducing the switching loss of the semiconductor switch SW and prolonging the life of the switch. .

Next, with respect to the current I ₀ , the saturable transformer ST operates in a non-saturation region, and operates as a transformer for obtaining a voltage boosted by the turn ratio (1: n) in the secondary winding.

[0020] On the secondary side of the saturable transformer ST at this time, the capacitor C ₁ and C ₂ flow secondary current I _1, the voltage obtained by boosting the capacitors C ₁ and C ₂ (n times the voltage of the primary side) Charge in parallel with.

After that, when the saturable transformer ST enters the saturation region, the primary side and the secondary side are uncoupled, and the magnetic switch acts as a saturable reactor instead of acting as a transformer, and the secondary winding is low. The capacitor C ₂ is LC by the current I ₂ which becomes an inductance and is pulse-compressed.
Resonant operation charges the reverse polarity at high speed, and the series circuit of the capacitors C ₁ and C ₂ is applied to the laser head LH at a voltage twice (2 × n) or more the voltage boosted by the saturable transformer ST, and a short pulse is applied. supplying a current I ₃ to the laser head LH of.

The saturable reactor SI ₂ is a capacitor C ₂
Apply a reset current in the direction to charge the. As a result, the charging current of the capacitor C ₂ operates in a saturation region and becomes a small inductor, and the reverse current which is discharged to the laser head LH becomes a non-saturation region and the inductor is enlarged. The energy transfer to the laser head LH is made efficient.

FIG. 2 shows the current waveform of each part. The saturable transformer ST performs high voltage generation by the transformer operation and pulse compression by the magnetic switch operation to generate high voltage / large current pulse as the current I ₂ . Further, this current obtains a voltage doubled by the series circuit of the capacitors C ₁ and C ₂ and supplies the pulse current I ₃ to the laser head LH.

Therefore, in this embodiment, after the step-up of the saturable transformer and the pulse compression operation, the desired high voltage and high current are obtained by the voltage doubler effect of the capacitor. Therefore, the voltage and current of the first-stage switching element can be lowered and the pulse width can be lengthened as compared with a circuit without pulse compression operation.

Further, the semiconductor switch SW, which is the first-stage switch, has a saturable reactor SI as a magnetic assist.
_{Since 1} is provided, the switching loss of the switch SW is reduced and the current I ₀ is increased in the rate of current increase.
Can be supplied to the saturable transformer ST.

FIG. 3 shows a voltage / current waveform (a) of the switch SW when the magnetic assist is not provided and a voltage / current waveform (b) when the magnetic assist is provided. The shaded area in FIG. 6A corresponds to the switching loss of the switch SW,
By providing the magnetic assist, the switching loss is reduced as shown in FIG. 3B, which enables reduction of the element capacitance of the switch SW and miniaturization of the heat radiation circuit.

From the above, in this embodiment, a short pulse of high voltage and high current is obtained by using a semiconductor element having a lower withstand voltage and withstand current and a slower switching speed than the discharge type switch such as the conventional thyratron. be able to.

Further, since the operating voltage of the saturable transformer can be lowered, the voltage-time product of the magnetic core material can be reduced to reduce the required volume or the number thereof.

Further, in this embodiment, the laser head LH
Since the C electrode is provided on the back surface of the B electrode through the dielectric D, pre-ionization is performed by corona discharge between the B and C electrodes, which facilitates obtaining uniform glow discharge.

That is, an excimer laser or TEA-CO ₂
Pre-ionization is necessary to obtain a uniform glow discharge in discharge excitation of lasers, etc. By obtaining this pre-ionization, the pin electrode is unnecessary compared to the conventional structure in which the pin electrode is attached to the peaking capacitor, and further peaking Eliminates the need for capacitors. Moreover, the damage of the electrode is reduced by the preionization by the corona discharge rather than the preionization by the arc discharge using the pin electrode.

[0031]

As described above, according to the present invention, the semiconductor switch that is the first stage switch is magnetically assisted by connecting the saturable reactor in series, and the discharge pulse current of the energy storage capacitor is boosted and magnetized by the saturable transformer. Pulse compression is performed by the switch operation, the series connection capacitor is charged by the transformer operation of this saturable transformer, and one capacitor is inversely charged by the magnetic switch operation of the saturable transformer after that to obtain a voltage double and discharge. Since the high voltage and large current is supplied to the tube, the following effects are obtained.

(1) The magnetic assist by the saturable reactor can reduce the switching loss of the semiconductor switch and increase the current increase rate.

(2) The load of the switching voltage on the semiconductor switch can be reduced by the boosting operation of the saturable transformer and the generation of the double voltage due to the reverse charging of the capacitor.

(3) The saturable transformer, which is supplied with the primary current with reduced voltage burden, can reduce the number of cores and can reduce the inductance after saturation to enhance the pulse compression effect.

(4) It is possible to reduce the number of component steps for boosting and magnetic pulse compression by the saturable transformer.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment.

FIG. 2 is a current waveform diagram during a compression operation in the embodiment.

FIG. 3 is a switch waveform diagram.

FIG. 4 is a circuit diagram of a conventional example.

FIG. 5 is a circuit diagram of a conventional example.

[Explanation of symbols]

SW ... Semiconductor switch, SI ₁ ... Saturable reactor, S
T: saturable transformer, LH: laser head.

Claims (2)

[Claims] 1. A semiconductor switch, a saturable reactor connected in series with the semiconductor switch for magnetic assist, a first capacitor charged with a DC voltage, a primary capacitor connected to the capacitor, the semiconductor switch and the saturable reactor. A saturable transformer having windings connected in series and having a primary current supplied by turning on the semiconductor switch to obtain a boosted output and a magnetic switch operation, and the saturable transformer connected in parallel to the secondary winding of the saturable transformer. Second capacitor that is charged by the secondary output current during the transformer operation and is inversely charged by the magnetic switch operation after the transformer operation of the saturable transformer, and the transformer of the saturable transformer that is connected in series to the second capacitor. It is charged by the secondary output current during operation, and the pulse discharge current is applied to the discharge tube in the series circuit with the second capacitor. A pulsed power supply comprising a third capacitor for supplying. 2. The discharge tube is provided with a third electrode C on the back surface of the electrode B among the discharge electrodes A and B via a dielectric, and a corona discharge is obtained between the electrodes B and C to perform preionization. The pulse power supply according to claim 1, wherein the pulse power supply is configured to perform.