JPH05190952A - Pulse generating equipment - Google Patents

Abstract

PURPOSE:To obtain a pulse generating equipment wherein a power supply part is easy to be designed, small sized, and manufactured at a low cost. CONSTITUTION:In a pulse generating equipment provided with a high frequency power supply generating high frequency electric power of high voltage, a capacitor 5 charged by said high frequency power supply, and a switch 4 for discharging said capacitor 5, the high frequency power supply is a step-up chopper 17, and a control circuit for controlling ON/OFF of switches 10, 14 of the step-up chopper 17 turns off the switches of the step-up chopper 17 at every time when the value of a current flowing in an inductance element 13 of the step-up chopper 17 becomes equal to a current set value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copper vapor laser,
The present invention relates to a pulse generator for generating excitation energy such as excimer laser and carbon dioxide laser.

[0002]

2. Description of the Related Art FIG.
It is a circuit diagram of the conventional pulse generator shown by the 2nd publication. In the figure, 1 is an inverter that generates high-frequency power on the low voltage side, 2 is a boosting transformer, 3 is a rectifying diode, 4 is a discharge switch (thyratron), 5 and 6 are capacitors, and 7 is a laser discharge tube. , 8 are reactors for charging.

The operation of this pulse generator will be described below with reference to FIG.
The waveform time chart will be described.

When the inverter 1 generates high frequency power (time period t _{1 to} t ₂ ), this high frequency power is boosted by the boosting transformer 2, and the transformer 2 → diode 3 → capacitor 5
→ Reactor 8 → Current is passed through the closed circuit of the transformer 2 and the capacitor 5 is charged to a high voltage of several thousand kilovolts. Since the reactance value of the reactor 8 is made sufficiently smaller than the reactance values of the capacitors 5 and 6, the output voltage of the step-up transformer 2 remains unchanged.
It becomes the charging voltage of. At time t ₃ , when the thyratron 4 is triggered and becomes conductive, the capacitor 5 is discharged through the thyratron 4 to the capacitor 6 and the laser discharge tube 7,
In the laser discharge tube 7, it is consumed as excitation energy and heat energy within several hundred nanoseconds. Hereinafter, the same operation is repeated at time points t ₄ , t ₅ , and t ₆ .

[0005]

In this conventional device,
In order to boost the high frequency voltage from low voltage to a considerably high voltage,
Since the transformer 2 is used, the number of turns is large, and a large insulating space is required to secure the insulation between the windings and the insulation between the low voltage winding and the high voltage winding. It becomes large and expensive. Further, since the high frequency voltage is transformed, the voltage drop increases if the leakage inductance (proportional to the square of the number of turns) is large, so it is necessary to keep the leakage inductance low, and there is a problem that its design is not easy. ..

The present invention has been made to solve this problem, and an object of the present invention is to provide a pulse generator in which the power supply section can be designed easily, and can be made small and inexpensive.

[0007]

In order to achieve the above-mentioned object, the present invention provides a high frequency power source for generating high frequency high frequency power, a capacitor charged by this high frequency power source, and a pulse generation provided with a switch for discharging this capacitor. In the apparatus, the high-frequency power source is a boost chopper, and the control circuit for controlling ON / OFF of the switch of the boost chopper is configured to boost the boost voltage every time the value of the current flowing through the inductance element of the boost chopper becomes equal to the current setting value. It is configured to turn off the switch of the chopper.

According to a second aspect of the present invention, the switch on the high potential side is turned on when the charging voltage of the capacitor reaches the set voltage.

According to a third aspect of the present invention, the switch of the step-up chopper comprises an ON / OFF function controllable element and a series-parallel circuit of the ON function controllable element, and the drive command signal of the ON function controllable element is ON / OFF operation of the ON / OFF function controllable element. It is configured to be generated by.

[0010]

In the present invention, when the boost chopper switch is turned on, energy is stored in the boost chopper reactor, and when the boost chopper switch is turned off, the energy stored in the reactor is released to the capacitor.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 9 is a DC power source (voltage E
d) 10 is a semiconductor switch GTO (gate turn-off thyristor), 11 is a diode, 12 is a current transformer CT,
13 is a choke reactor (inductance value Ld),
14 is a switch composed of a multi-stage series circuit of a plurality of GTOs,
Reference numeral 15 is a control circuit, 16 is a direct current setting device, and these constitute a step-up chopper 17. The direct current set value of the direct current setter 16 is I _m .

The operation of this pulse generator will be described below with reference to FIG.
The waveform time chart will be described.

At time t ₀ , the charge command is the control circuit 1
5, the control circuit 15 causes the switch GTO10
ON command is given to 14 and. Switch GTO 10 and 14
When and are turned on, the circuit of DC power supply 9 → switch 10 → reactor 13 → switch 14 → DC power supply 9 is closed, and a current i flows through this closed circuit.

I = Ed × t / Ld (1)

Time t ₁ when time T has elapsed from time t ₀
so,

I = I _m = Ed / Ld

Therefore, the detected value of CT12 becomes equal to the DC current set value I _m , and the control circuit 15 switches the switch GT.
An OFF command is given to O10 and O14. Switch GTO
When 10 and 14 are turned off, reactor 13 → diode 3 → capacitor 5 → reactor 8 → diode 11
→ CT12 → Current circulates in the closed circuit of the reactor 13. If the loss of this closed circuit is made small enough to be regarded as zero and the inductance value Ld of the choke reactor 13 is much larger than the inductance value of the reactor 8,

[0019] Is established. Given t ₀ = 0 and i = I _m as initial conditions, the solution of this equation is

[0020]

[0021] On the other hand, the charging voltage V of the capacitor 5
_C1 is _calculated from equation (3),

[0022]

[0023] At time t ₂ , the current i becomes zero.
This time t ₂ can be calculated from equation (3) from time t ₁ by π (Ld ·
It is the time when only C ₁ ) ^{1/2/2 has} elapsed. From this, when the equation (4) is integrated up to t = 0 to π (Ld · C ₁ ) ^1/2 / 2,

[0024]

[0025] Time t ₂ after the charge of the capacitor 5 is because there is no discharge path, and remains V _C1 = V _m = constant. At time t ₃ , when the thyratron 4 is triggered and becomes conductive, the capacitor 5 is discharged through the thyratron 4 to the capacitor 6 and the laser discharge tube 7, and the laser discharge tube 7
At, in the several hundreds of nanoseconds, it is consumed as excitation energy and heat energy. Hereinafter, the same operation will be repeated at each of the times t ₄ and t ₅ .

In this embodiment, for example, Ld = 10 ×
10 ⁻³ [H], C ₁ = 10 × 10 ⁻⁹ [F], Ed = 20
If 0 [V] I _m = 20 [A], then from equation (5),

[0027]

From equation (1),

The charging time Tc (time t _{1 to} t ₂ ) is

Therefore, Tc is approximately 15.7 × 10 ^-6 = 15.
It becomes 7 [μs]. From this, since the time T + Tc required for one oscillation is 1.0157 [mS], the repetitive oscillation of approximately 1000 / sec is achieved.

It is also understood that low voltage can be directly charged to high voltage.

The charging voltage value of the capacitor 5 can be adjusted by changing the setting value of the current setting device 16.

As described above, in this embodiment, a high voltage is obtained by the choke reactor 13, but the choke reactor 13
Since it does not require low-voltage and high-voltage windings to be insulated from each other like a transformer, it is compact and easy to design.

Further, the switch 10 of the rising 4 chopper 17,
Since 14 is a semiconductor switch, it has a high degree of freedom in design and can be easily made compact.

In the above description, the switch 14 is composed of a plurality of GTs.
Although it has been described that the switch is composed of a multistage series circuit of O, the switch may have the configuration shown in FIG.

In FIG. 3, 18a to 18e are ON-function controllable devices such as thyristors, and 19 is an ON / OFF-function controllable device such as GTO. In this example, both devices are rated, for example, 4Kv, 100A, 20
a to 20e are resistors for supplying the gate current of the thyristors 18a to 18e, 21a to 21f are voltage dividing circuits, and 22 is a drive circuit, which receives the on / off command of the control circuit 15 and receives the GT signal.
Controls ON / OFF of O19.

Next, the operation of the switch 14 shown in FIG. 3 will be described.

When an ON command is input from the control circuit 15 to the drive circuit 22, the drive circuit 22 gives an ON gate signal to the GTO 19 to make the GTO 19 conductive (time t in FIG. 2).
₀ ). As a result, the current i is supplied from the DC power supply 9.
Since the resistance values of the resistors 20a to 20e for supplying the gate current are set so that the thyristors 18a to 18e are ignited by the current i, the GTO 19 and the thyristor 1 are connected.
8a to 18e are conductive at almost the same time.

When an off command is input from the control circuit 15 to the drive circuit 22, the drive circuit 22 gives an off gate signal to the gate of the GTO 19 to make the GTO 19 non-conductive (time t _{1 in} FIG. 2). Thereby, the thyristors 18a to 18e
The gate current supply circuit and the circuit for the energizing current of the switch 10 are cut off, and the gate current and the energizing current disappear, so that the thyristors 18a to 18e become non-conductive. The switch 10 also becomes non-conductive. When it becomes non-conducting, the forward voltage starts to be applied (t ₁ to t _{3 in} FIG. 2), but the forward voltage is evenly divided by the voltage dividing circuits 21a to 21f.

The charging repeating cycle is, for example, 1 kHz.
In the case of the use exceeding the limit, in order to turn off the thyristor at a high speed, as shown in FIG.
23e, impedance elements (resistors) 24a to 24e
And a circuit including diodes 25a to 25e is added.

In the configuration of FIG. 4, each thyristor 18a is
The forward voltage drop of ~ 18e is about 2V, and due to this voltage drop, a current flows through the reactors 23a-23e to store electromagnetic energy. When the switch 10 is made non-conductive, the GTO 19 becomes non-conductive, and the reactors 23a to 23e
The electromagnetic energy stored in the resistors 14a to 24e and the diodes 25a to 25e are respectively stored as shown in FIG.
A current i _e will be passed through. Since the product voltage of this current and the resistance value of each resistor is applied as a reverse voltage to the thyristors 18a to 18e, the thyristors 18a to 18e.
Residual carriers disappear quickly and thyristors 18a-1a
High-speed turn-off of 8e becomes possible.

In the circuits of FIGS. 3 and 4, one GTO is used, but a plurality of GTOs may be used in series and the switches may be a plurality of parallel circuits instead of one parallel.

FIG. 5 shows another embodiment of the present invention in which a voltage detector 30 is provided to detect the voltage of the capacitor 5, and the control circuit 15 compares this detected value with a set value V _0m. ing. In the present embodiment, 16 is a charging voltage setting device, which sets the above V _0m . The other configuration is the same as that of FIG.

The operation of this pulse generator will be described below with reference to FIG.
The waveform time chart will be described.

In this embodiment, the current i becomes zero at time t ₂ ^' . This time t ₂ ^' is a time point when π (Ld · C ₁ ) ^1/2 / 2 has elapsed from the time t _{1 according} to the above-mentioned formula (3). If the capacitor 5 is charged up to this time t ₂ ^' , the charging voltage V _C1 is

[0046]

It becomes In practice, the charging setting voltage is a low value V _{0 m} than V _m, becomes V _m = V _{0 m} at time t _2. At this time t ₂ , the switch 14 is turned on. As a result, the residual energy of the reactor 13 is
The current circulates in the closed circuit of 3 → switch 14 → diode 3 → CT12 → reactor 13, and the switch 14 turns on time t.
Continue to turn on until ₄ . Time t ₂ Thereafter, the charge of the capacitor 5 since there is no discharge path, and remains V _C1 = V _m = constant. At time t ₃ , when the thyratron 4 is triggered and becomes conductive, the capacitor 5 passes through the thyratron 4,
It is discharged to the capacitor 6 and the laser discharge tube 7, and is consumed as excitation energy and heat energy in the laser discharge tube 7 for several hundred nanoseconds. Hereinafter, the same operation will be repeated at each of the times t ₄ and t ₅ . Period from the time t ₂ -t ₂ ^'can be used as the charging voltage control adjustment tolerance.

The charging voltage value of the capacitor 5 can be adjusted by changing the setting value of the setting device 16.

Although the above embodiments have been described as pulse generators for pulsed lasers, the present invention may also be used for other applications, such as accelerator power supplies for electron beam welders and high voltage power supplies for Cottrell dust collectors. be able to.

[0050]

As described above, according to the present invention, since the step-up chopper is used as the high-frequency power source and the step-up transformer is not used, the high-frequency power source is smaller and less expensive than the conventional one, and the device is compact. And cost reduction can be achieved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a waveform time chart of each part of the above embodiment.

FIG. 3 is a circuit diagram showing a specific configuration of a switch of the boost chopper in the above embodiment.

FIG. 4 is a circuit diagram showing another specific configuration of the switch of the boost chopper in the above embodiment.

FIG. 5 is a circuit diagram showing another embodiment of the present invention.

FIG. 6 is a waveform time chart of each part of the other embodiment.

FIG. 7 is a circuit diagram of a conventional pulse generator.

FIG. 8 is a waveform time chart of each part of the conventional example.

[Explanation of symbols]

 4 Discharge Switch 5, 6 Capacitor 7 Laser Discharge Tube 8 Reactor 9 DC Power Supply 10 Semiconductor Switch 11 Diode 12 CT 13 Choke Reactor 14 Semiconductor Switch 15 Control Circuit 16 DC Current Setting Device 17 Boost Chopper 18a-18e Thyristor 19 GTO 21a-21f Voltage divider 22 Drive circuit 30 Voltage detector

Claims (3)

[Claims] 1. A pulse generator comprising a high-frequency power source for generating high-frequency high-frequency power, a capacitor charged by the high-frequency power source, and a switch for discharging the capacitor, wherein the high-frequency power source is a step-up chopper. The control circuit for controlling ON / OFF of the switch of the chopper turns off the switch of the boost chopper each time the value of the current flowing through the inductance element of the boost chopper becomes equal to the current setting value. .. 2. The pulse generator according to claim 1, wherein the switch on the high potential side is turned on when the charging voltage of the capacitor reaches the set voltage after the switch of the boost chopper is turned off. 3. A switch of the step-up chopper comprises an on / off function controllable element and a series-parallel circuit of an on function controllable element, and a drive command signal of the on function controllable element is generated by an on / off operation of the on / off function controllable element. The pulse generator according to claim 1 or 2, characterized in that.