JPS5965492A - Power supply for pulse laser - Google Patents

Abstract

PURPOSE:To prevent the fluctuation of DC voltage from occurring by a method wherein a DC input into an inverter is detected to add the differential value of this DC to a voltage command value which controls the phase of the converter. CONSTITUTION:A current detecting signal from a current detector 25 is differentiated by a differentiator 2 to add the differential value to an output from a voltage command unit 6 and the added signals are compared with a DC voltage to control the phase of an electric switch 2 of a converter 1 by an error amplifier 7 further controlling the DC voltage V. When a DC I fluctuates, the output signal from the differentiator 26 fetches the fluctuated values of the DC I as the differntial values as shown in (b). When the output from the voltage command unit 6 and the output from the differentiator 26 are added together, the sum will fluctuate as shown in (c) and when the sum is compared with the DC voltage V to input it into the error amplifier 7, the output from the amplifier 7 will take a wave form as shown by a solid line in (d). Consequently, the response time may be accelerated minimizing the fluctuation of DC voltage V as shown in (e).

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to improving the pulse response characteristics of a pulsed laser power supply device that supplies power to a laser oscillator. Conventionally, as this type of pulsed laser power supply device, the one shown in FIG. It is being FIG. 1 is a circuit diagram showing a conventional pulse laser power supply device. In FIG. 1, reference numeral 1 denotes a converter device, which is composed of an electric switch 2 such as a thyristor, and converts the AC voltage of a three-phase AC power source 3 into a DC voltage by controlling the phase thereof. This DC voltage is smoothed by a smoothing circuit constituted by an actor t and a capacitor j to reduce ripples in the DC voltage output from the converter device l.

The DC voltage V that has passed through the smoothing circuit is compared with the voltage command value of the voltage command device t, and based on this result, the phase of the electric switch 2 of the converter device l is controlled by the error amplifier 7, whereby the DC voltage V is kept at a constant value. It is controlled so that The inverter device is composed of switching elements 9 such as transistors and thyristors, and this inverter device converts a DC voltage V into an AC voltage. This converted AC voltage is boosted by a transformer 10, and then the laser medium gas is introduced into the container 11 at the electrodes of the laser oscillator. A,/,7B. For this reason,
In order to generate a discharge /Q between each electrode /3 and excite the laser medium gas 12, the total reflection mirror /jt and the partial transmission mirror 16 are opposed to each other along the longitudinal direction of the emission t/l. When installed, laser oscillation occurs and a laser beam of /7 can be output.

On the other hand, if the AC power of the inverter r is controlled by pulse width modulation (PWM) or the like based on a signal from the pulse generator /g, and the intensity of the discharge /It is changed.

The laser beam /7 becomes a pulsed laser beam according to the signal intensity from the pulse generator lza.

As mentioned above, in the pulse laser power supply device shown in Fig. 1, the output power of the inverter device is equal to the pulse generator/g.
When the DC current (2) in the inverter device (f&) changes as shown in FIG. In response to such sudden changes in the DC current, the smoothing circuit composed of the converter device I, the reactor Hiroshi, and the capacitor S has a slow response speed, so as shown in Fig. 2(b), To explain this operating mode with reference to FIG. 3, where the DC voltage V fluctuates, if the DC voltage V is v2 and the DC current is , the operating point is /de, and its operating characteristic curve is It is indicated by 2o. Here, when the DC voltage increases from Step 1 to Step 2, the operating point moves to 21 and the DC voltage V drops from v2 to v3. After a short period of time, the error amplifier 7 corrects the phase of the electric switch 2 of the converter device l so that the DC'
Voltage V returns to v2. The operating point at this time is U, and its operating characteristic curve becomes an illusion. In addition, a DC electrician was installed from beginning to end.

When the voltage decreases to 2Il, the operating point moves to 2Il, and the DC current EEv increases from v2 to vl. And after a short time,
The electrical switch 2 of the converter device l is controlled by the error amplifier 7.
The phase of is corrected and the DC voltage V returns to v2, and at this time the operating point returns to /.

As mentioned above, since the converter device 1 rectifies the three-phase AC power supply 3, the response speed is slow (and the response time of the error amplifier 7 for stabilizing the control system is generally about 0.
It is set to about -0.3 seconds. For this reason, when the direct current voltage varies, the speed at which the variation ΔV of the direct current voltage V is corrected becomes slow.

The conventional power supply device for a pulsed laser is configured as follows, so when the DC current in the inverter device t increases, the DC voltage V drops instantly, and when the DC current decreases, the DC voltage V increases rapidly. However, the DC voltage V was very prone to fluctuations. For this reason, as shown in FIG. 2(C), the intensity of the laser beam 17 is affected by fluctuations in the DC voltage V, resulting in a deformation of the pulse waveform. Also, when the DC voltage V increases by 1, this DC voltage V exceeds the withstand voltage of the switching element of the inverter device t, destroying the switching element 9. There were some drawbacks, such as:

The present invention was made in order to eliminate the drawbacks of the conventional ones as described above, and includes a converter device that obtains a constant DC voltage by controlling the phase of a commercial power supply using an electric switch such as a thyristor, and a converter device that obtains a constant DC voltage from a commercial power source. In a pulsed laser power supply device that consists of a smoothing circuit that smoothes the output and an inverter device that converts the DC voltage that has passed through the smoothing circuit into an AC voltage using a switching element such as a transistor, and supplies the output of this inverter device to a laser oscillator. , a configuration configured to detect a direct current input to the inverter device and add a differential value of this direct current to a voltage command value for controlling the phase of the converter device, and a laser beam with a good pulse waveform. It is an object of the present invention to provide a power supply device for a pulsed laser, which is capable of generating a power supply voltage and prevents damage to a switching element due to overvoltage.

Figure 1 is a circuit configuration diagram showing a pulse laser source device which is an embodiment of the present invention, and the same parts as in Figure 1 are denoted by the same reference numerals. The detailed explanation will be omitted. In FIG. q, 2j is a current detector, 26 is a differentiator, and the other components are almost the same as those shown in FIG.

The current detection signal from the current detector J is differentiated by a differentiator 2B, and the differential value is added to the output of the voltage command device B.
This added signal is compared with the DC voltage V to control the phase of the electric switch 2 of the converter device I by the error amplifier 7, thereby controlling the DC voltage vl.

FIG. 5(a) is a waveform diagram showing changes in the DC current I of the inverter used in the pulsed laser power supply device of FIG. 1. When the DC current increases or decreases, the output signal of the differentiator 2A changes. As shown in Figure S (1)), it can be extracted as a differential value corresponding to the change in DC current. Furthermore, when the output of the voltage command 4B and the output of the differentiator 2B are added, the result changes as shown in Figure 5(e), and this is converted into the DC voltage V
When compared with the input to the error amplifier 7, the output of the error amplifier 7 becomes the waveform shown by the solid line in FIG. Compared to the waveform shown by the dotted line in a),
The response time is fast (because of this, the fluctuation of the DC voltage V is
As shown in the figure (θ), it becomes very small.

That is, as shown in FIG. 5(d). 27 is the phase signal corresponding to the operating characteristic curve 20 in FIG.
By setting the signal level of the differentiator 2 so that g becomes a phase signal corresponding to the operating characteristic curve phantom in Fig. 3,
The DC electrician shown in Figure S (a) is installed.

Even if it changes from to 2, or from 1 to 2, the DC voltage
The fluctuation of is corrected by the differential value of the DC current, so
As shown in FIG. 5(e), almost no fluctuation can be achieved. FIG. 5(f) shows a waveform showing the intensity of the laser beam /7, and it is possible to output the pulsed laser beam /7 in faithful response to the signal from the pulse generator. Also,
According to the device of the present invention, even if the DC voltage has an arbitrary waveform such as a triangular wave or a sawtooth wave, it is corrected by its differential value, so fluctuations in the DC voltage V can be effectively eliminated. .

FIG. 6 is a circuit diagram showing an example of the differentiator 2B used in the pulsed laser power supply device shown in FIG.

In FIG. 6, a differentiator 26 is configured by adding a current detection signal from a current detector 25 to an input 30, and a time constant circuit element including a capacitor 31 and a resistor 33 connected to an operational amplifier 111. The capacitor 3S is provided to directly limit the upper limit of the differential value. input,
? When the signal shown in Fig. 5(a) is added to Q, the signal shown in Fig. S(b) is obtained at output 3S, and the signal of output 35 is proportional to the change in the DC current. I sat□１１
In the above embodiment, the DC current input to the inverter g is detected by the current detector PJ, but the AC current output from the inverter or the laser oscillator is The discharge current flowing in the electric current 'flit/3h, /, 7B may also be detected, as in the above embodiments.
According to the power supply device for a pulsed laser according to the present invention, the direct current input to the inverter device is detected, and the differential value of this direct current is added to the voltage pulse value for controlling the phase of the converter device. Since it is configured to eliminate voltage fluctuations, it can improve the reliability of the inverter device due to overvoltage, and it also has the excellent effect of easily generating laser light with a good pulse waveform. be.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional pulse laser source device, and FIGS. Waveform diagram of each part, 3rd. The figures are an operating characteristic diagram of a converter device used in the pulsed laser power supply device shown in FIG. 1, FIG. (a) to f) are waveform diagrams of various parts to explain the operation mode of the pulsed laser power supply shown in Fig. q, and Fig. 6 shows an example of a differentiator used in the pulsed laser power supply shown in Fig. 1. FIG. l...Converter device, 2...Package switch, 3-phase AC power supply, t...Reactor, 3.3/, 33...
Capacitor, 6...Voltage command unit, 7...Error amplifier,...Inverter device, 9...Switching element, 10...Transformer, //...Container, lco...Laser Medium gas, /,? A, /JB...electrode, /l...
・Discharge, i3... Totally reflecting mirror, 16... Partially transmitting mirror,
17...Laser light, /za...Pulse generator, 25.
...Current detector 1.26...Differentiator, 30...Input, 32.3J...Resistance,...? lt...Operation amplifier 1
,? 5... Output. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Agent Makoto Kuzuno - Figure 1 Figure 2 To Figure 5 2 Go L

Claims (1)

[Claims] A converter device that obtains a constant DC voltage by controlling the phase of a commercial power supply using an electric switch such as a thyristor, a smoothing zero circuit that smoothes the output from the converter device, and a switching device such as a transistor that uses the DC voltage that has passed through the smoothing circuit. An inverter device that converts the output into an alternating current voltage using an element, and a pulse laser power supply device that supplies the output of the inverter device to a laser oscillator, which detects the direct current input to the inverter device and differentiates the direct current. 1. A power supply device for a pulsed laser, characterized in that the value is added to a voltage command value for controlling the phase of the converter device.