JPS61168280A - Output stabilizing circuit - Google Patents

Abstract

PURPOSE:To equalize the peak value at pulse output mode time to that at continuous mode time by inserting an amplifier of 1/N of relative amplification factor varying in cooperation with a pulse duty ratio N into a feedback loop. CONSTITUTION:An amplifier 31 has relative amplification factor 1/N varying in cooperation with the duty ratio N of a pulse generator 27. If the duty ratio N at pulse output mode time is N=0.5, the amplification factor 1/N of the amplifier 31 becomes 2 at pulse output mode time. Thus, the average value of the feedback to a comparator 33 is 1 equal to the continuous pulse output mode time, and the peak value of the output current can be set to 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an output stabilizing circuit for a power supply for laser oscillation.

[Technical Background of the Invention and Problems Therein] There is a conventional output stabilizing circuit for a power source for laser oscillation of a laser processing machine as shown in FIG.

This output stabilization circuit includes a feedback loop, including a thyristor rectifier circuit 1 for rectifying a commercially available commercial current IAC, a smoothing circuit 3, a switching circuit 5, a pulse generator 7 for controlling the switching circuit 5, and a laser A discharge electrode 9 is provided as a power supply circuit section. Further, the feedback loop for stabilizing the output includes a current transformer CT that detects the output current, a comparator 11, and a characteristic compensation circuit 13 that controls the thyristor rectifier circuit 1.

To explain the operation of the above output stabilization circuit, the commercial power supply AC
The alternating current is rectified by a thyristor rectifier circuit 1 and added to a smoothing circuit 3 to obtain a direct current, and this direct current is intermittent by ON/OFF operation of a switching circuit 5 to obtain a direct current pulse output. Furthermore, if the switching circuit 5 is kept in the ON state, a continuous DC output instead of a pulse output can be obtained.

The thyristor rectifier circuit 1 has an input for controlling the conduction angle,
Output voltage can be controlled. The output current is detected by a current transformer CT, compared with an output command in a comparator 11, and fed back to the thyristor rectifier circuit 1 through a characteristic compensation circuit 13 that performs PTD control, thereby making the output a constant current.

Here, instead of making the output current constant, if the output voltage or output laser light is detected and fed back, the output can be made constant voltage or the laser light can be made constant.

Here, when the characteristic compensation circuit 13 has an integral characteristic, when the switching circuit 5 is operated to pulse the output, the pulse detected by the current transformer CT and fed back will have an average value of the pulse when passing through the integral circuit. Since the value shown is taken and given to the thyristor rectifier circuit 1, the average value of the output becomes constant.

If we explain this operation based on Fig. 6, if the output command is set to 10A, the switching circuit 5 will be
In the case of N, since it is a direct current, the average value and the peak value are equal and both are 10A. However, when the switching circuit 5 is operated and the output is a DC pulse, the average value and the peak value are different.For example, if the pulse duty is set to 0.5, the peak value is twice the average value. It becomes 20A.

In the case of conventional output stabilization circuits, the peak value of the output differs between continuous output mode and pulsed output mode, and when switching from continuous mode to pulsed mode, the peak value increases, causing abnormalities in the laser discharge section. There was a problem with the generator causing inconveniences such as electrical discharge.

[Purpose of the Invention] The present invention was made in view of the above-mentioned conventional problems, and it is possible to improve the performance of the relay laser discharge section by keeping the peak value at the same value both in the continuous output mode and in the pulse output mode. It is an object of the present invention to provide an output stabilizing circuit that can prevent the occurrence of inconveniences.

"Structure of the Invention" The present invention includes a pulse generator and a switching circuit that switch between continuous output mode and pulse output mode, detects and feeds back output voltage, output current, or output laser light, and according to the characteristics of the characteristic compensation circuit. In an output stabilization circuit that keeps the average value of the output voltage, output current, or output laser beam constant, the pulse duty ratio of the pulse generator is adjusted to equalize the peak value of the output in continuous output mode and pulse output mode. Relative amplification 1/ that changes in conjunction with N
This is an output stabilization circuit consisting of N amplifiers inserted into a feedback loop, which multiplies the average value in pulse output mode by the reciprocal of its duty ratio to equal the peak value, and outputs the corrected average value. By comparing it with the command value and performing feedback control, the peak value in the pulse output mode is controlled to be equal to the peak value in the continuous output mode.

[Embodiment of the Invention] FIG. 1 shows a circuit of an embodiment of the invention. The configuration of this embodiment is almost the same as the output stabilizing circuit shown in the conventional example, except that an amplifier with an amplification factor of 1/N is inserted in the feedback loop. To explain the circuit of this embodiment, the iris rectifier circuit 21 rectifies the commercial current mA C.
, a smoothing circuit 23 that smoothes the rectified output of this thyristor rectifier circuit, a switching circuit 25 that turns on and off smoothed DC to output pulsed DC, and a pulse generator 27 that controls ON and OFF of this switching circuit 25. A power supply circuit is constituted by a laser discharge electrode 29 to which a pulse current is applied.

The feedback loop is a current that detects the output current]
an amplifier 31 with a relative amplification of 1/N that changes in conjunction with the pulse duty ratio N of the front pulse generator 27 and the Lance CT;
, a comparator 3 that compares the output command value and the feedback skewer.
3. A characteristic compensation circuit 35 is provided which performs PTD control of the conduction angle of the thyristor rectifier circuit 21 based on the output from the comparator 33.

To explain the operation of the output stabilizing circuit having the above configuration, AC power from a commercial power supply AC is rectified by the thyristor rectifier circuit 21 and converted to continuous DC by the smoothing circuit 23.

The DC output from this smoothing circuit 23 is the switching circuit 2
5 is intermittent, resulting in a pulse output.

ON and 01F control of this switching circuit 25 is performed by pulses from a pulse generator 27. Therefore, if the pulse generator 27 is not a pulse but a continuous ON signal, the switching circuit 25 maintains the ON state,
Continuous DC output is applied to the laser discharge electrode 29. When the pulse generator 27 gives a pulse offset, the switching circuit 25 turns on and off to give a DC pulse output to the laser discharge electrode 29.

In this situation, in the feedback loop, current 1 to lance CT
feeds back the output pulse signal to the comparator 33, where it is compared with the output command value, and the deviation is given to the compensation circuit 35. The characteristic compensation circuit 35 then controls the conduction angle of the thyristor rectifier circuit 21 under PID control.

Here, the amplifier 31 has a duty ratio N of the pulse generator 27
By having a relative amplification factor of 1/N that changes in conjunction with each other, the operation shown in FIG. 2 can be obtained.

When the duty ratio is N-1 in the continuous output mode, and when the duty ratio is N-=('), 5 in the pulse output mode, the amplifier 31
The amplification degree 1/N is 1 in continuous output mode and 2 in pulse output mode.If the output of the amplifier 31 is 1 in continuous output mode, the peak value is 2 and the average value is 1 in pulse output mode. Therefore, the average value of the feedback to the comparator 33 is equal to 1 in both continuous and pulse output modes, and the peak value of the output current can be set to 1 in both cases. Therefore, the output current has a peak of 1 even in pulse mode.
The following output is obtained.

FIG. 3 shows an embodiment of the present invention, and the insertion position of the amplifier 31 with an amplification factor of 1/N is not limited to the embodiment shown in FIG. It is also possible to install it elsewhere, for example downstream of the comparator 33. In this case, an amplifier 37 that multiplies the output command value by N in conjunction with the leverage ratio of the pulse generator 27 is required = 7-. The other circuit components are the same as those in the first embodiment.

FIG. 4 shows still another embodiment, and shows an embodiment of a power supply circuit equipped with a PWM switching circuit. To explain this PWM switching power supply circuit, a DC current is obtained from the commercial AC power supply AC by a rectifier circuit/11 and a smoothing circuit 43, and is controlled to be turned on and off by a carrier switching circuit 45, and can be output in continuous output mode or pulse output. Transformer 47 as mode
, a rectifier circuit 49, and a smoothing circuit 51 to remove carriers, and provide a continuous mode or pulse mode output to the laser discharge electrode 53.

The feedback loop includes a comparator 55 for comparing the output current obtained by the current transformer CT with an output command value, a characteristic compensation circuit 57, and a high frequency PWM carrier generator 59 as main components.

Furthermore, the high frequency PWM carrier generator 59 is connected to the gate circuit 6.
1 to the carrier switching circuit 45,
A pulse generating circuit 63 is connected to this gate circuit 61. Furthermore, an amplifier 65 that provides a relative amplification factor of 1/N that changes in conjunction with the pulse decoty ratio N of the pulse generating circuit 63 is inserted in the feedback loop.

In the case of the output stabilizing circuit of the PWM switching power supply having the configuration described in 1 above, the high frequency carrier from the high frequency PWM carrier generator 59 is superimposed with the pulse from the pulse generating circuit 63 by the gate circuit 61 to generate the carrier switching circuit 45.
A pulse 'output according to the pulse mode generated by the pulse generation circuit 63 is obtained.

In the case of this embodiment as well, waveforms as shown in FIG. 2 are obtained at each part, and the peak value in the pulse output mode is controlled to be equal to the peak value in the continuous output mode.

[Effects of the Invention] This invention inserts an amplifier with a relative amplification of 1/N that changes in conjunction with the pulse decoerty ratio N of the pulse generator into a feedback loop, and calculates the average value of the output current, voltage, or output laser light. Since it is designed to keep constant, the peak of the pulse output in pulse output mode can be kept equal to the peak value in continuous mode, and when switching from continuous mode to pulse mode, the -b peak value can be kept constant. It does not rise and can prevent abnormal discharge and other inconveniences from occurring in the laser discharge section.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of one embodiment of the present invention, FIG. 2 is a time chart 1 to 1 showing the operation of the same embodiment, FIG. 3 is a circuit block diagram of another embodiment, and FIG. 4 is a circuit block diagram of another embodiment. FIG. 5 is a circuit block diagram of the conventional example, and FIG. 6 is a time chart explaining the operation of the conventional example. 21... Lee Iristor rectifier circuit, 23... Smoothing circuit, 25... Switching circuit, 27... Pulse generator, 29... Laser lightning electrode, 31... Amplifier, 3
3... Comparator, 35... Characteristic compensation circuit, 41...
Rectifier circuit, 43... Smoothing circuit, 45... Carrier switching circuit, 47... Transformer, 49... Rectifier circuit, 51... Smoothing circuit, 53... Laser discharge electrode,
55... Comparator, 57... Characteristic compensation circuit, 59...
・High frequency PWM Kisa 9F generator, 61...Goo 1
circuit, 63...pulse generation circuit. r-. to times

Claims (1)

[Claims] Equipped with a pulse generator and a switching circuit that switch between continuous output mode and pulse output mode, detects and feeds back the output voltage, output current or output laser light, and adjusts the output voltage, output current or output laser light depending on the characteristics of the characteristic compensation circuit. In an output stabilization circuit that maintains a constant average value, in order to equalize the output peak values in continuous output mode and pulse output mode, relative amplification that changes in conjunction with the pulse duty ratio N of the pulse generator is used. An output stabilization circuit consisting of a 1/N amplifier inserted into a feedback loop.