JPH0665234B2 - Output stabilization circuit - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an output stabilizing circuit for a laser oscillation power supply.

[Technical Background of the Invention and Problems Thereof] There is a conventional output stabilizing circuit for a laser oscillation power source of a laser beam machine as shown in FIG. This output stabilizing circuit has a feedback loop,
Thyristor rectifier circuit 1 for rectifying commercial AC power supply AC, smoothing circuit 3, switching circuit 5, and this switching circuit 5
A pulse generator 7 and a laser discharge electrode 9 for controlling the are provided as a power supply circuit section. The feedback loop for stabilizing the output is the current transformer C that detects the output current.
It includes a T, a comparator 11, and a characteristic compensation circuit 13 for controlling the thyristor rectifier circuit 1.

The operation of the output stabilizing circuit will be described. The alternating current from the commercial power supply AC is rectified by the thyristor rectifying circuit 1 to obtain the direct current in addition to the smoothing circuit 3, and the direct current is supplied to the switching circuit 5
The DC pulse output is obtained intermittently by the ON and OFF operations of.
If the switching circuit 5 is kept in the ON state, continuous DC output is obtained instead of pulse output.

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

Here, instead of making the output current constant, by detecting and feeding back the output voltage or the output laser light, 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 is given to the thyristor rectifier circuit 1 by taking a value indicating the average value of the pulse when passing through the integrating circuit, so that the output has a constant average value.

If this operation is explained based on FIG. 6, if the output command is set to 10 A, it is direct current when the switching circuit 5 is continuously turned on, so the average value and the peak value are the same.
It becomes 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, when the pulse duty ratio is 0.5, the peak value is 20 A, which is twice the average value.

As described above, in the case of the conventional output stabilization circuit, the peak value of the output is different between the continuous output mode and the pulse output mode, and the peak value becomes large when switching from the continuous mode to the pulse mode, and the laser discharge part becomes abnormal. There is a problem that inconvenience such as electric discharge occurs.

[Object of the Invention] The present invention has been made in view of such a conventional problem, and inconveniences in the laser discharge part by keeping the peak value at the same value in both the continuous output mode and the pulse output mode. It is an object of the present invention to provide an output stabilization circuit capable of preventing the above.

[Configuration of the Invention] The present invention includes a pulse generator and a switching circuit that switch between a continuous output mode and a pulse output mode, detects an output voltage, an output current, or an output laser beam and feeds back the detected voltage, and adjusts the characteristics of a characteristic compensation circuit. In the output stabilization circuit that keeps the average value of the output voltage, output current or output laser light constant, in order to equalize the peak value of the output in the continuous output mode and the pulse output mode, the pulse duty ratio of the pulse generator Relative amplification 1 / that changes in conjunction with N
An output stabilizing circuit in which an N amplifier is inserted in a feedback loop, the average value in the pulse output mode is multiplied by the reciprocal of the duty ratio to equal the peak value, and the corrected average value is output. By performing feedback control in comparison with the command value, 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 present invention. The configuration of this embodiment is almost the same as that of the output stabilizing circuit shown in the conventional example, except that an amplifier having an amplification factor of 1 / N is inserted in the feedback loop. Explaining the circuit of this embodiment, a thyristor rectifier circuit 21 that rectifies a commercial light current power supply AC, a smoothing circuit 23 that smoothes the rectified output of this thyristor rectifier circuit, and a smooth DC input is turned ON / OFF to produce a pulse DC output. A power supply circuit is configured by the switching circuit 25, a pulse generator 27 that controls ON / OFF of the switching circuit 25, and a laser discharge electrode 29 to which a pulse current is applied.

The feedback loop includes a current transformer CT that detects an output current, an attenuator 31 having a relative amplification factor of 1 / N in conjunction with the pulse duty ratio N of the pulse generator 27, and a comparator that compares an output command value and a feedback amount. 33, a characteristic compensating circuit 35 for PID controlling the flow angle of the thyristor rectifier circuit 21 by the output from the comparator 33.

Explaining the operation of the output stabilizing circuit having the above configuration, the AC power source of the commercial power source AC is rectified by the thyristor rectifier circuit 21 and converted into a continuous flow value by the smoothing circuit 23. The DC output from the smoothing circuit 23 is interrupted by the switching circuit 25 and becomes a pulse output.

The ON / OFF control of this switching circuit 25 is performed by the pulse generator 2
Performed by pulses from 7. Therefore, if the pulse generator 27 is not a pulse but a continuous ON signal,
The switching circuit 25 maintains the ON state and gives a continuous DC output to the laser discharge electrode 29. If the pulse generator 27 gives a pulse signal, the switching circuit 25 turns ON, OF
F operation is performed and a DC pulse output is given to the laser discharge electrode 29.

At this time, in the feedback loop, the current transformer CT feeds back the output pulse signal to the comparator 33, compares it with the output command value, and gives the deviation to the characteristic compensation circuit 35. Then, the characteristic compensation circuit 35 controls the flow angle of the thyristor rectifier circuit 21 by PID control.

Here, since the amplifier 31 has the relative amplification factor 1 / N which changes in association with the duty ratio N of the pulse generator 27, the operation as shown in FIG. 2 is obtained.

When N = 1 in the continuous output mode and the duty ratio N = 0.5 in the pulse output mode, the amplification degree of the amplifier 31 is 1
/ N is 1 in the continuous mode and 2 in the pulse output mode. If the output of the amplifier 31 is 1 in the continuous output mode, the peak value is 2 and the average value is 1 in the pulse output mode.
And pulse output.

Therefore, the average value of the feedback to the comparator 33 is continuous,
Both are equal in the pulse output mode, and the peak value of the output current can be set to 1. Therefore, the output current is such that the peak becomes 1 even in the pulse mode.

FIG. 3 shows another embodiment of the present invention. The insertion position of the amplifier 31 having an amplification factor of 1 / N is not limited to the embodiment shown in FIG. It may be provided at another place, for example, on the downstream side of the comparator 33. In this case, the amplifier 37 that multiplies the output command value by N in conjunction with the duty ratio of the pulse generator 27 is required. Other circuit constituent materials are the same as those in the first embodiment.

FIG. 4 shows still another embodiment, which is an embodiment of a power supply circuit having a PWM switching circuit. Explaining this PWM switching power supply circuit, a DC current is obtained from a commercial AC power supply AC by a rectifier circuit 41 and a smoothing circuit 43, and ON / OFF control is performed in these carrier switching circuits 45, and a continuous output mode or a pulse output mode is applied. Device 47, rectifier circuit 49, smoothing circuit 51
Carriers are removed through and the laser discharge electrode 53 is provided with a continuous mode or pulse mode output.

The feedback loop includes a comparator 55 that compares 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. Further, the high frequency PWM carrier generator 59 is connected to the carrier switching circuit 45 via the gate circuit 61, and the pulse generating circuit 63 is connected to the gate circuit 61.
Are connected. Further, an amplifier 65 that gives a relative amplification degree 1 / N that changes in association with the pulse duty ratio N of the pulse generation circuit 63 is inserted in the feedback loop.

In the case of the output stabilization circuit of the PWM switching power supply with the above configuration, the high frequency PWM carrier generator 59 is provided by the gate circuit 61.
The high frequency carrier from is superposed on the pulse from the pulse generation circuit 63 and given to the carrier switching circuit 45,
The pulse output according to the pulse mode generated by the pulse generation circuit 63 is obtained.

Also in the case of this embodiment, the waveform as shown in FIG. 2 is obtained in 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] The present invention inserts an amplifier having a relative amplification factor of 1 / N in conjunction with the pulse duty ratio N of a pulse generator into a feedback loop to make the output current, voltage, or average value of output laser light constant. The peak value of the pulse output in pulse output mode can be kept equal to the peak value in continuous mode, and the peak value will rise even when switching from continuous mode to pulse mode. Therefore, it is possible to prevent abnormal discharge and other inconveniences from occurring in the laser discharge part.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of an embodiment of the present invention, FIG. 2 is a time chart showing the operation of the above embodiment, FIG. 3 is a circuit block diagram of another embodiment, and FIG. 4 is still another embodiment. An example circuit block diagram, FIG. 5 is a conventional circuit block diagram,
FIG. 6 is a time chart for explaining the operation of the conventional example. 21 …… thyristor rectifier circuit, 23 …… smoothing circuit, 25 …… switching circuit, 27 …… pulse generator, 29 …… laser discharge electrode, 31 …… amplifier, 33 …… 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 carrier generator, 61 …… Gate circuit, 63 …… Pulse generating circuit.

Claims (1)

[Claims] 1. A pulse generator for switching between a continuous output mode and a pulse output mode, and a switching circuit, which detects and feeds back an output voltage, an output current or an output laser beam, and outputs the output voltage and the output according to the characteristics of a characteristic compensation circuit. In an output stabilization circuit that keeps the average value of current or output laser light constant, in order to equalize the peak value of the output in the continuous output mode and the pulse output mode, it is linked with the pulse duty ratio N of the pulse generator. And an output stabilizing circuit formed by inserting an amplifier having a relative amplification degree of 1 / N into a feedback loop.