JPH11233862A - Laser power supply control method and laser power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a laser power supply by quickly responding to an overload in the laser power supply. SOLUTION: A current flowing from an RF inverter 5 to a laser oscillator 7 is measured by a current detector 9, a control circuit 13 judges an overload at the laser power supply 1 by comparing the current measured to a chopping wave, and a pulse wave modulating circuit 15 decreases the pulse width of a pulse command which controls the current during the overload. In this way, the current is reduced and the laser power supply 1 is protected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laser power supply control method and a laser power supply, and more particularly, to a PWM.
The present invention relates to a laser power supply control method controlled by (pulse width modulation) and a laser power supply.

[0002]

2. Description of the Related Art Referring to FIG.
At 01, the DC / DC converter 103 varies the DC output voltage, and the RF (high frequency) converter 105 converts DC into high frequency AC to control the output of the laser oscillator 107.

Here, the RF inverter 105 only converts DC to high frequency, and has no control function or any means for overload.
7 is detected in the DC / DC converter 103.

[0004]

In such a conventional technique, an overload is detected in the DC / DC converter 103, and an alarm output, an output voltage is stopped, or a current is limited. However, the DC / DC converter 103 is provided with an LC filter for converting the output voltage into a direct current, and there is a problem that there is a limit in stopping the output and increasing the speed of the current limit because the time constant is delayed.

[0005] Further, since the energy stored in the LC filter is supplied to the RF inverter 105 as a load, there is a problem that overload protection cannot be completely performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a laser power supply capable of quickly responding to an overload in the laser power supply and protecting the laser power supply. It is to provide a control method and a laser power supply.

[0007]

According to a first aspect of the present invention, there is provided a laser power supply control method for converting a DC power into a high frequency power by an RF inverter and supplying the RF power to a laser oscillator. In the method, the current supplied from the RF inverter to the laser oscillator is measured, and the measured current is compared with a triangular wave, and when the current limit operation point is reached, the pulse width of the pulse command for controlling the current is reduced. , Is characterized.

Therefore, the current flowing from the RF inverter to the laser oscillator is compared with the triangular wave to determine the overload of the laser power supply, and the pulse width of the pulse command for controlling the current is reduced to reduce the current and reduce the overload. To protect the laser power supply.

A laser power supply according to a second aspect of the present invention is a laser power supply for operating a laser oscillator by converting a direct current to a high frequency by an RF inverter, and a current detecting means provided between the RF inverter and the laser oscillator. A control circuit for comparing the current detection means with a triangular wave,
A pulse modulation circuit for narrowing a pulse width of a pulse command for controlling the current when the measured current reaches a current limiting operation point by comparing the measured current with a triangular wave.

Therefore, the current flowing from the RF inverter to the laser oscillator is measured by a current detector, and the control circuit compares the measured current with the triangular wave to determine whether the laser power supply is overloaded. The width modulation circuit narrows the pulse width of the pulse command for controlling the current, thereby reducing the current and protecting the laser power supply.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a laser power supply 1 according to the present invention.
It is shown. In the laser power supply 1, a DC / DC converter 3 that varies a DC output voltage and an RF inverter 5 that converts DC into high-frequency AC and supplies the high-frequency AC are connected to a laser oscillator 7.

A current detector 9 and a voltage detector 11, which are current detecting means, are provided between the RF inverter 5 and the laser oscillator 7, and emit respective signals to a control circuit 13. The control circuit 13 is connected to a pulse width modulation circuit 15 through which the R is controlled by PWM (pulse width modulation).
The control of the F inverter 5 is performed.

The PWM will be described with reference to FIG.
The current flowing through the RF inverter 5 is obtained from the current detector 9, and this current is compared with a triangular wave as shown in FIG. When the triangular wave reaches the current limiting operation point, the pulse duty is reduced from Ton to Ton 'by PWM to limit the current.

[0015] From the above results, the PW of the RF inverter 5
Since the current is limited for each M pulse, a quick response can be taken without any delay when an overload occurs. Therefore, the RF inverter 5 can be reliably protected.

Also, in the laser power supply 1 shown in FIG.
Although the current control loop is configured by the RF inverter 5, the current is limited only at the time of overload as a voltage control loop in a normal state, so that the PWM pulse duty can be narrowed.

The present invention is not limited to the above-described embodiment, but can be embodied in other modes by making appropriate changes. That is, if not only the current control loop but also the voltage control loop is constituted by the PWM of the RF inverter 5 in FIG.
It is also possible not to use the / DC converter 3, and it is possible to reduce the cost.

[0018]

As described above, in the laser power supply control method according to the first aspect of the present invention, the current flowing from the RF inverter to the laser oscillator is compared with the triangular wave to determine whether the laser power supply is overloaded and to control the current. By narrowing the pulse width of the pulse command to be performed, the current is limited for each pulse and the current is reduced to protect the laser power supply, so that the laser power supply can be protected quickly and reliably.

In the laser power supply according to the second aspect of the present invention, R
The current flowing from the F inverter to the laser oscillator is measured by a current detector, and the control circuit compares the measured current with the triangular wave to determine whether the laser power supply is overloaded. By narrowing the pulse width of the pulse command for controlling the current, the current is reduced for each pulse to reduce the current, so that the laser power supply can be quickly and reliably protected.

[Brief description of the drawings]

FIG. 1 is a block diagram of a laser power supply according to the present invention.

FIG. 2 is a graph showing overload protection by PWM.

FIG. 3 is a block diagram of a conventional laser power supply.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 laser power supply 5 RF inverter 7 laser oscillator 9 current detector (current detection means) 13 control circuit 15 pulse modulation circuit

Claims (2)

[Claims] 1. A laser power supply control method for converting DC power into RF power by an RF inverter and supplying the RF power to a laser oscillator, wherein a current supplied from the RF inverter to the laser oscillator is measured, and the measured current is converted into a triangular wave. A pulse width of a pulse command for controlling a current when the current limit operation point is reached as compared with the current limit operation point. 2. A laser power supply for converting a direct current into a high frequency by an RF inverter to operate a laser oscillator,
A current detecting means provided between the RF inverter and the laser oscillator, a control circuit for comparing the current detecting means with a triangular wave, and comparing the measured current with a triangular wave to reach a current limiting operating point, A laser power supply, comprising: a pulse modulation circuit for narrowing a pulse width of a pulse command to be controlled.