JPS6423589A - Method and apparatus for controlling power supply for laser - Google Patents

Abstract

PURPOSE:To easily dissipate the heat of an inverter by detecting the output voltage and current of the inverter, calculating the displacement of the phases of the output voltage and current generated by the electrostatic capacity and a high frequency reactor of a discharge tube connected to the output side of the inverter, and bringing the switching frequency of the inverter into coincidence with the resonance frequency of the electrostatic capacity and the high frequency reactor of the tube. CONSTITUTION:The output current and voltage of a high frequency transformer 5 are detected by detectors, and output current and voltage waveforms are output to a power factor first controller 13. The controller 13 detects the phase advancing amount to the output voltage waveform of the output current waveform, amplifies it to obtain a frequency increment DELTAf, adds it to a frequency f0 so far, and outputs a frequency command value as f=f0+DELTAf to a PWM controller 10. Further, the controller 13 outputs a current detection value to the controller 10. The controller 10 feeds the pulse width command of the output voltage amplified from the difference between the current command and the current detected value to an inverter 4, and so instructs to set the switching frequency of the inverter 4 to f by the frequency command value. Thus, the switching frequency is brought into coincidence with the resonance frequency of the electrostatic capacity 7 and the high frequency reactor 6 of the discharge tube.