Research On The Key Electrical Technologies In High-power CO₂ Laser

The output power of CO₂ laser has been increased with the development of related technologies,and it has been widely used in laser propulsion,laser cleaning,laser processing and other fields.The core work of the high power CO₂ laser is the repeated charging and discharging of the high-voltage capacitors in the energy-storage and discharge chamber.The electrical system of high-power CO₂ laser mainly includes energy-storage and discharge circuit,high-voltage capacitor charging power supply,high-voltage pulse trigger generator for spark-gap switch and the laser electronic control system.Based on a high-power TEA CO₂ laser,this dissertation focuses on three key technologies in the electrical system: suppression technology for conducted EMI in power supply,design technology for high-frequency high-voltage pulse transformer and working mode and structural arrangement design technology for laser electronic control system.In the power switch converter circuit of the high-voltage power supply in the laser system,power switches?such as IGBTs?produce high-frequency interference current at switching frequency and harmonic frequency,which conducts on the power line and affects other components.In this dissertation,the causes of common-mode and differential-mode conducted noise in switch-mode power supply are analyzed.The circuit models of power rectifier,power switch converter and line impedance stabilization network are established by circuit simulation software Saber,and the conducted EMI current on AC power line is measured by FCC F-16 current probe.Design and optimization of the component parameters in power line EMI filter are completed.High-frequency high-voltage pulse transformer is one of the important devices in power supply for laser system.In this dissertation,after calculating the leakage inductance and the winding capacitance and analyzing the core loss and winding loss of the high-frequency transformer,a high-frequency pulse transformer equivalent model is established.The core and windings of the high-frequency high-voltage transformer are designed,and finite element simulation software is used to optimize the parameters such as the number of turns of the primary winding,the form of the primary winding,the insulation material and the winding size.A prototype of high-frequency pulse transformer is made for switch-mode power supply,which meets the application requirements.The electronic control system in the laser system completes the distribution control,analog signal acquisition,air pressure adjustment,lens adjustment,serial communication and other functions.It is susceptible to the strong radiation EMI of high-voltage discharge in laser.In this dissertation,the electronic control system is designed as two separate parts,power circuit and controlling circuit,and a grounded metal plate is added to ensure effective isolation.EMI coupling paths and suppression methods for the electronic control system are analyzed form the views of field coupling into loops,crosstalk and aperture coupling.The electric field and magnetic field probes are used to measure the near-field radiation EMI of the laser,and the EMC optimization of the shielded cables and shelter of the electronic control system is completed.