Design And Simulation Of 2MHz RF Power Supply For Fast Axial Flow CO₂ Laser

For the discharge technology in the fast-axial-flow (FAF) CO₂ laser, RF excited has more advantages than DC excited technology such as better discharge stability, higher injection power density, pollution discharge gas free, and excellent power control characteristics. Moreover, RF excited FAF CO₂ laser is better to meet the requirements of the industrial development. The traditional RF excited source based electronic tube has a large volume and low efficiency. Nowadays, the development of the semiconductor technology enables more choices to generate RF power source. In our paper, a prototype inverter based on low-profile package RF Power MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) operation around frequencies as high as 2MHz was designed. The main work is shown as follows.Firstly, according to the investigation of the properties of RF discharge, the system structure and parameters of RF power unit were designed, and the scheme of inverter was selected..Secondly, in order to achieve a small loss of electric power conversion, the ZVS (Zero Voltage Switching) mode of the inverter and the dead time of the operation were analyzed, and the PLSRC (Parallel load series resonant converter) was studied. Moreover, the PSPICE simulation software with the SPICE (Simulation Program with Integrated Circuit Emphasis) module of RF MOSFET was used for validation of the operation of the main inverter circuit.Finally, the structure and hardware of the inverter main circuit was designed. The main circuit consists of a single-phase Full bridge inverter using four RF MOSFET modules which are newly designed for high frequency applications. Each leg of the bridge inverter consists of two new MOSFET modules forming a back-to-back layout which enables a significant reduction of the line inductance between the modules to reduce its inner inductance. Otherwise, the drive system based on the combination of DSP (Digital Signal Processing) and CPLD (Complex Programmable Logic Device), with optical fiber connection was presented in the thesis.In this thesis, by the investigation of the 2MHz high-power RF generator unit, the theory analysis, simulation and hardware design were completed. Our work provided a profitable attempt on the development of the compact high-power RF FAF CO₂ laser.