แหล่งจ่ายกำลังดีซีสำหรับหลอดเทโทรดในเครื่องกำเนิดแสงสยาม

Abstract

This article presents the development of a   800 V, 500 W DC power supply feeding the tetrode tube of the Siam Photon Source. The developed technology has a 3-phase parallel-resonant converter as its main structure that is fed by a single-phase source of 220 V, 50 Hz. The converter employs 6 MOS transistors of 1,700 V, 16 A ratings as its main switches connected in full-bridge topology having the DC-link voltage of    311 Vdc . A dsPIC30F2020 microcontroller drives the switches at 85.2 kHz switching frequency. Resonant tanks having L = 233 µH and C = 22.5 nF are used. Based on a step transient test and identification via MATLAB-System Identification Toolbox, a second-order ARMAX transfer function is obtained for representing the converter. An output voltage regulation is accomplished by a closed-loop control using an analog PI-controller built around op-amps to achieve  K_P = 3 and K_I = 900. Circuit simulations using PSIM and experiments on a prototype converter confirm that, with a 1,280 Ω load (an equivalent resistance of the tetrode tube under steady state operation), the converter produces 800 Vdc output having 2.12 mS rise time,  6.67 mS settling time (at 1 % errors), and percent overshoot of 2.3%.