本篇論文採用全橋相移式零電壓切換轉換器(Full Bridge Phase Shifted Zero Voltage Switching Converter)為基本架構,並以UCC3895這顆晶片作為PWM控制器,利用此輸出訊號相移調控工作週期以應對負載變動,以及運用開關上的寄生電容和變壓器之漏電感產生共振,使開關切換時處於零電壓狀態以降低切換損失。 整個電路架構以兩組全橋相移式零電壓轉換器併聯供應同一負載,並使兩組轉換器達到均流輸出,降低輸出電流漣波大小,縮小濾波器元件尺寸,本文所研製電路規格如下:輸入直流電壓:DC 48V;輸出直流電壓:DC 3.3V;輸出功率:72W。 全橋相移式零電壓切換基本原理、PWM控制晶片、控制電路、電路架構及設計準則皆在論文中之各章節討論。
The thesis adopts full-bridge phase-shifted zero-voltage isolated switching converter as the basic structure. First, the hardware of proposed converter is established using a phase-shift current controller UCC3895 manufactured by Texas Instruments (TI). In order to control output voltage of converter, the UCC3895 is in charge of current control, phase-shift and PWM generation. Then the zero voltage switching (ZVS) is yielded by parasitic capacitance of MOSFETs and a leakage inductance of transformer to reduce the switching losses of MOSFETs. Finally, a paralleled operation of two UCC3895-based phased-shifted converter is devised to improve the current sharing behavior in steady-state. And the clock inputs of the paralleled converter are provided by a pair of synchronous interleaved clocks to let the converter possess lower output voltage ripple