全數位化高功因高效率AC/DC轉換器研製

Abstract

本文旨在研製一全數位化高功因高效率AC/DC轉換器，作為LCD-TV之供應電源，系統架構包含前級為無橋式功因修正器，減少橋式整流器的導通損失，電流控制迴路使用預測電流模式控制使輸入電流追隨輸入電壓，並達到單功因目標，電壓控制迴路使用PI控制器達到輸出穩壓;後級為LLC諧振轉換器，利用變頻控制器調節輸出電壓，一次側利用諧振元件達成零電壓切換以減少切換損失，二次側加入同步整流技術以減少導通損失增加效率。

本文電路使用PSIM模擬軟體對設計結果進行分析。系統採用數位信號處理器TMS320F28035作為控制核心，發展電壓及電流迴路控制，並完成300W之系統，輸入電壓為110V/60Hz，輸出電壓為24V。滿載情況下，效率達91.8%，功率因數為0.996。

This thesis present the design and implementation of a Fully-digitalized AC/DC converter with high power factor and high efficiency for LCD-TV power system. The front stage is a bridgeless power factor corrector, the conduction loss in the rectifier bridge can be reduced. The predictive current control with constant switching frequency is used for current loop to force the input current and voltage in phase and raise the power factor to unity, the PI control law is used for voltage loop to stabilize output voltage; The second stage is LLC resonant converter, a variable frequency controller is used to regulate output voltage, the resonant component which makes the switch of primary side to achieve zero voltage switching and reduce switching loss, a synchronous rectifier is added in the secondary side to reduce conduction loss and improve efficiency. In this thesis, the proposed circuit is simulated by PSIM to analyze the performance of the design results. The digital signal processor TMS320F28035 is used to develop the control functions of voltage and current loop. An experimental system of 300W output power with 24Vdc for AC110V/60Hz input is constructed, experimental data show that the power factor and the efficiency is 0.996 and 91.8% under full load condition.