超高壓水銀燈電子安定器之設計

Abstract

目前一般單槍投影機所使用的投影燈為200~250W 的複金屬燈，複金屬燈雖然具有高演色性的優點，但在高度需求高亮度的投影機系統中，複金屬燈的照度仍嫌不足。超高壓水銀燈利用水銀在高壓下可以產生高照度的原理提供了投影機一個絕佳的光源。 本論文提出一完整之超高壓水銀燈電子安定器之設計方法，其架構包括一啟動燈管所需之點火電路，及使電路具高功率因數的昇壓式功因修正器，還有提供超高壓水銀燈正常工作所需能量之返馳式轉換器，以及一全橋式換流電路來避免音頻共振的問題；本論文除了利用市售的臨界電流模式控制器L6561來控制昇壓式功因修正器及電流模式控制器UC3843控制反馳式轉器，並提出最大電流及功率限制的辦法保護了轉換器及超高壓水銀燈。硬體方面的架構已經建立起來，實驗結果顯示了燈管正常工作時之電壓電流能與我們的設計規格吻合。

In the market, one can find that most of the single gun projectors use 200~250W metal halide lamps. Although halide lamps present high color rendering, their illumination are insufficient to meet the requirements preferred by high quality projectors. Thus, the Super-High Pressure Mercury (SHP) lamps, which have high illumination, are introduced to be the strong light sources of LCD projectors. This thesis proposed a complete design of the electronic ballast for SHP lamps. The whole design includes an igniting circuit, a boost power factor corrector, a flyback converter, and a full-bridge inverter to provide square ac power for lighting the SHP lamps. The boost power factor corrector is implemented by L6561 and produce 400 V output. The flyback converter transfers the 90 V dc to and isolated dc output and is implemented by UC 3843, which operates in current mode control. Both the maximum current and power limits are designed to protect the SHP lamp from burning out. The whole electronic ballast works well and meet the requirements.