多模控制返馳式轉換器之類比補償器設計

Abstract

多年以來，返馳式電源轉換器在電力電子之應用上，一直是受歡迎的電路架構。近年一種可改善電腦電源供應器電路整體效率之“多模控制”方法，已提出且應用於返馳式電源轉換器上。“多模式控制?針對電路不同的負載強度，提供不同的控制策略。當電路操作於重載時，電路運作於準諧振模式。當負載減輕時則採用固定切換頻率之不連續導通模式。而當電路運作於輕載，例如電腦的待機睡眠模式時，則採用頻率返折模式。如此電路整體效率即可獲得提升。 本論文針對多模式控制返馳式電源轉換器之回授特性，使用小訊號模型做分析。由於同一組補償器線路將使用在三種不同的控制模式上，本論文也針對了三種控制模式之環增益頻寬以及確保系統穩定度之相位邊限作分析。基於上述分析，可發展出一套補償器設計流程。此流程亦將以模擬結果作證實。此外，此補償器設計流程也將衍伸至“通用串列匯流排電力傳輸?之應用，是為即將誕生於電子產品充電應用上之新技術。本論文之分析，也為此類應用提供了有效的資訊。

Flyback converter configuration has been a popular choice for many power electronic applications for many years. Recently, a so-called multi-mode control (MMC) scheme has been reported to improve the overall performances for applications requiring wide line voltage and wide load range such as the computer power systems. The idea of MMC is to provide different control strategies according to the load level. When the load is heavy, quasi-resonant (QR) control mode is used. When the load is reduced, a discontinuous conduction mode (DCM) is used. When the load is very light such as in the computer sleeping mode, frequency-foldback mode (FFM) is used. This way, the converter overall efficiency can be improved. In this thesis, the feedback behavior of the MMC flyback converter will be analyzed using the small-signal model. Since one compensator is used for the three different modes of control, an analysis is given for the control loop gain bandwidth and stability margin for each mode. Based on this analysis, a design procedure is developed for the feedback compensator design. Simulations are conducted to verify the theoretical results. The procedure is also extended to the so-called USB-PD (Universal Serial-Bus Power Delivery) power that is an up-and-coming household DC converter application for charging mobile devices. For the USB-PD applications, the converter output voltage contains three different voltage levels. The results obtained from this thesis provide useful information for such applications.