本論文針對直流降壓型轉換器，提出精準功率損耗估算以及改進主動式虛擬漣波導通時間控制和抵銷固有輸出電壓偏移。首先，進行詳細分析與介紹精準功率損耗估算方法，切換損失主要是由金屬氧化物半導體場效電晶體寄生電容造成，針對切換損失提出一個完整研究與分析。另外，考慮金屬氧化物半導體場效電晶體阻抗之溫度特性，提出疊代方式來預測金屬氧化物半導體場效電晶體接合點溫度，進而導出金屬氧化物半導體場效電晶體實際阻抗。近年來直流降壓型轉換器控制架構採用主動式虛擬漣波導通時間控制，概念在較低責任週期操作時，具有架構簡單、快速暫態負載之優點，此種控制架構解決傳統導通時間控制，在使用陶瓷電容下所產生的不穩定諧波振盪。然而，此種控制架構在某些責任週期應用條件下有較慢暫態負載響應及固有輸出電壓偏移等缺點。本論文提出主動式可調整虛擬漣波導通時間控制去改進較慢暫態負載響應，另外提出新方法去抵銷固有輸出電壓偏移。最後，本論文針對提出功率損耗估算方法，進行理論分析和實驗結果比較，證明其可行性和可靠性。並藉由模擬和實驗比較結果，證明所提出主動式可調整虛擬漣波導通時間控制和抵銷固有輸出電壓偏移，具有快速暫態負載響應及無輸出電壓偏移。

This dissertation presents an accurate power-loss estimation method and a ripple based adaptive on-time (RBAOT) control with adjustable virtual-ripple and offset cancellation for buck converters. First, the accurate power-loss estimation method is introduced and analyzed in detail. The switching loss is mainly caused by parasitic capacitance of the metal oxide semiconductor field-effect transistor (MOSFET), and the switching loss on power MOSFETs has been thoroughly researched and analyzed. Besides, considering the thermal characteristics of MOSFET resistance, the dissertation presents iterative method to predict the junction temperature to get the new integration resistance of MOSFET. Recently buck converter control topology uses ripple based adaptive on-time (RBAOT) with virtual-ripple which is a conceptually simple topology and features fast dynamic transient response at lower duty ratio application. This control scheme solves the sub-harmonic oscillation instability when using ceramic capacitors in conventional control scheme. However, this control scheme has some drawbacks, such as poor dynamic transient response at a specified duty ratio range and inherent output voltage offset problem. This dissertation presents a new method which called RBAOT control with adjustable virtual-ripple to improve dynamic transient response, and a new method for output voltage offset cancellation. Theoretical analysis and experimental results are shown and compared to validate the feasibility and reliability of proposed power-loss estimation method. Simulation and experimental comparison results show that the proposed concept of ripple based adaptive constant on-time control with adjustable virtual-ripple and offset cancellation achieved fast dynamic transient responses without output voltage offset.

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