電流模式定導通時間適應性電壓位置直流電源轉換器之容忍度分析

在過去電腦電源供應器，大部分使用定頻操作的直流-直流(DC-DC)轉換器，然而定頻的控制模式在系統操作輕載時，因為系統的基本損失，導致系統效率不佳，近年來手持式電子產品或個人電腦，大部分時間均操作在輕載的模式下，故提昇系統輕載效率變成電源供應器重要的課題，因此最近一種新的控制策略，固定開關導通時間(Constant on time)的控制策略，被廣泛應用在許多電源供應器上，此種控制策略在系統重載時為操作頻率約為定值，但系統輕載時，卻有著比傳統定頻控制策略有著較高效率。本篇論文中，主要探討使用固定開關導通時間控制策略的電路容忍度分析，電路架構為一個多相式(Multi-phase)降壓型轉換器(buck)，此電路有電壓適應性(AVP)和固定開關導通時間(COT)的特性，本篇論文主要包含系統穩定度(system stability)容忍度分析和直流系統輸出負載線(system output load-line)容忍度分析，分析方法主要使用極值分析法(extreme value analysis), 均方根法(root sum squared analysis)和蒙地卡羅分析法(monte-carlo analysis)，本篇論文中也包含元件參數的敏感度(sensitivity analysis)分析，其目標在於產品真正進入大量生產前，預先設計改善其元件參數。

關鍵字

容忍度分析；穩壓器；適應性電壓定位；固定開關導通時間控制；電流模式；直流輸出負載線；穩定度條件

並列摘要

In the past, the DC-DC converters used for computer power applications usually employ a constant-frequency variable-duty-cycle controller. This type of control, however, often causes low conversion efficiency under light-load conditions. In recent years, light-load efficiency has become a major design consideration for the reason that most of the electronic devices, whether for desk-top or hand-held applications, are most of the time operated under light-load conditions. Therefore, a new controller type, the constant-on-time controller, has been proposed and adopted in many applications recently. DC converters employing such a control scheme features relatively high light-load efficiency, compared to a conventional constant frequency converter, while maintaining good heavy-load efficiency. In this thesis, a tolerance analysis of a converter using a constant-on-time controller will be performed. More specifically, a multi-phased buck converter with adaptive-voltage positioning (AVP) feature employing a constant on-time controller will be analyzed. Two performance features of the converter will be the focus. One is the converter output load line with AVP feature, and the other is the feedback stability performance. The three traditional tolerance analysis methods are used. There are the extreme value analysis, the root-mean-square analysis, and the Monte-Carlo analysis. Sensitivity analysis is also performed that provides an insight into the sensitivity of the converter performances to component value tolerance. The results of these analyses provide useful design information in a high-volume production situation.

並列關鍵字

Tolerance analysis ； Voltage regulator (VR) ； Adaptive voltage position (AVP) ； Constant on-time control ； Current-mode control ； DC load line ； Stability criteria

參考文獻

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[3] M. Lee, D. Chen, C.-W. Liu, K. Huang, E. Tseng, and B. Tai, “Compensator design for adaptive voltage positioning (AVP) for multiphase VRMs,” in Proc. IEEE Power Electron. Spec. Conf., 2006, pp. 1–7.

[4] M. Lee, D. Chen, K. Huang, C. W. Liu, and B. Tai, “Modeling and design for a Novel Adaptive Voltage Positioning (AVP) Scheme for Multiphase VRMs,” IEEE Trans. on Power Electronics, vol. 23, no. 4, pp. 1733-1742, Jul. 2008

[6] Jian Li, Lee, F.C. “New Modeling Approach for Current-Mode Control,” Applied Power Electronics Conference and Exposition, 2009. APEC 2009, pp. 305-311

[7] Yu-Cheng Lin, Ching-Jan Chen, Dan Chen,and Brian Wang, “A Novel Ripple-Based Constant On-Time Control with Virtual Inductance and Offset Cancellation for DC Power Converters”, in Proc. IEEE ECCE Conf. 2011, pp. 1244–1250.

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電流模式定導通時間適應性電壓位置直流電源轉換器之容忍度分析

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