多迴路鋰電池充電器之穩定度分析

Abstract

近年來，鋰離子電池廣泛使用於可攜式電子產品中，其充電器具有多種不同類型和控制架構。本篇論文所研究之充電器電路是以降壓轉換器實現，採用峰值電流控制並擁有多組回授迴路，另外，本充電電路僅使用一組補償器電路。 本篇論文詳盡分析完整充電過程中之電路運作方式。在充電過程中，電路運作因回授迴路之導通或切斷，共形成八種不同之電路型態。透過自行建立之小訊號模型，分析並得到不同電路狀態下之特性。由於本充電電路僅使用一組補償網路來穩定八種不同之工作狀態，需分析各狀態迴路增益中之未補償轉移函數，尋找出最差之工作狀態，同時根據分析結果，提出一套補償器設計流程。 最後以模擬軟體驗證電路分析結果及確認所提出之補償器設計。本論文之研究結果為開發此充電器電路IC前評估工作的重要部分。

Lithium batteries have recently become popular energy-storage devices for many portable products. There are a variety of control schemes for the charging of such a battery. In this thesis, a specific charging configuration composed of a buck converter with a peak current-loop control and multiple outer feedback-loops control is the focus. In addition, only one feedback compensator network can be used. In the thesis, a detailed analysis of the circuit operating modes throughout a complete charging cycle is given. This analysis leads to eight different feedback paths, depending on the stage/condition of the charging process. Small-signal models are developed for each of the eight configurations. Since only one compensator circuit is used for stabilizing the eight different configurations, a worst case analysis of the uncompensated loop gain transfer functions is necessary. Based on the analysis, a design procedure for the compensation network is developed. Simulations are conducted to verify the small-signal model and the compensator design procedure developed. The results reported in the thesis are primarily part of the evaluation efforts preceding an IC development for such the specific charger.