以TL494為架構降壓式電源轉換器之非線性分析

Abstract

本論文以一般商業用脈波寬度調變控制IC TL494設計及製作降壓型電源轉換器電路，並建立此系統電路之數學模型，以分析此基本的實用電路所可能發生的非線性不穩定現象。本論文之主要目的為探討當降壓型電源轉換器電路之不同系統參數發生改變時，系統平衡點發生分叉現象的條件與參數空間之變化情形。首先應用以取樣資料方法建立電路數學模型，以分析系統之穩定性，接著，建立Isspice軟體之降壓電路模型，以模擬各種系統參數發生分叉現象的特性空間；最後，經由實際電路實驗以驗證分叉現象之發生情形。從本論文所提出之分析結果發現，此電路在連續電流導通模式(CCM)與不連續電流導通模式(DCM)下均會發生不穩定之分叉現象，在不同的系統參數之分叉圖中顯示此電路會發生雙週期分叉，而後可能會進入混沌現象。本論文所提出的各種參數之分叉圖將有助於瞭解此系統的穩定區間與發生不穩定條件，對於降壓型電源轉換器之製作將可提供良好的設計參考。

In this thesis, the commercial TL494 PWM IC is used to design and implement the buck converter for studying the nonlinear characteristics of PWM-controlled power circuits. Applying the sampled-data approach, the mathematical model is constructed to analyze the instability dymanics of buck converter. The major goal of this thesis is to study the possible bifurcation phenomena operated in buck converters while the different system parameters vary. Moreover, the bifurcation conditions and the parameter spaces of the system equilibrium points are analyzed and estimated by the numerical simulations and the experimental demonstrations. Via the Isspice simulations, the system stability is studied and the bifurcation diagrams are depicted for the TL494-based buck converter. Finally, the bifurcation phenomena are demonstrated by implimenting the experiments of the practical circuit. According to the analysis results of this thesis, it is observed that the bifurcation behaviors might occur in the operations of the Continuous current Conduction Mode (CCM) and Discontinuous current Conduction Mode (DCM) of the PWM power circuits proposed. The bifurcation diagrams also reveal that the system dynamics might undergo the period-doubling bifurcation as the different system parameters are changed, and possibly enter into the chaos phenomenon. Furthermore, the nonlinear analysis of system dynamics is helpful to understand the stability conditions and domains which will provide the valuable reference to improve the performance of buck converter.