昇壓直流-直流轉換器中存在非線性現象使其工作狀態不穩定,本文利用雙迴路模糊時間延遲回授控制器抑制其混沌與分叉現象。在轉換器進入非線性混沌狀態時,取系統部份信號做時間延遲,再分別進入模糊系統調整其回授參數值,將系統控制在週期1之穩態。 本研究先將電流模式控制昇壓型直流-直流轉換器之數學模型推導出來,並以MATLAB/SIMULINK建模,經由調整輸入電壓、參考電流和負載電阻等元件參數值,可以觀察轉換器輸出特性由週期性穩態進入倍週期分岔直到呈現混沌狀態以及輸出電壓、電感電流波形及輸出電壓-電感電流相平面圖的變化。在混沌現象發生時,適時介入控制器,經由誤差及誤差變化率調整雙迴路模糊時間延遲回授控制器參數 ,能使系統快速穩定在週期1之軌道上。 由實驗結果可知,雙迴路模糊時間延遲回授控制器具有良好的抑制混沌現象能力,且較單迴路控制器能減小輸出電壓及電感電流漣波大小,以及改善混沌切換至穩定時之暫態響應。
To suppress the influences of chaos and bifurcation which arise out of the nonlinear dynamics of DC-DC boost converters on the stability, this thesis investigates the use of double-loop fuzzy time delay feedback controllers. When nonlinear chaotic states of boost converters are observed, the voltage and current signals are adopted to generate the time-delayed input of the fuzzy logic system to adjust the time delay feedback parameter K and make the chaotic system having a period-1 orbit. Firstly, the current-mode controlled boost DC-DC converters are built and simulated in MATLAB / SIMULINK environment. By adjusting the input voltage ( ), the reference current ( ), and load resistance ( ) values, the transition from the periodic steady-state output characteristics to the period-doubling bifurcation and chaos, the changes of the output voltage, inductor current waveforms and - phase-plane portraits can be observed. When the chaos phenomenon occurred, the proposed controller was activated. By the adjustment of the parameter K according to the error and the change of error, the double-loop fuzzy time delay feedback controller can effectively stabilize the system on period-1 orbit. Finally, from the simulation results, the proposed double-loop fuzzy time delay feedback controller has great suppressing ability on chaotic phenomena. Moreover, it is more effective than single-loop controller for reducing the ripples of output voltage and inductor current, as well as improving transient response from chaotic states to stable states.
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