直流-直流電源轉換器之迴路增益調整與負載暫態響應改善之新型數位控制方法

Abstract

近年來，直流電能轉換器之數位控制受到廣泛的討論與研究。在本論文中，主要提出兩種數位控制方法以改善直流電能轉換器之性能。第一種方法可實現可控制直流輸出負載線之直流電能轉換器；第二種方法是在負載電流發生步階變化時，控制器可使輸出電壓有快速的暫態響應。 首先，本論文先回顧直流電能轉換器之數位控制之理論與技術，其主要以傳統類比控制理論為基礎。基於此基礎，一種新型數位控制方法被提出，其主要是藉著LSB (Least Significant Bit)的調整而達到可控制直流輸出負載線之直流電能轉換器，但又不影響系統的穩定度，並且可在直流電能轉換器運作時，輕易地改變直流電能轉換器之直流輸出負載線。此方法不易以類比控制電路實現。 此外，一種數位控制方法被提出，其主要是在負載電流發生步階變化時，控制器可使輸出電壓有快速的暫態響應。此控制方法主要藉著量測輸出電壓，由量測到的輸出電壓值，即時算出功率電晶體全開與全關的時間，藉著功率電晶體開關一次的動作所達成。 本論文所提出的兩種數位控制方法都以實驗加以驗證。

Digital control of DC power converters has been an important research topic in recent years. In this dissertation, two digital control methods are proposed to improve the DC converter performances. One of the methods deals with variable load line feature and the other deals with step-load transient response. A review of digital control of power converters is first given from the point of view of conventional DC converter with analog feedback control. From the review, a novel digital feedback control scheme is proposed. It uses digital LSB (Least Significant Bit) tuning to achieve an adjustable converter DC load line without affecting the stability behavior of the system, and this can be done smoothly while the converter is in operation. The opens up new possibilities of applications an analog-controlled converter can’t achieve. Besides, a digitally control algorithm is proposed to provide fast output-voltage transient response to step-load changes. This involves sensing the converter output voltage and on-line calculation of the transistor on-time and off-time in a one-step on-off switching during the transient period. Both the methods mentioned above were experimentally verified.