陳德玉臺灣大學：電機工程學研究所徐健國Shei, Chein-KuoChein-KuoShei2007-11-262018-07-062007-11-262018-07-062005http://ntur.lib.ntu.edu.tw//handle/246246/53501使用頻率調變(Frequency modulation)去壓低切換式電源供應器的EMI技術，已行之有年，而且市面上也有產品使用此項技術；有許多調變方法如正弦波、三角波、亂數波以及雙頻調變已有人提出，以上這些方法大都只強調數學上的分析，以及探討頻譜上的展頻形狀，沒有人提出使用此項技術對電路的性能會有何影響。 在本文中將對這些調變方法重新評估，並實際做出硬體以實驗的方式加以驗證，由諸多實驗發現使用頻率調變後，輸出端電壓會有漣波發生，對量測的數據作圖分析，發現頻率調變所造成的擾動，猶如輸入端電源的擾動，做開回路測試，發現與輸入輸出(Audio-suspectibility transfer function)變化相似，但尚未經數學理論驗證，閉回路測試在本文亦有實驗結果討論。Employing frequency modulation techniques for EMI reduction in switching converters was reported some years ago and the techniques have been gaining some momentum in actual product applications. There were different modulating schemes reported, including sine-wave modulation, triangular wave modulation, random modulation and bi-frequency modulation. However, the results reported were mostly focused on the mathematical analysis of the resulting EMI spectrum without much discussion on the side effects of the schemes on converter performances. In this thesis, these modulating schemes were reevaluated and compared. A hardware circuit to modulate the converter switching frequency was designed and built for the experiments. From the experiments, it’s observed that significant output voltage ripple can be caused by the modulating schemes. The transfer function between the output ripple and the modulating signal seems to follow the input-to-output (audio susceptibility) transfer function of a converter power stage but this has not been theoretically derived. The effects of feedback control loop gain on the output ripple are also discussed in the thesis.索引 第一章 緒論……………………………….…………….……….1 1-1研究背景與動機………………………………………..…1 1-2 頻率調變的技術來源…………………………….………2 1-3 章節概要與簡述………………………………………….2 第二章 原理概述與簡介各調變技術………………………..….4 2-1 正弦波調變信號…………………………………….……5 2-2 其它調變波形…………………………………………….9 2-3 其它EMI控制的方式………………………………...….9 第三章 數學推導與實驗驗證………………………………..…16 3-1 使用正弦波調變信號原理說明……………………..…16 3-2 β與fm對頻寬影響………………………………….…24 3-3 調變電路說明………………………………………..…27 3-4 使用三角波調變信號…………………………………..32 3-5 使用方波調變信號…………………………………..…35 3-6 時域與頻域的相關聯性…………………………….….37 3-7 使用雙頻調變信號……………………………..……….41 3-8 頻率調變對高頻段EMI的影響………………………44 3-9 頻寬解析度RBW對EMI的影響…………………….49 第四章 調變信對輸出漣波的影響…………………...……..…..50 4-1 輸出漣波………………………………………………..50 4-2 如何改變切換頻率……………………………………..50 4-3 開回路測試(輸出漣波對調變頻率的變化)…………..56 4-4 閉回路測試(輸出漣波對調變頻率的變化)……….….65 4-5 理論假設………………………………………….…….69 4-6 雙頻率調變………………………………………….….79 第五章 結論………………………………………..…………….82 5-1 結論……………..…………………………….…………82 5-2 未來研究方向………………………………….….…….83 參考文獻 ………………………………….….…........….851616939 bytesapplication/pdfen-US頻率調變EMIthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/53501/1/ntu-94-R92921072-1.pdf