順向式轉換器LCD緩衝器之研究

Study and Implementation of LCD Snubber for a Forward Converter

劉文淵(Wen-Yuan Liu)

指導教授 ： 郭松村

共同指導教授 ： 黃昭明

崑山科技大學/工程學院/電機工程研究所/碩士(2010年)

https://doi.org/10.6828/KSU.2010.00028

摘要

本論文探討順向式轉換器LCD緩衝器之電路設計、模擬與研製。LCD緩衝器是由電感、電容及二極體所組成的被動式且無損耗之磁通重置電路，大部份應用於單端順向式轉換器磁化電感電流之重置，此緩衝器的電容也能夠重置儲存在變壓器漏電感中的能量，因此在開關截止期間，可抑制電壓突波，減少EMI/RFI干擾。
本論文對LCD緩衝器在穩定狀態期間運作情形作詳細分析，根據共振重置模式時能量平衡原則，推導一組非線性方程式並使用牛頓-拉福生法求解，求得磁化電感電流各轉折點的瞬時值及確認變壓器鐵心在磁化曲線之第一、三象限激磁。文中並使用IsSpice軟體作電路模擬於驗證理論分析之正確性。
最後在研究室中研製了一組輸入電壓為48 V、輸出為5 V/ 6 A與切換頻率為100 kHz之順向式轉換器。在實作結果與理論分析的驗證與比較下，均呈現良好的符合結果。

關鍵字

順向式轉換器 ； LCD緩衝器 ； 磁通重置 ； 牛頓-拉福生法

並列摘要

The circuit design, simulation, and implementation of a forward converter with LCD snubber are presented in this thesis. The LCD snubber is composed of an inductor, a capacitor and a diode, known as passive and non-dissipative flux reset mechanism for single-ended forward converter. The capacitor of the snubber also resets the energy stored in the leakage inductor and hence, minimizes the spike voltage and reduces the EMI/RFI during the OFF period.
The operational principles of the LCD snubber are analyzed in detail during steady state. According to the energy balance at resting resonant mode, a set of non-linear equation is derived and solved using the Newton-Raphson method. The magnetizing current in each breaking point is evaluated and the transformer core excited in the first and the third quadrants of the B-H plane is confirmed. The IsSpice simulation is also applied to verify the accuracy of theoretical analysis.
Finally, the prototypes of a forward converter with an input of 48 V, output of 5 V/ 6 A, and switching frequency of 100 kHz has been implemented in the laboratory. In general, good agreement is observed between the theoretical and experimental results.

並列關鍵字

forward converter ； LCD snubber ； flux reset ； Newton-Raphson method

參考文獻

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