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標題: | 發光二極體電流調節器與源極切換降壓轉換器之分析設計與實作 Analysis, Design and Implementation of LED Current Regulator and Source Switching Buck Converter |
作者: | Tse-Ju Liao 廖澤儒 |
指導教授: | 陳秋麟(Chern-Lin Chen) |
關鍵字: | 發光二極體,降壓式轉換器,效率,穩定度, LED,buck,efficiency,stability, |
出版年 : | 2014 |
學位: | 博士 |
摘要: | 本論文包含兩個主要部分。首先,探討傳統發光二極體電流調節器所遭遇的穩定度問題,並提出一電流調節器。當電流調節器的寄生線感大於0.1uH,且電流調節器的功率電晶體操作在線性區時,會產生輸出電流震盪的情形。此係寄生線感所造成的極點會影響控制迴路的相位裕度。本論文提出一新發光二極體電流調節器,該調節器會產生相對應的零點來彌補導線的寄生電感所產生的極點的效應,使得新電路擁有足夠的相位欲度。透過模擬以及實驗證實了新的電流調節器可以在0.1uH至1uH的寄生線感情形下,切換頻率為200赫茲至50千赫茲,仍能達到穩定的電流輸出。
另,為降低在降壓式發光二極體轉換器之閘極驅動能量損耗(Gate Driving Loss),本論文提出了一個新的源極切換電路。此電路包含了一高壓功率電晶體以及一低壓功率電晶體,一齊納二極體,以及一個電容。藉由控制低壓功率電晶體的切換,使得高壓功率電晶體的閘極電荷可以回收並儲存到電容上,並再下一個需要導通的時候,將該電荷重新充入到高壓功率電晶體內。以此方式降低了傳統的功率電晶體於切換時刻,所消耗的閘極能量損耗。此電路另一特點為提供一低靜態功率消耗的IC供電路徑。實驗於12瓦輸出的情形下,與傳統降壓型轉換器相比較,應用源極切換電路之降壓轉換器於156 V 電壓輸入時,效率提升3.7%,於326V 電壓輸入時,效率提升4.8%。 There are two major parts contained in this thesis. First, an unstable oscillation in a commercial LED current regulator is investigated and a solution circuit is proposed. The studied LED current regulator suffers from an oscillation problem due to the parasitic inductance of the connection wire is larger than 0.1uH when the power MOSFET is operated in deep triode region. Moreover, an oscillation-free LED current regulator system is proposed and the analysis of the proposed circuit has been discussed. The proposed regulator generates corresponding zeros to eliminate the excess parasitic inductance pole. Simulations and experiments show that the proposed circuit achieves stability when the parasitic inductance is 0.1uH and 1uH, at 200 Hz and 50 KHz switching frequency, 1.2V pulse signal, the LED current is 300mA, and VDS of power MOSFET is 0.5V. Secondly, to reduce gate driving loss of power MOSFET in conventional buck driver, a source switching circuit is discussed. It comprises a high voltage power MOSFET (HVMOS) and a low voltage power MOSFET (LVMOS) in series, a capacitor, and a zener diode. By switching the HVMOS by different source voltage and constant gate voltage, it recycles gate charges of HVMOS to reduce gate-driving loss. Gate charges are stored in capacitor when LVMOS is turning off, and be reused when LVMOS is turning on. This circuit also provides a new power feeding route for control chip, and power consumption is relatively low on the proposed route. With a 12 W LED load, experiment shows that efficiency of the proposed driving circuit is improved by 3.7% with 156 V input voltage and 4.8% with 326 V input voltage comparing with the converter using single HVMOS. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/58515 |
全文授權: | 有償授權 |
顯示於系所單位: | 電子工程學研究所 |
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