應用於液晶電視之高效能交流-直流電源模組

Abstract

隨著大尺寸發液晶顯示電視的蓬勃發展，交流/直流電源模組的發展是非常重要的一環，除了用來提供穩定的電壓源給電視系統中的子電路方塊使用，更必須具有高能量轉換效率和低成本的特性。在一個液晶顯示電視的交流/直流電源模組中通常會具有高功率和電氣隔離功能的需求，因此，功率因素校正器和隔離型降壓式轉換器是不可缺少的。本論文提出一個高效能的交流/直流電源轉換模組來實現上述的需求，而此交流/直流電源轉換模組分別包含有降壓式功率因素校正器、初次側控制穩壓器和二次側彈性電壓轉換器。在降壓式功率因素校正器的部分提出了正弦平方電流調變技術調節系統輸入電流，使輸入電流與輸入交流電壓源同相位並呈現一個正弦波的形狀以達到高功率因素的目標。此外，線電壓還原技術也被提出並用來消除降壓式功率因素校正器中的線電壓偏移現象並降低系統的總諧波失真。在初次側控制穩壓器的部分則移除了傳統馳返式轉換器中的回授網路，並利用提出具有自我校正功能的膝點電壓偵測器並透過輔助線圈精準的偵測系統輸出端的電壓。此初次側控制穩壓器透過0.5微米超高壓製成實現，利用500伏特超高壓元件使此初次側控制穩壓器可以直接透過交流電壓源啟動。最後，在二次側彈性電壓轉換器的部分則透過提出的總體電源管理並配合傳統的動態電壓調整技術提高整體電視系統的效率。在實驗結果中也證實了本論文所提出三種電壓轉換器功能正常並可符合液晶顯示電視系統對交流-直流電源管理模組的要求。

This thesis presents an AC/DC power module, composed of buck-type power factor correction (PFC) converter, primary side regulation (PSR) converter, and secondary side flexible voltage scaling (FVS) converter, for liquid crystal display (LCD) television (TV) system. First of all, the proposed buck-type PFC converter modulates the input current by the sine square modulation mechanism (SSCM) to shape the input AC current as sine wave and thus in-phase with input AC source. Moreover, high total harmonic distortion (THD) in conventional dead angle problem in buck-type PFC can be reduced by the proposed line voltage rebuilt (LVR) technique. Conventional line current is zero in dead angle period and the detected line voltage contains the output voltage information. Therefore, the proposed LVR technique rebuilds the line voltage to remove the offset problem for reducing THD. Second, the proposed PSR converter not only provides the standby power for TV system but also directly charges the battery by the AC source. The PSR converter removes the feedback network in conventional flyback converters. The proposed self-calibrated knee voltage detector (SC-KVD) accurately senses the output voltage information by an auxiliary winding. Moreover, the test chip fabricated in 0.5μm 500V UHV process can be powered on directly by the AC source for high efficiency and compact size through the use of 500V ultra-high voltage device. Third, the proposed secondary side FVS converter moves the controller of flyback converter from the primary side to the secondary side. The proposed overall power management (OPM) in TV system can improve overall conversion efficiency by the flexible voltage scaling (FVS) technique in cooperation with conventional dynamic voltage scaling (DVS) technique. The test chips of the buck-type PFC converter, PSR converter and FVS converter were fabricated in 0.5μm ultra-high voltage CMOS process with chip area of 4.75 mm2,3.125mm2 and 4.05 mm2, respectively, to demonstrate the improved performance. Overall performance can show high accuracy, compact size, high flexibility, and high efficiency in this thesis.