- 學位論文
低損耗被動式電流平衡法驅動多組LED輸出裝置
A Low Loss Passive Current Balancing Method for Multi-Channel LED Driver
摘要
本文提出一種低損耗的電流平衡法來驅動多組LED的驅動裝置。並利用LLC諧振轉換器來提供驅動裝置所需的交流電源。以達到改善電力損耗、簡化平衡裝置的結構及降低其成本的優勢。 本文的研究中採用一種被動式電流平衡法，而在其電路架構中的被動元件-電容器能夠同時驅動多組的LED輸出。在AC輸入電源通過此被動式電流平衡裝置後，若將其正/負半周之負載特性設計為相同時，則此時通過每串LED輸出之電流將會趨近於相等，進而達到電流平衡之目的。此外，我們搭配高效率的LLC諧振轉換器作為提供此電流平衡裝置所需的AC電源，可使整體功率損耗降至最低。為了確認所提出的驅動裝置的有效性，本文將在一台37吋LCD TV樣機上做實際驗證及確認。
並列摘要
This thesis proposed a low loss current balancing method to drive multi-channel LEDs. With a strategy that power source uses LLC resonant converter to supply the AC voltage. It takes the advantages such as improving the power loss, simplifying balancing apparatus and reducing the cost. For this study, the proposal is directed to a passive current balance driving method and which circuit topology is only utilize some passive elements-capacitance components and capable of driving a multi-channel LEDs simultaneously. The load characteristic of each of the LED strings is designed to identical during the continuous periodical variation of the positive and negative waveform of the AC power source through the passive current balance driving apparatus. Accordingly, the current flowing through each of the LED strings is basically or substantially to identical and thus can be well balanced. Furthermore, the LLC resonant converter has been used to supply the AC voltage source due to it is favorable advantages such as high efficiency. To confirm the validity of the proposed driver, its operation and performance are verified on a prototype for a 37” LCD TV. The features of this thesis include as: 1. Lower power loss: Due to the loss occur on current regulation chip or current sink transistor, the efficiency of active component is lower than capacitance components. Moreover, the soft-switching mode of the LLC resonant has using to supply the AC voltage source. Therefore, those strategies can achieve high efficiency requirement. 2. Improved reliability: Through the removal of the active device, the capacitance components have better reliability. 3. Reduced product cost: This proposed passive balancing method can arbitrarily choose the number of regulation driving channels. That is better than the ready-made and generally fixed current regulation chip. Therefore, there would not be unnecessary costs.