新型無橋式隔離型之AC LED 驅動器

本論文係研製一具調光之AC LED驅動器。為了改善LED串列顆數之運用靈活度與利用率，乃於功率開關與AC LED 模組之間加入耦合電感。藉由改變耦合電感之匝數比，使得耦合電感二次側電壓降低，如此一來便能使LED串列跨壓下降，其串列上之LED顆數亦能減少，增加了負載設計之彈性。由於所加入的耦合電感同時具有變壓器的行為，可將一次側與二次側隔離，因此本架構也具備了電氣隔離之優點。因此，耦合電感在開關導通時一方面傳遞能量使得LED串列導通，一方面激磁，儲存能量；當開關截止時，耦合電感去磁，導通另一串LED串列。因此就任一半週而言，正向與逆向LED串列皆會導通，以提高LED之利用率。就脈寬調變調光而言，乃直接調控功率開關來進行LED調光，可減少不必要的調光電路。最後，藉由理論推導及實作來驗證所提架構之可行性及有效性。

關鍵字

無橋式；隔離型； AC LED驅動器； LED利用率；調光控制；無電解電容器；數位控制；場效可規劃邏輯閘陣列；耦合電感；匝數比

並列摘要

A novel bridgeless isolated AC LED dimmable driver is developed, which improves LED utilization and application flexibility due to a coupled inductor inserted between the power switch and the AC LED module. By reducing the turns ratio of the coupled inductor, the voltage across the secondary side will be decreased so as to lessen the voltage across the LED string and hence to reduce the number of LEDs, thereby making the load design of the AC LED driver more flexible. It is noted that the coupled inductor plays the role of not only galvanic isolation but also inductor behavior as well as transformer behavior. Therefore, during the turn-on period of the power switch, the coupled inductor can transfer the energy to one LED string and store the energy simultaneously, whereas during the turn-off period of the power switch, the coupled inductor can release the stored energy to the other LED string. That is, two LED strings are conducted for any half cycle, implying that LED utilization is upgraded. As for PWM dimming, it is realized by directly tuning the control signal for the power switch without any dimming circuit. Finally, the basic operating principles and theoretical deductions are given along with some simulated and experimental results provided to verify the feasibility and effectiveness of the proposed topology.

並列關鍵字

AC LED Driver ； Bridgeless ； Isolated ； LED Utilization ； Digital Dimming ； Capacitorless ； Digital Control ； Field Programmable Gate Array ； Coupled Inductor ； Turns Ratio

參考文獻

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新型無橋式隔離型之AC LED 驅動器

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