無電解電容之新型高效率LED驅動電路

A Novel High-Efficiency LED Driver Circuit Without Electrolytic Capacitor

王啟祐(Qi-You Wang)

指導教授 ： 鄭宏良

義守大學/智慧科技學院/電機工程學系/碩士(2022年)

摘要

本文提出新型高效率LED驅動器，其架構是兩組降壓型轉換器，共用一個耦合電感，根據磁通守恆原理，轉換一次側與二次側電流。因交錯式轉換器之特性，兩組轉換器之主動開關交互導通，分擔輸出總功率，減少元件應力，降低輸出漣波電流。設計耦合電感互感電流工作於連續導通模式(CCM)，使電流漣波很小，因而不必使用電解質電容。利用耦合電感的漏感電流來釋放主動開關的寄生電容的儲存電荷，使主動開關滿足零電壓切換導通(ZVS)。並且設計電路參數使漏感電流工作於不連續導通模式(DCM)，因而飛輪二極體可以滿足零電流切換截止(ZCS)，以提高電路效率。。
　　本文針對電路工作模式詳細分析，設計一個180 W LED驅動器之雛型電路，使用脈波頻率調變之方式，使LED工作在100 %~25 %額定功率。由實作結果顯示，兩個主動開關皆滿足零電壓切換導通，飛輪二極體可以滿足零電流切換截止，有效的降低切換損失。電路滿載時的轉換效率可達97.3 %。

關鍵字

降壓型轉換器 ； 交錯式轉換器 ； 零電壓切換導通 ； 零電流切換截止 ； 發光二極體

並列摘要

This thesis proposes a novel high-efficiency LED driver which is interleaved buck converter, using a coupled inductor. Due to the magnetic flux conservation principle, the magnetic-excited current can be converted between the windings of the coupled inductor. By using the leakage inductance current to release the stored charge in the parasitic capacitance of the active switch, the active switch can operate at zero-voltage switching on (ZVS). And design the leakage inductance current work in discontinuous-conduction mode (DCM). Therefore, the flywheel diode can operate at zero-current switching off (ZCS). The switching losses can be effectively reduced. Design the mutual inductance current work in continuous-conduction mode (CCM), the output voltage ripple can effectively be reducing without electrolytic capacitor.
　　Finally, a 180W prototype LED driver was built and tested. Control the LED power from 100% to 25% rated power by pulse frequency modulation. According to the experimental results, the active switches are operated at ZVS, and the flywheel diodes are operated at ZCS, which can effectively reduce switching losses. The measured circuit efficiency can be as high as 97.3%.

並列關鍵字

buck converter ； interleaved converter ； zero-voltage switching turn on (ZVS) ； zero-current switching off (ZCS) ； light-emitting diode (LED)

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