| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 105 === LED lighting is gaining its popularity due to advantages such as high energy efficiency, extended lifetime, cold temperature operation and fast transient. For LED lighting system, dimming technique is important since it can further saves energy if the light intensity can be controlled according to consumer’s need. Hence, various LED dimming methods have been proposed in the literatures.
In this thesis, three LED dimming techniques: digital PWM dimming, dual PWM dimming and critical voltage dimming have been studied for performance comparison. A 15W LED driving circuit is first constructed and the three considered dimming techniques are realized in a digital signal controller. The evaluated performance indices include the dimming linearity and the total conversion efficiency. According to the experimental results, digital PWM dimming has the best dimming linearity and critical voltage dimming can achieve the best conversion efficiency.
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