A Universal Input CrCM Luo Converter With Low-Cost Pilot-Line Dimming Concept for General Purpose LED Lighting Applications

This paper deals with the design and implementation of a Luo converter operating in two different modes with an improved power quality (PQ) and flickerless operation over the universal ac mains for general purpose lighting applications. A cost-effective analog pilot-line dimming concept is incorporated and discussed in detail. The proposed dimming concept offers good PQ, even during dimming, with low cost for the energy efficient lighting solutions. The Bode plot analysis of this proposed Luo converter is presented using state-space analysis to ensure its stability with closed-loop control. The prototype is developed and tested in the laboratory for a 36-W light-emitting diode lamp load with rated current of 700 mA. The measured power factor in case of 30% dimming is 0.97 with total harmonic distortion of 8.7% only. The measured efficiency is 91% at rated ac mains voltage of 230 V.