A new high power factor, soft-switched LED driver without electrolytic capacitors

A novel high power factor, soft-switched Light Emitting Diode (LED) driver without electrolytic capacitors is proposed in this paper. Conventional electrolytic capacitors used in LED drivers as the energy storage element have relatively short lifespan and affect the lifetime of the entire LED lighting system. In the proposed design, coupled inductors are used to provide power factor correction (PFC) and to provide part of the required energy with the DC-link capacitor to the output. As a result, low ripple output current is still achieved even when the size of the DC-link capacitor is reduced, which allows the film capacitor to be used to replace the conventional unreliable electrolytic capacitor. At the same time, high input power factor is also achieved. The operating principles and theoretical analysis of the proposed circuit will be described in this paper. An experimental prototype is built and tested in the laboratory. All the experimental results are provided to support the merits of the proposed work.