A single-stage electrolytic capacitor-less AC/DC LED driver

Traditional LED drivers generally use electrolytic capacitor as the storage element which will restrict the lifetime and power density of drivers. In this paper, an electrolytic capacitor-less LED driver which pluses an auxiliary winding in the transformer and an additional full-bridge circuit to Flyback converter is proposed. It not only eliminates the electrolytic capacitor to extend the lifetime, but also achieves high input power factor and almost constant output current for LED load. The operational principle, detailed design of the main circuit, and control strategy are presented in this paper. A prototype with 48V/0.7A output is constructed and tested to verify the effectiveness of the electrolytic capacitor-less LED driver.