A Novel LED Driver With Enhanced Efficiency Using a Buck-Boost Converter and DC-DC Buck Converter

In single-phase ac/dc light-emitting diode (LED) drivers, a reduced power processing technique is currently being used to increase conversion efficiency while reducing the size and cost of the converter. This technology permits a significant quantity of power to be transferred directly to the load using a switching mechanism, resulting in increased efficiency. For optimal grid power quality, LEDs, which are dc loads when connected to a single-phase ac supply, must maintain an input power factor (PF) that is almost equal to unity with the minimum input current harmonics. To avoid health issues caused by light flickering, LEDs need to be fed with dc current. Electrolytic capacitors were necessary for single-phase ac-to-dc power conversion to balance the input and output power. However, the short life span of these electrolytic capacitors reduces the life span of the LED driver and prevents them from matching the life span of LEDs. This work implements ripple cancellation control logic to match ac and dc power and replace electrolytic capacitors with long-life capacitors. An electronic converter that serves as an LED driver is necessary to meet each of these needs. In this article, an LED driver that satisfies the aforementioned requirements by converting ac power to dc power through the use of a buck-boost converter and a dc-dc buck converter was built using a reduced power processing method. To validate the proposed converter, a prototype with a maximum power output of 27 W was designed and tested. The results were impressive, with an input PF of 0.99, low-current harmonics, peak-to-peak LED current ripple of 13%, and overall efficiency of 92.5%. The converter was thoroughly tested over a wide input voltage range and at different power levels to ensure an effective dimming functionality.