Non-isolated single stage PFC based LED driver with THD minimization using Cúk converter

This paper proposes a utility supply driven single stage PFC based LED driver using Cúk converter. For low DC voltage output requirement of LED driver, Cúk converter is a convenient choice due to its topological suitability for PFC application and stepping the voltage down at a desired level unlike the Boost Converter. A hysteresis current control scheme is adopted to operate the converter in Continuous Conduction Mode (CCM) and fast enough to follow the current reference causing power factor to approach near unity. Although the converter operates at variable switching frequency, the response is very fast and independent of the converter dynamics. At the same time the converter ensures a constant current drive at the output side to operate the LED. Theoretical analysis, design calculation and simulation results confirm that the proposed single stage control scheme operates with an improved THD and performs better compared to the commercially available controller because the same converter is used for both PFC and LED Driver. As it diminishes one stage of power conversion, the efficiency of the driver is increased whereas the complexity in controller design and implementation is decreased.