Delay-Lock-Loop-Based Inductorless and Electrolytic Capacitorless Pseudo-Sine-Current Controller in LED Lighting Systems

Light-emitting diode lighting system with the proposed pseudo-sine-current controller removes most of the external passive components, which include inductor, electrolytic capacitor, freewheel diode, blocking diode, and the bleeding circuit for Triac dimming control, for low cost and small volume. Delay-lock loop control can ensure the in-phase operation of ac input voltage and current for high power factor (PF) and low total harmonic distortion (THD). In addition, redundant power loss in Triac dimming control is eliminated to get a high efficiency of 85%. Furthermore, a high PF of 0.997 and a low THD of 7.74% are also achieved owing to in-phase line voltage and current.