Improved power quality opto-couplerless Cuk converter for flickerless LED lighting

This paper presents a single stage isolated Cuk converter for low power light emitting diode (LED) driver systems. An opto-couplerless feedback control using primary-side regulation technology is presented in discontinuous conduction mode (DCM). A complete analysis of the converter is carried out using pulse-frequency modulation technique. The primary focus of this work is to develop a cost effective solution for an LED driver with improved power quality and efficiency. For low power lighting, this work results in a maximum power factor (PF) of 0.99 and minimum total harmonic distortion (THD) in AC mains current of 3.37% over universal AC voltage. The proposed Cuk topology offers high efficiency and constant voltage-constant current (CV-CC) control. Moreover, for high efficiency, coupling capacitors at both sides of the transformer have been optimized to a film capacitor with low dissipation factor and long life as compared to commonly used electrolytic capacitors. A 27 W prototype with a converter efficiency of 88% has been developed to validate the proposed approach.