High efficiency wide input extreme output (WIEO) tapped inductor buck–boost converter for high power LED lighting

Abstract

A power factor corrected single switch tapped-inductor buck–boost converter is proposed to achieve improved efficiency in extreme step-up and step-down conditions. This new and modified topology is having diode-tapped and switch-tapped configurations for step-down and step-up modes of operation, respectively. The proposed modified buck–boost converter is designed to operate in critical conduction mode (CrCM) to achieve quasi-resonant operation. Both the buck and boost functionalities of the buck–boost converter are analysed using state space analysis with closed loop stability under varying input and output conditions. Several advantages and necessity of tapped versions are discussed and implemented under wide input and extreme output (WIEO) conditions. Two different prototypes are developed at extreme buck and boost levels to establish the benefits of the proposed arrangements. The efficiency improvement of the proposed converter is compared with the conventional buck–boost converter. The achieved efficiency of diode-tapped buck mode and switch-tapped boost mode is found 95% and total harmonic distortion is observed only 4% at 230 V AC mains for a prototype of 150 W, which is much improved results as compared to the previous research work on the tapped-inductor converter.