Analysis and design of buck-boost converter for power quality improvement in high frequency on/off-line UPS system

This paper presents cascaded buck-boost converter for improving power quality at ac mains input in terms of improved power-factor (PF), reduced total harmonics distortion (THD) of input current and regulated output dc voltage at 380 V for high frequency uninterruptible power supply (HF-UPS). Discontinuous conduction mode (DCM) of operation is used to achieve inherent power factor correction (PFC) and to evade from the complexity in feedback control loop. The proposed configuration is able to operate under varying input voltages operation and withstand severe fault conditions like "Double Phase in Single Phase Utility (through neutral wire)". A comparative analysis is carried out to avail the benefits of proposed configuration over (a) single switch boost "Improved Power Quality converter (IPQC)" and (b) single switch buck-boost IPQC Converter. The performance of proposed power supply is evaluated in MATLAB/Simulink environment under wide variations in input voltages (85V-300V) and loads.