Improved power quality switched mode power supply using buck-boost converter

The analysis, design, modeling and development of a switched mode power supply (SMPS) for computers is presented here for improved power quality. The proposed SMPS is capable to mitigate existing problems in a conventional SMPS. It is designed to attain close to unity input power factor (PF) and low harmonic distortion at the input ac mains with regulated multiple dc output voltages. A non-isolated front end power factor corrected converter is designed in discontinuous conduction mode (DCM) of operation and control. Simulated performance of proposed power supply is presented to validate the design and to demonstrate the performance with near unity PF operation. Experimental validation of the proposed SMPS is also carried on a prototype built in the laboratory and the test results are compared with the simulation results to validate the design and modeling. An improved power quality is achieved with almost unity power factor in wide range of input ac voltages and loads.