Comparison of Pi Controller and Fuzzy Logic Controller for the Improvement of Power Factor in SMPS

Due to severe power shortage, the power suppliers are unable to meet the power demand and are forced to purchase it from other states. One method to overcome power shortage, is by improving power factor at the customer side, thereby the energy wasted by various equipment due to low power factor can be reduced. Nowadays personal computers (PCs) are an inevitable part of our day to day activities for which Switched Mode Power Supplies (SMPS) is an integral part. The problem associated with multiple output SMPS is its very poor power factor and voltage regulation and the high total harmonic distortion, which violate the limits of harmonic emissions set by international power quality standards. Hence to improve the power factor and thereby the power quality a nonisolated power factor corrected (PFC) zeta converter is used which is able to reduce the 100 Hz ripple in its output. This improved output is fed to the second stage isolated converter (SMPS). Control of the Power factor correcting unit as well as the isolated converter is done by PI controller. In the new topology conventional controller is replaced with the Fuzzy logic controller. The major advantages of fuzzy over the conventional ones include better error detection and correction, wider range of operating conditions and more readily customizable. Simulation of the model using both the PI control and Fuzzy logic control has been performed in MATLAB/SIMULINK. This can be used in various server power systems, telecommunication systems and mobile applications.