Fuzzy logic and digital PI control of single phase power factorpreregulator for an online UPS-a comparative study

摘要

A fuzzy logic control (FLC) and a digital PI control are proposedfor the application in feedback control of a power factor corrected(PFC) pre-regulator used in a high performance online uninterruptiblepower supply (UPS). Performance of these two controllers are comparedthrough the digital simulation. Fuzzy logic controllers have anadvantage in coping with the time varying nonlinearity of switches inPFC pre-regulator, and it does not require an accurate mathematicalmodel of the PFC pre-regulator when the controller is being designed. Onthe other hand, digital PI controller design requires a accuratemathematical model of the plant and it failed to perform satisfactorilyunder parameter variation, nonlinearity, load disturbance, etc. Thesimulation results show that the fuzzy logic inference based controllercan achieve better dynamic response than its digital PI counterpartunder large load disturbance and plant uncertainties. The practicalimplementations of the two controllers for an online UPS are discussed