FUZZY LOGIC CONTROLLER FOR A MULTISTAGE CURRENT-CONTROLLED SWITCHED-CAPACITOR STEP-DOWN DC-DC CONVERTER

Abstract

Switched-capacitor (SC) based step down voltage dc-dc converter can be used for efficient power conversion when inductors are not used in order to reduce size and cost. In addition, switched capacitor dc-dc converters are superior to inductor –based converters for high-conversion ratio and wide range of load variation. In this paper, a multistage current - controlled switched - capacitor step down dc-dc converter is analyzed, designed and simulated. The converter features are good regulation capability and continuous input current waveform when two step-down converter cells are connected in parallel and operating them in antiphase. Classical SC converter with pulse width modulation technique is also analyzed, designed and simulated. For the PWM converter and current- controlled converter, third – order state-space averaging method is used for analysis. A fuzzy logic controller is used with the current– controlled converter to obtain fast dynamic response, low ripple in the output voltage and robustness against load and supply variations. A 70W, 48/12V converters are designed and simulated and Matlab/Simulink is used for simulation.