Abstract: This paper presents a fuzzy logic controller (FLC) model for buck converter topology of Switched Mode Power Supply (SMPS).In order to obtain the improved voltage regulation in SMPS, we use digital control using FLC which significantly more efficient than analog control. FLC maintains a constant or fixed output voltage irrespective of variations in input voltage. In this paper, Buck converter used in SMPS converts the input voltage to a desired voltage. The very high speed integrated circuit hardware description language (VHDL) Coding of fuzzy logic is dumped into Field Programmable Gate Array (FPGA).Fuzzy Logic compares obtained voltage with the threshold value by applying feedback control. FPGA is the most important tool for hardware implementation due to low consumption of energy, high speed of operation and large capacity of data storage. FPGA generates Controlled Pulse Width Modulation (PWM) pulses of required duty cycle which produce gating signals to MOSFETs of buck converters to maintain the required constant output voltages. The controller algorithm is developed using Xilinx ISE 12.0 and is implemented on FPGA Spartan 3AN.

Keywords: Buck Converter; Field Programmable Gate Array (FPGA); Fuzzy Logic Controller (FLC); Pulse Width Modulation (PWM).