Fuzzy Logic Controller for Three Phase PWM AC-DC Converter

Abstract

Abstract. This paper discusses control strategy for the voltage regulation of a three phase pulse width modulation (PWM) AC-DC converter. A fuzzy logic controller (FLC) is employed in the outer voltage loop. Fuzzy logic controllers are preferred over the conventional proportional integral (PI) controllers because they are based on linguistic description and do not require a prior mathematical model of the system. The objective of the presented control system is to regulate the output DC voltage during both transient and steady state period. Also the line currents drawn from the grid should be sinusoidal and in phase with respective phase voltages to achieve a low total harmonic distortion (THD) and unity power factor. PI and FLC based control systems are implemented for three phase PWM AC-DC converter in MATLAB/Simulink and dynamic performance of the system is tested. The results demonstrate that compared to the conventional PI, the FLC based system is more robust and has a much better dynamic response. The low value of THD and sinusoidal current response ensures the system avoids polluting the utility grid.