Fuzzy variable structure control for PWM inverters

This paper proposes the practical realization of a fuzzy variable structure control applied to a PWM inverter. Variable structure Control (VSC) is a robust control method for handling nonlinear systems where occur parameter variations and external disturbances. However, control input chattering round sliding surface exists, and may deteriorate the system performance. To reduce the chattering, a fuzzy logic for VSC is applied to overcome the problem. By composing the advantages of both VSC and fuzzy logic (FL), the PWM Inverter system can be designed and produces low total harmonic distortion (THD) output voltage and fast dynamic response under different types of load. Experimental results on a single-phase PWM inverter laboratory prototype controlled by a dSPACE-based DSP controller are presented to illustrate the improved performance, particularly under severe rectifier load. Moreover, for comparison purposes, a conventional variable structure controlled single-phase PWM inverter is also tested on the same experimental system.