Abstract

A lot of topologies of pulse-width modulated (PWM)-AC voltage controllers for single-phase and three-phase systems are proposed up to date. PWM-AC controllers have important advantages compared with the phase-controlled AC voltage controllers using thyristors and triacs. This article presents a novel control technique for application to PWM-AC controllers with ability of generating smaller harmonics. In the proposed control method, both the traditional AC voltage controllers and the PWM-AC controllers are combined, smaller THD values are obtained and switching losses are minimized. Thus, the harmonic pollution in the power system will be reduced and the power quality will be increased. In order to investigate the proposed controller performance, computer simulations and experimental studies are performed. Obtained results are compared with those of the conventional PWM-AC controller.

Key words: Power quality, AC choppers, PWM-AC controllers, AC sector-control voltage converters.