Two-switches-based AC-link three-phase voltage regulator

This paper presents a topology for a PWM controlled three-phase voltage regulator which uses only two driven switches giving high reliability and making the switching stage simpler and cheaper compared with other available configurations. The proposed topology is suitable for voltage regulation on the distribution power system and able to regulate the steady state voltage and to reject voltage variations such as flicker or sags caused by big motors start, the compensator is free of energy storage elements. The PWM control is based on DC signals asynchronous from the grid, it doesn´t need a phase locked loop nor trigonometric calculations are needed for synchronization purposes which makes the PWM scheme insensitive to frequency or phase perturbations, while the control can be accomplished with an analog controller or a low-cost micro controller. Detailed analysis is presented with a 220V three-phase voltage regulator which is simulated and prototyped to exhibit the principle. Simulation and experimental results show the proposition validity.