Voltage sags and extended under voltages have the largest negative impact on industrial productivity and could be the most important type of power quality variation for many industrial and commercial customers. This paper proposes a 3-phase PWM ac-ac Cuk converter with minimum switches to maintain constant output voltage irrespective of the variation of input voltage and load. By PWM duty ratio control the ac-ac converter become a ldquosolid state transformerrdquo with a continuously variable turns ratio. The proposed ac-ac converter employ only two switches compared to the existing circuits that use six switches or more. For minimum number of switches the proposed circuit reduces cost, improves reliability. The operating principle, control method and simulation results of the proposed converter circuit are presented in this paper.
