AC voltage regulation by switch mode PWM voltage controller

Abstract

Voltage sag is an important power quality problem. It may affect domestic, industrial and commercial customers. Voltage sags may either be decreasing or increasing due to faults or change in loads. In this paper a switch mode AC to AC regulator is investigated to maintain constant voltage across the domestic appliance during the voltage deviation from the rated value. Such deviation may occur due to change in load or change in input voltage due to voltage sag of the system itself. The proposed system incorporates insulated gate bipolar transistor (IGBT) with high frequency switching technology. The Pulse Width Modulation (PWM) controls the ON/OFF time (Duty cycle) of switching devices (IGBTs) of this regulator. By regulating duty cycle of the control signal, output voltage can be maintained almost constant for wide range of input voltage variation. Simulation results show constant voltage can be achieved in either cases of increasing or decreasing input voltage as long as it is within specified limit.