Single-Phase AC-AC Zeta Converter-Based Automatic AC Voltage Regulator

In this paper, an AC chopper-based automatic AC voltage regulator (AVR) is analysed. The power circuit is made of a single-phase (1 - ϕ) AC-AC zeta converter with voltage step-up and step-down capability in order to compensate the load voltage under sudden input voltage sag or swell. The use of direct pulse width modulated (PWM) AC-AC converter as AVR for various load and source disturbance such as voltage sag/swell, does not require energy storage devices with bulky DC links, and thus provides the advantages of single-stage power conversion, low cost, and small footprint. In this direction, delta- sigma modulation (DSM) technique is employed for the output voltage control of the AC chopper. It is observed through simulation studies in MATLAB/SIMULINK software that during a sudden input voltage (sag or swell) or load perturbation, the control approach fixes the duty ratio to quickly retrieve the desired output voltage. Hence, the presented AVR when modulated using DSM technique gives good steady-state performance and dynamic response under step load voltage reference change, input voltage perturbation and load change.