Fuzzy Logic Based Closed Loop Buck Boost AC-AC Automatic Voltage Regulator

Abstract

Automatic voltage regulators are very important in the recent developments in the industry. Some industrial units can bear voltage fluctuation up to some extent like motors but control & instrumentation sections are very sensitive. Voltage regulators are very important for industrial and residential uses. The proposed voltage regulator is buck boost converter based which is very compact as these converters are designed using inductor, capacitor and switching devices like Insulated-gate bipolar Transistor (IGBT). Also fuzzy logic controller is AI based and provides better control of the system. Our proposed system is compact, cost effective, durable & efficient in keeping output voltage at a constant level. The concept of automatic voltage regulator (AVR) with fuzzy logic technique has been presented to handle the mentioned problem. The proposed fuzzy controller based AVR will have the capability of delivering sinusoidal output current with good output voltage regulation. The proposed topology has also reduced conversion losses. So a buck boost converter deployment has been proposed with fuzzy controller. The proposed system is designed and tested under different conditions. Under Sag and Swell conditions, the system has maintained constant output voltage. This acts as an AC boost converter when the utility voltage is lower than the specified voltage. On the contrary, this acts as an AC buck converter when the utility voltage is higher than the specified voltage. The AVR maintains power for both sides with the help of AC buck and boost converter. Hence, the size is decreased, the cost is reduced, and the life of the power convertor is extended. THD during source induced Sag condition is 0.77%, during normal operation it is upto 0.70 %, during load induced Sag it is 2.06% and Swell condition it is 2.11%. All these values are within the standard IEEE rating of 5% THD.