An Advanced Control Architecture of Three-phase Bidirectional Buck AC Voltage Controller

This research introduced a new three-phase buck AC voltage controller consisting of two three-phase bidirectional switches for maintaining the stable output voltage under load and input voltage variations for suitable AC-AC applications. Existing pieces of literature on AC-AC controller topology have limitations of unbalanced output voltage for rapid load and input voltage variations. Addressing these shortcomings, a new and modified AC buck controller topology has been proposed which operates on per phase basis and thus maintains the constant output voltage for unbalanced loads. These topologies allow simple control circuits and reliable operation with acceptable efficiency, improved power factor, and input current shaping. A voltage mode feedback control system is introduced for controlling the regulator and thus shows the capability to get desired output voltage by adjusting the duty cycle. Obtained results for open and close loop control systems from both topologies have been compared and found improved performance regarding output voltage, input current, and THD values in the case of modified buck AC voltage controller topology.