Review and comparison of control methods for uninterruptible power supplies

High performance UPS inverters have stringent control requirements both under steady-state and under transient conditions. Many different control techniques have been applied to UPS inverters. However, there are few publications reviewing the literature on these control techniques and classifying the same, particularly with regard to the recent developments in this area. In this paper, a review of the most solutions for control of UPS inverters is carried out. These control techniques are classified as conventional or classical control, predictive control, learning control and nonlinear control. The major advantages and disadvantages of these methods are highlighted and compared. Then, five control methods were compared using simulation and a hybrid controller (Repetitive Controller plus Deadbeat Controller) is evaluated by using experiments.