Dissipativity-based adaptive and robust control of UPS

In this paper, we investigate the output voltage control for a three-phase uninterruptible power supply (UPS) using controllers based on ideas of diss ipativity. To provide balanced sinusoidal output voltages, even in the pres ence of nonlinear and unbalanced loads, we first derive a dissipativity-bas ed controller using a frequency-domain representation of system dynamics. A daptive refinements have been added to the controller to cope with parametr ic uncertainties. Second, based on the first adaptive controller, we propos e a controller which turns out to have the proportional-plus-integral-type structure on rotating-frame variables, but with a special design of gain ma trices. A sufficient rendition in terms of the design parameters is present ed for this controller that guarantees stability of the desired equilibrium and robustness against parameter uncertainties. Finally simulation and exp erimental results on a three-phase prototype show effectiveness and advanta ges of the proposed approach.