An energy based LQR tuning approach applied for Uninterruptible Power Supplies

This paper proposes a tuning method for a linear quadratic regulator (LQR) and its application to Uninterruptible Power Supplies (UPS). A performance index is established based on the desired behavior of system variables, such as maximum values permitted on the states and control law saturation. The tuning method is based on the Q and R weighting matrices, which relate the energy of the state variables involved on the process. From this index it is possible to find an optimal point to reach the required performance. The design procedure is exemplified with an output voltage control of an Uninterruptible Power Supply and dynamic results are presented.