Optimal control for single-phase UPS inverters based on linear quadratic regulator approach

Abstract

An optimal control strategy based on the linear quadratic regulator approach is proposed for single-phase uninterruptible power supplies in continuous time. The objective of the controller is to achieve a fast transient response, good voltage regulation, and low total harmonic distortion of the output voltage under linear and nonlinear loads. It is shown that these objectives can be met provided that the optimal feedback gains minimizing a cost function are utilized in the closed-loop system. These gains are chosen taking into consideration the poles of the system and input limitation. Simulation and experimental results are presented to verify the performance of the proposed control method under linear and nonlinear loads.