A Modified Lyapunov-Based Control Scheme for a Three-phase UPS with an Optimal Third-order Load Current Observer

This paper proposed a modified Lyapunov-based control strategy for the three-phase UPS in d-q frame, which successfully solved the inherent steady-state error problem brought by standard Lyapunov-function based method. Continually, the third-order optimal load current observer in natural frame was designed to estimate the real-time load current, resulting in the omission of three load current sensors. Finally, experimental results validated the effectiveness and efficiency of proposed approach.