Prof. Naser Mohammed Bayoumy Abdel-Rahim Elghetany :: Publications:

This paper presents the analysis and design of a three-feedback loop control strategy for single-phase voltage-source uninterruptible power supply (UPS) inverters with an L-C filter. The proposed feedback control scheme employs the inverter output current in the most-inner feedback loop, the load current in the middle-inner feedback loop and the capacitor (load) voltage in the most outer one. This scheme results in stable and successful feedback operation of the UPS system. Appropriate feedforward regulators of the closed-loop feedback system are chosen using the power circuit small-signal dynamic model and Bode diagrams. Simulation results show that the proposed control scheme is capable of producing a well-regulated sinusoidal load voltage that faithfully follows its command signal with very low total harmonic distortion and excellent transients, steady-state, and dynamic response under adverse loading conditions.