A Digital Control System for UPS Systems With Smart-Grid Capability

In this article, a new control system is introduced for use in uninterruptible power supply (UPS) systems. The proposed control system is able to improve the dynamic performance of UPS systems, facilitating their integration into smart grids. The proposed control system isolates the battery from the double-frequency ripple both in the normal mode (charging) and in the backup mode (discharging). The new UPS control system is tailored for single-phase systems utilizing lithium-ion battery storage systems, where current ripple must be limited. Simulation and experimental results verify the feasibility of the proposed control system and demonstrate its superior performance.