Design considerations for single-phase uninterruptible power supplies using double-layer capacitors as the energy storage element

The use of uninterruptible power supplies (UPSs) has grown dramatically in the recent past. However, there have been only minor advances in the technology used in the devices. The advantages and disadvantages of using double-layer capacitors as the energy storage element in UPSs are presented in this paper. Capacitor bank configurations and power converter topologies and control methods are examined via computer simulation to determine the most suitable designs for low-voltage single-phase UPSs. In addition to performance evaluations of the proposed designs, comparisons with battery, motor-generator, and superconducting magnetic energy storage systems are provided. Both performance and cost are considered.