New control techniques for UPS dynamic efficiency optimisation

In mission critical power installations, such as data centres, the use of double conversion UPS has been considered the best choice to date for protecting against power quality problems. Indeed, this UPS technology allows for a high level of load protection against any type of electrical disturbance of the network and isolation of the mains against the load´s non linear behavior. The cost saving related to this type of solution is linked to efficiency (from 90% up to 95% in the latest transformer free UPS). With Chloride´s development of Digital Signal Processing (DSP) and Vector Control technologies, it has been possible to introduce specific high efficiency solutions that, by continuously checking the mains quality, allow the load to be supplied through the bypass line while it is inside the selected thresholds. This solution has been present and widely adopted in the high power UPS market for the last decade with similar alternatives available from different UPS manufacturers. The biggest limitation of this type of solution is that, while the UPS works on the bypass, the mains is directly linked to the load without any sort of filtering. In this paper we will demonstrate a new technology which solves this issue and improves the energy usage by means of a new UPS control technique for dynamic efficiency.