Lorenzo Giuntini

Active damping control of multi-mode UPS for power quality improvement

Double-conversion UPS provide top protection to critical loads, but limited efficiency. However, such UPS often support alternative high-efficiency operating modes (e.g. so-called ECO Mode). This paper discusses Active ECO Mode operation, introducing Active Damping Control for improving Power Quality with minimal losses. The system evolves into a Multi-Mode UPS, where the operating mode is selected for optimal trade-off between power conditioning and efficiency. Performance improvement is confirmed by experimental results and field experience.

Double-conversion UPS efficiency under varying mains conditions

Efficiency is a fundamental UPS performance criterion. Remarkably, UPS efficiency in field applications may deviate from controlled laboratory conditions. This paper focuses on the impact of mains supply on double-conversion UPS efficiency. As the mains supply mostly affects the rectifier section, the results also provide a reference on the impact of mains supply on rectifier efficiency.

Voltage stress on power switches in active NPC topologies

Neutral-Point-Clamped topologies have been widely applied to improve power conversion efficiency. Active NPC variants may offer an advantage in terms of efficiency and losses distribution. Remarkably, Active NPC topologies differ from traditional NPC in terms of power semiconductors characteristics and commutation paths. This paper investigates Active 3L NPC converters in double-conversion UPS applications. Particularly, it discusses voltage stress on power switches in Active NPC converters, presenting experimental results from high-power 3ph UPS implementation.