Modern refrigeration systems are under increasing pressure to deliver not only high energy efficiency, but also reliability, power quality and operational intelligence. As chillers are often among the largest electrical loads in commercial buildings, data centers and industrial facilities, the selection of variable speed drive (VSD) technology for compressor control has a major impact on both cooling system and electrical grid. Variable speed drives significantly improve refrigeration efficiency by matching compressor speed to the actual cooling demand. Compared to fixed-speed operation, partial-load efficiency improvements of 25 - 50% are common. However, selecting the right drive technology is critical, as not all VSDs offer the same performance. To maximize efficiency, drives should ...