Comparative Performance Analysis of Induction and Synchronous Reluctance Motors in Chiller Systems for Energy Efficient Buildings

A significant portion (ca. 40%) of the world's total energy is utilized in buildings. Cooling of large buildings worldwide is done by centrifugal chiller systems, where the compressors, pumps, and fans are driven by ac motors. These motors are energy hungry parts of the chiller. All-variable speed chillers, taking into account load variations, reduced the energy demand significantly compared to the constant speed ones. Induction motors (IMs) are commonly used in modern chillers. However, as the efficiency of the IM decreases with the speed, the overall efficiency drops, as the chiller operates most of the time in part-load condition. In this paper, SimulationX software is used to quantitatively investigate about the energy efficiency improvement by using synchronous reluctance motor (SynRM) in all-variable speed centrifugal chillers. The system was tested for three distinct building load profiles. The results are judged in comparison with the state-of-the-art IE2 IMs. The results provide quantitative evidence that SynRM can significantly increase the energy efficiency in the chiller systems and has a big potential to substitute IMs in these applications.