Experimental performance evaluation of a fractional power induction machine at ambient and cryogenic temperatures

The demand for energy-efficient solutions in electric machine design is increasing due to growing environmental concerns. Cryogenic motors offer benefits over traditional systems, especially in terms of efficiency, torque and power density. These advantages make them suitable for a wide range of applications, such as industrial, aeronautical and maritime. A 90W induction motor was tested in standard conditions and then in a liquid nitrogen environment to understand the differences in performance. The variation of the parameters of the equivalent single phase circuit from room to cryogenic temperature has been analyzed as well. The results show that in the cryogenic environment, the motor has higher mechanical and iron losses. However, a significant reduction in Joule losses was observed. This led to an overall increase in motor efficiency by +26.8%. Additionally, the motor displayed a +51.6% increase in torque and a +69.6% increase in power output under cryogenic conditions. For validation, a similar 90W induction motor was tested under the same conditions. The results from both motors aligned closely, thus reinforcing the reliability of the data. Lastly, an overview of the stray load losses in cryogenic conditions for the two motors was provided.