Tangential-Rib-Free SynRel Machine With Improved Torque Density and Manufacturability for an Electric Assist Turbocharger

The Synchronous Reluctance Machine (SynRel) designed for any high-speed application is found to exhibit an inferior saliency ratio due to the increased total rib thickness for handling the centrifugal force. Therefore, this paper aims to identify a new rotor topology which offers an improved saliency ratio for high-speed SynRel machines. Based on this, a tangential rib-free SynRel rotor is recognized as the peerless SynRel configuration for all high-speed operations. A 3.5 kW, 60 krpm SynRel machine is designed for an electric assist turbocharger (EAT) to ascertain the superior performance of the tangential rib-free rotor over its conventional counterparts. The Tangential rib-free SynRel machine is found to achieve a minimum improvement of 16% in the electromagnetic torque performance compared to other conventional rotor topologies. In addition, the tangential rib-free SynRel machine is subjected to static structural, rotordynamic, and thermal analysis to validate its rigidity during high-speed operation. Finally, the tangential-rib-free SynRel machine is fabricated and its performance is experimentally validated.