A Comprehensive Review of Prior Art in Bearingless Induction Machine - Part II: Topology

This paper seeks to present a comprehensive review of the state of the art in the topology of bearingless induction machines, aiming to equip researchers in this field with a clear and thorough understanding of the topic. Such an overview is needed, as the last reviews of bearingless induction machine research, which were published in 2014 and 2019, were more control themed. Since then, significant improvements in the design of bearingless induction machines have been reported. The current review is part of a two-part series: the first part [1] focuses on the control of bearingless induction machines, while this second part reviews all publications that primarily address topology. This review begins with a categorization of the relevant papers, followed by a discussion of key technologies. Additionally, comparative metrics such as rotor surface velocities, shear stress, and thrust stress are introduced to systematically evaluate and benchmark different designs. Using these parameters, the designs are compared and conclusions drawn. The paper concludes with a brief outlook on potential directions for future research.