Review of Bearingless Synchronous Motors: Principle and Topology

A bearingless synchronous motor (BLSM) is a special type of electric machine that integrates the functions of traditional synchronous motors and magnetic bearings. It not only has the advantages of magnetic bearings, such as no friction, pollution-free, and maintenance-free, but it also realizes the high integration and system simplification. Therefore, the BLSM is becoming increasingly attractive in applications such as rotating stages, compressors, artificial hearts, and centrifugal pumps. This article provides a comprehensive review of the BLSM topologies after a brief introduction to the basic suspension force generation principles and the typical BLSM mathematical models. The recent BLSM topologies are classified based on the features of the suspension force generation principle. Moreover, the advantages and disadvantages of each BLSM type are discussed and compared in detail. Future potential BLSM applications in aircraft, aerospace, and flywheel energy storage systems are discussed after a short description of the BLSM application status. Several potential topology development directions are presented based on the requirements of the potential application.