Comparative Analysis of Bearingless Switched Reluctance Motors With Decoupled Suspending Force Control

In this paper, three types of bearingless switched reluctance motors (BLSRMs) which have decoupled flux characteristics between the torque and suspending current are presented in detail. The analyzed BLSRMs are an 8/10 hybrid BLSRM, a 12/14 hybrid BLSRM, and a double stator BLSRM. The 8/10 hybrid BLSRM has a low electrical frequency with decoupling characteristics. The 12/14 hybrid BLSRM has a short flux path to reduce core loss with higher decoupling characteristics. The double stator BLSRM has the best decoupling characteristics with a complex mechanical structure. All three structures have two types of stator poles: torque and suspending force poles. Due to the independent characteristics between the torque and suspending force poles, the torque control can be decoupled from the suspending force control. The characteristics of the three types, such as magnetic flux distribution, inductance, torque, suspending force, torque ripple, efficiency, and number of switches used in the drive systems, are analyzed and compared to induce the better magnetic structure and control scheme of the suspending force. To verify the validity of the three types, tests are executed and compared.