The Study of Switched Reluctance Motor for 4-DOF Bearingless Motor

High integration, low loss and high-reliability are the main development trends of flywheel battery. Thus this study presents the first prototype of a novel high-integration four degrees of freedom (4-DOF) bearingless motor with the advantages of weak coupling and low power consumption. The proposed bearingless motor can realize energy conversion and produce 4-DOF radial forces compared with the conventional bearingless motor for improving the integration of system. A biased flux for producing radial levitation forces is provided by the permanent magnets, which reduce the power consumption of the system. Moreover, a decoupling between the torque and the suspension systems is realized through a structural design, thereby improving the controllability. Structure and winding configurations are introduced and the operation principle of the 4-DOF bearingless motor is discussed. Magnetic circuits analysis and parameter design method are present and a three-dimensional finite element model is established. Electromagnetic characteristics that focus on the high integration, low loss and high reliability are discussed and validated comprehensively. Finally, a favorable controllability of radial suspension forces are verified using finite-element analysis and some experimental results.