A Novel Bearingless Switched Reluctance Machine With Axial Split Phase Inner Stator Permanent Magnet Structure

Flywheel energy storage system (FESS) is a kind of physical energy storage device for electromechanical energy conversion. In order to simplify the system structure and improve the critical speed, magnetic levitation electric machines that combine magnetic bearing and electric machine are applied in FESS. Bearingless switched reluctance machine (BSRM) fully preserves the excellent characteristics of switched reluctance motor, and improves the high speed performance and operation efficiency by active control of its own radial force. Introducing the BSRM into FESS, the system volume and loss could be greatly reduced, suspension could be improved, and critical speed and power density could be increased. BSRM is one of the ideal choices for flywheel suspension support and energy conversion. There are serious electromagnetic coupling between torque winding and suspension winding of the traditional 12/8 poles type BSRM, which lead to the difficulty of controlling. In this paper, a novel BSRM with axial split phase inner stator permanent magnet (PM) structure is proposed to cancel the electromagnetic coupling between torque winding and suspension winding.