Stator Controlled Magnetic Bearing for MWES

Active magnetic bearings (AMBs) appear practical for momentum wheel energy storage (MWES) rotors. However, AMB eddy current losses reduce the MWES efficiency and the accumulated heat can only be dissipated through ineffective thermal radiation which can cause rotor thermal problems. While homopolar AMB designs with extended pole edges can reduce the losses, they do not completely solve the eddy current problem. Mohawk Innovative Technology, Inc. (MiTi) proposes development of a MWES rotor system using a unique Stator Controlled Magnetic Bearing (SCMB) and powder lubricated backup bearing (PLB). The SCMB is a stiff, highly damped magnetic bearing that eliminates eddy current losses associated with the flux discontinuities of conventional AMBs. The PLB is a solid film lubricated journal bearing that has been successfully tested at speeds to 58,000 rpm using MoS{sub 2} space qualified lubricant. By integrating the SCMB and PLB, a low-power-loss, highly reliable MWES rotor suspension system will be possible. The Phase I effort will demonstrate feasibility of the SCMB, and will establish a preliminary MWES integrated rotor-bearing system design. The support of Boeing Defense and Space Group has been enlisted for Phase I to provide guidance and review the preliminary MWES system design. Under Phase II a prototype MWES system with SCMBs and PLBs will be tested.