High speeds up to several million DN are attainable. Friction losses are 5 to 20 times less than in conventional bearings and result in lower operating cost. Maintenance costs are low due to the absence of mechanical wear. The controller uses position sensor outputs to apply stiffness and damping forces to the rotor to achieve a desired dynamic response. In more sophisticated systems, the controller can automatically compensate for rotor imbalance, and selectively damp rotor resonant modes.
Size is an important design question that arises in all applications.
When magnetic bearings are fabricated from standard electrical steels, peak loads are attained with flux densities of roughly 16,000 Gauss. The challenge in magnetic bearing design is controlling these forces and achieving dynamic stability for feed back control. At Magnetic Moments, we use analytical models and finite element analysis of rotor systems to synthesize robust feedback control algorithms. More sophisticated controllers based on adaptive control techniques and machine learning are also available for active vibration cancellation, automatic rotor balancing, and mechanical impedance synthesis. The image depicts a conical magnetic bearing designed for research at Sandia National Laboratories on surface grinding using magnetic bearings.