Homopolar Active Magnetic Bearing Design for Outer Rotor Kinetic Energy Storages

For high speed kinetic energy storage systems in outer rotor topology, active magnetic bearings play a major role in enabling high energy efficiencies and energy densities. The outer rotor setup enables the use of a soft magnetic composite on the rotor, which in turn facilitates the use of homopolar magnetic bearings. Homopolar bearings typically show low drag losses. Different bearing designs regarding flux paths and coil arrangements are possible. Selected variants are discussed in this contribution regarding losses and possible energy density of the overall energy storage system.