ELECTRODYNAMIC PASSIVE MAGNETIC BEARING WITH PLANAR HALBACH ARRAYS

Active magnetic bearings are finding an increasing number of practical applications. However, system costs are still high. Passive conta ct free magnetic bearings need no sensors and no electronic control, such systems could therefore op en up new application fields such as e.g. flywheels. Furthermore, today’s active magnetic bearings have small air gaps between stator and rotor (some few tenths of millimeters) and therefore do not allow f or large rotor deviations from the nominal position. Th e presented passive magnetic bearing uses permanent magnet rings as radial bearings and an electrodynamic system as the axial bearing. The latt er is composed of two planar Halbach arrays and of two sets of short-circuited coils. The total rotor weigh t is magnetically compensated. For axial stabilization a t the rest or at low speeds two mechanical touch-down bearings are provided. If a certain moderate rotati onal speed is exceeded then the complete rotor levitatio n will be achieved. The clearance of air gaps is so ample that the rotor can spin about its principal a xis of inertia without touching the stator. For rotor stabilization no electronics is needed.