Bearingless Motor Technology

Levitronix is the first company to introduce the Bearingless Motor technology, a breakthrough in magnetic levitation, to the market. A key feature that distinguishes Bearingless Motor technology is that it combines both the motor and magnetic bearing in the same unit.

Figure 1: Schematic illustration (left) and photograph (right) of a bearingless motor unit

Figure 2: Subcomponents (left) and assembly (right) of a bearingless motor stator with redundant integrated control electronics

Three spatial degrees of freedom of the rotor, rotation and radial position are stabilized actively by electronically controlled magnetic fields. The radial rotor position and the rotation are constantly measured by sensors. A powerful Digital Signal Processor (DSP) controls the magnetic field by the current in the combined stator coils 10,000 times per second so that rotor is rotated at the desired speed and kept in the radial position. The remaining three spatial degrees of freedom are passively stabilized. Figure 3 shows the functional principle of such passive stabilization. Figure 3 (left) shows axial displacement of the rotor. Axial displacement results in attractive magnetic forces, which act in the opposite direction to the displacement, and therefore, stabilize the axial position of the rotor. Figure 3 (right) schematically illustrates tilting of the rotor. The magnetic forces generate a stabilizing moment so that the rotor is returned back to position.

Axial displacement of the rotor Tilting of the rotor Figure 3: Passive stabilization of axial and angular rotor position

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