Patent ID: 8542800

Claim:
An asynchronous motor comprising: a stator including a plurality of windings and being configured to generate a rotating magnetic field when a current is provided to the plurality of windings; a rotor positioned within the stator and configured to rotate relative thereto responsive to the rotating magnetic field; a component separate from the stator and the rotor and positioned within the rotating magnetic field, the component being configured to alter a magnetic reluctance of the rotor so as create a disturbance in the rotating magnetic field; and a motor drive to control current and voltage provided to the stator, the motor drive including a processor programmed to: measure a stator phase voltage spectrum of the stator; apply a fast Fourier transform to the stator phase voltage spectrum to translate the stator phase voltage spectrum from a time domain to a frequency domain; determine a speed of the rotor based on an applied stator frequency in the stator phase voltage spectrum and a stator phase voltage spectrum peak.