Torque ripple reduction using back-emf feedback

Abstract

Methods and apparatuses are provided to identify and extract a torque ripple signal found in the back-emf signal from an electric motor. The torque ripple signal is used in a feedback control loop to reduce the amount and effects of torque ripple in the motor and the motor system. A motor controller is provided to reduce torque ripple in an electric motor. The motor controller is suitable for controlling the speed or torque or other related parameters associated with the electric motor. A disc drive apparatus for use in information storage and retrieval systems is provided. The disc drive apparatus includes an electric motor, an information storage disc, and a motor controller. A method is provided for reducing the effects of torque ripple in an electric motor by sampling the back-emf signal generated by the electric motor, extracting the torque ripple signal from the back-emf signal, and generating an AC component signal proportional to the torque ripple signal. This AC component signal is then used to create an error-correcting feedback control signal that can be used to modify the drive signal supplied to the motor such that the torque ripple in the motor is reduced. This method may be embodied using analog or digital circuitry, or a combination thereof.

Dependencies are inferred from the claim text.