Patent ID: 8058828

Claim:
A compensating system for compensating a cogging torque of a motor, the compensating system comprising: a speed measuring apparatus to measure a speed of the motor; a moment of inertia measuring apparatus to measure a moment of inertia of the motor; a rotor position sensor to measure a rotor position of the motor; a processor to receive the speed, the moment of inertia, and the rotor position of the motor, and to determine the cogging torque of the motor according to the speed and the moment of inertia of the motor; a plurality of band-pass filters, wherein each of the plurality of band-pass filters is arranged to filter frequencies of a waveform of the cogging torque of the motor, and to have a different frequency from frequencies of the others of the plurality of band-pass filters, to determine a plurality of Fourier coefficients of the Fourier transformation of the cogging torque, wherein the processor determines a Fourier transformation of the cogging torque with the rotor position as a variable according to the plurality of Fourier coefficients, a cogging torque at a preset rotor position, and a cogging current according to the Fourier transformation of the cogging torque; and a current control apparatus to output a current to compensate the cogging torque of the motor, wherein the current flows opposite to the cogging current.