Patent ID: 7079964
Filing Date: 2006-07-18
Classification: G01P,H02P

Abstract:
1. A method for determining a frequency of current ripples contained in an armature current signal of a commutated direct current (DC) motor, the method comprising: determining a frequency spectral result of the armature current signal of the motor in which the armature current signal contains current ripples and interference; determining a frequency spectral result of a voltage signal of the motor in which the voltage signal contains the interference; determining a frequency spectral result of the current ripples contained in the armature current signal based on differences between the frequency spectral result of the armature current signal and the frequency spectral result of the motor voltage signal such that the determined frequency spectral result of the current ripples contained in the armature current signal is void of frequency components which are superimposed on the armature current signal as the interference; and determining the frequency of the current ripples contained in the armature current signal from the determined frequency spectral result of the current ripples contained in the armature current signal.