Patent ID: 7459872
Filing Date: 2008-12-02
Classification: G05B

Abstract:
1. A method for calculating a position of a motor by the analog output signals of a resolver with at least two stator windings arranged in a perpendicular alignment to each other on a stator and at least one rotor winding arranged on a rotor which can turn in relation to the stator, the method comprising the following steps: applying a sinusoidal excitation signal to the rotor winding; deriving a sinusoidal and a cosine resolver signal depending on the angular position of the stator in relation to the rotor form the stator windings; converting the sinusoidal and cosine resolver signals into a sine and cosine digital signal, wherein converting utilizes any two analog to digital conversion inputs capable of simultaneously sampling the sine and cosine resolver signals at least 8 times per cycle; filtering the sine and cosine digital signals through a FIR bandpass filter for bandwidth limiting; decimating the oversampled, filtered sine and cosine digital signal down to the baseband, said decimation by a factor K so as to create a decimated sine and cosine signal; rectifying the decimated sine and cosine signals; normalizing the decimated sine and cosine signals; correcting the quadrature of the decimating sine and cosine signals; computing an arctangent output signal to derive an angular value for the relative angular position between the rotor and the stator; converting the arctangent output signal to a position signal, said converting including adding a velocity feed-forward factor to remove lag due to the FIR filter and a velocity lag factor to remove residual velocity lag due to system components, the converting including the steps of: inputting a theta position for incorporation into a torque command to the motor.