A method for calibrating or field calibrating rotor position offset of an alternating current motor which is controlled by an inverter circuit connected to a current regulation controller connected to a phase converter receiving, during normal operation, rotor position data from a sensor , the phase converter converting respective three-phase digital representations of measured current into corresponding two-phase digital representations of measured current for the current regulation controller , the measured current sensed by a sensing circuit for measuring three phase currents applied to the windings of the motor and/or back EMF induced in the windings of the motor , the method comprising: while providing a fixed, fake rotor position data corresponding to approximately zero degrees instead of the position data from the sensor to the phase converter and while applying a zero direct-axis current command to the current regulation controller , applying positive and negative quadrature-axis current commands sequentially and at approximately same magnitude to urge the rotor toward an enforced position; measuring positive quadrature-axis current aligned raw position data after application of the positive quadrature-axis current command and measuring negative quadrature-axis current aligned raw position data for the rotor after application of the negative quadrature-axis command; determining a difference between the positive quadrature-axis current aligned raw position data and the negative quadrature-axis current aligned raw position data to determine, based upon the difference, whether a true averaging axis is aligned at approximately zero degrees or approximately 180 degrees for the rotor with respect to the stator; determining a raw averaging axis position data based on an average of the positive quadrature-axis current aligned raw position data and the negative quadrature-axis current aligned raw position data; and determining a position offset based on a difference between the determined true averaging axis and the determined raw averaging axis position data. while providing a fixed, fake rotor position data corresponding to approximately zero degrees instead of the position data from the sensor to the phase converter and while applying a zero direct-axis current command to the current regulation controller , applying positive and negative quadrature-axis current commands sequentially and at approximately same magnitude to urge the rotor toward an enforced position; measuring positive quadrature-axis current aligned raw position data after application of the positive quadrature-axis current command and measuring negative quadrature-axis current aligned raw position data for the rotor after application of the negative quadrature-axis command; determining a difference between the positive quadrature-axis current aligned raw position data and the negative quadrature-axis current aligned raw position data to determine, based upon the difference, whether a true averaging axis is aligned at approximately zero degrees or approximately 180 degrees for the rotor with respect to the stator; determining a raw averaging axis position data based on an average of the positive quadrature-axis current aligned raw position data and the negative quadrature-axis current aligned raw position data; and determining a position offset based on a difference between the determined true averaging axis and the determined raw averaging axis position data. <EOS>