SIGNAL CONDITIONING APPARATUS AND METHOD FOR DETERMINATION OF PERMANENT MAGNET MOTOR ROTOR POSITION

摘要

An apparatus and method for estimating rotor angle information for the control of permanent magnet AC motors having sinusoidal current excitation. The disclosed motor drive can provide full load operation at very low speeds including zero speed without the use of a shaft position sensing device. The rotor angle is estimated through injection of high frequency current, and rotor angle is extracted by a signal-conditioning algorithm, which utilizes current amplitude differential to discriminate the rotor angle. Rotor angle magnetic axis orientation (North or South pole) at startup is detected by comparing time average current ripple (at signal injection frequency) content between two different levels of d-axis current injection.