Patent ID: 11936313

Abstract:
Described is a method of aligning a rotor of a polyphase synchronous motor having a permanent magnet rotor to a predetermined, selected, or specified rotor angle. The method comprises sensing or measuring the stator winding voltages/currents during synchronous operation of the motor. Based on the sensed or measured stator winding voltages/currents, a synchronously rotating reference frame vector voltage (Vq) in the q-axis is determined as a product of stator winding resistance (Rs) and stator winding current (iq) in the q-axis. Corresponding polyphase drive voltages for the synchronous motor for the predetermined, selected, or specified rotor angle (θ) are determined from the synchronously rotating reference frame vector voltage (Vq). The polyphase drive voltages are applied to align the rotor on stopping at said predetermined, selected, or specified rotor angle (θ). The polyphase drive voltages are applied by suitable PWM drive signals.