System and method for determining rotor shaft position of high voltage PM AC synchronous machines using auxiliary windings

A method for determining rotor shaft position of a permanent magnet AC synchronous machine system including a permanent magnet AC synchronous motor having a stator with a main set of coils and an auxiliary set of coils co-located with the main set of coils about a plurality of stator teeth, wherein each auxiliary coil is wound in the same magnetic configuration as a corresponding coil of the main set of coils, and a drive controller with a digital signal processor, the method comprising:

• placing the motor in predetermined initial position;
• accelerating the motor until a final open-loop speed is attained;
• initiating sensorless phase-locked loop speed calculations via the digital signal processor when the digital signal processor determines that the final open-loop speed has been attained;
• determining an error rate, using the digital signal processor, between a phase-locked loop speed calculated from the phase-locked loop speed calculations and the final open-loop speed;
• when the error rate between the phase-locked loop speed and final open-loop speed falls below a predetermined error rate, transitioning the digital signal processor to a sensorless mode;
• in the sensorless mode, utilizing the digital signal processor to calculate a motor electrical angular speed utilizing current and voltage measurements from the main set of coils and the auxiliary set of coils.