Patent ID: 7034497

Claim:
A method of determining the angular position and velocity of a rotor for a polyphase alternating current (AC) wound field synchronous machine at or near rest that is driven by a motor controller that comprises a carrier injection sensorless (CIS) position sensing system, the rotor being excited by power generated by an exciter through a rotating rectifier, comprising the steps of: generating polyphase AC power for the machine that has a power frequency representative of rotor angular velocity and current representative of torque; generating a variable frequency polyphase AC carrier signal that has a frequency substantially higher than the power frequency; injecting the carrier signal until electromagnetic transients die away; activating a rotor position observer and phase lock to a rotor pole, initially estimating rotor angular velocity and position within a narrow low velocity range; establishing north-south pole alignment and correcting the estimated angle; increasing the frequency of the carrier signal using a controlled ramp; activating the motor controller at zero commanded torque; applying excitation to the exciter; and applying a ramped torque command from zero to full torque to the motor controller to accelerate.