Patent ID: 8339081

Claim:
A method for low speed sensorless control of a permanent magnet motor comprising: injecting a high frequency signal into a flux axis of the permanent magnet motor; and sensorlessly determining a rotor position and a rotor speed in response to both a flux axis error signal on a flux axis of the permanent magnet motor and a torque axis error signal on the torque axis of the permanent magnet motor, both the flux axis error signal and the torque axis error signal determined in response to current vector signals in a synchronous reference frame; wherein the step of determining the rotor position and the rotor speed comprises: generating the flux axis error signal in response to a first error signal and a flux axis error signal weighting factor; generating the torque axis error signal in response to a second error signal and a torque axis error signal weighting factor; combining the first error signal and the second error signal to generate a combined error signal; and sensorlessly determining the rotor position and the rotor speed in response to the combined error signal.