Patent ID: 8258736

Claim:
A method for operation of an internal permanent magnet motor having a rotor, the method comprising: determining whether a neutral point access signal is received from the rotor; operating the internal permanent magnet motor using sensorless signals corresponding to a rotor position and a rotor speed of the rotor derived by a first sensorless signal estimation method when the neutral point access signal is received from the rotor; and operating the internal permanent magnet motor using sensorless signals corresponding to a rotor position and a rotor speed of the rotor derived by a second sensorless signal estimation method when the neutral point access signal is not received from the rotor, wherein the first sensorless signal estimation method utilizes the neutral point access signal to generate the rotor position and the rotor speed, and wherein the second sensorless signal estimation method does not utilize the neutral point access signal to generate the rotor position and the rotor speed.