Patent ID: 7045988

Claim:
A sensorless control apparatus of an AC motor which separates a motor current into a magnetic flux component and a torque component based on an estimated magnetic flux position of a synchronous motor without using position and speed sensors and independently controls the magnetic flux component and the torque component, thereby implementing a high control performance of the synchronous motor, comprising: a high frequency generator for superposing a high frequency signal on an estimated magnetic flux axis of the motor; a high frequency component extractor for extracting, from a voltage or current detection signal having the same frequency component as a frequency component of the high frequency signal, an error signal of the magnetic flux position which is obtained based on a magnetic saliency of a physical quantity of the motor in a high frequency region generated by a magnetic saturation caused by a main magnetic flux or a conductor skin effect produced by a high frequency; a magnetic flux observer for estimating a magnitude and a position of a magnetic flux from a motor input voltage, a detection current and a speed estimation value; a first adaptive regulator for adaptively regulating an error signal of a magnetic flux position to be an output of the high frequency component extractor; a second adaptive regulator for adaptively regulating an error signal calculated from a magnetic flux estimation value and an error value of an output of the magnetic flux observer in a same observer; a hybrid device for switching the first adaptive regulator at a very low speed, the first and second adaptive regulators at a low speed and the second adaptive regulator at a high speed; and a speed estimator for generating a speed estimation value from an output value of the hybrid device.