Sensorless controller of AC motor and control method

A sensorless control method 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:

• means for superposing a high frequency signal on an estimated magnetic flux axis of the motor;
• means for extracting an error signal of the magnetic position from a voltage or current detection signal having the same frequency component as a frequency component of the high frequency signal, the error signal being 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;
• means for estimating a magnitude and a position of a magnetic flux from a motor input voltage, a detection current and a speed estimation value through a magnetic flux observer;
• first adaptive rule means for adaptively regulating an error signal of a magnetic flux position to be an output of the high frequency component extractor;
• second adaptive rule means 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 the same observer;
• means for switching the first and second adaptive rule means depending on a speed;
• and
• means for estimating a speed from an output signal of the adaptive rule means.

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 estimation value of a magnetic flux position of an induction motor without using a speed sensor and independently controls the magnetic flux component and the torque component, thereby implementing a high control performance of the induction 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 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 third adaptive regulator for adaptively regulating an error signal of a magnetic flux position to be an output of the high frequency component extractor;
• a fourth 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 third adaptive regulator at a very low speed, the third and fourth adaptive regulators at a low speed and the fourth adaptive regulator at a high speed;
• and
• a speed estimator for generating a speed estimation value from an output value of the hybrid device.

A sensorless control method of an AC motor which separates a motor current into a magnetic flux component and a torque component based on an estimation value of a magnetic flux position of an induction motor without using a speed sensor and independently controls the magnetic flux component and the torque component, thereby implementing a high control performance of the induction motor, comprising:

• means for superposing a high frequency signal on an estimated magnetic flux axis of the motor;
• means for extracting an error signal of the magnetic position from a voltage or current detection signal having the same frequency component as a frequency component of the high frequency signal, the error signal of the magnetic flux position being 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;
• means for estimating a magnitude and a position of a magnetic flux from a motor input voltage, a detection current and an estimated speed through a magnetic flux observer;
• third adaptive rule means for adaptively regulating an error signal of a magnetic flux position to be an output of the high frequency component extractor;
• fourth adaptive rule means 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;
• means for switching the first and second adaptive rule means depending on a speed or an output frequency;
• and
• means for estimating a speed from an output signal of the adaptive rule means.