Flux position estimation using current derivatives for the sensorless control of AC machines

This paper considers the general principles of saliency tracking in AC machines. Special attention is given to pulse type injection for the extraction of a rotor or flux position signal. The saliency is tracked by measuring the current derivative resulting from voltage 'test' vector application. Results show tracking of 'saturation' saliency on a standard induction motor to be used for sensorless control of AC machines in the low and zero speed region.