Speed sensor-less control of an induction machine with rotor flux tracking at very low speed

This paper presents a novel method to estimate the rotor flux position of an induction machine by injecting a high frequency signal at very low speed, including zero speed. When the high frequency fluctuating signal is injected in the terminal of an induction machine, the difference of impedance between the d-axis and q-axis of the synchronous rotating reference frame can be measured. This phenomenon is explained by a high frequency model of the induction machine, which is oriented with a high frequency signal space vector. The rotor flux angle can thus be tracked by tuning the space vector of the high frequency signal. Experimental results are provided to verify that this algorithm is robust against parameters variations and load changes.