Rotor Resistance Estimation for Induction Machines Using Carrier Signal Injection With Minimized Torque Ripple

This paper presents a technique for estimating the rotor resistance of an induction machine over the machine's entire speed and torque range. This technique is based on injecting a relatively low-frequency carrier signal into the reference of the rotor flux linkage magnitude and extracting the induction machine's response to the carrier signal, which is then used in a model reference adaptive system. This paper also presents a technique to minimize the torque ripple generated by the carrier signal. This technique utilizes the rotor flux linkage reference in conjunction with a proportional-integral-resonant feedback plus feedforward control to generate references for the direct and quadrature axis stator currents. This paper also improves tracking of the torque and rotor flux linkage in direct field-oriented control of the induction machine through employing electromotive force and resistive compensation methods for tracking q-axis and d-axis reference stator currents, respectively. Simulation and experimental results demonstrate the effectiveness of the technique over the entire operating range.