On-line Rotor Time Constant Estimation in IFOC Induction Motor Drives

The indirect Field Oriented Control is the standard control technique for high performance induction motor drives. It is simple and effective, but it requires an accurate estimation of the rotor time constant in order to achieve the best possible performance. The paper presents a procedure for on-line estimating the rotor time constant which does not need other transducers than those already present on a standard system, does not affect normal operation and features good precision and robustness. The estimation is performed by processing the effect of a low frequency additional signal and can be used either for on-line tuning working drives, either for commissioning newly installed drives. Simulation and experimental tests demonstrate the effectiveness of the proposed procedure.