Standstill Parameter Identification of Vector-Controlled Induction Motor Using Frequency Characteristics of Rotor Bars

This paper suggests a current injection-based estimator to accurately identify standstill induction motor (IM) parameters necessary for the vector control. A mathematical model that faithfully represents the general deep bar effect is introduced. Then, two exciting signals with a different frequency are sequentially injected to track the parameters based on the frequency function of the rotor bar. Little knowledge of the unknown motor allows the proposed methodology to employ a closed-loop control of an injected current, rather than open-loop voltage injection approaches commonly used in sensorless control schemes. Subsequently, this control scheme proactively prevents electrical accidents resulting from an inadequate open-loop voltage injection. We develop a specialized offline commissioning test to compensate the phase delay resulting from the drive, which significantly affects the estimation precision. The effectiveness of the identification technique is validated by means of experiments performed on the three different IMs. The developed algorithm is scheduled to be fully applied to the IM drive system in rolling mill plants of Pohang Steel Company (POSCO) by 2009.