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

We propose a current injection-based estimator to identify accurately standstill induction motor (IM) parameters necessary for 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. The proposed methodology employs closed-loop control of an injected current due to little knowledge of the unknown motor, rather than the open-loop voltage injection approaches commonly used in sensorless control schemes. Subsequently, this control scheme proactively prevents electrical accidents resulting from inadequate open-loop voltage injection. Our developed specialized offline commissioning test compensates for the phase delay resulting from the drive, which significantly affects estimation precision. The effectiveness of the identification technique is validated by means of experiments performed on three different IMs.