Offline Identification of Induction Machine Parameters With Core Loss Estimation Using the Stator Current Locus

High-performance control of induction machines in electric drives requires accurate knowledge of the machine parameters. While parameters have traditionally been identified using the standard no-load and locked-rotor tests, performing the locked-rotor test as prescribed in the IEEE standard requires special test equipment, and is difficult to implement with an inverter due to the low voltages involved. This paper presents a new method for induction machine parameter identification, including core loss conductance, which is based on fitting steady-state experimental data to the stator current locus for various slip frequencies in the stator flux linkage reference-frame. Numerical analysis confirms the accuracy of the method, while experimental results demonstrate its ability to characterize an induction machine over a range of flux levels which include magnetic saturation. Finally, it is shown that model-based predictions of the steady-state machine behavior computed using the parameter estimates provided by the proposed technique are more accurate than those obtained using the IEEE standard, when compared to measurements of the power factor, three-phase input power, and RMS line current.