Multiplane Rotor Resistance Online Estimation Strategy for Multiphase Induction Machine Under Nonsinusoidal Power Supply

The proposed technique focuses on the online estimations of multiplane rotor resistances for the multiphase induction machine operating under the flux-oriented frame. The deviations in regard to the steady-state performance caused by the mismatched fundamental and harmonic rotor resistances are analyzed in detail. The reactive-power-based model referenced adaptation system (MRAS) is formulated for the third harmonic plane, which is air gap flux-oriented. The quasi-normalized method with respect to the error terms between the referenced and adjustable models is addressed to improve the adaptive mechanism under various load conditions. Experimental validations have been performed to confirm the effectiveness of the proposed algorithm. The simultaneous online identifications for the fundamental and harmonic rotor resistances are achieved. The approximate convergence processes and steady performance can be obtained for a large range of load conditions by using constant adaptive gains. The estimated results are indirectly verified by the comparisons between command and actual flux. In addition, the dynamic performance for the proposed MRAS is conducted with the sudden change of load. The effects of inverter nonlinearity and temperature rise are taken into account.