Harmonic Current Injection-Based Online Rotor Time Constant Estimation Method for IM

Accurate rotor time constant (RTC) is the key to achieving high-performance induction motor (IM) drives. To obtain an accurate RTC, a new robust online RTC estimation method based on harmonic current injection is presented. In the proposed method, the RTC is estimated from the speed response corresponding to the injected harmonic current. Compared with the existing schemes, the parameter mismatches will not influence the steady-state identification results of RTC. Thus, it has stronger robustness to parametric uncertainties. Finally, the effectiveness and correction of the proposed method is verified by simulations and experiments.