Improved Q-MRAS Based Online Rotor Time Constant Compensation for IFOC Induction Motor Drives

In the conventional Q-based MRAS scheme for rotor time constant estimation, the inductance information is crucial. If incorrect inductance value is used, the output of the Q-based MRAS model generates steady-state error, resulting in the degraded vector control performance. Such inductance parameter is generally obtained by self-commissioning tests, which are not only cumbersome but also imperfect. First, this paper presents a theoretical background of the effects of the inductance estimation error on the conventional Q-based MRAS model in terms of reactive power, angle error, and torque error. In sequence, a stator flux λ-based MRAS is proposed for the inductance compensation. The proposed scheme can update the inductance information in real time and improves the performance of IFOC. It does not require a self-commissioning test for inductance mapping with respect to motor current or flux. Additionally, the implementation of the proposed method is simple. Simulation and experimental results verify the effectiveness of the proposed method.