A rotor resistance MRAS estimator for EV induction motor traction drive based on torque and reactive stator power: Simulation and experimental results

The Field Oriented Controlled algorithm needs accurate estimation of motor state variables in order to ensure full torque and power performance. Good control results are strongly related to parameter values used by observers or estimators' algorithms, which vary according to the machine working conditions and the temperature. The most important parameter is the rotor resistance. The paper shows and compares two different MRAS rotor resistance estimators, based on reactive power and motor torque, studied by means of a sensitivity analysis for different load and speed operating conditions. A nonlinear correction algorithm has been proposed in order to assure a good rotor resistance estimation convergence. Since the algorithm has to be implemented on an electrical vehicle inverter, it has been defined taking into account that it has to operate under dynamic conditions, the typical situation occurring during a drive cycle. Sensitivity analysis, simulation and experimental results are reported for the proposed methods.