Estimation of the Rotor Flux in the Traction Systems with Induction Motors and Field-Oriented Control

This paper is focused on the estimation of the induction motor rotor flux in a rotor flux-oriented control system applied in the electric traction of locomotives. The rotor flux-oriented control of the induction motor is one of the most commonly used methods for torque and speed control, allowing to achieve indicators of high quality in both steady-state and dynamic regimes. Two possibilities of estimating the rotor flux magnitude and angular position are analyzed. The first considers the use of the measured speed and the stator current, and the second the use of the supply voltage and the stator current. As an alternative to measuring the highly distorted voltage at the inverter output, the possibility of using the control signals of the IGBTs is analyzed. The MATLAB/Simulink software is used as a simulation environment to analyze the obtained results for the associated algorithms.