Adaptive and robust techniques for torque and rotor flux control of induction motor drives for railway applications

This paper deals with the design of a controller for an induction motor electrical drive useful for high speed railway applications. The design of the controller is based on the cascade control mode using the standard model of the motor referred to d-q axes fixed with the rotor flux vector. It is assumed that the speed and the rotor flux are the variables to be controlled and their dynamics have to be decoupled, which is obtained by means of a non linear compensator which gives decoupling of the direct and in-quadrature currents. According to the above mentioned cascade control mode, the bandwidth of the current inner control loops has to be chosen higher than that of the speed and rotor flux outer control loops. In order to take into account the remarkable uncertainties in the knowledge of the inertia coefficient, adaptive control techniques are employed for designing the speed control loop. To cope with uncertainties in the electromagnetic parameters robust control techniques are used for designing the rotor flux, the direct and the in-quadrature current loops. Simulation experiments are displayed in order to test the whole controller.