Speed and traction control in electric vehicles with induction motors

An observer-based indirect field oriented control scheme is proposed for the speed and traction control of electric vehicles powered by induction motors with uncertain constant load torque and stator and rotor resistances. The novel control architecture transforms the vehicle speed reference into a suitable motor speed reference and then guarantees the motor speed regulation to the corresponding reference on the basis of the motor speed regulation error. The motor speed measurement, which is typically available in electric vehicles, is used not only for traction control but for regulation purposes as well. The closed loop on-line identification of the three critical uncertain parameters allows for on-line estimating and imposing the motor flux modulus reference value which minimizes power losses and improves power efficiency.