EKF-based on-line tuning of rotor time constant in induction motor vector control

Thanks to advances in power electronics and digital signal processor (DSP) technology, electrical drives for induction machines (IM), based on an indirect vector control strategy (IVC), are now widely available on the market. This control strategy allows high performance to be achieved from an induction motor. Crucial to the success of this well-known control method is a priori knowledge of the rotor electrical time constant, which varies with temperature, frequency, and saturation. In this paper, the author presents a Matlab-Simulink-based design and simulation of a high-performance induction motor vector control, which is robust against rotor time-constant variations. These variations are predicted and corrected using the Extended Kalman Filter (EKF) algorithm. The on-line estimated rotor time-constant actual value is fed forward to the controller and to the slip speed calculation module to obtain robust control performance with the proposed indirect field-oriented control scheme.