Stability Analysis of Vector Control of Induction Motor without Speed Sensor Taking Core Loss into Account

Abstract

The rotor flux has been constant and the core loss has been ignored in the conventional vector controller of induction motor. So far, in the stability analysis of vector control without a speed sensor, the core loss has also, been ignored. We propose a novel stability analysis method by introducing a new differential equation and analyze the stability of the vector control without speed sensor considering core loss by the analysis method.The vector control of the induction motor without a speed sensor requires the estimations of the rotor flux and the rotor speed. Since the estimations use the machine parameters and the stator voltage and current components as input quantities, the stability of the system is sensitive to the variations of the machine parameters. The errors of measured stator voltage and current are compared with those of the vector control system with a speed sensor. The stability of the vector control system of the induction motor without a speed sensor, in which the rotor flux speed is controlled with the torque producing current and the rotor flux is calculated from the stator voltage and current, is studied.At first, a novel differential equation for the rotor flux _??_ and torque-producing current _??_ estimator taking core loss into account is introduced and stability analysis method is proposed. Next, theoretical stability is analized by the method and the theoretical stability of rotor speed is compared with the experimental stability to verify the validity of the proposed stability analysis method.