Precise torque control of induction motor with on-line parameter identification in consideration of core loss

This paper describes improved torque control of an induction motor. The control is based on direct field orientation with a rotor flux simulator, and motor parameters in the simulator are estimated by a robust identifier with no sensitivity to the stator resistance. Owing to model mismatch in the controller caused by the equivalent core loss resistance, however, both the field orientation and the parameter identification cannot be carried out perfectly, which results in degradation of torque control performance. In order to improve accuracy of the output torque, the proposed system employs a modified machine model taking the core loss into consideration. Consequently, it has been verified through computer simulations that the technique achieves high precision in torque control within a few percent errors