On-line simultaneous estimations of the speed and the secondary resistance under the transient states of Induction Motor

Abstract

In the speed sensorless control of the induction motor, the machine parameters (especially the secondary resistance R₂) have a strong influence to the speed estimation. It is known that the simultaneous estimation of the speed and R₂ is impossible in the slip frequency type vector control, because the secondary flux is constant. But the secondary flux is not always constant in the speed transient state. In this paper the R₂ estimation in the transient state without adding any additional signal to the stator current is proposed. This algorithm uses the least mean square algorithm and the adaptive algorithm, and it is possible to estimate the R₂ exactly. This algorithm is verified by the digital simulations and the experiments.