Direct vector control of induction motors based on independent estimation of resistance and flux

This paper deals with the direct vector control (DVC) of induction motors. It is well known that the estimation of rotor flux plays a fundamental role in the DVC and the estimation precision is significantly affected by the motor resistance. So estimation of resistance is indispensable in practice. For fast estimation of the resistance, it is necessary to slow down the convergence rate of the current estimate. On the other hand, for fast estimation of the rotor flux, it is necessary to speed up its convergence rate. It is very difficult to realize such a trade-off in convergence rates in the full order observer. In this paper, we propose to decouple the current observer from the flux observer so as to realize independent convergence rates. Simulation results of the proposed method show a superior performance in the torque and flux responses.