Reducing estimation error due to digitizing problem in a speed sensorless control of induction motor

This paper proposes a strategy for reducing the estimation error due to the digitizing problem in a speed sensorless induction motor control using the speed adaptive observer. An estimated current error compensation is introduced into the rotor magnetizing current's and synchronous speed's calculations in the flux model. A modification of the full-order observer is made in order to affect the compensation strategy into the observer. This modified observer uses the rotor flux calculated by the flux model instead of estimating the flux by itself. The proposed strategy can reduce effectively the estimation error. Simulation results confirm the effectiveness of the proposed strategy.