An Improved Direct Decoupled Power Control of Doubly Fed Induction Machine Without Rotor Position Sensor and With Robustness to Parameter Variation

In this paper, coupling between active and reactive powers in conventional direct power control (DPC) strategies is analyzed and a new direct DPC method for doubly fed induction machine without rotor position sensors is presented. Coupling analysis is done on an improved DPC strategy with rotor flux controllers in the stator reference frame. The presented control strategy is done by controlling the rotor flux in the grid flux reference frame. The rotor flux command is calculated using a predicted stator flux, the stator current command, and the stator resistance. Moreover, the rotor position is estimated by comparing measured and estimated values of the rotor current. Furthermore, to reduce the method´s sensitivity to the parameter inaccuracies, the mutual inductance of the machine is updated during the machine operation by the error between the magnitudes of the measured and estimated values of the rotor current.