Power Control of a Doubly-Fed Induction Machine via Output Feedback

A new output feedback control algorithm for a Doubly Fed Induction Machine (DFIM) is presented. The asymptotic regulation of active and reactive power is achieved by means of direct closed loop control of active and reactive components of the stator current vector, presented in a line-voltage oriented reference frame. To get the maximum generality of the solution, the usual assumption of negligible stator resistance is not made. A full order DFIM model is used for the control algorithm development. The proposed control system is robust with respect to bounded machine parameter variations and errors on rotor position measurement. In the paper it is also shown how the proposed current control algorithm can be modified in order to achieve asymptotic active current tracking and zero reactive current stabilization during steady state. An extension for the speed control objective and output EMF control during the excitation synchronization stage are also presented. Simulation and experimental tests demonstrate high dynamic performance and robustness of the control algorithm for typical operating conditions. The proposed controller is suitable for both energy generation and electrical drive application with restricted speed variation range.