Study of the Cascaded Doubly Fed Induction Machine Dynamics Under Vector Control

Abstract

Brushless Doubly-Fed Induction Machines (BDFIM) present many industrial advantages due to the lack of brushes. A foreseen major application is for Wind Power Generation in substitution to the well known and used Doubly-Fed Induction Generator (DFIG). The Cascaded Doubly Fed Induction Generator (CDFIG), composed by two Doubly-Fed Induction Machines (DFIM), can be used as starting point to the study of BDFIM and is the object of the present paper. The dynamic model and vector control of the CDFIG will be discussed. The reference frame is given by the stator flux of the power machine. The proposed control has a cascaded structure, with internal current loop and two different possibilities of external control loop: speed control or power control. In both cases the reference is given by a Maximum Power Point Tracking (MPPT) scheme and the reactive power reference is established in accordance with the requirements of reactive power compensation. Experimental results are presented to validate the proposed methodology.