Loss Minimization Control for Brushless Doubly-Fed Induction Machine Based on a Unary Loss-Current Model

The brushless doubly-fed induction machine (BDFIM) experiences much losses due to its high operating slip and dual stator winding arrangement. The existing control strategies result in great variations in machine loss and are unable to achieve the minimum loss operating point. Meanwhile, it is difficult to regulate the loss accurately because of its complex relationship with the current and flux of the two set of windings. Thus, a novel loss minimization control (LMC) method for BDFIM based on a unary loss-current model is proposed in this article. First, the unary loss model is derived to represent the steady-state loss solely through the control winding <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i>-axis current, while other variables are appropriately considered as constants. Then, the LMC method by regulating the reference CW <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i>-axis current is developed utilizing the proposed unary loss model. Finally, comprehensive simulations and experiments have been conducted on a BDFIM prototype to validate the effectiveness of the proposed method. The results indicate that the method can significantly decrease the loss of the BDFIM in comparison to existing methods.