Starting Research of Brushless Doubly-fed Motor with Different Turn Ratio of Compound Coil Structure Rotor

Brushless doubly-fed motors (BDFMs) have the weakness of large staring currents and low starting torque. To overcome this starting disadvantage, a BDFM with compound coil structure rotor winding (RW) is proposed in this paper. This RW can effectively increase the starting resistance to boost the starting torque and reduce the starting current while not influencing the steady state. In addition, the influence of different turn ratios of the compound coil on the starting performance was studied, and a finite element (FE) model of a variable polarity starting BDFM was established to verify the correctness of the design.