Development of a multi-pitch unequal-turn-coil wound rotor for the brushless doubly-fed generator

Since the rotor winding (RW) of the Brushless Doubly-Fed Machine (BDFM) needs to be designed to couple the magnetomotive forces (MMFs) generated by the power winding (PW) and the control winding (CW), it is difficult to control the harmonic contents in the RW of the BDFM. Based on the principles of tooth harmonic and sinusoidal winding structure, a multi-pitch unequal-turn-coil wound rotor of the BDFM is presented in this paper to reduce the harmonic contents and improve the conductor utilization ratios of the RW effectively. The steady-state performance of a 100 kW generator with proposed wound rotor is analyzed by the simulation. Simulation results are presented to show the validity of new rotor structure. It is concluded that proposed wound rotor can provide a new method for the rotor design of the BDFM.