In this paper, an asynchronous operation mode of brushless doubly-fed machine (BDFM) with negative pole-pairs is introduced based on the principle of field differential modulation. The machine has the characteristics of negative pole-pairs under the magnetic field modulation of the specially designed rotor. This means that the rotor can rotate in reverse and operate stably when the three-phase positive sequence voltage is applied to the stator power wingding (PW) end of the machine. The electromagnetic braking torque of the traditional induction motor becomes the driving torque in BDFM with negative pole pairs. This paper first analyzes the reasons for the phenomenon of negative pole-pairs, calculates the asynchronous torque, then analyzes the influence of different factors on the starting torque, and finally validates its rationality through finite element simulation.
 

BDFM,negative pole-pairs,differential modulation,torque,MMF