Schematic diagram of a brushless dc motor

BRUSHLESS DC MOTOR

The rotor flux density distribution produced by the permanent magnets is represented by the green space vector B_r. A power-processing unit supplies three-phase currents to the stator windings in such a manner that the resultant stator current space vector I_s is 90^o ahead of the rotor flux vector. The mmf distribution produced by the stator currents flowing in the stationary three-phase windings is equivalent to that produced by Is flowing in a single sinusoidally-distributed rotating winding whose magnetic axis lines up with I_s as illustrated in this animation.

 

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