The action of the commutator is to produce a fixed spatial distribution of current directions in the armature conductors independent of shaft rotation. The field created by these currents (armature reaction) is horizontally directed and is represented by the space vector
Ia. The field established by the excitation of the stator poles is directed along the vertical axis and is represented by the space vector
λf . The electromagnetic torque may be expressed as Te = k( Ia x λf ) .
© M. Riaz