Theory-alternating-current-machines-alexander-langsdorf-pdf

For three-phase currents ( i_a = I_m \cos(\omega t) ), ( i_b = I_m \cos(\omega t - 120^\circ) ), ( i_c = I_m \cos(\omega t - 240^\circ) ) in windings spaced ( 120^\circ ) apart, the resultant magnetomotive force (MMF) is: [ F(\phi, t) = \frac32 F_\textmax \cos(\omega t - \phi) ] where ( \phi ) is the spatial angle. This represents a wave traveling at angular velocity ( \omega ).

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