Section 14.2: Magnetomotive Forces (MMF’s) and Fluxes Due to Armature and Field Windings cont.
Stator windings can be designed to produce flux patterns in the air gap that are spatially sinusoidal ¾ and these windings can then be driven by balanced three-phase sinusoidally time- varying electric voltages/currents
The resulting sum-total mmf in the air-gap is governed by a traveling-wave equation as indicated below (and illustrated in the next slide) Fa = Fmsin(wt )cos(pq) Fb = Fmsin(wt - 120°)cos(pq - 120°) Fc = Fmsin(wt + 120°)cos(pq + 120°) F(q,t) = Fa + Fb + Fc = 1.5Fmsin(wt - pq)