FLUX PLOT
A rotating sinusoidally distributed winding is excited with
a constant current. The flux plot in the air gap also rotates. Where the lines
are crowded, the corresponding magnetic field density B is high, and where the
concentration of lines is reduced so is B. Thus the air gap B-field is
sinusoidally distributed in space and is also rotating. It can be represented by
a rotating space vector of constant magnitude pointing to where the field is
maximum positive.