Magnetic Field of a Rectangular Commutating Pole

Mathematical investigation of flux density on armature surface is described. The actual profile of the space between stator and rotor has been simplified by assuming a rectangular commutating pole (compole), a straight armature surface, and a straight main-pole side. The magnetomotive force (mmf) of the compole coil is assumed as caused by a thin current layer with constant linear current density, extended between two arbitrary points on the compole sides. The distribution of the armature mmf is assumed to be arbitrary over the commutating zone and uniform outside it.