Large DC machines with the slotless armature

A series of large DCV slotless machines manufactured by SKODA for rolling mill applications is special in that its design had to incorporate requirements for similar operating characteristics as these of classical DC machines. Particular attention was given to decreasing the additional losses in the active conductors of the armature while maintaining high magnetic flux and current densities, to minimize the excitation magnetomotive force and to suppressing the commutator bar voltage ripple by special design of the double parallel lap winding of the armature. Before the actual design started, the methods of solution including computer programs had to be elaborated for the calculation of magnetic fields