Distribution of electromagnetic forces in separately excited dc and ac induction machines

this paper provides an in-depth analysis of distribution of the electromagnetic forces in separately excited dc and ac squirrel cage induction machines. Investigation of local forces acting on the stator and rotor core and windings will shed light on inherent similarities in the mechanism of force generation in two families of electrical machines. This paper also provides a physically insightful explanation of the impact of armature and field currents (quadrature and direct component of current in induction machine) on radial and tangential components of the magnetic forces.