Analytic examination of coupled axial-flux induction machines with reduced yoke

This paper presents an analytical method for describing a stack of two partial machines built out of single-stator axial-flux induction machines with squirrel cage. First, the principal design possibilities for axial-flux induction machines are discussed. Afterwards, the variations when arranging them in a stack by reducing the rotor yoke are explained and the consequence for the magnetic fluxes are shown. As a next step, the system equations are deduced from the current sheet theory, where the current sheets and the magnetic flux densities of all partial machines are calculated, depending on the amount of the rotor yoke reduction. Also the equations of the self and mutual-inductances are presented. At last, the influence on the operating behavior is described and shown by some simulations results.