Analytical calculation of d- and q-axis synchronous reactances of homopolar inductor alternator

In this paper, the d- and q-axis synchronous reactances of homopolar inductor alternator (HIA) are calculated. First, an approximate 2D model of HIA is developed and its relative air-gap permeance function is described. The harmonic amplitudes of the per-unit quantity of relative air-gap permeance function are determined by 2D finite element analysis (FEA). Then, the analytical expressions for the synchronous reactances in the direct-axis (d-axis) and quadrature-axis (q-axis) are derived from magnetomotive force (MMF)-relative air-gap permeance function theory, including armature reaction reactance and armature leakage reactance. Finally, theoretical results are compared with the simulation and experimental results.