Analytical prediction of armature-reaction field in disc-type permanent magnet generators

A two dimensional (2D) analytical method to predict the armature-reaction field in the slotted opening airgap/magnet region of a permanent magnet (PM) disc-type generator is presented. The currents in the slot are modeled by a uniform distributed current sheet along an arc at the slot opening. The analysis takes into account the harmonics in the armature current waveforms which are calculated from the voltage equations. The effects of the stator slot openings are being accounted for by the introduction of a 2D relative permeance function which is calculated directly from the nonlinear equation described by conformal transformation. A more refined permeance distribution can then be obtained easily.