Semi-Analytical Magnetic Field Calculation for Dual-Rotor Permanent-Magnet Synchronous Machines by Using Hybrid Model

Based exclusively on the exact subdomain (SD) technique and finite-difference method (FDM), this article proposes a 2-D hybrid model (HAM) for the semi-analytical magnetic field calculation in electrical machines at no-/on-load conditions. It is applied to dual-rotor permanent-magnet (PM) synchronous machines. The magnetic field is computed by solving Laplace's and Poisson's equations through exact SD technique in all regions at unitary relative permeability (i.e., PMs, air gap, and slots) with a numerical model based on FDM in ferromagnetic regions (i.e., teeth and rotor/stator yokes). These two models are specifically coupled in both directions (i.e., r- and theta-edges) of the (non-)periodicity direction (i.e., in the interface between teeth regions and all its adjacent regions as slots and/or air gap). To provide accurate solutions, the current density distribution in slots regions is modeled by using Maxwell's equations. The finite-element analysis (FEA) demonstrates highly accurate results of the developed technique. The 2-D HAM is approximate to 6 times faster than 2-D FEA.