Analytical Determination of Slot Leakage Field and Inductances of Electric Machines With Double-Layer Windings and Semiclosed Slots

Slot leakage field and inductance computation are, in general, nontrivial tasks in the analysis of electric machines equipped with semiclosed slots, even under the hypothesis of neglecting magnetic saturation. This paper proposes an analytical method to evaluate the slot leakage field and inductances in dual-layer distributed winding machines, extending the results of a previous work where the single-layer winding design was addressed. A direct solution to Poisson's differential equation in the slot domain is found by suitably defining boundary conditions in the slot opening area. Boundary conditions are defined exploiting the analytical form taken by the magnetic field in the neighborhood of ferromagnetic corner-shaped regions. The presented approach is successfully validated against finite element simulations.