Computation of Leakage Inductance of End Coils in Electrical Machines Considering Core Effects

A new analytical method is presented for computing the leakage inductance of the single-end coils of electrical machines, based on the solution of Maxwell’s equations, which considers core eddy currents. Maxwell’s equations are solved in general form in two regions: inside and outside the core, employing appropriate boundary conditions and an iteration scheme. Asymptotic methods are effectively employed for the analytical calculation of Green’s functions in both the regions. Analytical results are compared with 3-D finite-element computations. The comparison shows a close correspondence between the analytical and numerical results. Our formula is the basis for further computations of the end-winding leakage inductance of rotating electric machines.