Qualitative Estimation of Energy Conversion Efficiency of Winding Schemes for Electrical Machines

The demand for highest energy conversion efficiencies of electric machines and drives is steadily increasing caused by the ever-reducing resources of gas, oil and coal, and the different political policies to preserve the nature and to reduce the emission of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{CO}_{2}$</tex>. The winding design of an electric machine has a huge influence on the energy conversion efficiency, but the characteristics of the different winding schemes are only seldom analyzed and investigated only on a mathematical basis prior to numerical magnetic field analysis. In this manuscript different winding schemes will be analyzed only on the spectral content of their local current linkage waves or magneto-motive force (MMF) waves. Two novel qualitative measures (energy conversion efficiency, rotor loss density estimate) will be suggested based on the winding spectra to describe and judge both the different aspects of the electromagnetic energy conversion process in an electrical machine without the need of time-consuming electromagnetic finite element analysis. Both qualitative measures will be compared to the results from electromagnetic finite element analysis taken from the literature to prove their validity and their useful applicability.