Electrical Machines: Comparison of Existing Analytical Models and FEM for Calculation of Turn-to-Turn Capacitance in Formed Windings

Calculation of turn-to-turn capacitance (C-tt) in electrical machines (EMs) with formed windings is presented in this paper for rectangular and round crosssection wire. Variation of C-tt with wire/coil properties in formed windings and deviation between analytical methods (AMs) and finite element method (FEM) have not been presented until now. This dearth in publications, necessitates this comparison between methods for C-tt calculation in formed windings. As such, three calculation methods are used in this paper for the calculation of C-tt in case of rectangular conductors: an FEM and two previously published AMs. The influence of wire thickness and wire corner radius on C-tt is investigated. For round cross-section wires, four methods are presented: an FEM and three different AMs. The influence of wire size, insulation thickness and relative dielectric constant of the wire insulation on C-tt are considered. The relative error, i.e. deviation among the methods applied is presented for both types of wires. Finally, the results presented here demonstrate that the method for C-tt calculation should be carefully considered for different cases, since the wrong selected method can result in a deviation of even 400%.