Lifetime Analysis of the Insulation System of Traction Machines Based on the Partial Discharge Behavior of Hairpin Wire Pairs and Conventional Twisted Wire Pairs

There are many investigations regarding the lifetime behavior of conventional enameled twisted wire pairs (CTP). CTPs are chosen to imitate the winding insulation of a machine with round wire winding. However, in automotive traction machines, flat wires with a rectangular cross-section (hairpins) are mostly used. Since the geometry of the wires determines the electric field distribution and its degree of non-uniformity, it has a significant effect on the partial discharge (PD) behavior. There is no detailed publication yet that compares CTPs with hairpin wire pairs (HWP) in terms of lifetime analysis at pulsed voltage with very steep switching slopes
$(^{\mathrm{d}v}/\mathrm{d}t)$
using wide band gap (WBG) semiconductor devices such as silicon carbide (SiC). The in-depth analysis will show that the PD and lifetime behavior of the HWP differs significantly from CTP.