Effects of twisted windings on the impedance of e-traction drives

摘要

The increasing degree of electric power in automobiles from mild hybrids up to battery electric vehicles leads to the need for very efficient traction drives with an output of 100 kW and above. Today, most of the electric drives in this performance range can be found in residential applications, where constructed space, weight and efficiency are of minor importance. Furthermore, they are often only produced in low quantities with a high degree of manual labor. In order to meet the challenges imposed by the new trend of electromobility, the production techniques for electric drives gains further importance. The need for a high degree of efficiency at low weight whilst reducing installation space and simultaneously increasing the production volume, leads to a need for new processes. One approach to raise the efficiency of electric drives is to increase the slot fill ratio by pressing the windings which also gives the windings more stability and allows the automation of subsequent handling processes. In addition to that, the twisting of the parallel wires of the windings can reduce the negative impact of the current displacement in the slots. In order to be able to compare these newly developed, pressed windings called segmented hairpins, the measurement of the impedance is a suitable indicator. Due to the numerous variations and the complexity of the manufacturing process, the goal is to compare single coils. Since today's e-drives operate in a wide range up to frequencies about 2 kilohertz, a continuous frequency-dependent measurement is needed. This paper therefore covers the issue of quantifying influences caused by different kinds of twistings within the windings.