The influence of saturation on eddy currents in form-wound windings of electrical machines

Electrical machines for hybrid and electric vehicles are subjected to high requirements regarding power density and efficiency. One promising technology, which offers several advantages, are form-wound windings (e.g. hairpin- and i-pin-winding). These kind of windings usually consist of preformed, rectangular bars which are inserted into the stator during manufacturing. In contrary to conventional windings the combination of comparatively large cross-sectional area and high fundamental frequencies - usually exceeding 1kHz - can lead to high additional copper losses due to eddy currents that may not be neglected during design stage. The goal of this publication is to show eddy current's influence on copper losses within form-wound windings and to identify the impact factors. It is shown, that the additional copper losses due to eddy currents can exhibit many times its equivalent DC-losses. Certain numbers of layers should be avoided due to an extraordinary increase in copper losses. In some cases material with lower electrical conductivity can be advantageous.