Theoretical benefits of powder-coating based insulation layers regarding copper fill factor in electric drives

Abstract

Power density is a crucial requirement factor regarding high power traction drives for automotive application. As battery capacity is one of the most limiting factors regarding range of current electric vehicles, output efficiency in relation to package size is one of several levers to extend existing limitations. Within electric drives, efficiency is linked to the copper mass being implemented into the active components. The presented paper evaluates the possibility of expanding copper fill factor by the use of higher grade - and thus thinner - electric insulation materials. By using powder coatings with breakdown voltages superior to existing NMN and NKN laminates usually used as groundwall insulation system in electric drives, insulation layers can be reduced in size leaving more room for magnet wires. With regard to existing stator layouts and topologies, multiple slot cross sections are evaluated. Results show an increase of the electric copper fill factor by up to 13%, which leads to higher output or the possibility to reduce package size and mass without sacrificing output power.