Replacing Copper With Aluminum in Hairpin Windings Motors Intended for Utility Cars

Abstract

Along with efficiency and torque density, one of the key design objectives in today's traction electric machines is sustainability. This is especially true in the automotive segment, where a transition to electrification is occurring. A sustainable electric machine design implies the reduction of high environmental impact materials, such as copper for the windings or rare-earth materials for the permanent magnets. To this end, this study analyses the adoption of aluminum to replace the hairpin windings of an automotive 400 V interior permanent magnet machine, originally optimized with copper windings. First, a detailed optimization process for a copper-based motor is carried out, adopting a multiobjective genetic algorithm. Consequently, the efficiency map of the resulting design is compared to its aluminum-based version, which is directly obtained by changing the winding material. To validate the simulation and optimization trends, a copper-based prototype and its identical aluminum version are built and tested, and their efficiency maps are comprehensively compared and discussed.