Increasing the Energy Efficiency of Induction Machines by the Use of Grain-Oriented Magnetic Materials and Die Casting Copper Squirrel Cage in the Rotor

This paper deals with an induction machine whose squirrel cage is made of copper obtained by a die casting process. The major issue of this process is the thermal shock suffered by the laminations, leading to the deterioration of insulation coating as well as the generation of interbar currents, those currents being responsible for addition stray losses. This issue can be counteracted by using grain-oriented (GO) laminations on the rotor. In particular, the paper highlights that due to the specificity of the insulation coating of that kind of electrical steel, it does not suffer from the thermal shock. It is shown that using a squirrel cage made of copper combined to GO laminations in the rotor leads to a decrease of both core losses and stray load losses and an increase of the efficiency of 1.6%.