Efficient Numerical Optimization of Induction Machines by Scaled FE Simulations

Abstract

In this paper a scaling methodology for the solution of 2D FE models of electric machines is proposed. This allows a geometrical and rotor resistance scaling of a squirrel cage induction machine enabling an efficient numerical optimization. The 2D FEM solutions of a reference machine are calculated by a model based hybrid numeric induction machine simulation approach. In contrast to already known scaling procedures for synchronous machines the FEM solutions of the induction machine are scaled in the stator-current-rotor-frequency-map and then transformed into the torque-speed-map. This gives the possibility to use a new time-scaling factor, that is necessary to keep a constant field distribution. The scaling procedure is validated by the finite-element-method and used in a numerical optimization process for the sizing of an electric vehicle traction drive considering the gear ratio. The results show that the scaling procedure is very accurate, computational very efficient and suitable for the use in machine design optimization.