Mulitphysical Simulation improves Engineering of Electric Drives

In many electric drive applications - especially road and rail vehicles - dimensions and weight of the electric machine are crucial factors. Taking the time varying load conditions of such drives into account, fast and accurate prediction of the machine´s electro-mechanic and thermal behavior over a given load cycle is essential to achieve a design that is neither too small nor too large; these results are desired in an early phase of the drive´s engineering process. Additionally the cooling method is limited by the application´s specification, influencing the thermal behavior respectively the utilization of the machine´s active part. To support the design engineer, both an electro-mechanical model - taking all loss sources into account - and a thermal model - considering the cooling method - have been developed. For this challenging multiphysical modeling task, the object oriented modeling language Modelica is used. The main focus of the presented models is extensibility, easy adaption for different cooling methods, satisfying accuracy and performance of the simulation. To validate the developed models, simulation results are compared with measurements of a 4-pole standard induction motor 400 V / 50 Hz, 18.5 kW, totally enclosed fan cooled (TEFC). The drive is tested under varying load conditions, monitoring electrical, mechanical and thermal quantities.