Within this paper, a comparative approach will be presented, in order to evaluate electrical machines in electrical drive trains. The selection of the machine type is an essential task for the design of drive trains. This paper contains the comparison of induction machines and permanent magnet synchronous machines, whereas the comparison follows an abstract procedure, since almost no machine parameters are given. Therefore, assumptions are made in order to reduce the complexity of the machine design equations. Due to the concluding diagram, it becomes possible to get a first impression about the torque-current characteristic of both machine types. The characteristics are proved by parameters of commercial machines.