Modelling and simulation of a simple homopolar motor of Faraday's type

During the application of simulation tools of computational electromagnetics it is sometimes difficult to decide whether the problems can be solved by the computation of electromagnetic fields or circuit simulation tools have to be applied additionally. The paper describes a typical situation in an electromagnetic CAD course, not only for beginners. The modelling and numerical simulation of a simple homopolar motor, similar to that what has been presented by Michael Faraday in 1821 firstly, was used as an example. To simulate the current flow in the permanent magnet the FEM software codes COMSOL Multiphysics including the integrated SPICE module and MAXWELL have been used. The correct simulation of the entire electric circuit as well as the precise modelling of the impressed current and of the electrode contacts turned out to be very important.