This article describes simulation problems of hybrid excitation generator. As an example a conceptual prototype machine is build with two parts. One part of the machine is typical synchronous permanent magnet generator (with surface mounted magnets on rotor). The second part of machine has rotor with rotating-coil excitation. Both parts are integrated. Rotors are seated on a common shaft and stator is also common (the same) on whole length of both rotors. Article shows the problems of theoretical solving of electromagnetic circuit for this machine type. Main problem is regulating of excitation flux what Oyes directly problem with valuation of inducted voltage and power factor. There are three different methods used by authors to examine prototype of hybrid generator. In this article authors present a model of generator prepared in Ansoft Maxwell V.11. Pictures of machine intersections in different planes are presented.