For the purpose of providing a much fuller analysis of electromagnetic processes in electrodynamic devices, it is necessary to carry out the calculation of electromagnetic field in movable and immovable elements of their structure taking into account coordinate systems of moving and stationary items. Besides, another important problem while developing mathematical field models of electric devices consists in the reproduction of the mode of given voltages rather than currents, as the currents in windings are the result rather than the cause of the general electromagnetic phenomenon. In most scientific works dedicated to the calculation of electromagnetic field in movable media the difference between reference systems in which the process is considered is not taken into account while the mode of given currents is used. That fact causes errors in the results obtained from the analysis of real physical phenomena in the devices. In this paper, 2-D mathematical field models for calculating a quasi-stationary electromagnetic field in the cross-section of a turbogenerator at no-load with an equivalent rotor zone at the given voltage of the excitation winding have been developed. The models suggested provide the calculation of an electromagnetic field in all zones of the device on the basis of a vector potential in both a single system of coordinates of the moving rotor, and coordinate systems of the rotor and stator simultaneously. The results of computer simulation of the electromagnetic processes on the basis of the developed models show that while developing mathematical models of electrodynamic devices, it is necessary to consider the coordinate systems in which the calculation of electromagnetic phenomena is performed. In addition, the character of electromagnetic processes occurring in real structures of the object cardinally differs from those obtained on the basis of equivalent schemes of the device zones.

- Ya.V.Kovivchak,
**“**Features of the calculation of the electromagnetic field in moving environments”,*Elektrichestvo*, no., pp. 59-62, Moscow, Russia: “Znak” Publishing house, 2004. (Russіan) - Ya.V.Kovivchak, “Definition of boundary conditions in the spatial problems of electrodynamics”,
*Elektrichestvo*, no. 8, pp. 66-74, Moscow, Russia: “Znak” Publishing house, 2009. (Russіan) - Ya.Kovivchak, “Calculation of electromagnetic processes for a turbogenerator with equivalent stator and rotor tooth zones in no-load regime”,
*Computational Problems of Electrical Engineering*, vol. 2, no. 1, pp. 169-170, Lviv, Ukraine: Lviv Polytechnic National University, 2012. (Ukrainian) - E.Kazan and A.Onat, “Modeling of Air Core Permanent-Magnet Linear Motors with a Simple-Field Nonlinear Magnetic Analysis”,
*IEEE Transactions on Magnetics*, vol. 47, no. 6, pp. 1753-1762, June 2011. - S. A.Saied, K.Abbaszadeh, and M.Fadaie, “Reduced Order Model of Developed Magnetic Equivalent Circuit in Electrical Machine Modeling”,
*IEEE Transactions on Magnetics*, vol. 46, no. 7, pp. 2649-2655, Jule 2010. - B.Shekh-Ghalavand, S.Vaez-Zadeh, and A.H. Isfahani, “An Improved Magnetic Equivalent Circuit Model for Iron-Core Linear Permanent-Magnet Synchronous Motors”,
*IEEE Transactions on Magnetics*, vol. 46, no. 1, pp. 112-120, January 2010. - J.Faiz, M.Babaei, J.N.Zadeh, B.M.Ebrahimi, and S.Amini, “Diagnosis and Magnetic Field Analysis of Small Power Sailent-Pole Synchronous Generator with Static Eccentricity Using Time-Stepping Finite-Element Method”,
*Electromagnetics*, vol. 31, Issue 3, pp. 173-191, April 2011.