Calculation of the electromagnetic characteristics of an electrically excited synchronous motor for an EV

This paper depicts an analytical way for calculating the electromagnetic characteristics and the no-load iron losses of an electrically excited synchronous traction motor with salient poles for an electric vehicle (EV). The calculations are applied on a machine design, of the Department of Electronic and Electrical Engineering of the Pohang University of Science and Technology (POSTECH), Korea. The calculation of the winding parameters such as the coil length, the resistance per phase including the current displacement effect at high frequencies in the stator winding and the stray reactance as well as the rotor pole stray flux are discussed. The magnetic characteristic is calculated, leading to the no-load and the short-circuit characteristic of the machine at a certain frequency. The analytical results are compared with numerical results, obtained by the Finite Element Software JMAG. The last part is about the analytical calculation of the no-load iron losses using the methods of Bertotti and Steinmetz. Here also a numerical result is used as a validation of the analytic approach.