For the determination of static and dynamic characteristics of an electric drive and the analysis of the influence of chopper voltage/current supply on the motor itself, a relatively complex motor model is required. A mathematical model is described of a dc series motor, which enables the determination of eddy current influences on the motor stray-load losses and the torque pulsations. The armature reaction is taken into consideration. Winding equivalent circuit parameters and their dependence on the motor saturation are determined by the method based on the measured winding impedance in a frequency range from 1 Hz to 10 kHz. The model is verified by comparison of the simulation results of a chopper-controlled electric vehicle drive and the results obtained by measurement on a laboratory model.