A model of a silicon-controlled rectifier (SCR) dc-series wound motor drive is described and evaluated. The model, developed for use in a digital simulation of an electric vehicle (EV), requires a minimum number of input parameters while taking into account the fluctuating nature of the flow of motor current. The equations derived are solved explicitly for motor current, thus giving an efficient computer implementation. The control input to the model is the duty cycle of the switching waveform to the SCR. The output from the model is average motor torque. The results are valid over the ranges of frequency and duty cycle typically used in EV motor drives. A generalized formulation, which will accept a nonlinear magnetic flux characteristic, is derived and applied in the simulation of an EV driven by a 42-hp dc traction motor. All relevant simulation model parameters were taken from an EV used in a series of field tests. Experimental measurements of motor current demand over a complex driving cycle were compared with a corresponding set of simulation results. Agreement between the two sets of results was found to be good. © 1984, IEEE.