Automatic Control System for Currents of AC Locomotive Collector Traction Motors with Controlled Excitation Converters

This paper examines an automatic current control system for commutator traction motors of AC electric locomotives with controlled bridge transistor IGBT converters shunting the excitation windings of electric motors. This system enables the implementation of traction characteristics for independent and series excitation of motors, as well as axle-by-axle and bogie-by-bogie control of the locomotive’s traction force. A mathematical model of the traction motor is proposed that takes into account the nonlinearity of the magnetization curve and separately accounts for eddy currents generated by the main pole winding, as well as the windings of the auxiliary poles and compensation windings. Calculations of electromagnetic, electromechanical, and mechanical processes occurring during starting and accelerating the electric locomotive with a freight train confirmed the effectiveness of the proposed automatic traction motor current control system.