Improvement of the current-limiting devices of collector traction motors of direct-current electric rolling stock

Resumo

Special circuit designs making it possible to limit the current-surge amplitude are used to increase the reliability of traction motors with the voltage fluctuations under the conditions of a sharp increase of currents of the armatures. The simplest engineering solution, which entails the parallel connection of a larger capacitor to the excitation windings of the energy storage units, is imperfect, as it does not allow adjusting the excitation current. An alternative approach is proposed to provide the reliability of operation of the traction motors. The circuit designs are presented, and modelling is performed as a result of which the main characteristics and regularities of the studied designs are revealed. It is shown that the direct connection of the excitation winding to the network does not exclude current surges of the armatures, and the use of the resistors in the excitation windings is ineffective. The modelling of the processes and calculation show the feasibility of including a bypass diode and, if necessary, a reactor, as well as implementing pulse regulation of the excitation current.