Application of a shunting discharge arm based on fully controllable semiconductor devices in an ac-wire dc-motor electric locomotive power circuit in a regenerative braking mode

The article presents results of analytical-and-mathematical research into application of a shunting discharge arm based on modern fully controllable semiconductor devices in order to optimize power converter thyristor arms control and AC locomotive  electric energy efficiency increase. The discharge arm is installed into the power circuit’s DC subcircuit in parallel with the cathode and anode buses of the converter and acts as an alternative current route, allowing one to implement a swift turn-off of thyristor arms at the end of their work cycle. The Introduction gives a description to the problem in question. The first section of the article offers a brief history reference citing predecessor engineering solutions reflected in domestic patent publications. Achieved results are listed, as well as drawbacks caused by objective technical limitations. The second section describes the suggested converter thyristor arms control method defined by application of an IGBT-based discharge arm, demonstrates electromagnetic processes occurring in the electric locomotive power circuit in a form of an analytical diagram and presents the complete chart of control impulses for the new control algorithm. The third section visualizes results of mathematical simulation of the engineering solution in a comprehensive “traction substation – overhead line – electric locomotive” system in MATLAB Simulink environment. Simulation results support the conclusion of the full working capability of the suggested control method, as well as its achievement of significant increase in the locomotive’s regenerative braking mode power factor within full range of voltage (i. e. speed) regulation.