Thyristor Converters for Traction DC Motor Drives

Based on tests in laboratories and on German Federal Railways (GFR) trial vehicles type ET 25 as well as on an industrial locomotive type 500 of the Rheinische Braunkohlen AG the subsequent development has been concentrated on the improvement of the power factor ¿ and the displacement factor cos ¿ in four vital stages: 1) introduction of half-control, unsymmetrical half-controlled, fully-controlled single-phase bridge connection with specially designed control systems: 2) introduction of sequence connection of several half-controlled bridges; 3) optimization of the so far applied connections for major assemblies such as rectifier transformer, rectifier, and smoothing reactor for improving the power factor; 4) introduction of sector control with self-commutating unsymmetrical bridge for improving the power factor.