Improving the energy efficiency of electric drives for auxiliary units of traction rolling stock

Abstract

The review of technical solutions and schematic characteristics of auxiliary drives for traction vehicles has shown that the most rational variant is an electric drive with an induction machine. Given the operating modes of the auxiliary drives and the share of their power consumption in the total locomotive power, the task of using scalar control systems for induction machines becomes relevant. Based on a mathematical model describing the dynamic energy conversion processes in the T-shape substitution circuit of an induction motor, taking into account stator steel losses and current displacement effects in the rotor winding and saturation along the main magnetic path, possibilities for reducing stator current have been investigated. In order to improve the energy efficiency of electric drives two variants of control system have been proposed. One based on search method of self-tuning to the stator current minimum and the other - on maintaining the power factor of induction motor at the level that ensures equality of active and reactive components of stator current. The hardware and software requirements for implementing control systems have been analysed. Modelling using Matlab has shown that both control systems work - power loss reduction can be as low as 50% and as high as 60% in certain modes.

Modeling of energy-efficient direct torque control system for traction induction motor

“…In [19], a system is proposed, which is operable in the whole range of resistance torques (at torques higher than the rated value, loss reduction is possible only at reduced stator current frequencies, which fully corresponds to the working conditions of traction electric drive). It has similar requirements to the system [18] for hardware and software implementation but contains an additional stator winding voltage source, which forms a triangular signal, which leads to deterioration of harmonic composition of current and, consequently, torque, which can be critical when implementing traction electric drive control systems with anti-slip protection.…”