Повышение надёжности приводных асинхронных машин на электроподвижном составе

Abstract

The problem of failures of traction machines used in the electric rolling stock (ERS) is considered. In the course of ERS operation with microprocessor control and the use of electric drives with semiconductor converters and induction traction motors (ITMs), it is observed that the service life of bearings reduces from the 2 million km declared by the manufacturer, to 200-600 thousand km. The study of bearings shows the following types of damage: dulling of rolling elements and tracks of the outer and inner rings, grooving, and lubricant degradation. An analysis that was carried out shows that in the majority of cases, the bearings fail as a consequence of a current flowing through them. The currents flowing through bearings are generated due to different mechanisms. A classification of bearing currents is proposed, and possible current flow loops are analyzed. Based on an analysis of literature sources, methods for reducing the bearing currents are given, and their effectiveness is evaluated. To enhance the ITM reliability, several measures to prevent electric current from passing through the bearings have been developed, including the method of plasma deposition of aluminum oxide on the outer ring, which insulates the bearing outer ring from the motor body, and hybrid bearings with ceramic rolling bodies. To select the optimal solution and determine the difference between the outer ring insulation concept and the hybrid concept, operational tests were carried out. Conclusions have been drawn about the expediency of using hybrid bearings with rings made of bearing steel and rolling elements made of bearing silicon nitride (Si3N4).