Analysis and Optimization Measures for Overtemperature Fault of EMU Traction Motor Bearings
In view of the frequent occurrence of bearing overtemperature alarm faults of the traction motor of an electrical multiple unit(EMU)platform,an analysis was conducted on the causes of bearing overtemperature faults.According to the two types of fault characteristics of grease overtemperature deterioration and bearing electrical corrosion,the fault causes of unbalanced power distribution,excessive bearing voltage and low insulation capacity were determined.Based on the study of the influencing factors such as the motor power difference,the EMU grounding mode and the thickness of bearing insulation coating,the causes and mechanisms of bearing overtemperature faults were clarified.The results indi-cate that the slipping or spinning of some wheels of a train driven by vehicle control will cause overloading,heating up,and accelerated grease aging of other motors.The shaft voltage of the traction motor generated by the switching overvolt-age is related to the grounding position and loop parameters,and the difference in shaft voltage can be up to twice under the different grounding schemes at different positions.Under high shaft voltage,insufficient thickness of bearing insula-tion coating will lead to insulation breakdown,causing damage to the bearing by shaft current,until eventual abnormal wear and overheating of bearings.The corresponding solutions for optimizing control logic,train grounding methods,and insulation coating thickness were proposed,providing optimization solutions for safe train operation.
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