Diagnosis of Passing over Railway Joints and Reducing the Effects in Modern Traction Systems

This paper analyses the possibility to diagnose the disturbances due to the passage of wheels over the rail joints in a traction system and offers a solution to diminish theirs effects. This is one of the specific phenomena of railway traction associated with a sudden variation of the load torque that can lead to unfavorable effects on the traction system. Diagnosing the direct effects and taking the appropriate decision to reduce the negative effects is not a practical solution, due to the rapidity with which the variations in the friction force occur. The only way to reduce or eliminate the negative effects is the use of a closed control system with an adequate structure. The rotor flux-oriented control of the induction motor is one of the most effective vector control techniques that can be applied with good performance in electric traction. The fundamentals of rotor flux-oriented control are first pointed out, followed by the synthetic presentation of the structure of the control system, when current control of the voltage source inverter is adopted. The assessment of the control system performance when the wheels pass over the rail joints is carried out based on a dedicated Matlab-Simulink model. It is illustrated that the response of the system is very good, with superior performance both when the passage of wheels over the rail joints occurs during acceleration and in steady-state operation.