Analysis and Suppression of EMI for Traction Control Unit Speed Sensors of CRH380BL Electric Multiple Unit

The doors of China railways high-speed 380BL-type (CRH380BL) electric multiple unit (EMU) at Changchun station in China could not be opened. It was analysed that the traction control unit (TCU) speed sensors were disturbed by the pantograph-catenary arc while lowering the pantograph. To solve this problem, firstly, the electromagnetic interference (EMI) for the second train body (02TB) of CRH380BL EMU where the pantograph-catenary is located at is tested. The results show that the intensity of EMI in space is increased significantly because of the pantograph-catenary arc. The distribution of spectrum of EMI is generally random, but the spectrum is mainly distributed in the range from 5MHz to 10MHz. Based on the test results, the coupling mechanism of EMI for the TCU speed sensor is analyzed in this paper. Then a method of nesting magnetic rings on the shielded cable is proposed for suppression of the interference. It can reduce the EMI about 8dB at the main frequency bandwidth mentioned above with 12 centimeters long Ni-Zn ferrite magnetic rings.