Wireless condition monitoring of train traction systems using magnetoelectric passive current sensors

Novel power-supply-free, surface-mount-type magnetoelectric passive current sensors were developed and integrated with a four-channel, 2.4-GHz wireless communication (transmitter and receiver) unit to form a new generation of wireless condition monitor for train traction systems. The wireless condition monitor was deployed in a field study on the East Rail Line in Hong Kong. Four pairs of magnetoelectric passive current sensors and single-channel wireless transmitters were installed, respectively, on and near the electric cables of four electric motor drives located underneath the 2nd, 5th, 8th, and 11th cars of a 12-car mainline train. The four-channel wireless receiver was housed in the driver's cab of the train to provide real-time wireless monitoring of the current signatures of the four electric motor drives due to the operation of the train traction system in steady-state and acceleration conditions. The monitored current signatures were postprocessed to obtain the distributions of the ratio of harmonic-to-fundamental current, their total harmonic distortions and power factors as well as the frequency spectra. A practical implication and correlation of the postprocessed data with the operating conditions of the train traction system was established for application of the proposed wireless condition monitor as train traction system monitor.