Pickup Coil Counter for Detecting the Presence of Trains Operated by Wireless Power Transfer

An axle counter is a popularly used device for detecting passing trains. They detect train wheels by the change of the magnetic field, made by the train wheels, in a receiving coil. Wireless power transfer (WPT) systems are used to deliver tractive power to electric trains by magnetic resonance. They consist of a pickup coil onboard the train, a supply coil on the track, and related trackside electronic circuits. When a WPT system is proximate to an axle counter, the magnetic field of the WPT can produce significant electromagnetic interference, significantly affecting the performance of the axle counter. Since the WPT system is an emerging power supply system for future railways, an alternative device for detecting trains is considered necessary. A novel device called the pickup coil counter (PCC) is proposed for this purpose. Unlike the axle counter, which detects the train's wheels, the PCC detects the WPT pickup coil onboard the train using a sensor coil wound around the WPT supply coil on the track and a detection circuit in trackside equipment. The operating concept of the PCC is explained. Its detection performance was evaluated by 3-D FEM simulation and experiment, and the results are presented.