Coupling Coefficient Analysis and Experimental Evaluation of Dynamic Wireless Power Transfer for Battery-Electric Locomotives

Wireless power transfer (WPT) offers a promising solution for continuous and contactless energy delivery to battery-electric locomotives (BELs). It enables in-motion charging, which can significantly reduce the need for prolonged static charging sessions and allow for smaller onboard battery capacities. This paper presents a dynamic wireless power transfer (DWPT) system specifically designed for BEL applications, employing a parallel synchronized multiple LCL-S compensation topology operating at a switching frequency of 85 kHz. A method for calculating the dynamic coupling coefficient$k$is proposed to model the time-varying magnetic coupling during motion. To validate the system, a prototype incorporating three transmitters (Txs), one receiver (Rx), and a W-I-shaped magnetic coupler is developed and tested. During static charging, the experimental results demonstrate a peak DC-DC efficiency of 94.73% at 3.1 kW input power, with over 92% efficiency sustained across a wide range of input voltages and output load resistances. During dynamic charging, the system maintains a stable efficiency with the maximum value of approximately 89%. These results also show agreement with theoretical predictions, validating the system's performance and robustness.