A Novel Near-field Based Approach for Wireless Battery Management Systems

The growing complexity and density of battery systems in electric vehicles and stationary storage applications have highlighted the limitations of traditional wired Battery Management Systems (BMS), particularly in terms of weight, wiring harness complexity, and mechanical reliability. While various wireless BMS (wBMS) architectures leveraging far-field communication have been explored, this work focuses on a novel approach based on near-field wireless coupling, exploiting magnetic coupling between a microstrip Transmission Line (TL) antenna and compact loop antennas suitable for Radio Frequency Identification (RFID) sensor tags directly embedded on battery cells. The proposed system is analyzed through full-wave electromagnetic simulations at 866.5 MHz and 2.4 GHz. The coupling between the TL antenna and the loop in free space is studied in detail via S21 parameter extraction. Simulation results show consistent and predictable coupling behavior, which is experimentally validated through measurements using a magnetic probe on a 20 cm microstrip prototype. The impact of realistic packaging conditions is also evaluated, including the presence of silicone-based dielectric foam layers between the TL antenna and the loop antennas, confirming the robustness of the coupling. Values of scattering parameter S21 across both frequency bands demonstrate compatibility with low-power wireless BMS and scalable Internet of Things (IoT) applications without the need for intra-pack wiring. This work provides key insights for the development of efficient and reliable near-field architectures as an alternative to far-field or wired monitoring systems.