| Author: | Herath Mudiyanselage, Dinusha Dilhan Nawa |
| Title: | A magnetic field energy harvester for energizing wireless sensors in electric railways |
| Advisors: | Chung, C. Y. (EEE) |
| Degree: | M.Phil. |
| Year: | 2025 |
| Department: | Department of Electrical and Electronic Engineering |
| Pages: | xvii, 117 pages : color illustrations |
| Language: | English |
| Abstract: | Advances in technology have encouraged modern railway transportation systems to adopt real-time monitoring solutions to enhance operational efficiency, reliability, and passenger safety. Among these, condition monitoring systems play a critical role by utilizing sensor networks to detect faults and degradation proactively. The accuracy and effectiveness of such systems depend heavily on the availability of comprehensive sensor data. Wireless sensor networks (WSNs) offer an optimal solution for deploying diverse amounts of sensors in remote locations, enabling wireless data transmission without extensive infrastructure. However, the large-scale deployment of WSNs faces a significant limitation due to the finite energy capacity and lifespan of conventional electrochemical batteries used to power sensor nodes. Energy harvesting techniques present a promising alternative to powering autonomous devices in WSNs by utilizing ambient energy sources to sustain their continuous operation. In electric railways, the magnetic fields generated around current-carrying conductors represent a particularly viable energy source. Unlike alternative energy sources, magnetic field energy is independent of weather conditions and can be harvested by employing non-intrusive methods without interfering with railway operations. This study presents a comprehensive investigation into the design, development, and validation of a free-standing magnetic field energy harvester (MFEH) for powering autonomous sensors and devices in WSNs deployed in electric railways. The research contributes two key advancements to the magnetic field energy harvesting field: (1) Development of a practical MFEH capable of being deployed adjacent to rail tracks while delivering sufficient power for wireless sensors, and (2) Implementation of a power management circuit that maximizes power delivery to DC loads under varying operating conditions. The design of the MFEH was optimized through parametric finite element method (FEM) simulations, focusing on optimizing core geometry and coil parameters while minimizing associated loss mechanisms. The design process incorporated strategies to minimize core losses and eddy current losses induced by proximity to ferromagnetic rail tracks. Simulation results provided critical insights into loss reduction and output power enhancement. Following the conclusions derived using simulation analyses, a prototype MFEH was fabricated and validated under AC load conditions, achieving a maximum power output of 4 W. Since WSN loads operate in DC mode, a power management unit was designed, comprising a full-bridge rectifier and a four-switch buck-boost (FSBB) converter. The conditions for maximum power extraction through the FSBB converter were derived through a theoretical analysis, which was experimentally verified through integrated MFEH system testing. The final implementation demonstrated a maximum DC power output of 3.27 W at a rail current of 450 A. The FSBB converter showcased its power management capacity by delivering maximum power output across varying load and rail current conditions by adjusting its duty cycle. This thesis successfully presents an efficient, free-standing MFEH unit developed capable of energizing wireless sensors and autonomous devices employed in electric railway applications. The study demonstrates significant improvements over existing solutions and provides actionable guidelines for further advancing magnetic field energy harvesting in railway environments. |
| Rights: | All rights reserved |
| Access: | open access |
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