Abstract

Introduction: A 3D chip-scale solenoid coil was fabricated by micro-electro-mechanical system (MEMS) and wafer-level micro casting technology, and an electromagnetic vibration energy harvester was manufactured with an NdFeB permanent magnet.

Methods: Three coils with different turns were designed, namely 45 turns, 90 turns, and 150 turns. The coils had a wire width of 40 microns, a pitch of 25 microns, and a thickness of 150 microns. The permanent magnet was cylindrical with a diameter of 1.8 mm. According to the length of the coil, three specifications of 3/6/10 mm were selected for the permanent magnet. Special PCB circuit testing tooling was processed to test the actual performance of three kinds of permanent magnet energy harvesters with different specifications.

Results: The vibration frequency was set to 10 Hz~150 Hz, and the acceleration was designed to be 50 m/s²~300 m/s^2. For the energy harvester with 90 turns, a maximum output power of 75 μW was obtained under vibration conditions of 100 m/s² & 30 Hz. The experimental data showed that vibration frequency, acceleration, and sample size had a certain influence on the energy conversion and output power of vibration.

Conclusion: Through the above study, the design and performance of vibration power generation devices can be optimized better to match the actual application requirements of rail transit.

Keywords: Rail transit, micro casting, chip-scale coil, electromagnetic vibration energy harvester, vibration frequency, vibration acceleration, output power.