Nonlinear Electromagnetic Vibration Energy Harvester With Closed Magnetic Circuit

A novel electromagnetic energy harvester structure with a highly efficient closed magnetic circuit is presented. An opposite polarity arrangement of a permanent magnet pair results in the maximum change of magnetic flux linkage in the solenoid when the energy harvester is in vibration. The strong coupling between the stator iron cores and the vibrating permanent magnets leads to significantly enhanced output voltage and power and a broadened operation bandwidth. Compared to open magnetic circuits, a closed magnetic circuit can effectively improve the output voltage and power. A maximum root mean square output voltage of 67 mV, a working bandwidth of 7.3 Hz, and a load power of 3.04 μW are obtained from the prototype at an acceleration of 5 m/s
²
.