Design of a Vibration Energy Harvester Powered by Machine Vibrations for Variable Frequencies and Accelerations

A vibration energy harvester (VEH) based on the principle of variable magnetic reluctance has been developed to enable wireless and maintenance-free power supply for condition monitoring sensors in vibrating machinery. Conventional battery or wired solutions are often impractical due to limited lifetime and high installation costs, motivating the use of vibration-based energy harvesting. The proposed VEH converts mechanical vibrations into electrical energy through the relative motion of a movable ferromagnetic core within a magnetic circuit. Unlike conventional VEH designs, where the magnet is the moving element, this concept utilizes a movable ferromagnetic core in combination with a stationary pole piece for voltage induction. This configuration enables a compact and easily adjustable proof mass, as neither the coil nor the magnet needs to be moved. The VEH is designed to operate effectively under excitation frequencies between 16 Hz and 50 Hz and acceleration levels from 9.81 ms2 (equivalent to 1 g) up to 98.1 ms2 (equivalent to 10 g). To ensure a reliable power supply, the VEH must deliver a minimum electrical output of 0.1 mW at the lowest excitation (1 g) while maintaining structural integrity. Additionally, the maximum permissible displacement amplitude of the movable core is limited to 1.15 mm to avoid mechanical damage and ensure durability over long-term operation. Coupled magnetic-transient and mechanical finite element method (FEM) simulations were conducted to analyze the system’s dynamic behavior and electrical power output across varying excitation frequencies and accelerations. A laboratory prototype was developed and tested under controlled vibration conditions to validate the simulation results. The experimental measurements confirm that the VEH achieves an electrical output of 0.166 mW at 9.81 ms2 and 16 Hz, while maintaining the maximum allowable displacement amplitude of 1.15 mm, even at 98.1 ms2 (10 g) and 50 Hz. The strong agreement between simulation and experimental data demonstrates the reliability of the coupled FEM approach. Overall, the proposed VEH design meets the defined performance targets and provides a robust solution for powering wireless sensor systems under a wide range of vibration conditions.