Development and modeling of an electromagnetic energy harvester from pressure fluctuations

This paper develops a miniature electromagnetic energy harvester, which can absorb gas pressure fluctuations in industrial piping or natural environment and then supply energy to electronic devices. The fabricated prototype mainly consists of a hermetic cylindrical housing with a gas inlet, a movable magnet suspended by a magnetic spring structure, and two fixed coils. The movable magnet in the middle of the housing is utilized as a piston on which the gas pressure directly acts. Taking mechanical, electromagnetic and fluidic dynamics into account, a mathematical model of the energy harvester is developed and simulated by combining finite element method and analytical equations. Experiments under various operating conditions are implemented to verify the model and evaluate the prototype's performance. The induced peak-to-peak voltage and output power are 2.41 V and 2.01 mW when the input peak-to-peak pressure and fluctuated frequency are 81.4 kPa and 20 Hz. The power density and normalized power density of the non-optimized prototype can reach 145.08 W m−3 and 0.0219 W m−3 kPa−2 respectively, which are comparable to existing harvesters for similar applications.