Theoretical and experimental investigations of a non-linear single degree of freedom electromagnetic vibration energy harvester

There is an increasing need for sensors to be self-powered and hence autonomous in order to operate in remote and inaccessible locations for long periods of time. Amongst the various ambient sources of energy, mechanical vibration is a viable wasted source of energy and can be found in rotating equipment including generators, motors and compressors as well as structures including bridges. The current research deals with developing a novel non-linear single degree of freedom electromagnetic vibration energy harvester using spatial variation of the magnetic field. Initially, approximate linear methods using Laplace transforms and the linear state space methods were considered, where the magnetic field and hence the coupling coefficient were considered as constants. The linear methods were used to derive the frequency response behavior of the system and also its eigenvalues to determine the approximate resonant frequency range. This was followed by more accurate non-linear single degree of freedom electromagnetic energy harvester model simulation considering the spatial variation of the magnetic field and hence a spatially varying coupling coefficient. An experiment of the single degree-of-freedom one-direction electromagnetic vibration energy harvester (SDOF1D EMVEH) prototype was conducted for a range of frequencies to obtain the time domain data to validate against the theoretical data obtained from theoretical time domain simulation.