Chaotic behavior of new nonlinear electromagnetic microgenerator harvesting energy from mechanical vibrations

A low-frequency nonlinear cantilever-beam-type electromagnetic vibration energy harvester is analyzed. The nonlinearity brought into system kinematics by the “magnets-on-magnets” action provides approximately 20 Hz frequency bandwidth. A simulation study based on solution of coupled dynamic equations of motion and equation of electric balance shows that within major part of the bandwidth the system is capable to produces the voltage with magnitude proportional to magnitude and frequency of the excitation force. At very low frequency and large external forces it falls, however into region where it exhibits chaotic behavior. In this paper the impact of the phenomenon on waveform of the generated voltage is analyzed using the Poincare maps and spectrograms. The results prove a detrimental impact of the phenomenon on overall performance of the system. In order to avoid the chaotic operation the impact of the hard-stop barriers of relative displacement is analyzed showing rise of generated power and reduction of a low-frequency limit of the bandwidth.