Modelling and experimental characterization of an energy harvester with bi-stable compliance characteristics

This paper presents a novel design for a vibrational energy harvester. The design uses high permeability magnetic materials which brings about two key advantages. First, it gives strong coupling between the mechanical and electrical domains, thus enabling effective energy conversion. Second, it gives the device a bi-stable compliance characteristic, which gives the harvester a broad-band frequency response. An explicit analytical model is developed using a combination of experimental data and finite element modelling in order to accurately incorporate the magnetic forces. The model is then validated using dynamic tests of the experimental rig. The main features of the dynamic response of the bi-stable oscillator are highlighted and benefits discussed in the context of energy harvesting. Finally, comments are made on the relationship between the complicated behaviour resulting from the bi-stable compliance characteristic and the benefits of increased electrical coupling.