Passively-switched, non-contact energy harvester for broad operational range and enhanced durability

Impact-based vibrational energy harvesters that switch passively among dynamical modes to best match the ambient conditions and perform frequency up-conversion to maximize power output can increase the operational range over which harvesters output useful power. The disadvantage of impact-based harvesting is that it can lead to premature system failure. This paper presents modelling and experimental validation of a harvester with passively- switched dynamics in which a magnetic non-contact interaction replaces the impact-based interaction of previous systems for greater robustness. A low-frequency driving beam couples to a higher-frequency generating beam via tip magnets. Simulations predict that the noncontact interaction drives a diversity of dynamical modes in which the tip of the driving beam variously is repelled from and passes the tip of generating beam. Experiments validate the predicted dynamical behaviour of the system. Output power levels are similar to predictions, with a power of 903 μW on the primary resonance at 1 g acceleration.