Energy harvester for vehicle tires: Nonlinear dynamics and experimental outcomes

This article presents a very compact electromechanical wideband energy harvester optimized for tire applications. The device exploits an asymmetric magnetic spring to be adaptive and effective at almost any vehicle speed. The device has been simulated through an experimentally validated SIMULINK block-oriented model. The simulation takes into account nonlinear dynamic and adaptive resonant behavior of the seismic mass, electromagnetic, and magnetostatic coupling between floating magnetic mass and coils, and the transfer of the generated power to an external load by means of a nonlinear circuit interface. A particular focus on the pneumatic effect on the floating magnet has been made. A convenient choice of clearance between moving and fixed parts can be used to create an effective air brake preventing or softening shocks with end stops and to modify system dynamic. A nonlinear equivalent spring dashpot model of the pneumatic effect and a method to estimate its parameters from geometry have been proposed. An analysis of different nonlinearities of the system at different vehicle speed and a study on the combined effect of softening and hardening behavior of the device have been performed and discussed.