Stochastic dynamics and performance optimization of a bistable hybrid energy harvester with rectifier circuits

This paper investigates the stochastic dynamics and output performance of a bistable piezoelectric-electromagnetic hybrid vibrational energy harvester (VEH), which is integrated with a standard rectifier circuit and operates under Gaussian white noise excitation. Based on experimentally identified dimensionless parameters, a coupled electromechanical model is established to capture the strong interaction between the bistable mechanical motion and the electrical interface circuit. A semi-analytical solution is developed to characterize the system dynamics and output power through stochastic averaging, enabling efficient evaluation of the stationary probability density and mean electrical response. To enhance harvesting performance, a hybrid genetic algorithm-pattern search (GA-PS) strategy is employed to simultaneously optimize multiple tunable parameters, including key geometric and circuit parameters. The results indicate a noticeable improvement in energy harvesting performance under optimal conditions. Experimental investigations are conducted to examine the stochastic dynamic behaviors. In particular, the influence of key parameters, such as magnet spacing, is experimentally confirmed. The results show trends consistent with the theoretical analysis and lead to an increase in output voltage.