Enhanced DC power delivery from a rotational tristable energy harvester driven by colored noise under various constant speeds

This paper investigates the DC power delivery from a rotational tristable energy harvester (TEH) interfaced with a rectifier circuit driven by colored noise. The nonlinear electromechanical coupling equation of the rotational TEH under colored noise is derived, where the mutual coupling behavior caused by the rectifier circuit is also included. Then, the analytical expressions of the joint probability density function (JPDF) and mean DC power are derived under different constant speeds by using the stochastic averaging based on energy-dependent frequency. In order to enhance the DC power delivery, the effects of colored noise, rotational constant speed and structural parameters on dynamical behaviors and harvesting performance are analyzed. The obtained results suggest that by choosing an appropriate rotational speed or electromechanical coupling coefficient, the rectified voltage can reach the maximum while the JPDF has a symmetric tristable structure. The optimal nonlinear stiffness coefficients can be obtained by adjusting the position of the magnets to maximize the DC power. Unlike the monotonically decreasing rectification efficiency, the power conversion efficiency is approximately proportional to the time constant ratio. Therefore, a proper choice of time constant ratio is very important for the optimal design of the harvester. Finally, the numerical simulation and experimental results verify the effectiveness of the theoretical analysis.