Means of Enhancing the Power Output and Widening the Operational Frequency Band of Vibration-Based Electromagnetic Energy Harvester

PurposeThis paper presents the design, development, and performance analysis of a Two-Degree-of-Freedom Vibration-Based Electromagnetic Energy Harvester (TDOF VBEEH). The purpose is to enhance power output and widen the operational frequency band of the harvester. In the literature, various techniques such as mechanical amplification, resonance tuning, and nonlinear oscillations etc., have been explored. The proposed TDOF VBEEH incorporates a mechanical amplifier in series with a traditional Single-Degree-of-Freedom (SDOF) VBEEH.MethodsThe paper derives an analytical expression for the average power output of the TDOF VBEEH based on the principles established by Tang and Zuo. The effects of mass ratio, electrical damping ratio, and tuning ratio on the power output and effective operational frequency band of TDOF VBEEH have been studied to provide design guidelines for TDOF VBEEH. Also, the experimental analysis is conducted to examine the effects of a purely resistive load and mass ratio on the average harvested power of the TDOF VBEEH. The study utilizes a specially designed setup for TDOF VBEEH. Furthermore, by employing the method of surface plots and contour diagrams, the global optimum values of power output for the TDOF VBEEH under various electrical damping ratios and normalized excitation frequencies have been determined.ResultsThe results demonstrate that the appropriate selection of mass ratio, tuning ratio, and electrical damping ratio can enhance the power output and widen the effective operational frequency band of the TDOF VBEEH. Notably, the maximum harvested power is achieved when the electrical circuit connected to the harvester has a resistive load of approximately 1500 & omega;, which aligns with the internal resistance of the copper coil. The results show that the increased power output is attainable over a widened operational excitation frequency band compared to the traditional Single-Degree-of-Freedom (SDOF) VBEEH. From the comparison of the experimental and analytical results, it is seen that the TDOF VBEEH performs better than the SDOF VBEEH when the parameters are properly chosen.ConclusionThese findings highlight the superior performance and potential of TDOF VBEEHs over SDOF VBEEHs, emphasizing the importance of parameter selection in maximizing power output and widening the operational frequency band. Also, the findings offer valuable design guidelines for selecting system parameters when developing TDOF VBEEHs to power small electronic devices.