A Force-Electric Coupling Model and Power Optimization of Piezoelectric Vibration Energy Harvester

In order to overcome the disadvantages of the traditional lumped parameter model of piezoelectric vibration energy harvester( PVEH),this article presents an improved force-electric coupling model( FECM) to predict the output performances of the PVEH by considering the dynamic mode shape and the strain distribution of the bender.A dimensionless correction factor is adopted in the FECM to formulate the relationship expression between the mode shape and the vibration amplitude of the PVEH with curve fitting method.The equivalent parameters( such as mass,stiffness) of FECM are obtained by using the Rayleigh-Ritz modal analysis method,the governing motion equations and the exact analytical solution of cantilevered piezoelectric vibration energy harvester excited by persistent base motions are developed according to the elastic dynamics principle.The steady state electrical and mechanical output response expressions are derived for arbitrary frequency excitations.Finally,the optimizations of the load resistance and the output power of the PVEH are carried out and the optimized output power under short circuit and open circuit conditions are obtained,respectively.The accuracy of the output performances of FECM is identified from those of the coupled distributed parameter model( CDPM).A good agreement is found between the analytical results of FECM and CDPM,which tests the validity of the proposed FECM and can improve the predictions of output performances of PVEH.