Linear stiffness compensation

Basic idea: improve energy conversion efficiency by compensating the stiffness of a cantilever.

Compensation of stiffness of the harvester by utilizing magnetic effects.

In particular, a linear magnetic field effect is synthesized by placing properly configured magnetic elements in the vicinity of the piezoelectric cantilever. The magnetic field produced by these elements yields a linear force with respect to the cantilever displacement that is equivalent to the negative spring element effect, thereby reducing the portion of energy stored in transducer and host structure and improving the electromechanical coupling of the system.

very good linearity of the magnetic flux density is achieved

Without stiffness compensation, the maximum power output is 14.2 .W. With the stiffness compensation scheme proposed in this research, the maximum power output is increased to 16.05 .W.

Publications:

* J. Xu and J. Tang, “Linear stiffness compensation using magnetic effect to improve electro-mechanical coupling for piezoelectric energy harvesting,” Sensors and Actuators A: Physical, 235(1), 2015.

* J. Xu and J. Tang, “Enhance piezoelectric energy harvesting by stiffness compensation using magnetic effect,” 「運動と振動の制御」 シンポジウム講演論文集 2014 (12).

* J. Xu and J. Tang, “Enhance piezoelectric energy harvesting by stiffness compensation using magnetic effect,” Proc. SPIE 8688, Active and Passive Smart Structures and Integrated Systems, 2013.