Electrostatic energy harvesters and fundamental limits to power

Abstract

Analysis of fundamental performance limits to vibration energy harvesting reveal how damping and electromechanical coupling affect performance both for narrow and wide-band excitations. This talk summarizes the performance limits and presents examples of how electrostatic energy harvesters should be made to perform close to the fundamental limits. It is demonstrated how the overwhelmingly dominant contribution to loss, gas damping, can be understood and limited in an electrostatic harvester. It is seen that for wide-band noise excitations, minimizing loss and maximizing coupling largely suffice to approach the fundamental limits closely. For narrow band harvesting, a successful reduction of damping in a design can make optimization complicated because proof mass displacement increases and displacement limitations become important. Performance optimization then also involves adjusting the electrical load and the mechanical stiffness when the acceleration amplitude changes. Approaches to optimize performance are presented and discussed.