Electrostatic energy harvesters and fundamental limits to power

Einar Halvorsen

doi:10.1088/1742-6596/1052/1/012004

Einar Halvorsen

Open Access

https://doi.org/10.1088/1742-6596/1052/1/012004

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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.

Highlights

A successful reduction of damping in a design can make optimization complicated because proof mass displacement increases and displacement limitations become important
Ever since microscale vibration energy harvesting was proposed as a solution to power wireless microsystems [1, 2], there has been much focus on how much power can be obtained and how to do it
This is always a pertinent question for a power system, but it is pressing in this case since the devices are driven by inertia so that minimizing size reduces proof mass and the excitation force

Summary

Introduction

Ever since microscale vibration energy harvesting was proposed as a solution to power wireless microsystems [1, 2], there has been much focus on how much power can be obtained and how to do it. Analysis of fundamental performance limits to vibration energy harvesting reveal how damping and electromechanical coupling affect performance both for narrow and wideband excitations. It is demonstrated how the overwhelmingly dominant contribution to loss, gas damping, can be understood and limited in an electrostatic harvester.

Results

Conclusion