With the advent of ultra-low power sensor packages, there is renewed interest in harvesting vibration energy to power them, thus creating a self sustaining battery-less sensor system. The optimal algorithms previously developed in literature to harvest vibration energy are complex and hence require controllers that consume a significant amount of power. The relatively high power requirement combined with the inherent complex design of these algorithms would also limit them to only applications in which sustained vibration energy is available for harvesting. To address these issues, this paper presents new control systems to optimize the amount of energy harvested from short duration vibrations. Only algorithms that can be implemented using simple ultra-low power analog electronic components are considered. The first algorithm termed ?fixed threshold switching?, has been adapted from literature on harvesting energy from sustained vibration. The second and third algorithms are new optimal control algorithms termed ?maximum voltage switching? and ?switched inductor?, respectively. The three algorithms are theoretically evaluated and compared for a short duration vibration application. The final section of this paper presents experimental results from the implementation of all the three algorithms on a new battery-less wireless traffic sensor.
['Krishna Vijayaraghavan', 'Rajesh Rajamani']
Ultra-Low Power Control System for Maximal Energy Harvesting From Short Duration Vibrations