LOW TEMPERATURE THERMAL MICRO ENERGY HARVESTER

Abstract

The implementation of a micro energy harvester capable of powering commercial ultra low power electronics devices from small temperature gradients is described in this work. Commercial thermoelectric generators are not suitable for extracting low temperature gradients since they are optimized for high temperatures and gradients, therefore are not adequate for extracting power from sources like solar radiation or the human body heat. Experimental research on similar harvesters has been done, but it is necessary that they can power standard commercial devices. The application of Peltier effect transducers acting as thermoelectric generators is proposed and their output is coupled to a very recent commercial ultra low power conditioning circuit aimed to extract the maximum available energy and adjust to commercial electronics voltage levels. Three Peltier modules were characterized, obtaining their internal resistance, generated power and Seebeck coefficient values, related to the power generation from temperature gradients. These values were used as guidelines for selecting the most appropriate module; also components for the power conditioning circuit were chosen by simulation and experimentally for interfacing the output of the module for boosting the low voltage generated in modules to standard regulated voltages, achieving conversion efficiencies of 18 to 30% with delivered power from 5 to 8 mW with gradients of 10 to 25 °C, generating 6 to 9 times more power than the required for a wireless network node.