Characterization of thermoelectric generator for energy harvesting

This paper presents a system for characterization of thermoelectric generators (TEGs) for energy harvesting. This system can monitor and characterize up to three TEGs simultaneously and it is comprised by two main electronic circuits: The first one is composed by twelve input channels being three for reading voltage, three for reading current by making use of instrumentation amplifiers (reference ACS712) and six thermocouples for signal reading (<400 °C). The second electronic circuit consists of a proportional-integral-derivative (PID) controller with two pulse width modulation (PWM) input channels for controlling the heat (thermoresistance) and cooling (controlled cooler) sources respectively, following a pre-defined temperature gradient. The TEG measured data for the voltage, current and temperature can be acquired in real-time with development in Delphi® language and displayed through both a numeric and graphical display. In order to validate the precision and accuracy two commercial TEG modules (reference inbC1-127.08HTS) compatible with temperatures up to 200 °C without signal degradation were used in series. The acquisition system resulted in a precision of ±5%, ±2% and ±1.5% for the temperature, voltage and current respectively, with a maximum error value of 1%. Its possible utilizing this acquisition system acquire data from TEG obtain graphics response and determinate some characteristics how internal resistance, open circuit voltage, power output and temperatures gradient form any conditions of operation. All of these features combined with the low-cost under R$973.80 (≈324.43 €) makes this system suitable for a wide range of applications for standalone power system or heat recycling systems for cogeneration of electricity. Knowledge of the electrical characteristics of TEGs is of great interest in co-generation systems to design the same in order to achieve the best possible performance.