Evaluation of Power Harvesting on DC--DC Converters to Extract the Maximum Power Output from TEGs Arrays under Mismatching Conditions

Thermoelectric generators (TEGs) can transform wasted heat from industrial processes into electrical power. The power provided by TEGs systems depend on the temperature gradient, where an ideal situation for the TEGs operation is when all the modules of an array are exposed to the same temperature difference. Unfortunately, that condition is not always possible since the TEG arrays are exposed to non-uniform thermal conditions (known as mismatching). This paper proposes a novel equivalent model to represent the electrical behavior of a TEG, including a high-order approximation for the temperature dependence properties of the internal resistance and output voltage. Several configurations proposed to mitigate the mismatching phenomenon on TEGs arrays were tested, which are based on boost converters, PI controllers and the perturb and observe algorithm for maximum power point tracking: ۱) TEGs serial connection with a single power converter, ۲) a parallel connection where each TEG has its own converter, and ۳) a serial connection where each TEG has its own converter. Those tests were performed in three temperature differences (۵۰°C,  ۱۰۰°C and ۱۸۰°C) to study the impact of the mismatching thermal condition over the total output power. The maximum power delivered by the traditional case ۱ was ۱۰.۷ W; while the output power provided by case ۲ was ۱۲.۰۷ W (۱۲.۸ % higher) and ۱۱.۱ W (۳.۷ %) for case ۳.

Keywords:

Mismatching conditions , power converters , thermometric systems