Maximum power point tracking method with perturb and observe for thermoelectric generators

Thermoelectric generators (TEGs) are used in small power applications to produce electrical energy from waste heat. Maximum power is obtained when the load resistance connected to the ends of the TEG is equal to the internal resistance. However, this impedance equation cannot always be achieved. Thus, TEG operates with lower efficiency. Therefore, maximum power point tracking methods (MPPT) are commonly used. In this study, a detailed modeling and simulation of TEGs for MPPT were performed by using MATLAB®/Simulink® program. Firstly, after determining the equations that are effective at the TEG output, a TEG modeling was designed, based on only the surface temperatures and Seebeck coefficient offered by the manufacturers. In order to increase the power of TEG generated in TEG model, series-parallel connected TEG numbers were enabled to enter and the power obtained from the output was determined by connecting different load values the output of this model. Then, along with the TEG model, both a boost and a buck-boost converter were modelled for the simulation of the MPPT. Afterwards, a perturb and observe (P&O) MPPT algorithm was embedded in these models and the MPPT was performed for different loads connected to their outputs. Thanks to the TEG model and the DC-DC with P&O MPPT and both the boost and buck-boost converter, the maximum power of TEG was able to be traced up to values reaching 98.64% and 98.95%, respectively. According to these values, the power obtained from TEG was not affected by these load changes. MATLAB®/Simulink® simulation results were also confirmed experimentally. In conclusion, thanks to this TEG model, DC-DC both a boost and buck-boost converter TEG model system with a P&O MPPT have been obtained which can easily simulate TEGs with different Seebeck coefficient and temperature values.