Investigation of bismuth telluride based thermoelectric modules connected to square series parallel configuration with isolated power electronics converter for dc micro grid applications

Abstract

This research work investigates the power-current (P-I) and voltagecurrent (V-I) characteristics of the thermoelectric modules (TEMs) in seriesparallel configurations under homogeneous and heterogeneous temperature difference (and#916;T) condition. To study its performance, 5 different series-parallel combinations were formed using 16 TEMs. The comparisons among the different configurations have been done to determine the best series-parallel configuration. The total load power extracted from 16 individually connected TEMs was 18.2 W, which was placed as a reference load power. The optimal series-parallel combination for maximizing the load power is square series-parallel configuration, whose maximum load power is 17.38 W, when compared to the reference load power. Moreover, in square series-parallel configuration, the total internal resistance value that remains constant is equal to the internal resistance of a single TEM, and the total open-circuit voltage increases gradually on adding any number of TEMs. Thus, it produces higher load voltage and higher load current simultaneously, which is recommended to power DC micro-grid applications. Furthermore, the series, parallel and square series-parallel configurations are connected as star to obtain 3 separate DC output to power the same application. The performance of TEMs under various configurations is analysed, and the obtained results are verified experimentally. Moreover, this research work offers a thermoelectric (TE) energy harvesting system that makes use of the heat generated within the stator windings of a wind generator in the operation of a 1.25 MW wind turbine. A single thermoelectric generator (TEG) can generate only lower power. To deliver higher output power, the Bi2Te3 based TEMs may be associated as an array. The square series-parallel configuration is adopted in this work owingto the advantage of unaffected internal resistance value for any quantity of TEMs. The power generated by the TEMs is unsteady owing to irregular wind velocity. Therefore, a power