Reliability and Circuit Analysis of Thermopiles with Redundant Elements

Thermoelectric generators are gaining increased usage in connection with low-power sources for remote areas and for oceanographic and space applications. These applications require a terminal voltage which must be supplied by connecting many thermocouple elements in series. The reliability of such an array of series-connected thermocouples is determined by the inherent reliability of the individual thermoelectric elements and decreases rapidly as the number of elements is increased; however, appreciable increases in thermopile reliability can result from the use of active redundant elements in parallel. This paper analyzes and compares the reliability of the simple series, parallel/series and series/parallel thermocouple interconnection modes. The results are presented as a function of individual couple reliability and the number of couples determining the no-load potential. The series/parallel connection scheme is shown to yield the highest reliability, and an stant power and voltage output despite the failure of several elements.