A Study on the Reliability of Thermoelectric Couple Networks
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Thermoelectric generators (TEGs) rely on a network of individual thermoelectric couples that collectively contribute to the overall power output of the system. As individual couples experience catastrophic failure, complete generator failure occurs when the power output fails to meet the required threshold. A series–parallel wiring arrangement accommodates failure of individual couples without catastrophic failure of the generator, however there exist failure paths that interrupt electrical continuity of the network. In assessing the reliability of a TEG system, the probability of success is measured according to a network’s ability to meet both the power level and electrical continuity criteria. A closed-form probabilistic model based on Karr’s mathematical formulation (Karr in IEEE Trans Reliab 19(3):116–119, 1970) is used to assess the implications of catastrophic thermoelectric couple failure on the reliability of a complete network. A system-level analysis is performed to evaluate the reliability effects of various network configurations, based on the distribution of a finite number of couples across different numbers of strings. The study explores the tradeoff between redundancy and reliability by assessing the effect of additional couples added to parallel strings and continuing to satisfy acceptable power margins. This model is shown to be a useful tool for designing and understanding the electrical network wiring configurations of TEGs and other power devices.
KeywordsSystems engineering reliability thermoelectrics RTG TEG
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The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration through the Radioisotope Power Systems Program. The information in this paper about future Radioisotope Power Systems is pre-decisional and is provided for planning and discussion purposes only.