Mathematical Modeling and Measurement of Low Frequency Characteristics of Single-Junction Thermal Converters

We derive the analytic solution of the heat flow equation of a single-junction thermal converter (SJTC). The heat is generated by the flow of an electric current through the heater wire, while the thermocouple attached via a ceramic bead to the middle of the heater wire acts as a heat sink. We consider the nonlinearities caused by the Thomson and radiation effects, as well as the temperature dependence of the physical properties of the heater material. The results are used to obtain the expression for the ac–dc transfer difference as a function of the device geometry and material parameters. We report on the very good agreement between the analytical, numerical, and experimental results of the ac–dc difference of the SJTC in the frequency range from 10 Hz to 1 kHz. The results will be useful for the design of thermal converts and their further use in the ac voltage and current metrology.