Development Of A Measurement System Of The Thermoelectric Conversion Difference For Thin Film Thermoelectric Converters

Thin film thermoelectric converter is a reference standard for measuring AC voltage and AC current,and it plays a very important role in the field of electrical standard.Therefore,it is of great significance for evalueating the thermoelectric conversion characteristic test system of thin film thermoelectric converter.In this paper,the signal source using for evalueating thermoelectric conversion characteristics of thin film thermoelectric converters was designed by using the Fastreversed DC method(FRDC),which is called The FRDC source.The FRDC source includes a 7V reference voltage circuit,a voltage dividing buffer circuit,and an analog switch circuit.7V reference voltage circuit generates a high stability of the reference voltage with stability of 1ppm.After the voltage of the reference voltage is divided by the voltage dividing buffer circuit,the FRDC waveform is generated by the switching of the analog switch,and therefore the heating resistance of the thin film thermoelectric converter is loaded.The output voltage of the thin film thermoelectric converter is then measured,and the error of the AC / DC conversion is calculated.The reference voltage of the 7V reference voltage circuit was tested.The test results showed that the stability index is about 0.7ppm/h.What's more,due to the influence on the thermoelectric conversion characteristics of thin film thermoelectric converters from the chip substrate temperature,so only as far as possible to stabilize the thin film thermoelectric converter substrate temperature to improve the performance of thin film thermoelectric converter,and reduce the measurement error.Therefore,a constant temperature platform based on thermoelectric cooler(TEC)was designed in this paper,which is able to stabilize the temperature of the substrate of the thin film thermoelectric converter substrate.It is calculated that the maximum change of substrate temperature is only 2.5×10-4 degrees during half an hour.At last,a FRDC prototype was made,and the preliminary thin film thermoelectric converter which was made in our laboratory was tested.The measurement error was analyzed.