Performance of Single Junction Thermal Voltage Converter (SJTVC)

[AshLu]

Performance of Single Junction Thermal Voltage Converter (SJTVC)

at 1 MHz via Equivalent Electrical Circuit Simulation

Mamdouh Halawa

National Institute for Standards (NIS), Egypt

Electrical Metrology Department, National Institute for Standards (NIS)

Tersa St., Giza, El-Ahram, Box: 136, Code: 12211, Egypt

Tel: 0020105402742 Fax. 0020233867451 E-mail: mamdouh_halawa@yahoo.com

Abstract

The physical structure of the SJTVC can be represented via simulation using an

equivalent RLC circuit to investigate the performance and estimate the error sources

when using this device as a precise tool for AC voltage and current measurements. This

paper describes instruments and techniques that apply on 0.6 V thermal converters to

achieve this target. The technique was performed, theoretically and practically, to

investigate the frequency-dependence of the SJTVC up to 1 MHz. The LTspice/SwCAD

III simulator was used to analyze the effect of the physical structure of SJTVC in an

effort to better understand the origin of errors at 100 kHz and 1 MHz. The practical

results were firstly measured at National Institute for Standard and Technology (NIST),

US to validate the simulation model at 100 kHz. The model then used to estimate the

AC-DC transfer error of the SJTVC at 1 MHz. Some of the dominated error sources

such as the changes of the real part of the heater impedance, the effect of thermocouple

grounding and the power consumed in the internal resistance of the thermocouple are

estimated at 100 kHz and 1 MHz. The expanded uncertainty assigned to the AC-DC

automated calibration system of NIS is also described.

Keywords

Single Junction Thermal Voltage Converter; AC-DC Transfer Error; Equivalent

Circuit Simulation; Automated Calibration System, Uncertainty analysis.