Exploring the low-frequency performance of thermal converters using circuit models and a digitally synthesized source

Oldham, N.M.; Parker, Matthew; Bell, Brent; Avramov-Zamurovic, Svetlana

doi:10.1109/19.571854

Cited by 18 publications

(5 citation statements)

References 5 publications

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“…In the frequency range below 0.1 Hz, the AC-DC transfer differences appear to approach a constant value due to perfect tracking of the temperature with the instantaneous AC input voltage. The resulting AC-DC transfer differences in the modified model describe the experimental data below 10 Hz (determined by a digitally synthesized source) [11] better than the previous low-frequency model does.…”

Section: Very Low Frequency Properties Of Ac-dc Transfer Difference Umentioning

confidence: 82%

Numerical analysis of low‐frequency properties in single‐junction thermal converters

Amagai

Nakamura

2012

IEEJ Transactions Elec Engng

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We have performed numerical calculations to analyze the low-frequency properties of a single-junction thermal converter using a modified low-frequency model. A feature of the modified low-frequency model is the incorporation of the heat capacity of the thermocouple and ceramic bead, which had been previously neglected. Since thermocouple and ceramic bead can increase the thermal inertia of the heater, they can modify the thermal time constant, which plays a crucial role at low frequencies. The calculated data using modified low-frequency model for the AC-DC transfer differences correspond better to the experimental data. The difference of the AC-DC transfer difference between calculated and measured data is less than 10 μV/V down to 10 Hz.

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Section: Very Low Frequency Properties Of Ac-dc Transfer Difference Umentioning

confidence: 82%

Numerical analysis of low‐frequency properties in single‐junction thermal converters

Amagai

Nakamura

2012

IEEJ Transactions Elec Engng

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“…We should expect deviations from square and inversesquare laws that rule AC-DC differences at low frequencies in such standards to be related mainly to Thomsom heating and non-linear contributions to emissivity and thermal diffusivity in the heater [2,5,6,10,13], as well as non-linear contributions from circuitry in electronic standards, though the contribution of sistematic fluctuations of statistical nature should also be investigated.…”

Section: Results For Pmjtc Datamentioning

confidence: 99%

Power-law picture for the interpolation of AC-DC differences in thermal standards

2010

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In this work we present a general method, commonly applied to the numerical analysis of stochastic models, to interpolate AC-DC differences (usually denoted by the greek letter δ) between calibration points in thermal transfer standards. This method assigns a power-law behaviour to AC-DC differences, solely under the assumption that δ must be some smooth-varying function of voltage and frequency. We argue it may be straightfowardly applied to all working ranges of the standards, with no distinction.

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“…As the period of the input voltage increases and approaches the thermal time constant of the TVC, the heater temperature begins to track the square of the instantaneous input voltage. Thus, the temperature variation in the heater in the TVC becomes negligible at low frequencies [1,2]. Even in such situations, the precise DC components of the output voltage from the thermocouple were obtained by selecting the integration period of the nanovoltmeter to cover an integer number of signal periods of the thermocouple in the TVC.…”

Section: Ac-dc Difference Measurementmentioning

confidence: 99%

“…The AC-DC difference, which is defined as the difference in the response of the TVC to AC and DC signals, is indispensable for accurately determining the root-mean-square (rms) value of an AC sinusoidal waveform. However, it is difficult to theoretically accurately evaluate the low-frequency AC-DC difference below 10 Hz because of the complex heat transfer of the TVC caused by Joule heating oscillations, the change in the electrical resistance of a heater, and the nonlinear heat transfer of the TVC [2][3][4]. Direct sampling methods are widely used for calibrating AC voltage in a frequency range below 10 Hz [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Extending voltage range to 10 V rms in AC–DC difference measurements with AC programmable Josephson voltage standard

Amagai

Maruyama

Yamamori

et al. 2020

Meas. Sci. Technol.

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The larger-scale programmable Josephson voltage standard (PJVS) chip composed of 524 288 niobium nitride-based overdamped Josephson junctions enables us to generate stepwise-approximated AC waveforms with a root-mean-square (rms) amplitude of up to 10 V. In this study, we have extended the voltage range of the differential sampling system based on the AC-PJVS to an rms value of 10 V with the larger-scale PJVS chip. The sampling digital voltmeter (DVM) that is employed to measure differential voltages is modified to use a 10 MHz reference clock instead of an internal clock. This modification substantially improves the uncertainty of AC-DC difference measurements at low frequencies, which is caused by the internal clock error of the sampling DVM, by preventing the incoherent sampling of the differential voltages. The expanded uncertainties (k = 2) of the AC-DC difference measurements are reduced from 7.0 µV/V to 1.8 µV/V for a frequency of 62.5 Hz and from 8.0 µV/V to 4.4 µV/V for a frequency of 1 Hz. The improvements in the uncertainty are more significant compared with a conventional method at low frequencies, where the accuracy of a thermal voltage converter is reduced.

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Exploring the low-frequency performance of thermal converters using circuit models and a digitally synthesized source

Cited by 18 publications

References 5 publications

Numerical analysis of low‐frequency properties in single‐junction thermal converters

Numerical analysis of low‐frequency properties in single‐junction thermal converters

Power-law picture for the interpolation of AC-DC differences in thermal standards

Extending voltage range to 10 V rms in AC–DC difference measurements with AC programmable Josephson voltage standard

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