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The characterization of near-field couplings becomes an extremely important activity to optimize the best nominal performance of any electronic device in the presence of others. In order to handle the electromagnetic compatibility (EMC) problems at the initial design phase, a predictive method based on multipolar expansion in spherical harmonics has been developed. A new automatic measurement system...
The Joule balance method is one of the several approaches to measure the Planck constant for the redefinition kilogram. The first prototype has been built to check the feasibility of the principle and the relative uncertainty is 2.6×10−6. To get better result and make contribution for the redefinition, since 2013, a new Joule balance has been designed with several new approaches to decrease the main...
In the electromagnetic compatibility (EMC) behavior of power electronic converters, it is important to predict the near-field coupling between the complex components (e.g., in EMC filter). Using the components of the near-field multipolar expansion of electromagnetic sources, the close magnetic coupling between two elements is determined from their equivalent model. In this paper, a new measurement...
The Joule balance method to measure the Planck constant and redefine the Kilogram ultimately has been going on at the National Institute of Metrology of China (NIM) since 2007. The first prototype has been built to check the feasibility of the principle. In 2012, the relative uncertainty of the plank constant measurement result is at 10−5 level. Self-heating of the coils, swing of the coil, etc.,...
Traditionally, the most precise way to get the mutual inductance value is by a calculable mutual inductor. Here a new approach of measuring the mutual inductance at low frequency with compensation method is described. The mutual inductance is traced to the value of the frequency and resistance directly. The measurement uncertainty is 0.1 ppm and could be improved further.
DDS sources were developed in NIM for impedance measurements. Stable and accurate phase difference can be obtained easily by this technique. It has been used for mutual inductance measurements and an uncertainty of 1×10-7 has been obtained.
The Teflon frame is used in establishing NIM's AC Resistance Calculable Standard. Comparison with the suspended design such as coaxial, quadrifilar and octofilar types, the frame of resistor gives better stability. However, the dielectric loss of Teflon frame will bring additional ac/dc difference. To measure this dielectric loss precisely, a new measurement structure is provided and the substitute...
In this paper, the uncertainty of the QHR standard system at NIM is estimated and the combined standard uncertainty is given out. A new method to calibrate CCC ratio unit working in-situ is introduced.
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