Doctoral Thesis: AC Magnetic Flux Density Standards and Their Use in Metrology

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00177016%3A_____%2F21%3AN0000042" target="_blank" >RIV/00177016:_____/21:N0000042 - isvavai.cz</a>

Result on the web

<a href="https://dspace.cvut.cz/handle/10467/89411" target="_blank" >https://dspace.cvut.cz/handle/10467/89411</a>

DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Doctoral Thesis: AC Magnetic Flux Density Standards and Their Use in Metrology

Original language description

This dissertation describes the development of AC magnetic flux density standards and their use in metrology. The dissertation focuses mainly on the design and realization of new standards, which will extend the existing ways of calibrating AC magnetometers in the primary laboratory of the Department of Electromagnetic Quantities of the Czech Metrology Institute.Various coil systems and various types of solenoids are commonly used for calibrating magnetometers (teslameters with a Hall probe, or 3-axis coil probe analyzers) up to several mT. The maximum value of the AC magnetic flux density generated in the center of the standard, and its homogeneity, depend on the dimensions and the type of the coil standard and the winding parameters. The induction and parasitic capacity of the winding affects the value of the resonance frequency and thus the frequency range in which the standard can be used. An electromagnet has to be used when a higher magnetic flux density value needs to be generated for calibration up to hundreds of mT. Here, some standard sensor (Hall probe, search coil) with traceable calibration should be used for precise measurements of the AC magnetic flux density generated in the center of the air gap.In the first part of the dissertation, various types of coil standards (Helmholtz, Maxwell, Garrett, Barker, Braunbek, etc.) and available AC electromagnets are described and are compared in terms of their parameters and their uses in AC applications. The standards for AC calibrations available in the primary laboratory of the Department of Electromagnetic Quantities of the Czech Metrology Institute before starting this dissertation work are also presented here.The second part of the dissertation describes the design and realization of the Helmholtz-type single-layer coil standard for calibrating magnetometers in the frequency range up to 100 kHz. The serial resonance effect was used in order to generate a magnetic flux density of 105 microT up to 100 kHz. For this purpose, a capacitive programmable array was designed and realized. To ensure the metrological traceability of the generated AC magnetic flux density, a calibration method was developed involving special search coils and an AC current shunt with calibrated AC/DC differences, by which the coil standards can be calibrated up to 100 kHz with expanded uncertainty of (0.12 to 0.25)%. This section of the dissertation also describes the possibilities of using coil standards in metrology.The last part of the dissertation is devoted to the design and realization of the system with an AC electromagnet, which can be used for calibrating teslameters with a Hall probe up to 1 T at low frequencies (mainly at a frequency of 50/60 Hz). An AC electromagnet with a UNICORE core has been developed from oriented electrotechnical steel with a cross-section of 36 cm2 and with a length of the air gap of 10 mm. A single-layer, a double-layer and a 10-layer special PCB search coil were designed and fabricated for precise measurements/adjustments of the AC magnetic flux density generated in the center of the air gap, ensuring the metrological traceability of the teslameter calibration using the system with an AC electromagnet. The serial resonance effect was used when powering the electromagnet. A feedback was also implemented to improve the stability of the AC magnetic flux density generated inside the air gap. The value of the generated AC magnetic flux density can be measured/adjusted in the center of the air gap with expanded uncertainty of 0.2%. To extend the frequency range of the calibrations, an AC electromagnet made from amorphous MetGlass 2605HB1 material was also realized, enabling it to generate magnetic flux density of about 100 mT up to a frequency of 1 kHz.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

20201 - Electrical and electronic engineering

Project

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2021

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů