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Faculté des Sciences appliquées
Faculté des Sciences appliquées
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Non-Invasive Current Sensor

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Teles Varandas, Mario José ULiège
Promotor(s) : Kraft, Michael ULiège
Date of defense : 27-Jun-2016/28-Jun-2016 • Permalink : http://hdl.handle.net/2268.2/1533
Details
Title : Non-Invasive Current Sensor
Translated title : [fr] Capteur de courant non invasif
Author : Teles Varandas, Mario José ULiège
Date of defense  : 27-Jun-2016/28-Jun-2016
Advisor(s) : Kraft, Michael ULiège
Committee's member(s) : Vanderbemden, Philippe ULiège
Laurent, Philippe ULiège
Geuzaine, Christophe ULiège
Language : English
Number of pages : 107
Keywords : [en] Non-invasive
[en] Current Sensor
Discipline(s) : Engineering, computing & technology > Electrical & electronics engineering
Institution(s) : Université de Liège, Liège, Belgique
Degree: Master en ingénieur civil électricien, à finalité approfondie
Faculty: Master thesis of the Faculté des Sciences appliquées

Abstract

[en] The design and creation of a multi-wire non-invasive current sensor is presented in this work.
First a magnetic flux model is developed in order to simulate and study the behavior of the magnetic flux around different cable structures.
Three different methods to deduced the applied current were analyzed. Solving non-linear equation system, using lookup tables containing magnetic flux measurements around the cable and finally combination of both methods.
In order to test the methods the wires position inside the cable are randomized and the current is increased from 1mA to 1A by steps of 1mA and at each iteration the applied current is deduced.
Deducing the applied current for monopolar cables was easily achieved by solving a non-linear square system containing 3 equation and 3 unknowns. The solver returns very accurate measurements.
However bi/tripolar cables contains 5 unknowns (i.e 2 wires position on the plane and the current), therefore at least 5 equations were necessary to solve the system and deduce the current since cable constructor do not specify exactly the position of the conductors inside a given cable.
One note that placing the sensors not directly at the cable surface but between 1.4 to 1.8 times the cable radius give more accurate results. Again encouraging results were obtained (i.e maximal error of 2mA).
The results with the lookup tables were not so accurate as for the solver (i.e maximal error of 0.25A in best scenario and a mean error of 0.006A). However one can use the approximated solution found by the lookup table as initial point for the solver. Unfortunately using a given fixed initial point gave better results than using the solution of the lookup table.

Knowing that in theory deducing the current was feasible the practical part could be started.
The design of the electronic circuit has taken into account the small order values due to measurements of low magnetic flux, therefore low noise amplifiers and high resolution ADC were chose. In order to be able to test all theoretical methods 5 sensors are used. Particular attention was paid during the design of the sensor board. The device is optimally designed to measure current in a cable of 4mm radius. Therefore sensors should be uniformly distributed around a hole of 4mm times 1.6 $\simeq$6.4mm radius. The sensor positions have to be as precises as possible in order not to introduce error into the values used by the resolution methods.
The design of the PCB were finished but unfortunately due to time constraints practical test could not be performed.


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Author

  • Teles Varandas, Mario José ULiège Université de Liège > Master ingé. civ. électr., fin. appr. (ex 2e master)

Promotor(s)

Committee's member(s)

  • Vanderbemden, Philippe ULiège Université de Liège - ULg > Dép. d'électric., électron. et informat. (Inst.Montefiore) > Capteurs et systèmes de mesures électriques
    ORBi View his publications on ORBi
  • Laurent, Philippe ULiège Université de Liège - ULg > Dép. d'électric., électron. et informat. (Inst.Montefiore) > Systèmes microélectroniques intégrés
    ORBi View his publications on ORBi
  • Geuzaine, Christophe ULiège Université de Liège - ULg > Dép. d'électric., électron. et informat. (Inst.Montefiore) > Applied and Computational Electromagnetics (ACE)
    ORBi View his publications on ORBi
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