SE455448B

SE455448B - DEVICE FOR COMPENSATION OF A GREAT, MAGNETIZABLE AND / OR ELECTRICALLY CONDUCTIVE MATERIALS EXISTING BODY'S MAGNETIC OWN FIELD

Info

Publication number: SE455448B
Application number: SE8203373A
Authority: SE
Inventors: G Trenkler; W Bornhofft
Original assignee: Thomson Sintra Asm
Priority date: 1981-06-06
Filing date: 1982-06-01
Publication date: 1988-07-11
Also published as: DE3122686A1; GB2103395A; FR2510805B1; FR2510805A1; SE8203373L

Description

455 448 . 10 15 20 25 30 35 2 försämrar kompensationstillståndet. _ e) Virvelströmsfält undertryckes icke i tillräcklig ut- sträckning. f) Avbrott eller fel m m i de magnetiska sensorerna och/ eller lindningarna försämrar kompensationstillståndet. 455 448. 10 15 20 25 30 35 2 deteriorates the compensation state. e) Eddy current fields are not suppressed to a sufficient extent. f) Interruptions or faults etc. in the magnetic sensors and / or windings impair the compensation state.

Uppfinningen har fått till uppgift att eliminera dessa olägenheter och att säkerställa placerings-, tids- och lägesoberoende kompensation av de magnetiska egenfälten.The invention has been given the task of eliminating these inconveniences and of ensuring location, time and position independent compensation of the magnetic natural fields.

Denna uppgift löses enligt uppfinningen genom de i hu- vudkravets kännetecknande del upptagna särdragen. Med an- ordningen enligt uppfinningen förbättras kompensationsför- farandet väsentligt och kostnaderna för apparater och erfor- derliga strömlindningar nedbringas avsevärt.This task is solved according to the invention by the features included in the characterizing part of the main claim. With the device according to the invention, the compensation method is significantly improved and the costs for apparatus and required current windings are considerably reduced.

Vidareutvecklingar av uppfinningen framgår av under- kraven.Further developments of the invention appear from the subclaims.

På bifogade ritningar återges ett utföringsexempel av uppfinningen. Därvid visar fig 1 en cylinderformad, magnetiserbar och konduktiv kropp i ett homogent fält och fig 2 ett elektriskt blockkopplingsschema.An accompanying embodiment of the invention is shown in the accompanying drawings. In this case, Fig. 1 shows a cylindrical, magnetisable and conductive body in a homogeneous field and Fig. 2 an electrical block circuit diagram.

Enligt fig 1 befinner sig i ett homogent fält E; en cylindrisk, ihålig kropp l av magnetiserbart material med permanent magnetisering MP i cylinderaxelns riktning. Kring kroppen 1 är lagd en,kompensationslindning 2 som genomflytes av en strom i(t). Vidare visas i fig 1 en magnetisk sensor 3. ' Cylinderns 1 magnetiska verkan kan beskrivas approxi- mativt genom en magnetisk dipol med momentet E; i z-rikt- ning Ewy"- varvid V är cylindervolymen. Befinner sig cylindern i ett magnetiskt fält ä: och är permeabilitetstalet /ur # l är en approximativ beskrivning av den magnetiska verkan möjlig genom en ytterligare dipol med momentet mg m =._(_/_u_f_"__l_7_______. i 1+(/ur-1)-N a ' _- 10 15 20 25 30 35 H 44551118" 3 varvid N är avmagnetiseringsfaktorn.According to Fig. 1 is in a homogeneous field E; a cylindrical, hollow body 1 of magnetizable material with permanent magnetization MP in the direction of the cylinder axis. Around the body 1 is laid a, compensating winding 2 which is flowed through by a current in (t). Furthermore, Fig. 1 shows a magnetic sensor 3. The magnetic action of the cylinder 1 can be described approximately by a magnetic dipole with the moment E; in the z-direction Ewy "- where V is the cylinder volume. If the cylinder is in a magnetic field ä: and is the permeability number / ur # l, an approximate description of the magnetic action is possible by an additional dipole with the moment mg m = ._ (_ / _ u_f _ "__ l_7_______. i 1 + (/ ur-1) -N a '_- 10 15 20 25 30 35 H 44551118" 3 where N is the demagnetization factor.

Vid en rotationsrörelse av kroppen i vinkelns 9 rikt- ning, såsom antytts ovanför cylindern såsom visardiagram, induceras enligt induktionslagen en ström I, som flyter i cylinderväggen cirkulärt runt sin axel. Även strömmens mag- netiska verkan kan approximeras medelst en dipol med det magnetiska momentet Ei: ' I-O . mw - 1 A med AZ såsom cylindertvärsnitt. För strömmen i gäller i första approximation med L som induktans för cylindern l och R som motstånd i cirkulär riktning i =IQ77ub ' ga _ d 9 (t) L dt I motsats till dipolmomenten mg och mg är dipolmomentet E; sine (t) -eçå -- tjat-exp (šPwnf en av vinkeländringshastigheten beroende tidsfunktion.During a rotational movement of the body in the direction of the angle 9, as indicated above the cylinder as a pointer diagram, a current I is induced according to the law of induction, which flows in the cylinder wall circularly around its axis. The magnetic effect of the current can also be approximated by means of a dipole with the magnetic moment Ei: 'I-O. mw - 1 A with AZ as cylinder cross section. For the current i applies in the first approximation with L as the inductance of the cylinder l and R as resistance in the circular direction i = IQ77ub 'ga _ d 9 (t) L dt In contrast to the dipole moments mg and mg, the dipole moment is E; sine (t) -eçå - tjat-exp (šPwnf a time function dependent on the angular change rate.

Med dessa formler kan mekanismen för uppkomsten av mag- netiska egenfält He i kroppen beskrivas såsom matematisk modell.With these formulas, the mechanism for the emergence of magnetic eigenfields He in the body can be described as a mathematical model.

H = §L§f _ cos 0 e r 2 r3 2: ïf ' sin 6 He°' 4 ' rs Matas kompensationslindningen av en styrbar kontant- strömgenerator med strömmen is erhålles vid approximering av den magnetiska verkan genom en dipol med momentetïí: I? H _ _§ cos 9 s r _ 2 3 r 7: H = _§ sin 9 _ s 9 4 r3 varvid'ﬁ; = is - As med AS såsom verkningsyta. Kompensa- tionslindningen undertrycker fullständigt kroppens egenfält om 10 15 20 25 30 35 H e G _ Hs 9 = 0 Det ovan sagda kan enligt fig 2 återges i ett blockdiagram som uppvisar tre avsnitt, nämligen mätorgan 4, elektrisk anordning S och ställorgan 6. Mätorganet 4 innehåller mag- netsensorer 3 som mäter det yttre fältet Ha och avger en ingângssignal x till anordningen 5. Denna anordning uppvisar en ingångsenhet 7, en utgångsenhet 8 samt ett däremellan kopplat kopplingsverk 9. Från den elektriska enheten 5 går signaler y till en strömstyrenhet 10, vilka alstrar strömmen i för kompensationsanläggningens lindningar ll. De ström- förande lindningarna ll alstrar ett magnetiskt fält, som reducerar kroppens egenfält till ett minimum.H = §L§f _ cos 0 e r 2 r3 2: ïf 'sin 6 He °' 4 'rs If the compensating winding is fed by a controllable cash current generator with the current is obtained by approximating the magnetic action through a dipole with torque: I? H _ _§ cos 9 s r _ 2 3 r 7: H = _§ sin 9 _ s 9 4 r3 varvid 'ﬁ; = is - As with AS as the surface of action. The compensation winding completely suppresses the body's own field if 10 15 20 25 30 35 H e G _ Hs 9 = 0 According to Fig. 2, the above can be represented in a block diagram which has three sections, namely measuring means 4, electrical device S and adjusting means 6. 4 contains magnetic sensors 3 which measure the outer field Ha and emit an input signal x to the device 5. This device has an input unit 7, an output unit 8 and a coupling unit 9 connected therebetween. From the electrical unit 5 signals y go to a current control unit 10 , which generate the current in for the windings 11 of the compensation plant. The current windings 11 generate a magnetic field, which reduces the body's own field to a minimum.

Under hänsynstagande till ett lineärt samband mellan det yttre fältet Ha samt den elektriska anordningens 5 in- gångssignal x samt mellan styrenhetens 10 ström i och den elektriska anordningens 5 utgângsstorhet y skall i kopp- lingsverket 9 såsom algoritm som skall lösas inbyggas en matematisk modell med formeln 1 u 1 Y'í:“[V[MP+1"fF"(/1l1r-1)-N' KJ* u 0A ' “L -bLq-ll-(fådšê - expL t'dt)-exp( ïf't) L ä .Taking into account a linear relationship between the outer field Ha and the input signal x of the electrical device 5 and between the current i of the control unit 10 and the output quantity y of the electrical device 5, a mathematical model of the formula shall be built into the switchgear 9 as an algorithm to be solved. 1 u 1 Y'í: “[V [MP + 1" fF "(/ 1l1r-1) -N 'KJ * u 0A'“ L -bLq-ll- (fådšê - expL t'dt) -exp (ïf 't) L ä.

Denna mdellfunktions parametrar är bestämbara såsom av ma- terialet eller geometrin beroende konstanter och kan följa kända ändringar av dessa storheter. För att kompensera krop- pens egenfält i hela rummet skall modellen utvidgas på ax- larna och motsvarande anpassas beträffande parametrarna.The parameters of this model function are determinable as constants dependent on the material or geometry and can follow known changes of these quantities. In order to compensate for the body's own field in the entire room, the model must be extended on the shoulders and correspondingly adjusted with regard to the parameters.

Denna anpassning kan ske kontinuerligt eller med bestämda tidsintervaller. ¿ Den matematiska modellen i kopplingsverket 9 kan ha formen av en elektronisk räknare. För att göra kompensa- tionsanläggningen mera tillförlitlig kan flera likartade elektriska anordningar 5 anordnas parallellt. IThis adjustment can take place continuously or at fixed time intervals. ¿The mathematical model in the switchgear 9 may take the form of an electronic calculator. In order to make the compensation system more reliable, several similar electrical devices 5 can be arranged in parallel. IN

Claims

10 15 20 25 30 455 448 PATENT CLAIMS

Device for compensating for the magnetic field of a movable, demagnetizable and / or electrically conductive material consisting of body (1) by means of current-carrying windings (2; ll) located inside or outside the body, whose magnetic moments with respect to its magnitude and time course are controllable by means of magnetic sensors (3), characterized in that the output signals of the magnetic sensors (3) are present as input signals (x) in an electrical device (5) which contains a mathematical model which takes taking into account the originating mechanisms of the indwelling magnetic fields and the compensation fields generated by the current-carrying windings (2; ll1) and emitting output signals (y) which control the currents (i) in the windings (2; ll) in order to minimize the body-specific outer magnetic field.

Device according to claim 1, characterized in that the parameters of the mathematical model are continuously caused to follow changes in the magnetic properties of the body (1).

3. A device according to claim 1, characterized in that the parameters of the mathematical model with predetermined time intervals are adapted to changes in the magnetic properties of the body (1).

4. Device according to claim 1, characterized in that the mathematical model in the electrical device is an electronic calculator.

Device according to one or more of the preceding claims, characterized in that the mathematical model is constructed in such a way that three mutually orthogonally standing windings are arranged to compensate for the body's own magnetic field.

Device according to claim 1, characterized in that in order to increase the reliability, several similar electrical devices (5) are connected in parallel. 455 448 10 15 20 25 6

Device according to claim 1, characterized in that the mathematical model compensates for the effect of interruptions in one or more compensation windings by changing the currents in the other compensation windings via an adjustment of model parameters.

Device according to claim 1, characterized in that the mathematical model compensates for the effect of an interruption in one or more magnetic sensors by adapting model parameters. k n e n e t e c k n a d thereof, that significant parameters of the mathematical

Device according to claim 1, the part is determined in whole or in part in a measuring system (4) and is transmitted to the electrical device (5) via a data line or data connection.

Device according to Claim 1, characterized in that the movable body's own magnetic field is determined in a measuring system (4) and that the associated field value is transmitted to the electrical device (5) via a data line or data connection.

11. ll. Device according to Claim 1, characterized in that the setting of the significant parameters or system parameters of the mathematical model takes place with the aid of an alphanumeric keyboard. k ä n n e t e c k n a d thereof, that for reproducing the mathematical model

Device according to claim 1, significant parameters and the compensating state of the magnetizable body a monitor is used.