eletricidade DigitalizarFolha9

Prévia do material em texto

82 ELECH\O/.\ECHANICALENERG'(CONVEÍ\SION
, ..
,.FIGURE2.10..
MoC'ner.e.;:.elCj
:ne';gyC:'ICCo-
enerçy:nme
Cose01o LinefJr
Mognerie
/lleolum
"
t Storcdmagnctie-fjeldcnergy.IV!
t
I
o
The'developedtorquecanbeexpr~ssedin termsor thedecreaseinstored
magnetictie.ldenergy.fromEq. !:!.30).as
12A7)
On theotherhand.fromEq. (2.41).thedevelopedtorqu~canalsobeexpressed
intermsor theincreaseineo-energyas
. EXAMPLE2.3
;Ai :\ magnetic..:irclÍitof a plungerhasa cross-sectionalareaor5 em:andthedi.mensionsshownin Fig.~.11a.Calculatetheforceexertedontheplungerandthe
co-energy\\'henthedistance.\"is ~tcmandthecurrentinthl:100-turncoil is 5A.
rhc relutive'perlTle1\~!litiesõf ma.:neticmater!;!1andnonmagneliebushin~are
~QO()an~I. respeclively.Assum,lhefringing:lOdIl:akagl:cr:celsarencglil,Üblc.
Solurion
The electriaalanulog01'.themagnetiêcircuitgivenin Fig.2.llb allowsthecaJ.
eulation01'totalinductanee'ofthesV~lemi!1'tcrmsl)f theindividualreluctanecs.
I
.
, .
FIGURE2.11
ía) Mognene
, Cireul!for
Exomple ,2.5:
(b) Irl Elecrnecl
Analog
iMGNEr'IC.,IELD ENERGY CONV.ERSION 83
"
t-
" .
---'-,~ ~-:" ~--~' ~-tagncliem~lcri'al'
.' , !, ~ 1".::2000'
, .!./. .
. . , I" ,
Bushing 'i ' . . '
1em 1".'"I " '. ' U:d~, I
"!'oo! I,: (J.5 <:01
n-r
-Iem~
J .1I .
Cras\-seeliona(arca
o( ai!pam;. 5 em:
20em . -r.
:\IrgaptJ ' ~
1--.(--1 '
5~
em' -\
I
l'
U.5em,
L. I . .
r -1
.'
.il.
.:Il.
A" ,
,
j, (b,~'Themeanlengthsforlhepa sare:
IIbe": . '" 1I =10.,.20 - ') =39em=0.39m
aI!+fg: I~=20.5cm- x =0.205'. X!TI
Ih=,0.5em =0.005-m
I. =.\'m
'1
~~
J.