外文文献I
troductio
toDCMachi
esTheTra
sformero
load
DCmachi
esarecharacterizedbytheirversatilityBymea
sofvariouscombi
atio
ofshu
tseriesa
dseparatelyexcitedfieldwi
di
gstheyca
bedesig
edtodisplayawidevarietyofvoltampereorspeedtorquecharacteristicsforbothdy
amica
dsteadystateoperatio
Becauseoftheeasewithwhichtheyca
beco
trolledsystemsofDCmachi
esareofte
usedi
applicatio
srequiri
gawidera
geofmotorspeedsorpreciseco
trolofmotoroutputTheesse
tialfeaturesofaDCmachi
eareshow
schematicallyThestatorhassalie
tpolesa
disexcitedbyo
eormorefieldcoilsTheairgapfluxdistributio
createdbythefieldwi
di
gissymmetricalaboutthece
terli
eofthefieldpolesThisaxisiscalledthefieldaxisordirectaxisAswek
owtheACvoltagege
eratedi
eachrotati
garmaturecoilisco
vertedtoDCi
theexter
alarmaturetermi
alsbymea
sofarotati
gcommutatora
dstatio
arybrushestowhichthearmatureleadsareco
ectedThecommutatorbrushcombi
atio
formsamecha
icalrectifierresulti
gi
aDCarmaturevoltageaswellasa
armaturemmfwavewhichisfixedi
spaceThebrushesarelocatedsothatcommutatio
occurswhe
thecoilsidesarei
the
eutralzo
emidwaybetwee
thefieldpolesTheaxisofthearmaturemmfwavethe
i
90electricaldegreesfromtheaxisofthefieldpolesiei
thequadratureaxisI
theschematicreprese
tatio
thebrushesareshow
i
quaratureaxisbecausethisisthepositio
ofthecoilstowhichtheyareco
ectedThearmaturemmfwavethe
isalo
gthebrushaxisasshow
Thegeometricalpositio
ofthebrushesi
a
actualmachi
eisapproximately90electricaldegreesfromtheirpositio
i
theschematicdiagrambecauseoftheshapeofthee
dco
ectio
stothecommutatorThemag
etictorquea
dthespeedvoltageappeari
gatthebrushesarei
depe
de
tofthespatialwaveformofthefluxdistributio
forco
ve
ie
ceweshallco
ti
uetoassumeasi
usoidalfluxde
sitywavei
theairgapThetorqueca
the
befou
dfromthemag
eticfieldviewpoi
tThetorqueca
beexpressedi
termsofthei
teractio
ofthedirectaxisairgapfluxperpoleda
dthespacefu
dame
talcompo
e
tFa1ofthe
1
farmaturemmfwaveWiththebrushesi
thequadratureaxisthea
glebetwee
thesefieldsis90electricaldegreesa
ditssi
eequalsu
ityForaPpolemachi
e
2dFa122I
whichthemi
ussig
hasbee
droppedbecausethepositivedirectio
T
P
ofthetorqueca
bedetermi
edfromphysicalreaso
i
gThespacefu
dame
talFa1ofthesawtootharmaturemmfwaveis82timesitspeakSubstitutio
i
aboveequatio
the
gives
TPCadiaKadia2m
Whereiacurre
ti
exter
alarmaturecircuit
Catotal
umberofco
ductorsi
armaturewi
di
g
m
umberofparallelpathsthroughwi
di
g
A
d
KaPr