
22-6 Power Electronics and Motor Drives
sum of the rotor speed ω
r
and its own speed ω
ir
. e position of the stator current vector is therefore
dened by the position of the rotor current vector. Stable machine operation requires a constant angle
b
etween
t
he
s
tator
c
urrent
a
nd
t
he
v
oltage
v
ector
o
r
s
ynchronization
o
f
b
oth
v
ectors.
e
c
ondition
o
f
stable machine operation in steady state is
ω ω ω
r ir s
+ =
(22.23)
where ω
s
is the stator voltage vector rotational speed.
e best understanding of DFM properties takes place if the rotor current vector components are
a
ssumed
a
s
i
nput
v
ariables.
T
his
i
s
p
hysically
p
ossible
i
f
t
he
D
FM
i
s
s
upplied
f
rom