
Double-Fed Induction Machine Drives 22-11
• Electromagnetic subsystem
dz
d
R
L
z
R L
L
z u
s
s
s m
s
sf
21
21 22 2
2 2 2
τ
= − + + ,
(22.39)
dz
d T
z m
v
22
22 2
1
τ
= − +
( )
.
(22.40)
w
here
m
1
, m
2
are new inputs
u
sf2
is the distortion
T
v
= W
δ
/(L
s
R
r
+ R
s
L
r
) is time constant
Equations
2
2.37
t
hrough
2
2.40
d
escribe
a
m
odel
o
f
t
he
D
FM
b
ased
o
n
n
ew
v
ariables
to
gether
w
ith
n
onlinear
f
eedback.
e
i
nput
m
1
controls the machine torque z
12
and the input m
2
controls the variable z
22
.
From the m
1
and m
2
point of view, the system is linear and decoupled. However, in the electromagnetic
subsystem (22.39), a disturbance u
sf2
u u u
sf sx sx sy sy2
= +ψ ψ
(22.41)
appears. e inuence