
16-16 Power Electronics and Motor Drives
ere is a possibility to estimate the line voltages by adding the input voltage U
p
= U
dc
S
1
of the VSR to the
v
oltages
d
rops
o
n
t
he
i
nput
c
hoke
U
I
. erefore, active and reactive power of the line can be calculated
i
n line voltage sensorless manner as follows:
P U S L
dI
dt
I U S L
dI
dt
I U S L
dI
dc A
LA
LA dc B
LB
LB dc C
L
= +
+ +
+ +
CC
LC
dt
I
(
16.23)
Q L
dI
dt
I
dI
dt
I U S I I S I I
LA
LC
LC
LA dc A LB LC B LC LA
= −
+ − − + −
1
3
3 ( ) ( )) ( )+ −
( )
S I I
C LA LB
(
16.24)
Such
c
alculated
p
ower
c
an
b
e
u
sed
a
s
a
f
eedback
si
gnal
f
or
D
PC
s
cheme.
P
lease
c
onsider
t
hat
p
ower
l
osses
o
n
t
he
r
esistance
o
f