gefran SM32

39-GB
—————— INSTRUCTION MANUAL——————
Considering a series resistance (sum of the capacitor parasite drag and of the connection
contact resistances) equal to 100mOHM (0.1 OHM), act as following:
DATA: R = 0.1 Ω C = 3760 mF
L = 0.14 mH e = 2.718
V = 70V
1)
)
L*2
R
(
-
C*L
1
=
2
ω
Having as a unit of measure the “L” inductance in Henry, the “C” capacitor in Farad and
the “R” resistance in Ohm, according to the above mentioned data:
ω = 1331.21 rad/S
2)
L*2
R
=α
from which: a = 357.14
3)
ω
π
*2
=
t
M
from which: t
M
= 0.00117 s
( t
M
states the time needed by the current to reach its maximum value )
4) the peak current can be calculated with the following formula:
e
*)
L*
V
(=
I
t
*
P
M
α
ω
from which : I
P
= 572.3A
It is obvious that considering a 70V discharge of the DC-LINK (3-mS mains dip) the
current is too high for the converter. As a consequence, it is necessary to consider a
lower voltage reduction (corresponding to a shorter mains dip). Therefore, with a voltage
reduction of 35V (1.5-mS mains dip), the new value will be:
I
P
= 286.1 A