FSB16M0134J AVX Corporation, FSB16M0134J Datasheet - Page 59

• Manufacturer Part Number: FSB16M0134J
• Description: Medium Power Film Capacitor
• Manufacturer: AVX Corporation

Medium Power Film Capacitors
Application Notes
58
1) DC LINK FILTER: HIGH CURRENT
1a) Energy supplied with batteries
Applications will be:
In that case, capacitor will be used as a decoupling capacitor.
Film capacitor is particularly well adapted for this use,
because main criteria for DC link capacitor will be rms.
current withstanding.
It means that DC link capacitor can be designed on rms.
current value.
If we take an electric car in account as example:
Minimum capacitance value will be:
So, it will be easy to find a capacitance value close to these
values.
Comparison with electrolytic capacitor.
If we take in account 20mA per µF for example, in order to
handle 80 Arms, capacitance value minimum would be:
Requirement data:
DESIGN & CAPACITANCE VALUE DESIGN
Working voltage:
Ripple voltage allowed: 4Vrms
Rms. current:
C =
U
C =
ripple
0.02
I
rms
80
x 2 x
electric car
electric fork lift truck
120Vdc
80 Arms. @ 20kHz
= 4000 F
x f
= 159 F
1b) Industrial motor drive, energy supplied
DC link voltage waveform:
Capacitance value will be defined taken in account that
supply frequency is lower than converter frequency.
To determine needed capacitance, we can use the following
approached equation:
Irms. through capacitor will be (approached expression):
Of course this current doesn’t take in account frequency
converter current.
So, with this approximation, Irms. through the capacitor will
be depending of the Power of load, Umax and U ripple.
I
rms
=
from supply network
U
2 x 2
ripple
C =
U
U
U
x C x 2 x
ripple
x U
DC Link Filter
max –
x F
P
load
rectifier
U
ripple
2
=
U max
U
x F
max –
t
rectifier
P
load
U
x
ripple
2
2