AIF04ZPFC-02NTL Astec Power, AIF04ZPFC-02NTL Datasheet - Page 19

• Manufacturer Part Number: AIF04ZPFC-02NTL
• Manufacturer: Astec Power

RMS ripple current
The maximum permissible rms ripple current for the output capacitor should be greater than the rms ripple current for the
application. The ripple current for the PFC module can be approximated as
where :
P
Eff = efficiency
V
V
This gives the ripple current at 125KHz. The maximum ripple current for capacitors is usually specified at 120Hz. To
convert from 125KHz to 120Hz the Irms figure should be divided by 1.3 .
Peak to Peak Output Ripple Voltage
The ac input causes a ripple on the output voltage. The size of the ripple is inversely proportional to the size of the capacitor.
Therefore the maximum allowable ripple voltage should be decided in order to calculate the size of capacitor required. This
may be calculated using the following equation:
where :
C
Eff = efficiency
f = input voltage frequency (Hz)
V
V
Hold-Up Time Requirement
The output capacitor value is different for different hold-up time requirements. The minimum capacitance corresponding to
the required hold-up time of a system comprised of ASTEC DC/DC power modules and an PFC module can be calculated as
follows:
where :
C
P
T
V
V
V
MODEL : AIF -
March 2006 REVISION 09
O
O
hold
O
O min
O
rms
O
ripple
O
ripple
min
= output power (W)
= output power (W)
= output capacitance (µF)
= output voltage (V)
= output voltage (V)
= output voltage (V)
= hold up time (sec)
= input rms voltage (V)
= minimum input voltage for DC/DC module
= output ripple voltage (V)
= output ripple voltage (V)
= output capacitance (µF)
C
C
O
O min
= P
= (2 x P
O
PFC Series
/ (2Sf x Eff x V
I
rms
= (P
O
x T
O
/Eff) x 1/—(V
hold
)/[(V
O
O
x V
-V
ripple
ripple
Technical Reference Note
O
AIF - PFC Power Factor
)
)
x V
2
- (V
rms
Correction Series
min
)
)
2
]
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