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Input Capacitor calculations

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Bjtpower

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Dear Friends

I am verifying the One PCB.

PCB Specifications are
Input Voltage:110VAC=155.54V (Max)

Output Power: 100W

Line frequency=50HZ

now they have used the 100uF/450V capacitor of Rubycon.

When i was calculating
Power=voltage x Load current
Load Current=Power/Voltage=100/155.54=0.64A

now, Capacitor Required=I(load)/2xFXRipple=0.64/(2X50X15.55)=0.64/(1555)=0.64/10=411uF

Pls Help me Where i am getting wrong because my cap value is 4 times bigger.

Marx
 

Welll here is ltspice simulation which shows your dc bus variation with 100uf

- - - Updated - - -

but yes, generally, most cheaper electrolytics of 100uf would get over ripple currented by being attached as a dc bus cap in a non pfc smps of 100w power level. But maybe your load is not on max all the time?
 

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  • Constant power load _100W.TXT
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