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Design >> High-Power Design >> Boost Converter
https://designers-guide.org/forum/YaBB.pl?num=1409579640

Message started by bki on Sep 1^st, 2014, 6:53am

Title: Boost Converter
Post by bki on Sep 1^st, 2014, 6:53am

Hi,

i have a regular Boost Converter with L=70uH, f=40k, Ron of MOSFET is 82 Ohm, Vin=5V, Vout=285V, Diode is DFLU1400. Duty Cycle=0.99 .
load capacitor is 5nF and load resistance is 5MOhm, therefore output current is 57uA. Operating in DCM.

I calculate the power efficiency through: Vout*Iout/Vin*Iin.
I receive Iin through integrating the input current over 1 Period and divide it by the Period.

The result for power efficiency that i receive lies below 1%. I am wondering what is the reason why the power efficiency is so bad?
Can i do anything to increase the efficiency?

Title: Re: Boost Converter
Post by AnilReddy on Sep 2^nd, 2014, 4:11am

Hi,

A rough calculation showed me that it is around 57%.

Vout = 285 V & Iout = 57uA

Vin = 5 V & Iin = 57uA/(1-0.99)--your D is 0.99 and therefore Iin = Iout/(1-D).

--Anil Reddy

Title: Re: Boost Converter
Post by bki on Sep 2^nd, 2014, 7:49am

I also calculated this. But this is not the result i get, if i simulate it.

My Iin lies at around 370mA in this case with D=0,99 f=40k.
(Calculated value would be 5,7mA)

What can be the reason for the discrepancy?

Title: Re: Boost Converter
Post by AnilReddy on Sep 2^nd, 2014, 10:19am

Hi,

I suspect the set-up of simulation. Your simulation set-up is taking 1.85 watts of power from the input and giving out only ~16mW, which is, of course, can't be true.

--Anil Reddy