My boost converter doesn't work

[dontexist]

My parameter are 25-23V input 80V 31.25A output. I took the design from webench designer why isn't working?

 

[KlausST]

Hi,

I can´t open .rar files on my old tablet. I guess this is a simulation...

please give a more detailed error description:
* What are your operation conditions
* What do you expect
* What does not work like expected
* What did you do to debug .. and what are the results

Upload your schematic as .png.


Klaus

 

[dontexist]

 

[dontexist]

I expect 80V output but result is 10 V.

 

[KlausST]

Hi,

Try a filter at CSP and CSN.
R5 is useless
you may try a bigger soft start capacitor
did you check the values of the compensation netowork?

Klaus

 

[dontexist]

Hi,

Try a filter at CSP and CSN.
R5 is useless
you may try a bigger soft start capacitor
did you check the values of the compensation netowork?

Klaus

I chanced R5 connection and choosed bigger ss capacitor. This time gives 25V output

--- Updated Aug 17, 2021 ---

Hi,

Try a filter at CSP and CSN.
R5 is useless
you may try a bigger soft start capacitor
did you check the values of the compensation netowork?

Klaus

here is webench design

 

[Easy peasy]

you're losing 3V across the fet for 30A, that is 90W, you need much larger fets,

also I imagine your freq is too high, 70kHz would be a max for 2.4kW ....

also your gate drive is too aggressive at turn on,

also, in a sim it's pointless to have caps in //

 

[BradtheRad]

Simulation of basic boost converter using your specs. Scope traces depict theoretical waveforms.

The 20 milliOhm resistor represents some amount of parasitic resistance in the system. It must be minimized because it saps a lot of power. Duty cycle needs to be longer as a result.

You can only get so much boost out of a boost converter. There is a point where longer duty cycle fails to increase output voltage. You may need to consider interleaving two or more boost converters.

 

[KlausST]

Hi,

do some simulation with less load current.
Just to see what happens.

In your simulation did you use all the ESR and additional part values?
What about inductor satuaration? Is it an ideal inductor?

Klaus

 

[Easy peasy]

you may have set the input current limit too low, for full power there is ~ 100 amp or so

 

[dontexist]

Hi,

do some simulation with less load current.
Just to see what happens.

In your simulation did you use all the ESR and additional part values?

I didnt use the ESR values, my inductor ideal.
I tried less load current result is same.

--- Updated Aug 17, 2021 ---

you may have set the input current limit too low, for full power there is ~ 100 amp or so

How can i set this limit?

--- Updated Aug 17, 2021 ---

My parameter are 25-23V input 80V 31.25A output. I took the design from webench designer why isn't working?

25-32V in*

 

[KlausST]

Hi,

How can i set this limit?

This means you did not read the datasheet thoroughly. But this is urgent if you want to design electronics.
Every professional needs to do this.

The general answer: do a PDF search on "current limit"

Then you will find the chapter: "7.3.10 Cycle-by-Cycle Current Limit"

Klaus

 

[Easy peasy]

350kHz ( 26k ) is way too high for this power level, try 70kHz, ( 128 k ) and a decent sized choke, say 39uH .... approx +/- 10A pk ripple ...

--- Updated Aug 18, 2021 ---

you don't need C1 for the sim.

--- Updated Aug 18, 2021 ---