MOSFET FOR DC-DC BOOST CONVERTER

Thread Starter

Amirudin97

Joined May 1, 2021
5
Hi!

Currently I'm studying on how to make and design a Dc Boost converter. My design details are Vs=12V,2A. Switching frequency f=25kHz, output voltage=120V at duty ratio 0.9. For the switching I use a MOSFET. I found a MOSFET IRL510 (details as attached). The VDS for that MOSFET is 100V. So, my question is can I use that MOSFET for my circuit?
 

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Papabravo

Joined Feb 24, 2006
16,103
Consider for a moment that with a duty cycle of 0.9V your converter is spending most of the time shorting the input supply to Ground. Is this really a good idea in your estimation?
 

Ian0

Joined Aug 7, 2020
2,189
You see buck regulators with 10% duty cycles, so why not boost regulators with 90%?
I know it’s not the most efficient, but it will work.
It’s not exactly shorted to ground, it‘s storing energy in the choke.
 

Papabravo

Joined Feb 24, 2006
16,103
You see buck regulators with 10% duty cycles, so why not boost regulators with 90%?
I know it’s not the most efficient, but it will work.
It’s not exactly shorted to ground, it‘s storing energy in the choke.
If you seldom see load transients and you're not worried about having adequate headroom to adjust the duty cycle and the MOSFET can dissipate the heat then I guess it can work but my question goes deeper and asks if it is a good idea. I think not, but YMMV.
 

Ian0

Joined Aug 7, 2020
2,189
If you seldom see load transients and you're not worried about having adequate headroom to adjust the duty cycle and the MOSFET can dissipate the heat then I guess it can work but my question goes deeper and asks if it is a good idea. I think not, but YMMV.
I totally agree it won’t make the world’s greatest boost converter; but for someone who is just learning the basics of boost converters, it’s a place to start.
I do remember a while ago, asking for opinions on what was the best way to get 200V from an 18V supply, and a single stage boost converter was suggested by quite a few people.
https://forum.allaboutcircuits.com/threads/switched-mode-conundrum.175319/
 

Papabravo

Joined Feb 24, 2006
16,103
I totally agree it won’t make the world’s greatest boost converter; but for someone who is just learning the basics of boost converters, it’s a place to start.
I do remember a while ago, asking for opinions on what was the best way to get 200V from an 18V supply, and a single stage boost converter was suggested by quite a few people.
https://forum.allaboutcircuits.com/threads/switched-mode-conundrum.175319/
I think that many people do not appreciate that the cost you must pay for boosting the voltage is a reduction in the available current to the load. They keep imagining a universe in which power out can be greater than or "at least" equal to the power in. The shock that this is not true is often sudden and quit "rude". You can literally see the light go out of their eyes.
 

crutschow

Joined Mar 14, 2008
27,184
Likely better would be a flyback circuit, where the two-terminal inductor becomes a 4 terminal coupled inductor.
But that is obviously a more complex circuit.
 

Audioguru again

Joined Oct 21, 2019
3,173
My cheap solar garden lights boost the voltage with a circuit like that in an IC. They limit the boosted voltage with an LED.
What will limit the boosted voltage in your circuit?
 

Thread Starter

Amirudin97

Joined May 1, 2021
5
Consider for a moment that with a duty cycle of 0.9V your converter is spending most of the time shorting the input supply to Ground. Is this really a good idea in your estimation?
This is just for an experiment. I want my circuit can produce maximum output voltage about 90v at 0.9 duty ratio.
 

Ian0

Joined Aug 7, 2020
2,189
Okay thanks ya. I try my best
I have two projects that need this type of circuit - one to power some LED luminaires containing LED modules that run at 90V from a 12V source, and one to power some valves at 200V from 18V, and I'm going to use this circuit, after the discussion we had (linked in Post #7) with a turns ratio of 1:9
 

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