help designing regulated PS 13v8@50A w/ IRFZ44

[kroto]

help me to design a simple regulated power supply capable to 50A in 13v8 with IRFZ44 ( shunt regulator maybe).
not gona be used to welding ofcourse
just want to learn designing PS with HEXFET, and IRFZ44 fit the purpose I think...

thx folks...

[djQUAN]

what's the input voltage?

also: the words simple, regulated and 50A don't usually go together in a SMPS.

[kroto]

Originally Posted by djQUAN

what's the input voltage?

Hi djQUAN,
Lets assume 15-0-15 from the Trany.

Originally Posted by djQUAN

also: the words simple, regulated and 50A don't usually go together in a SMPS.

A conventioanal regulated PS, not a SMPS.
maybe the MOSFET used as the pass transistor, can it be?

maybe, give me a basic circuit (a few if any?), and then give me the calculations needed or discuss how it should work with MOSFET.
like Drain Current is controlled by Gate-Source voltage isn't it? so, how to maintain these etc.etc.

sorry, not quite well know how MOSFET should work with well.

[stoc005]

A quick look at Ebay finds 12V @ 29A SMPS at $42 to $50 USD with free shipping. Use (2) of them. It used to be about $1 USD per watt but it seems that prices are much lower than that today. I will not build something if I can buy it for what it will cost me to build it. My time is worth something.

Designing and building a SMPS is not for beginners. Do you understand the magnetic components needed to design/make a SMPS?? This aspect usually is the deal breaker for most people. There is much more to it than picking a MosFET. Picking the right output filter caps can be a real challenge but those folks that know nothing about SMPS design think they must be easy since they have so few parts.

How much help will you need?? Do you want guidance only?? Do you want somebody else to design it and hand you the completed design?? Go to Linear Tech and download LTSpice. Many of their SMPS parts have example circuits that might be applicable to what you want to do. You will be able to simulate many SMPS circuits. But you will have to invest some OF YOUR TIME into it.

As someone else pointed out, your specification is incomplete as well.

[ikoflexer]

50A shunt regulator? Sounds crazy, but I think it can be done. You'd need enormous heat dissipation, and paralleling lots of mosfets. Otherwise, no problems. Many circuits will work, in theory, but to make it work in practice it's a another matter.

[kroto]

Originally Posted by stoc005

A quick look at Ebay finds 12V @ 29A SMPS at $42 to $50 USD with free shipping. Use (2) of them. It used to be about $1 USD per watt but it seems that prices are much lower than that today. I will not build something if I can buy it for what it will cost me to build it. My time is worth something.

Designing and building a SMPS is not for beginners. Do you understand the magnetic components needed to design/make a SMPS?? This aspect usually is the deal breaker for most people. There is much more to it than picking a MosFET. Picking the right output filter caps can be a real challenge but those folks that know nothing about SMPS design think they must be easy since they have so few parts.

How much help will you need?? Do you want guidance only?? Do you want somebody else to design it and hand you the completed design?? Go to Linear Tech and download LTSpice. Many of their SMPS parts have example circuits that might be applicable to what you want to do. You will be able to simulate many SMPS circuits. But you will have to invest some OF YOUR TIME into it.

As someone else pointed out, your specification is incomplete as well.

Hi stoc005,
I'm not about buying PS, but learning how to design a shunt reg PS with MOSFET as the pass transistor, or the short-circuit protection

[kroto]

Originally Posted by ikoflexer

50A shunt regulator? Sounds crazy, but I think it can be done. You'd need enormous heat dissipation, and paralleling lots of mosfets. Otherwise, no problems. Many circuits will work, in theory, but to make it work in practice it's a another matter.

Helo ikoflexer,
ha ha,,, yes it is seems crazy, but thats is what I want to "learn".
Would you like to help me on these?

[djQUAN]

why a mosfet? and in a TO-220 package? with that much heat dissipation, TO-220 devices won't help. you need ones in big TO-3 or TOP-3 cases to handle the power dissipation.

there are a lot of circuits online using transistors boosting the current capability of LM317 regulators...

[kroto]

With these (IRFZ44) mosfet, I've got the benefit of the compact size of TO-220, big drain current, cheap, rugged device (I think).
dissipation won't much if the Vin isn't too high.

if use BJT, I've know already how they work...



so? how?

[russo]

Dont know if i'm wrong, but you will need to dissipate 13,8v*50A=690watts, thats something