SMPS 30-300Volt Input and constand 24vdc output

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highjump2

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i need a SMPS 30-300Volt Input and constand 24vdc output. any ideas? would like an off the shelf unit, of to modify an off the shelf unit. i need 50 watts min output.
 

Surely feasible, but probably not available off the shelf. You are talking about AC or DC input? Isolation?
 
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    ir2153

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I am taking some generated voltage that will vary between 30-240VAC. I then have been running it through a bridge rectifier to get the 40-330VDC. This rectification is not required, depending on the SWPS. I need to take that voltage and generate a constant 24VDC. At the 30VAC/40VDC input, I need 25 watts minimum. Once it gets up to about 60VAC/80VDC input, I need the 50 watts.
 

over what time span would the voltage vary?
 

it will infinately vary. the generator is driven by a conveyor belt. the time it takes to change voltage is relatively long. A change from 30-40 volts on the input side may take 5 seconds.
 

I like your suggestion of a servo-controlled Variac very much.

However, there is a question for highjump2: When the voltage changes, does the frequency vary too? If it does, what is the range?
 

this is a 3 phase generator. i dont think the frequency will vary, but am not for sure.

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also, i am looking for something much smaller. similar to this small SMPS.

http://obrazki.elektroda.pl/4965667500_1396019142.jpg
http://obrazki.elektroda.pl/6444190200_1396019144.jpg
 

schmitt trigger said:
this is a 3 phase generator. i dont think the frequency will vary, but am not for sure.
Click to expand...

If it is a synchronous generator (most likely), the frequency varies directly with speed.

The key here is whether the voltage/frequency ratio remains constant during those speed changers. Otherwise the Variac or any transformer could saturate.
 

I then have been running it through a bridge rectifier to get the 40-330VDC.
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If you filter this with a smoothing capacitor, then you can feed it to a buck converter, to step this down to 24VDC.

This simulation shows the basic concept (using your low and high figures for supply voltage):



Component values are identical. The control clocks are at different duty cycles.

These show identical loads (11 ohms), although your spec suggests the load will be greater resistance when the supply is in the 40V range.
 

BradtheRad thanks for the idea with the smoothing capacitor as it made a big difference. For the buck converter, is this something that I'll have to build? Or is it off the shelf? From your picture, it appears to be a one size fits all for my application, which is what I'm after.
 

For the buck converter, is this something that I'll have to build? Or is it off the shelf? From your picture, it appears to be a one size fits all for my application, which is what I'm after.
Click to expand...

My simulation only shows the basic concept, using the minimum components. It shows your plan is feasible, since you are asking about a SMPS.

Additionally you will need the controller IC. Several SMPS IC's are mentioned often at this board. (I have no experience with this type of IC.) You must select one which can handle a 300 V supply, or else it must interface with a switching device which can withstand 300V.

The controller IC reacts quickly to changes in your load and supply voltage. It adjusts the duty cycle to deliver your desired output voltage.

There have been many threads here which discuss making a homemade SMPS. It seems to be a popular project. It is up to you whether you would want to tackle it, if you do not have success finding a ready-made SMPS to suit your specifications.
 

BradtheRad, do you know where I can go within the US to have something made or modified to meet my needs? I need 4 working prototypes initially, with plans to go into production quantites of about 1000 per year.
 

highjump2 said:
BradtheRad, do you know where I can go within the US to have something made or modified to meet my needs? I need 4 working prototypes initially, with plans to go into production quantites of about 1000 per year.
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Sorry I cannot advise about how to get them manufactured.

Evidently the commercially-available units have a narrower range of input voltages. This suggests it will be a major challenge for you to achieve your spec of 30-300V input. For example, a switching device that can handle 300V at 50W, may have a high On-resistance at 24V and 50W.

Although you do not plan to connect it to mains AC (but rather a generator), it's possible you will need to isolate the output from the input, by using a transformer. Then we are talking about a flyback, or forward, converter.

Here is another thread which may be of interest:

https://www.edaboard.com/threads/13858/
 

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