Power Supply Design

[alok1982]

I want to make a power supply to generate 18Vdc/ 30A. Output current is high, can we design power supply for this specification? If possible can you please share the application notes, circuit diagram of the same? Also, please suggest me the points what I consider while designing the Power supply for this specifications.

Note: The Power supply should be CV (constant voltage).

Thanks!

 

[Misterbenn]

Hi Alok,

• What input voltage do you have and is it AC or DC?
• What is the minimum power supply loading?
• What kind of tolerance do you need on the 18V output
• Will you be using a fan to cool the PSU or just convection?

Is there a reason you can't just use an off-the-shelf 18V power supply or a bench top power supply?

 

[MikeMl]

I just got a HP rack-mount supply, 0-40V constant-voltage, 0-30A constant-current, dual meters given to me for free. The sucker weighs about 120# and has a noisy fan. It makes a great lead-acid battery charger. These come up in the industrial surplus electronics market from time to time. I would be looking at locally first, then ebay, eham, etc if I needed to buy one.

If I was looking for a switcher, I'd look here.

DIY is problematic. Parts cost will exceed the cost of a new or used supply.

 

[MikeMl]

Have you thought about just using 3each 6V lead-acid batteries in-series with a suitable charger. If your load demand is only occasional 30A peaks, with an much lower average current , then that would work.

 

[simonbramble]

If you want to get involved in circuit design (instead of just buying a box), try the LTC3890:
http://cds.linear.com/docs/en/demo-board-schematic/1804asch.pdf
The above is the schematic of a 12V/25A design. For 30A you will need to parallel up the FETs. For design notes, please see:
http://www.simonbramble.co.uk/dc_dc_converter_design/buck_converter/buck_converter_design.htm
(I seem to be having some problems with IE. Use Firefox if the page formatting is strange)

 

[alok1982]

Hi Alok,

• What input voltage do you have and is it AC or DC?
• What is the minimum power supply loading?
• What kind of tolerance do you need on the 18V output
• Will you be using a fan to cool the PSU or just convection?

Is there a reason you can't just use an off-the-shelf 18V power supply or a bench top power supply?

Hi,
1) Input voltage is 110V/60Hz
2)For loading = Output voltage is 18Vdc and Output current can vary in between min. 25A to 30A
3)1% tolerance
4)Fan cooling

Thanks!

 

[alok1982]

I want to add some more in the query;
Actually this power supply I want to design is for a pressing tool. I measured it's working current, for normal operation it is 7A but, when it starts it takes a high peak current of 28A and then it comes to 7A. When this tool is in working condition, sometimes as according to load the current rises up to 28A (When the tool press the load).

That's why I am thinking to make a power supply of 18V/ 30A. Please suggest I am wrong or right?

 

[MrAl]

Hi,

Well, this thing is nearly 600 watts and that's not exactly a power supply that should be your first power supply you ever built. If it was 18v and 1 amp, that would be entirely different. But that 30 amp requirement makes this a lot more involved. And if you are going offline rather than with a transformer then you've got some safety issues to think about due to the line voltage hazard potential of 120vac.

So you think you really want to tackle this thing, or start with a smaller power supply first?
Im not sure what your electronics background is either though, maybe you can fill us in with some info like what kind of projects did you do in the past, what kind of test equipment you own, etc.

 

[avrilcory]

UPS power supply backup is an apparatus that provides emergency power to a load when the input power source typically mains power fails. Power Designer is most commonly used switch mode power supplies. It is also a great assistance for getting a deeper understanding of voltages and current flows inside converters.

Thanks
Riello-ups

 

[ChrisP58]

I suggest getting the 15 volt version of something like the following, and setting the voltage trim up to 18V.

**broken link removed**

 

[KeepItSimpleStupid]

The DCR series form Sorenson isn't too bad. They probably need recapping. See: **broken link removed** usually service info is available from Sorenson with a serial number.

Here **broken link removed** is an 18V 22A. At $50 it might be worth trying.

This: https://www.bravoelectro.com/se-1000-24.html?gclid=CInapLarr7wCFUYOOgodBigAVg is adjustable as low as 18V.