Hi guys,

I have zero experience with power supply design so I hope you can help me with choosing the right one. The system I want to run has the following properties:

Input (either or, not simultaneously):
- 230VAC
- 24VDC

Required outputs (simultaneously):
- 24V @ 2,5A
- 24V @ 1A
- 12V @ 0,1A
- -12V @ 0.1A
- 12V @ 3.5A
- 12V @ 3.5A
- 5V @ 3A
- 5V @ 2.5A
- 3.3V @ 0.1A
- 2V @ 0.4A

My idea was 1. a converter from 230VAC to 24VDC and then stepping to the respective voltages from there. But maybe there's a better solution? I thought about an ATX computer power supply unit but one that runs with 24VDC input but the only one I found is ~$360. Any help is greatly appreciated!

 

If your inputting 24V dc, then you only need a Variable buck regulator, or a separate regulator for each voltage under 24V..

 

I'd drop the AC input option and just accept 24VDC input. Is that 24V power source capable of sourcing 18-20 amps?

 

Critical question - when running on the 24 Vdc input, do the output have to be galvanically isolated from the input? If the application is vehicle or MIL power, the answer almost always is yes.

Also, does the supply have to meet safety certifications (UL, CSA, TUV, etc.)?

Also also, do the duplicated outputs need to come from separate regulators?

Also also also, is there any specific power-up or power-down sequencing required?

I've done this more than once. Typically I'd use a 24V/24V DC/DC converter with enough output current to run everything, then post-regulate all of the other outputs with linears or bucks. A 555 or a small buck/boost can generate the -12 V.

ak

 

It's a bad idea to start out with such a difficult project.

A desktop computer power supply will give you over half of the stated specs. 30 bucks brand name amazon. Cheaper on ebay.

Then add separate 24 V and 2 V supplies.

 

Is that 24V power source capable of sourcing 18-20 amps?

Sounds a bit high; more like 12 A. The total output power is around 200 W, or 8.33 A at 24 V. With 80% efficient main and post regulators, that's about 4.4 A for an isolated 24 V output. The other outputs are dual-converted and add up to about 7.5 A at 64% efficiency (80% in the 24 V DC/DC and 80% in the post regulators).

-ish

ak

 

Probably some actual info on what the load for each supply is may help. Why do you need so many?
Would 1 x 24V, 1 x 12V, 1 x 5V, along with the -12V, 3.3V and 2V be ok?
Is there any reason you need the separate ones?

 

Thank you very much for all your replies, I'll try to answer them as good as I can:

I'd drop the AC input option and just accept 24VDC input. Is that 24V power source capable of sourcing 18-20 amps?

Unfortunately I cannot simply drop it, the system is required to run with both options. The 24V source should be fine with the amps.

Critical question - when running on the 24 Vdc input, do the output have to be galvanically isolated from the input? If the application is vehicle or MIL power, the answer almost always is yes.
Also, does the supply have to meet safety certifications (UL, CSA, TUV, etc.)?
Also also, do the duplicated outputs need to come from separate regulators?
Also also also, is there any specific power-up or power-down sequencing required?
I've done this more than once. Typically I'd use a 24V/24V DC/DC converter with enough output current to run everything, then post-regulate all of the other outputs with linears or bucks. A 555 or a small buck/boost can generate the -12 V.

- I'm not sure about the isolation. The source is a 25 Ah battery if that has anything to do with it?
- It doesn't have to meet safety certifications. As long as it doesn't inflame spontaneously, it'll be fine. ;-)
- The list of outputs may be misleading, it's the loads that I listed here. So I guess the duplicated outputs could come from the same regulator.
- There's no sequencing required.
- Thanks for your design idea!

It's a bad idea to start out with such a difficult project.
A desktop computer power supply will give you over half of the stated specs. 30 bucks brand name amazon. Cheaper on ebay.
Then add separate 24 V and 2 V supplies.

- Can't do nothing about the level of the project, I have to do it. ;-) I'm the guy with the most experience in electronics in the team.
I thought about an ATX supply as well and there are even some with 24V support but unfortunately the ones I found don't provide enough current @ 24V.

Probably some actual info on what the load for each supply is may help. Why do you need so many?
Would 1 x 24V, 1 x 12V, 1 x 5V, along with the -12V, 3.3V and 2V be ok?
Is there any reason you need the separate ones?

As mentioned above, I don't think seperate ones are necessary. The "output" list is misleading, it's a "loads" list (but I cannot edit it anymore).

 

If the 24 V input is coming from a battery, does it have to be regulated or stabilized or can it run the 24 V loads directly with an output that varies from 21 V to 28 V depending on charge?

What is your experience base with DC/DC converters like non-isolated buck converter modules?

For an AC/24 Vdc converter, are you considering a high-density "brick" or an industrial single-output switcher?

What are you initial thoughts on packaging, connectors, fans/heatsinks/cooling?

ak

 

If the 24 V input is coming from a battery, does it have to be regulated or stabilized or can it run the 24 V loads directly with an output that varies from 21 V to 28 V depending on charge?

That is a very important question. If your application can run on raw 24V, as from a battery, then the supply just go easier. All that is needed is the 24V to lower voltage regulators and a battery charger.

 

In the manual of the 24V source, it says: "In all cases where input sensitive hardware is used, DC-DC converters are recommended." I think all our hardware is capable of tolerating fluctuations to a certain level, should be fine.

What is your experience base with DC/DC converters like non-isolated buck converter modules?

Due to my electronics background, I understand how they work but I don't have hands-on experience.

For an AC/24 Vdc converter, are you considering a high-density "brick" or an industrial single-output switcher?

I was thinking about this guy here https://www.arrow.com/en/products/hrp-300-24/mean-well-enterprises A little oversized but those with less power are more expensive and only have none or a small current buffer.

What are you initial thoughts on packaging, connectors, fans/heatsinks/cooling?

Haven't spend many thoughts on that yet tbh.

What do you think about the 230V converter mentioned plus this one here? https://www.bicker.de/index.php/eng/content/view/full/1118 Runs with 24V and has all the outputs I need in one compact box and as far as I see it, has sufficient amps in every channel.

 

Sorry, wrong link but I cannot edit it anymore. I meant this one here: https://www.henri.de/stromversorgun...255/400w-pc-netzteil-mit-24v-eingang-atx.html (sorry, couldn't find an english shop that offers it). Oversized and a little pricey though but I couldn't find any other one so far that runs with 24V input.

 

My idea was 1. a converter from 230VAC to 24VDC and then stepping to the respective voltages from there. But maybe there's a better solution?

Building a 200W supply that operates from AC or DC isn't a simple task. $360 seems like a good deal to me for an off-the-shelf solution.

 

Alternatively, two of these (two due to only 4A@12V) here could also work? https://www.comp-mall.de/artikel,ip...teil,494535,IDD-9364120A-R11?pVariante=494535

 

I used Meanwell supplies (but not that exact one) a few times over the years and I like them.

Where are you located?

What is the final application (industrial, medical, military, outdoors, etc.)?

ak

 

I'm located in Germany and the final application is a scientific experiment. Meanwhile I found some more 24V ATX power supplies such as https://www.comp-mall.de/useruploads/files/Datenblaetter_manuell/ACE-717CX.pdf (196€) so I think I'll go for one of those. Off-the-shelf will probably result in a much better solution that designing one on my own, that's right @dl324 .