# 30VDC to 480VAC Input range to 24 V 10 Amp powersupply

Discussion in 'Power Electronics' started by Ally Cat, Jul 26, 2016.

1. ### Ally Cat Thread Starter Member

Mar 28, 2016
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0
Hi I am looking into what it would take to design a power supply that can handle 30 V DC input that can also handle up to 480 AC. Not sure this can be done. I was thinking of TDK Lambda bricks that are really good at the AC portion of the design but fall short of the 30 DC(85 VAC min). Is there an easy solution that can meet such harsh input conditions that can be achieved. Still I would like to know what it would take to meet these demands.

2. ### #12 Expert

Nov 30, 2010
16,705
7,358
Stupid question: What do you have that needs less than 30 volts DC and also 480 VAC?
Answer: Use a transformer to reduce the 480 VAC to 120 VAC

3. ### Ally Cat Thread Starter Member

Mar 28, 2016
34
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Wouldn't the transformer reduce the 30 V to a 7.5 V, which would be a problem.

4. ### #12 Expert

Nov 30, 2010
16,705
7,358
Transformers don't work at all with DC so it would reduce the 30 volts DC to zero.

5. ### Ally Cat Thread Starter Member

Mar 28, 2016
34
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That would still be a problem.

6. ### #12 Expert

Nov 30, 2010
16,705
7,358
OK. Let's get to the bottom of this. You would need to design a switching regulator that can work with anywhere from 30 VDC to over 700 VDC, or use a switch to connect the DC directly to the switching regulator at one moment, then connect the 480VAC reduced to 120VAC when you are using that source. Your choice.

7. ### Ally Cat Thread Starter Member

Mar 28, 2016
34
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Can't switch the input between two states. It has to work off the same input. I really think it involves a custom brick power solution. This would be out of bounds of my resources.

8. ### Kermit2 AAC Fanatic!

Feb 5, 2010
3,854
968
Can't switch the input between two states...

You want a device that has two wires for input and must accept your low voltage DC and dangerously high AC limits?

Wouldn't the various types of plug adapters for your AC requirements alone be a cumbersome detail?

What could possibly make a two wire universal input power supply superior to one with separate AC and DC input wires? Does the dumb brute employing the powersupply get confused when he sees three or more wire thingys sticking out of it?

Asking to many questions makes me cranky and as you can tell I went over my limit. My apologies.

9. ### tcmtech Well-Known Member

Nov 4, 2013
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Okay, let's start with the necessary info first rather than wasting 30+ posts to get there.

#1. What do you need to power to begin with that requires a stable 24 VDC at up to 10 amps?
#2 What power source do you have that puts out 30 to 480 volts in both or either DC and AC ?
#3 Where is this wide range of power located?
#4 Realistically how often do you expect to see either end of this range of voltage being available?

Just because it could be done does not mean it's needed.

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10. ### Ally Cat Thread Starter Member

Mar 28, 2016
34
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Sorry tcmtech, I don't have the answers to the questions you asked. I was only asked if it were possible and how much it would cost. I am mostly just curious what would it take to achieve this power supply circuit. Usually when it comes to that type of power supply I use Bricks. That is not going to work in this case. I don't know how else to ask but the end client wants these parameters met and I honestly don't know how. My instinct tells me it is possible but I am not certain on how to achieve it.

11. ### Papabravo Expert

Feb 24, 2006
10,340
1,850
There is no known technology that will generate both types of input, just as there is no known technology that will convert both types of input to the output. It is my considered opinion that either your or the client do not understand the requirements. If there was someone who claimed they could do this then I would buy from them in a heartbeat because the cost of designing and building such a device would certainly exceed your combined economic resources.

I was thinking of TDK Lambda bricks that are really good at the AC portion of the design but fall short of the 30 DC(85 VAC min).

Even in your original post you conflated 30DC with 85VAC min. So even if the brick were to work at 30VAC this would still not meet your requirement. Take another look at the actual requirements.

12. ### tcmtech Well-Known Member

Nov 4, 2013
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I don't think it would bee all that hard.

I would start off with a full wave bridge rectifier that makes sure everything is DC inside the unit.

Next would be a basic control circuit that reads the input voltage and switches between three switching devices that are each attached to a different tap on the main HF transformer primary side.

Everything else is just standard SMPS control circuitry with but with one modification that it has three switching devices on different taps that can be selected from depending on what the additional control circuit selects.

One tap handles 25 - 100 volts the next can do 80 - 360 volts and the last does 300 - 800 volts.

That's how I would approach it.

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13. ### Ally Cat Thread Starter Member

Mar 28, 2016
34
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Thanks tcmtech

Could you elaborate on how you would do the three switching devices. Are you talking about relays and have a processor turn on and off the different voltages using a ADC to measure the voltages? I can't use a manual switch.

14. ### Papabravo Expert

Feb 24, 2006
10,340
1,850
This is absurd. There is no power source on the planet that is both 480VAC and 30VDC at the same time. If the source is DC at some instant of time it cannot make it through the transformer. If the device has no transformer it violates the TOS. You can't win on this one. Maybe if the TS/OP would offer a schematic of what he has in mind it would help.

15. ### tcmtech Well-Known Member

Nov 4, 2013
2,120
1,754
Well, that's for me to know isn't it!

You supply the info for my first post ndI will consider sharing my info on how I would do it provided your info makes the least bit of rational sense of course.

I take it you have no clue how a Switch Mode Power Supply is designed and works huh?

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16. ### Ally Cat Thread Starter Member

Mar 28, 2016
34
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Sorry tcmtech

Don't really have any info any of these questions

#1. What do you need to power to begin with that requires a stable 24 VDC at up to 10 amps?
#2 What power source do you have that puts out 30 to 480 volts in both or either DC and AC ?
#3 Where is this wide range of power located?
#4 Realistically how often do you expect to see either end of this range of voltage being available?

Just got an email to say yes I can do it or no I can't.

The answer I sent was no. I don't know anything else. I believe such a power supply is possible just out out of my capabilities. I thought it would be a good topic to test this site one as well.

17. ### joeyd999 AAC Fanatic!

Jun 6, 2011
2,759
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I would have said yes, but that's just me.

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18. ### Papabravo Expert

Feb 24, 2006
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It would be hard to alledge that since I have designed well over two dozen of them. I have to admit that none of them would work on a power source that was either AC or DC at the same time. I'm waiting for all the believers to put up or shut up.

19. ### tcmtech Well-Known Member

Nov 4, 2013
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So you've never fed DC through the bridge rectifiers of an AC input unit and used it as a universal input unit?

Of those units you built were any isolated types or all basic isolated buck/boost designs?

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20. ### Papabravo Expert

Feb 24, 2006
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Yes I have and that is manifestly not the problem. The problem seems to require both a 30 VDC Input and an 480 VAC Input on the same pair of pins. That implies a transformer and the transformer will in fact block the DC voltage. You're just changing the problem to fit your experience instead of listening to the TS/OP requirements. You might want to pick your knuckles up off the ground. It is time to put up or shut up.