Is it possible use a single voltage PSU e.g +54V to generate a dual 54-0-54 V supply? How can such a circuit be constructed?

 

hi One,
Welcome to AAC.
What current is required from the +/-54v.?
E

 

hi One,
Welcome to AAC.
What current is required from the +/-54v.?
E

5 Amps.

 

hi.
I guess you know that if you want 5A from both the +54v and -54v, being generated from the the original 54V, that it will require that the existing 54v can deliver at least or greater than 10A, say 12A.?
E

 

You could use a switch-mode DC-to-DC converter to get an isolated 54V output. Which way round you connect the output wires would dictate whether that's +54V or -54V.

 

hi.
I guess you know that if you want 5A from both the +54v and -54v, being generated from the the original 54V, that it will require that the existing 54v can deliver at least or greater than 10A, say 12A.?
E

Actually the original supply is rated 20A.

 

You could use a switch-mode DC-to-DC converter to get an isolated 54V output. Which way round you connect the output wires would dictate whether that's +54V or -54V.

Okay but the requirement is to have both +54V and -54V not just one of the two. You might be familiar with dual supplies in audio amp ccts. It is easy when you have a center tapped transformer. Now I am considering a situation where a +54 voltage SMPS is available.

 

With all DC-Dc conversion schemes you need to understand that the power out will always be less than the power in. Sometimes it will be much less.
The calculation goes like this:

1. 54 volts times 5 amperes is 270 watts
2. -54 volts times 5 amperes is 270 watts
3. total output power is 270 + 270 = 540 watts
4. Assume for the sake of argument that the conversion process is 80% efficient
5. That is 540 watts divided by 80% = 675 watts
6. 675 watts / 54 = 12.5 amperes

If you're efficiency is less than 80% you're going to need a bigger input supply. At these power levels, IMHO it makes more sense to do an offline line supply.

 

Okay but the requirement is to have both +54V and -54V not just one of the two.

Which is exactly what @Alec_t told you how to do.

 

Okay but the requirement is to have both +54V and -54V not just one of the two. You might be familiar with dual supplies in audio amp ccts. It is easy when you have a center tapped transformer. Now I am considering a situation where a +54 voltage SMPS is available.

The DC-DC Isolated convertor will give you -54 volts.

 

hi onedrop,
I was thinking along the same lines as @Ramussons add a DC-DC Isolated sepic converter for -54v @5A.
The original 54V @20A should be able to handle the load requirement.

E

 

Is it possible use a single voltage PSU e.g +54V to generate a dual 54-0-54 V supply? How can such a circuit be constructed?

Possible? Yes. Practical? Probably not-- unless you're willing to devote a lot of time and money on a very challenging design task.

You'd be a lot better off simply buying a second 54V PSU and putting the two in series.

 

Isn't the idea to have a bipolar supply with a common ground? How does doing an isolate converter help with that proposition, unless you do two isolated converters which can be hooked up in the desired configuration?

 

Possible? Yes. Practical? Probably not-- unless you're willing to devote a lot of time and money on a very challenging design task.

You'd be a lot better off simply buying a second 54V PSU and putting the two in series.

That is just too obvious. Just because the original question implies an answer, doesn't mean there are no alternatives.

 

Isn't the idea to have a bipolar supply with a common ground? How does doing an isolate converter help with that proposition, unless you do two isolated converters which can be hooked up in the desired configuration?

You take the plus of the isolated supply and connect it to the minus of the original supply, and voila, you have a bipolar supply.

Bob

 

You take the plus of the isolated supply and connect it to the minus of the original supply, and voila, you have a bipolar supply.

Bob

But then you've broken the isolation barrier

 

But then you've broken the isolation barrier

Where is the requirement for isolation mentioned?

 

Where is the requirement for isolation mentioned?

@Alec_t mentioned it.
You could use a switch-mode DC-to-DC converter to get an isolated 54V output. Which way round you connect the output wires would dictate whether that's +54V or -54V.
and at least one other person mentioned as a potential solution.
@Ramussons also mentioned it
The DC-DC Isolated convertor will give you -54 volts.

I actually misread the original post and thought he was starting from a DC supply that was lower than 54 volts, and wanted to end up with a bipolar supply of 54-0-(-54). Apparently he just needs a boost converter and it doesn't need to be isolated. He still has to worry about efficiency and having sufficient headroom on his primary supply.

 

Čuk converter running at 50:50 mark:space ratio. produces a negative supply same voltage as the positive one, and doesn’t mess up either by taking high pulse currents.

Couldn’t you start with a 108V supply? That would make the job much easier.

 

Couldn’t you start with a 108V supply? That would make the job much easier.

Don't see how.
Splitting a 108V supply is not a trivial design for 5A if there's any significant unbalance in current.