Stacking offline PSU's to give twice the voltage and power?

[treez]

Hello,
We wish to supply 96V, 100W to a LED luminaire which has a constant current led driver and dimmer with it.

Can we simply “stack” two 48V offline psu’s in series to provide the 96V? (eg two CLG-100-48 type PSU’s)…

CLG-100-48 PSU.
https://www.meanwelldirect.co.uk/public/ranges/pdfs/r763/r763_3.pdf

...also, can we ask Meanwell to pot this power supply inside so we get better conduction of heat to the metal case?

 

[schmitt trigger]

My first thought is "no".

But.........
Those questions though, should be asked directly to Meanwell, as they have detailed knowledge about its operation.

 

[treez]

Thanks, but surely there's no reason why not, - they are both isolated outputs

 

[dick_freebird]

For ESD / transmission line pulser work I have stacked every
(low voltage) supply in the lab to get the few hundred volts
I wanted. You'd need to be sure the supplies you have, are
fully isolated and you probably need to keep the cases from
touching, etc. just on the chance that the chassis is not
isolated (to the needed extent) from + and - terminals.

 

[Orson Cart]

Yes you can stack 2 of without problem, ideally place an inverse diode on each o/p, this is commonly done in a lot of test situations...

 

[mrinalmani]

It goes without saying that a current source cannot be dumped directly into another current source, it needs a voltage sink/source.
Similarly, a voltage source cannot be dumped in another voltage source.
Since the PSUs are essentially working as a current source, a parallel combination seems reasonable but a direct series combination may result in voltage spikes at their connecting terminals during transients.
So terminating the 1st PSU wit a small capacitor and then connecting the other in series should help, provided of course that they are isolated internally.
The capacitor ensures that a current source is terminated in a voltage source and thus will absorb spikes during transients.

 

[treez]

sorry but this is a fixed vout PSU..not current regulated.

 

[Orson Cart]

Best if you ignore post#6 it is not informative in any way.

 

[schmitt trigger]

My only concern for series connected PSUs would be feedback loop dynamics.

Maybe I'm a little paranoid, but last year I've had a nightmare with an unstable feddback loop.

 

[mtwieg]

If they are voltage regulated and well matched then sure you can. To prevent RFI between them I would make sure they have independent input CM filters, maybe put a ferrite bead or something at the point their outputs tie together.

 

[Anna Conda]

As long as they have some internal o/p capacitance (and they will) and its not your feed back loop in the power supply then they will be fine, it is a common practice, esp for test rigs...