Physically huge SMPS is just 1KW ?

1kw smps

Hello,

I once Acceptance Tested An SMPS unit which was for supplying a TWTA.

I was not allowed to see circuit diagrams due to confidentiality.

The output of this SMPS was 13KV.

It was said to be a 1KW SMPS

….The thing is, the unit was around 50cm by 42cm by 15cm.

How could such a huge thing have been just 1KW ?

What power rating would you think it was likely to be ?

It was cooled by an internal fan, which wasn’t all that big –about 9cm diameter and 3cm deep.

smps 1kw

just a guess, it maybe because it's a high volatge. :idea:
so, to meet safety requirements (i.e. isolation) they must have large "space" between the components (and the pcb traces)..

cockroft-walton voltage multiplier

What I think is that there must be a "Cockroft Walton Voltage Multipliers" it should be potted (epoxy etc). And it is control by some PWM SMPS.

1kw smps circuit

yus:
i believe you are right....though it still seems big?

Awarapunshee:
Most of their power supplies were indeed potted.....but for some reason this one was not potted......i dont know what those cockcroft's are but i sneeked a peep inside for a nanosecond or so and saw lots of diodes.

smps 1 kw

The unit should have a type plate (required by most safety regulations, e.g. UL).

one option wold be a Cockroft walton voltage multiplier ckt.
assuming an input supply of 230V or 110 V the supply must have some kind of step up transformer to step up the supply to al least 4 or 5 kV. the next stage would be 3 or 4 stage a cockroft walton voltage multiplier which would give a output of 13 to 15 kV. CW type of supply can not have a high current(100mA) capacity with large no of stages. this kind of supply has no noise and would have large capacitors and diodes at the output stage.


second option is a rectifier stage at input converting the AC in to DC. the DC is then fed to an inverter which will produce a high frequency ac voltage which could be then fed to a ferrite or Metglass core transformer. the output of the transformer is then rectified and filtered. this will have some mosfet or IGBT in the inverter stage. the regulation will be good in this stage.

in both the cases the caseing would be large to acomodate the high-voltage requirement. due to high voltage insulation requirement either all transformers would be pot core or would have milar insulation. no oil cooling but air cooling.


hock