Topologies for 5kW 60Vdc output?

[nov]

Hi all,
I would like to get your advice for selecting the power architecture(s) or topology(ies) for the following power supply:
Input: 200-250 Vac 1 phase
Output: 60V 75A
Industrial application
No isolation required
Cost sensitive
EMI class A required
Space not very limited
Ambient temperature up to 50 C or 122 F
Modularity is possible (ex.: 5 X 1KW instead af 1 X 1kW)
Can be fan cooled
No harmonic current requirement (EN6100-3-2)

For now I looked at resonant buck converter and full bridge phase shift. I think of using only a diode bridge with capacitor for the AC DC part since I do not have harmonic current requirement.

Witch power architecture would you suggest? What is your guest?

Thank a lot

 

[schmitt trigger]

Since you require NO isolation, a resonant buck is an intriguing possibility.

Having said that, the resonant passive components may be quite large, or its values not readily available.

I would do a feasibility study, that in essence means doing some paper-and-pencil calculations, probably some simulations, and then look into your favorite parts distributor to see if those components are available (and at what cost).
You do the same exercise with a full bridge configuration.

I don't think that you can get away without a feasibility study, and the time and effort involved on it. A lot of people here will have lots of opinions. But only cold, hard calculated facts will give you the optimal answer.

 

[mtwieg]

Most ZVS converters (LLC and phase shifted bridge) are based on transformers, and that would increase cost significantly. I would suggest using a vanilla buck converter based on IGBTs, probably with multiple interleaved phases. That would make modularity quite simple.

If you try to do the AC/DC conversion stage with a simple rectifier, make sure you rate everything for very high max current. You will probably see peak currents in excess of 100A easily. Also you will likely need a precharging circuit to avoid excessive inrush.

 

[nov]

Thanks you for your answers.

For now my best guess is the interleaved buck converter. I am planning 3 of 1500W in order to use high efficiency MOSFET TO-247 packaging. And yes I could reduce cost by using IGBTs instead of Mosfet but the frequency will be lower and the inductor size will increase. But it may be a good thing (or necessary) for EMI in this hard switching solution.

That’s why I’m looking for ZVC to achieve soft switching. Does someone have experience with a buck converter with ZVC at this power. I see a lot of university article but I was wandering if it is use in real application.

Thanks

 

[schmitt trigger]

Interleaved bucks it it, the next question: What is your expected switching frequency?

As you correctly mention, the inductor's size will increase proportionally with lower frequency.....which means that you could find yourself at a frequency/power boundary where the low perm of ferrite would make the inductor excessively large, and/or where magnetic steel would be too lossy.