Do Tesla Powerpacks use a 'Negative DC" bus?

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jonescg
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Do Tesla Powerpacks use a 'Negative DC" bus?

Post by jonescg » Jan 08, 2018 3:55 am

I came across this patent from Tesla, as discussed by Electrek:

https://electrek.co/2017/03/31/tesla-pa ... e-station/

There is a link to the patent document, but only downloadable through Scribid (another means to make a buck out of the internet).

Anyway, what caught my attention was this:
patent-pp-3.png
patent-pp-3.png (42.77 KiB) Viewed 344 times
Are they suggesting that a +400 V DC and a -400 V DC bus be created? What is the advantage to this? As far as I can tell, there are 16 lots of 48 V - perhaps half of them are in series to create one potential, and the other half to create the opposite? Rather confusing. :?

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Re: Do Tesla Powerpacks use a 'Negative DC" bus?

Post by billvon » Jan 08, 2018 12:23 pm

jonescg wrote:
Jan 08, 2018 3:55 am
Are they suggesting that a +400 V DC and a -400 V DC bus be created? What is the advantage to this?
Twice the power transferred in the same wire, without twice the potential to ground being present (which would necessitate more expensive insulation, wiring and protection devices.)
--bill von

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Re: Do Tesla Powerpacks use a 'Negative DC" bus?

Post by jonescg » Jan 08, 2018 6:13 pm

Right. So the DCDCs step it up from 48 V to 400V DC, and this is inverted centrally. Kind of neat.

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Re: Do Tesla Powerpacks use a 'Negative DC" bus?

Post by billvon » Jan 08, 2018 7:37 pm

jonescg wrote:
Jan 08, 2018 6:13 pm
Right. So the DCDCs step it up from 48 V to 400V DC, and this is inverted centrally. Kind of neat.
For now, yes. In the future 400V will be the "native" voltage - first generated at the panel level, then stored in a battery, then distributed. The Pika RE-Bus is one example of such a system. In Asia, DC building power (370-400 volts) is becoming more and more common as high power industries (like server farms) seek simpler, more efficient, more reliable power systems.
--bill von

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Re: Do Tesla Powerpacks use a 'Negative DC" bus?

Post by jonescg » Jan 08, 2018 8:31 pm

I would have thought that ~600 V DC would be closer to the mark. When turned into 3-phase AC it's more like 415 V phase to phase.

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