Charging the Roadster - EU Style

[BBHighway]

The Dutch answer is "gas". We use gas to heat everything.

That sounds scary! Don't you worry about your house blowing up with all that explosive stuff flowing through!

I guess any high power appliance can be dangerous if it's not engineered properly, regardless of the energy source.

[dpeilow]

So a crude 3 phase -> DC rectifier looks like this.



Simple Tesla - stick one of those in the back please...

That *is* of course the best solution!

A cheaper solution could be to use a 400V->230V transformer (300 euro for a 10kVA model; I just found a supplier) and then charge from two phases. Someone with more knowledge on this will surely be able to tell how (and if) the 120-degree phase difference translates to sqrt(3) saving.

I'd say 400V/36A = 230V/63A (roughly).

Do you have a link to the supplier?

[EV_de]

Six-Pulse Bridge rectifier - B6

DC Voltage Waveform:


If you run this with only 1 Phase and Nutral the DC Voltage Output will have a bigger ripple (gap between the Bumps)
therefore the average Voltage is lower and of course the Power-Output

[raymond]

So a crude 3 phase -> DC rectifier looks like this.

But that doesn't make use of all available power, does it? It just spreads the load evenly of the three phases, but only draws a load from each single phase at it's peak voltage.

Using 400V (or better: a proper three-phase AC -> single-phase AC converter) *does* reduce the load on each phase. [I think; please correct me if I'm wrong]

Can anybody confirm that a crude 3 phase AC -> DC rectifier is a bad idea?

I got a very informal EUR 300-EUR 600 quote from Noratel for their 10kVA transformer.

If anybody can find the price for a 3-phase AC -> 1-phase AC converter I'd be interested.

[Alpine Driver]

raymond,
more technically experienced people will hopefully answer your questions in a more detailed way.
But look at the datasheet (wiring diagramm) of your mentioned device:

http://en.noratel.ezpublish.no/conte...ile/2LT-23.pdf

this is a "simple" voltage up/down or even only galvanic isolating device; it has nothing to do with more phases or with load balancing.

[dpeilow]

But that doesn't make use of all available power, does it? It just spreads the load evenly of the three phases, but only draws a load from each single phase at it's peak voltage.

I think that is sort of the point. As long as each phase is in the positive part of its cycle, it will be contributing to the DC output, hence contributing power. This is where your 1.73 is coming from...

raymond,
more technically experienced people will hopefully answer your questions in a more detailed way.
But look at the datasheet (wiring diagramm) of your mentioned device:

http://en.noratel.ezpublish.no/conte...ile/2LT-23.pdf

this is a "simple" voltage up/down or even only galvanic isolating device; it has nothing to do with more phases or with load balancing.

Which is why you can't do this with a "normal" transformer.

Seems there are dozens of single phase -> three phase products, but not much demand for going the other way...

[dpeilow]

In the absence of a suitable solution, a UPS with minimal batteries is the next best option. "Double Conversion Online" signifies that it is always going through the rectifier/inverter rather than passing through power straight from the input.

This one would supply 32A safely: Emerson GXT2 10kVA TOWER UPS - Misco.co.uk

Datasheet

As you can see, not very portable and not cheap, but in the ballpark of the HPC. It's cheaper than AlpineDriver's contact thought too. This may help out some people for their home charging situations. We'll keep working on the portable one

[dpeilow]

OK, there are some devices out there which do what we want (search for frequency converters, power factor correctors, that kind of thing), but the bottom line is that none are smaller or cheaper than that UPS when you are talking about 10+ kVA. I've reached that point where I am going around in circles finding the same products.

So it would appear that if you want to charge from three-phase at home and not annoy your supplier, get an online/double conversion/VFI UPS. At least you can charge for a bit during a power failure

[AndrewBissell]

Now, if only the Roadster allowed a trailer to be towed: we could mount such a UPS and a *lot* of battery. Trailable range extender! (not useable while driving of course, but get you out of a jam if you misjudge the range to next charger - and when you encounter say 16A 3-phase (common all over continetal Europe) you can simultaneously recharge the Roadster at 40A and use the remaining capacity to charge the battery.)

we can dream.

[raymond]

this is a "simple" voltage up/down or even only galvanic isolating device; it has nothing to do with more phases or with load balancing.

Yes and no. It IS a simple voltage transformer, however since the three phases are 120 degrees out of phase, you can load two of the three phases equally giving you 400V instead of 230V. This in turn enables you to draw a current which is 1.73x less than what you would need to draw from a single phase 230V.

It's a partial solution which only loads two phases, but it is highly efficient, affordable, low-tech, unlikely to break, etc. It's 1.73x as good as loading a single phase, and 1.73x as bad as using all three phases.

Are their any prices out their for a proper converter (with or without UPS capabilities)? Any ideas about efficiency?