Mini-QC Rapid-Charger (RC) Project for LEAF QC Port

[klapauzius]

Phil has discussed this a bit in this thread: http://www.mynissanleaf.com/viewtopic.php?f=9&t=9552&p=318475&hilit=Isolated+charger#p318475" onclick="window.open(this.href);return false;

Thanks, that explains it.

So we need an isolated design, which for high powers means a custom-designed transformer will be necessary in addition to somewhat more complicated circuitry.

 

[jclemens]

I like the idea of using isolated front-end rectifiers, if they are cheap, AND if we can control the output voltage somehow, but the other major issue with this is repeatability, is there a depot online to buy used ones? You can get new ones for around $700 for each 48V module, which is not an option. 10 units would get us 480V at 10kw if each unit is only 1kw.


Check this out if you are (like me) new to the whole concept of front-end rectifiers and power supplies.
http://www.power-one.com/sites/power-one.com/files/fe_rectifier_comparison.pdf

You'll note in the PDF file that it indicates that there are flavors available that are meant for charging batteries, thus the voltage output is adjustable!

 

[Cor]

I like the idea of using isolated front-end rectifiers, if they are cheap, AND if we can control the output voltage somehow, but the other major issue with this is repeatability, is there a depot online to buy used ones? You can get new ones for around $700 for each 48V module, which is not an option. 10 units would get us 480V at 10kw if each unit is only 1kw.

You can buy these 1-2kW units all day long for around $50 a piece as used server take-outs.
Sure, they need some modification to create a complete charger, but I expect that it is no problem to
make stand-alone isolate fast chargers for no more than $2k total (end user price) based on these modules.
It is a bit of engineering to create the smarts for the control system
and knowing how to control these supplies so they will work together in a safe way,
then package it together and you have a 1 cubic foot, air-cooled, isolated 12kW fast charger
that you can plug into and RV outlet (240V 50A), a dryer or stove outlet (240V, 30 or 50A) or
use with a J1772 charger inlet for the max current the J1772 can supply (up to 70A or so).
Since these supplies are modular, there is no problem getting double power by simply doubling the nr of supplies.
I already have that many supplies lying in my garage.
Somebody want a 50kW charger? no problem, other than that they will need to take care of the 300+ Amp service.
Just double the number of supply modules again (and control outputs)
Price will still be under $10k (and I do not mean component cost - I mean commercial price). Cost of the supplies will be no more than about $2k, but you need control circuits, man-hours for modifying each, wiring everything up, making a nice enclosure and providing the necessary cabling.
At the 100kW level (Tesla Fast Charger speed) the input power level will be 240V, 600A (accounting for losses) and the
cabling stiffness will become harder to handle (Tesla has a special way of plugging into the car's fast charge port) since you are handling cables of the fattest type Welding Cable. But it is still feasible for no more than $20k a pop. Just need to find a good (high volume) supplier of those units and don't mind going through dozens of supplies to modify them all.

 

[Cor]

OK, I found the output voltage control and just changed it with a different pot and resistor for testing, output is now controllable from 30 to 53V. Later that will be done through an opto-coupler, but for now manual control allows me to see what this supply can do. I could not find a regulator for over-voltage protection, so I suspect that there is a fixed zener diode protecting the output, I need to trace that out and remove it or at least allow it to go beyond 55V. To be continued.
Input on this model supplies *must* be 240V, they do not start on 110V, so that is good to know.

 

[valerun]

OK, I found the output voltage control and just changed it with a different pot and resistor for testing, output is now controllable from 30 to 53V. Later that will be done through an opto-coupler, but for now manual control allows me to see what this supply can do. I could not find a regulator for over-voltage protection, so I suspect that there is a fixed zener diode protecting the output, I need to trace that out and remove it or at least allow it to go beyond 55V. To be continued.
Input on this model supplies *must* be 240V, they do not start on 110V, so that is good to know.

Cor - this is awesome. Also, here's another suggestion (what I would do - and probably should - send me a PM): wire 10 of these in series, don't worry about the regulation at all, and just add a single-module buck downconverter like our output stage. At that voltage, we were actually able to pass up to 35kW through our buck stages based on a 200A IGBT module. Limited by the inductor heating, mostly... All the controls are already sorted out via our control board (some trivial mods to be made - and a few people already know how to make them here).

 

[valerun]

so I gather that there are no power magnetics design experts lurking here?

 

[Cor]

Also, here's another suggestion (what I would do - and probably should - send me a PM): wire 10 of these in series, don't worry about the regulation at all, and just add a single-module buck downconverter like our output stage. At that voltage, we were actually able to pass up to 35kW through our buck stages based on a 200A IGBT module. Limited by the inductor heating, mostly... All the controls are already sorted out via our control board (some trivial mods to be made - and a few people already know how to make them here).

PM sent. We can meet, I'm only 10 miles away.
With 2 strings of 10 series supplies you are talking about a 30kW isolated fast charger that in component cost would not be more than a handful k$ plus some assembly required (and a 200A service since it will draw 150A at 240V).
But let's first see what a single string can do.

 

[valerun]

so I gather that there are no power magnetics design experts lurking here?

looks like there are some cores we could use at up to 12kW level. T140/106/25-3C90 (140mm outer diameter) or T107/65/25-3F3 with a bit more aggressive cooling. The former is tough to find and even if available would be ~$200 apiece. The latter is ~$110 from Newark. Maybe we should try it sometime. But first I want to try Cor's idea + our buck stage. Jeremy / Gary - how can we get access to the modified firmware that you guys are running?

Valery

 

[valerun]

Also, here's another suggestion (what I would do - and probably should - send me a PM): wire 10 of these in series, don't worry about the regulation at all, and just add a single-module buck downconverter like our output stage. At that voltage, we were actually able to pass up to 35kW through our buck stages based on a 200A IGBT module. Limited by the inductor heating, mostly... All the controls are already sorted out via our control board (some trivial mods to be made - and a few people already know how to make them here).

PM sent. We can meet, I'm only 10 miles away.
With 2 strings of 10 series supplies you are talking about a 30kW isolated fast charger that in component cost would not be more than a handful k$ plus some assembly required (and a 200A service since it will draw 150A at 240V).
But let's first see what a single string can do.

this is pretty extreme: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=181161189355" onclick="window.open(this.href);return false;. $16 per used but tested unit. More than 10 available. There are indeed many listings like this.

New old stock tends to go for ~$100 apiece (e.g., http://www.ebay.com/itm/NEW-Power-One-1500W-AC-DC-Converter-Power-Supply-FNP1500-48-/150778423179?pt=US_Server_Power_Supplies&hash=item231b18278b" onclick="window.open(this.href);return false.

The problem is, of course, new new stock units like are expensive which makes this approach less attractive (New New stock tends to go for $230-$400 apiece). But you probably won't hit the supply limit until you're talking more than 1,000 of used + old stock (or 100 QC chargers ;-)...

 

[poweredbysun]

OK, I found the output voltage control and just changed it with a different pot and resistor for testing, output is now controllable from 30 to 53V. Later that will be done through an opto-coupler, but for now manual control allows me to see what this supply can do. I could not find a regulator for over-voltage protection, so I suspect that there is a fixed zener diode protecting the output, I need to trace that out and remove it or at least allow it to go beyond 55V. To be continued.
Input on this model supplies *must* be 240V, they do not start on 110V, so that is good to know.

Cor - this is awesome. Also, here's another suggestion (what I would do - and probably should - send me a PM): wire 10 of these in series, don't worry about the regulation at all, and just add a single-module buck downconverter like our output stage. At that voltage, we were actually able to pass up to 35kW through our buck stages based on a 200A IGBT module. Limited by the inductor heating, mostly... All the controls are already sorted out via our control board (some trivial mods to be made - and a few people already know how to make them here).

Is there a diagram-parts list for just the output stage?
Your charger is on this link?http://www.emotorwerks.com/tech/electronics
Thank you,
Jim

 

[garygid]

Stacking 10 units, producing a 480v 30 amp DC power supply,
isolated, which requires no control of the individual units,
might be a workable configuration, with a following buck stage.

Check noise, operation at low currents, and open circuit,
and voltage isolation limits, which might be OK at 100 or 300
volts, but perhaps not at 600 volts?

If somebody tests each individual unit at full rating, and investigates cooling limits
(will it run in 100 degree F ambient, will the center modules get
sufficient ambient air, etc.),...

And, are these power factor corrected?

And packages 10 together, and sends them to me,
we could probably use our existing buck stage to test them...
charging the car. I am not sure of the voltage limits
on the buck stage input.

 

[jclemens]

If you can control these at least manually and with a load test to ensure they function in series without blowing up, there is a plastic QC plug in it for you!, and I'm sure we can arrange for you to get informed on the QC communication codes, but the first step (before doing a micro-controller) is proving you have a controllable power supply that works with a load.

 

[Cor]

The spec of this supply says it has power factor corrected input and the 48V DC side is isolated to 1500V.
Just about the only drawback of this unit is the efficiency is only 80% at full load (1800W in for 1500W output)
That is probably also why they have two fans...

 

[valerun]

OK, I found the output voltage control and just changed it with a different pot and resistor for testing, output is now controllable from 30 to 53V. Later that will be done through an opto-coupler, but for now manual control allows me to see what this supply can do. I could not find a regulator for over-voltage protection, so I suspect that there is a fixed zener diode protecting the output, I need to trace that out and remove it or at least allow it to go beyond 55V. To be continued.
Input on this model supplies *must* be 240V, they do not start on 110V, so that is good to know.

Cor - this is awesome. Also, here's another suggestion (what I would do - and probably should - send me a PM): wire 10 of these in series, don't worry about the regulation at all, and just add a single-module buck downconverter like our output stage. At that voltage, we were actually able to pass up to 35kW through our buck stages based on a 200A IGBT module. Limited by the inductor heating, mostly... All the controls are already sorted out via our control board (some trivial mods to be made - and a few people already know how to make them here).

Is there a diagram-parts list for just the output stage?
Your charger is on this link?http://www.emotorwerks.com/tech/electronics
Thank you,
Jim

Yes, Jim - most of the info is there. Let me know in PM if you have any specific questions. If you are just interested in the Buck stage, I suggest you look at the non-PFC files / kits - that's pretty much a single buck stage with a front voltage doubler - just lose the doubler and you're set.

Valery

 

[Cor]

Stacking 10 units, producing a 480v 30 amp DC power supply,
isolated, which requires no control of the individual units,
might be a workable configuration, with a following buck stage.

Check noise, operation at low currents, and open circuit,
and voltage isolation limits, which might be OK at 100 or 300
volts, but perhaps not at 600 volts?

If somebody tests each individual unit at full rating, and investigates cooling limits
(will it run in 100 degree F ambient, will the center modules get
sufficient ambient air, etc.),...

And, are these power factor corrected?

And packages 10 together, and sends them to me,
we could probably use our existing buck stage to test them...
charging the car. I am not sure of the voltage limits
on the buck stage input.

Hi Gary, let me go through your points one by one:
- I can build a stack of 10 and verify that they can all be grounded (AC side, which is also their chassis) to the same ground, they they can be stacked together, bolted against a metal housing or whatever while operating as a 480V 30A supply. They are long modules (15" long with AC connector), 5" high and 2.5" wide, with two 60x60mm fans on one end and all connectors on the other short end. Look up a pic of the DPS-1500 to get an idea.

I will need to measure the noise of 10 series units; the spec says that one unit has a max peak-peak ripple of 480mV but when they feed directly into the cap of a buck converter, I doubt that 1% noise is an issue at all.
The spec says that their min current is 0.4A for some reason, but I have run one with only a DVM on the output without issue. Max output can overload at least 110% of nominal before limiting, though it can be turned down with a pot.

Cooling should not be an issue with their two high speed fans and the spec says that their max operating temp is 50C which is 122 deg Fahrenheit. Reliability will go down at elevated temps, but you are still talking about 200,000 hours MTBF at 100 Fahrenheit ambient.

Power Factor: corrected, spec'ed to be at least 95%.
I asked Valery the same question about the voltage limit on the buck stage.
I payed money to buy these units last week, so we will need to agree how to deal with this - probably best via PM.

 

[valerun]

And packages 10 together, and sends them to me,
we could probably use our existing buck stage to test them...
charging the car. I am not sure of the voltage limits
on the buck stage input.

I asked Valery the same question about the voltage limit on the buck stage.

Caps are 450V so that's where I'd keep it. They are rated for 500V surge but who knows. IGBTs are 600V devices so even with spikes (which should be minimal at 30A), 450V gives good margin.

I have just ordered 15 supplies from some ebay seller. They will be here in 3 business days. I'd love to get the whole system going on one of our Leafs here.

Valery

 

[poweredbysun]

Look up a pic of the DPS-1500 to get an idea.

Friday night I received the 12 units I ordered off ebay.
Took one apart yesterday. VERY nice!!! Quite a step above the ATX power supplies!
And there are 48 volt DC input versions available which could run off my 48 volt solar battery system...
A solar quick charging unit...hmmmm.
What are the pinouts for the output connector on the right?
Picture of it linked here:
http://www.google.com/imgres?imgurl=http://www.dakota-express.com/images/Delta_DPS-1500ABB%2520004.jpg&imgrefurl=http://www.ebay.com/itm/Delta-DPS-1500AB-B-1500W-Power-Supply-TESTED-/200732965711&h=480&w=640&sz=154&tbnid=Vzdf-HcBF5tpVM:&tbnh=95&tbnw=127&zoom=1&usg=__34f1G1CzonWjneoouqRlBK3uTnY=&docid=zmEMx_hGW4BgYM&sa=X&ei=1mgsUuDSK-za4APdpoD4CA&ved=0CDcQ9QEwAw&dur=674" onclick="window.open(this.href);return false;
Thank you,
Jim

 

[garygid]

Three purchases, great, that will give something to
try (very CAREFULLY, Please).

If they are only 80% efficient, then each one will need to
dissipate 300 watts, or about 3kW of cooling for the stack.
That is non-trivial if the local ambient temperature must be
kept under 120 degrees F maximum.

Is there thermal shutdown inside (I expect there is)?
What temperature (measure input and exhaust temperatures)
triggers it?

This loss might be acceptable for some applications, but
I was under the impression that Valery's Boost and
power factor front-end stage is much more efficient,
and really not that expensive to build.
What are its specs?

And, this loss does not include another 5% or so for the
Buck regulator stage.

Let's get some schematics for these units, to better see
what we are working with.

When you buy power units, it would be helpful to others
if you would post the link to what you actually bought.

15" x 5" x 2.5" in two stacks of 5 -> 15 x 10 x 12.5 approx.

How much does each one weigh?

A half volt of ripple, times 10 might be 5 volts of ripple
on the 480v output.

JasonA says the they typically have an internal sensor that
turns them off if you try to run two unmodified units in series.

 

[garygid]

If anyone has questions or suggestions they are welcome here.
Please, only PM me when the issue cannot be discussed here.
Most questions or issues are of interest to most of the others
trying to work on this project.

We are trying to help educate everyone, and want to share
our results openly, but without creating issues of personal
liability. Some information is already in the public domain,
but some is not.

We still do not have legal advice from an Intellectual Property
lawyer, and even then, releasing the information for personal
use ony, not commercial use, might be necessary. I do not know.

For example,
How many of you did NOT sign an agreement at the time
of purchase to NOT reverse engineer the/your LEAF?

 

[poweredbysun]

Let's get some schematics for these units, to better see
what we are working with.

When you buy power units, it would be helpful to others
if you would post the link to what you actually bought.

15" x 5" x 2.5" in two stacks of 5 -> 15 x 10 x 12.5 approx.

How much does each one weigh?

I do not know where to look for schematics for these,
it will be very time consuming reverse engineering them,
and some technology might be proprietary. I can not
find the pinout for the output, and a board probably must be
de-soldered to trace the lines from it.

Sorry about not posting the source:
Ebay Item #130781131307
I do not have a scale with me, but the box with 8 says
68 lbs. They put the other 4 in another box which says
31 lbs.

The case screws all have threadlock on them. I stripped
the first one and had to drill it out before I realized this.

Two fans and a lot of heat sinks, one heat sink is attached
to the case on one side. The stack could be
arranged so this side is always on the outside.

Maybe these things will not like stacking in series
because unlike the ATX power supplies which "see"
the voltage difference between the case ground and power
out, these have an isolated ground. It is hard to say
what they will "see". The reference will have to be the
(now incoming) DC negative voltage for them to work.

These are very clean and neat and look professionally
soldered and assembled. Unlike the ATX power supplies.
Everything that could possibly move is glued, wire tied,
soldered or screwed in place. So it is rugged enough for
portable use for a long time. More rugged than any of
my laptops, for example. I would not drop either one
on purpose, but I think this would withstand a few drops.

Jim