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

[JasonA]

OK, let's investigate a Bursa-based micro-QC solution,
even if not terribly practical at the moment.

Let's begin by getting answers to some basic questions...

The Bursa has an isolated HV output, right?
240v in, and air cooled, with around 3.3 kW out?

Correct.. Fully isolated between the in & outputs..

The only control of the is CAN, right?
Or, are there other control lines as well?

If you want "FULL REAL TIME" control then yes.. CAN is the way. There is an AUTO mode where you set control points, etc. This is how I ran it before we integrated it with Greg's unit. But for this project, it will require CAN control..[/quote]

Can the output voltage be ramped from zero to max
(or a few volts to around 450 volts), and then ramped back
down, under no-load conditions, using its CAN control?

I asked the "master" this.. waiting for a response.. the battery is not connected at this point correct?

How fast can the current be ramped up, under CAN control?
The car asks for 2 amps more each 1/10 second,
but the QC does not have to follow exactly.
However, the car does not tolerate too much delay.

Have not measured it with a scope, but as fast as I demand power, it comes up right away. So probably fast. I've watched all you guys with CHAdeMO units ramp up to 60a... The Brusa does just as quick, just to 9a :lol:

Can the output current be shut off abruptly, with the
Output voltage falling quickly?

Yes

How well regulated is the output current?

Dead on pretty much (+- 1%) it's the voltage that's off because the Brusa only has 8bit sampling. So towards the top end, it shows 395v (example) and the battery is really at 391v. I think newer units have upgraded CPU's.. waiting for response.

What noise is present in the HV output.

would have to meas with a scope.. I've read on DIY that it's "pretty damn clean"

Is there any reverse-polarity protection built in?

Fully on both sides so you can't screw it up!

Other than HV and CAN, does it have any other outputs?

It has all types of options and outputs. Victor uses the outputs to drive LEDS that look like the Leaf's 3 LEDS on the dash to give him status updates.

The CAN and any other control or status signals
are referenced to protective (earth) Ground?

Don't know what u mean by this?? They are all isolated and have their own outputs and seperate pins/ground. It's logic grnd.. not case/PE.

How often can the Bursa be "commanded"?

As often as you want to sample it. up to 1,500/sec CAN


Here's a link to their CAN MATRIX...
http://www.metricmind.com/data/can_201_nlg5xx.pdf

USER MANUAL...
http://www.metricmind.com/wp-content/uploads/2011/11/Manual_V1.792.pdf

Hooking MANY up together works great together.. and they communicate and command perfectly.

 

[JasonA]

If somebody has a contact at Andromeda.. maybe someone can "inquire" about a PS unit or replacement?

That's the heart and soul of their baby right there!

50kw in that small of unit and it'll take ANY power source!

he high power switching circuits of ORCA (On-Road Chargers from Andromeda) engines have been designed using an advanced proprietary patent-pending distributed power transformer with controlled impedance techniques. This makes it possible to operate at high switching frequencies so that the size and weight of the power engines are significantly reduced.

ORCA is a compact power engine (56 x 65.5 x 30 cm, 22 x 26 x 12 inches) that can be shaped in various forms for the best fit depending on the application of the charger (in the picture it is shaped as a cube to fit in the top left side of a crossover toolbox for pickup truck).

It looks like my Mark & Levinson monoblock amps inside! :lol:

 

[FalconFour]

Now we're cooking.

As for the subject of programming and the Arduino, that could be where I come in. Arduino was my fun little pastime for a short while, and I've come to understand it pretty in-and-out. Designed my first GID meter from scratch with a CAN transceiver/controller chip pair and really no existing library support... as well as developing a few handy-dandy tools that make use of I2C and SPI buses to communicate with peripherals (including the communication with the CAN controller via SPI). I could probably pitch in help with programming the thing whereever necessary.

If it's using a CAN bus though, I personally haven't yet heard of any Arduino capable of directly interfacing with CAN's voltage levels. I would assume it needs those same transceiver/controller pair I built my GID meter with (now decommissioned after finding Turbo3's Android app, so they can be re-used now). Will gladly eat my words if I stumble my way over to the Arduino page and find it actually has a built-in CAN transceiver. :lol:

 

[JeremyW]

The only problem I see with the Brusa chargers is that the manufacture is quite specific on having a pre-charge circuit in place before directly connecting them to a high voltage pack so that there is not a large inrush current. When we're working with hooking up these chargers to the car for faster L2, the pre-charge circuit in the Leaf is used. When using CHAdeMO... what is used!? :shock: If nothing, and there is a large inrush, you'll damage the current monitoring circuit on the output side.

 

[garygid]

The AVR-CAN board has a CAN transceiver on the board, but
no uP chips have the transceiver built in, as far as I know.

The Arduino Due uP chip can connect to two transceiver chips,
but CAUTION, all pins are 3.3v maximum.

Would adding a diode to the Bursa HV output solve the
back-current in-rush problem? When connecting to
the QC port, one is expected to deliver current, very soon
after the car closes the contactor to the battery, and
not draw current.

Did someone get permission to post the Andromada pics?
Luigi might prefer no public posting.

 

[FalconFour]

Did someone get permission to post the Andromada pics?
Luigi might prefer no public posting.

Psh! *saves them in geek pr0n collection* If anything, it's free advertising. :lol:

 

[JasonA]

Did someone get permission to post the Andromada pics?
Luigi might prefer no public posting.

Take it easy Gary.. its off their public site :roll:

http://www.andromedapower.com/ORCA_C3.html

 

[JeremyW]

Would adding a diode to the Bursa HV output solve the
back-current in-rush problem? When connecting to
the QC port, one is expected to deliver current, very soon
after the car closes the contactor to the battery, and
not draw current.

Seems like it, actually. No current would flow till the Brusa output voltage rose above the pack voltage. You'd just need a heafty one to handle the current!

Now that I think about it I'm pretty sure the spec calls for a diode between the car and charger.

 

[garygid]

We have been using an output diode with our 30 amp mini-QC
for several months, as it seems a proper thing to do.

Usually, it takes some time for the output voltage to
rise enough to "match" the battery, which is indicated
by a trickle of current starting to flow.

Soon, the car starts asking for current, and ramps up its request,
and the QC is expected to follow, as closely as it can, to
avoid "offending" the car, if the QC is not sufficiently
responsive.

Thanks for checking the picture.
Cheers, Gary

 

[garygid]

Is anybody looking for suitable female mates
for the "9mm" QC power connectors?

If we find these, we can design a female-to-male
"stubby" plug for the car's QC socket, allowing us
to "instrument" the QC connection without modification
to the car, or the QC unit.

With that, we could more easily log the QC-CAN activity,
monitor the control signals, and measure the HV
voltage and current.

Then, experimenters could concentrate on the Power
Supply design and Control.

We have programmed our experimental Robmo mini-QC
to create some debug-mode CAN messages with useful
data about the operation of the mini-charger, and we log
all the messages, and/or look at the data real time with
CAN-Do, and produce a ".qcc" log file for later analysis.

This would make good use of what we have developed
for our own use over the past many months.

Along with this, we would most likely provide a set of Recipes
for the QC messages, and the additional debug-mode
messages. One ongoing effort is to document our
discoveries and assumptions, but we are a bit behind.

 

[valerun]

Does anybody know of isolated DC power supplies, even of
modest power output levels, or of circuit diagrams of such
supplies, that we might be able to learn from?

Maybe a good textbook on isolated power supply design?

We need this before we can help others build working
mini-QC devices.

Hi Gary -

First off, great to see what you guys are doing with this non-isolated 12kW charger here!

Re your specific question on isolated supplies, there are some references in our new build manuals at http://emotorwerks.com/VMcharger_V12P/" onclick="window.open(this.href);return false;. Specifically:
a. Switching Power Supplies A - Z, Second Edition by Sanjaya Maniktala (Apr 18, 2012) - $60 on Amazon
b. Switching Power Supply Design, 3rd Edition by Abraham Pressman et al (2009) - $65 on Amazon
Lots of good stuff there.

Generally speaking, the easiest way to build this is to convert a simple non-isolated buck output stage into the isolated half-bridge. This way you can somewhat contain the number of semiconductor modules which makes layout less challenging. The tricky part is the transformer design - even for 12kW. The main challenge is a tradeoff between inductor size and the IGBT losses. Practically speaking, you can't really go higher than 20kHz with IGBTs. This means you'd need ~3-5mH magnetizing inductance at 30-50A current. Which means a super-massive ferrite core - we could not find one yet that we can easily order and try out. Perhaps there are some magnetics design experts here that we can team up with to solve this?

Of course, things get conceptually simpler when you drop down in power to 1-3kW. There are off-the shelf transformers available, as well. The problem is that there is no way it can be meaningful in a kit form for any reasonable aggregate power level. There's just way too much assembly - 10 half-bridge downconverters is easily 500 parts... So you'd need to set up outsourced production in 1000+ volume to make the costs reasonable. That requires either good (and free) working capital or market pre-orders. Herein lies the business problem. Nobody who has working capital wants to open the designs. And nobody wants to pre-order 100+ units before the design is proven.

Hence the high-power-per-component design in our current system. Which would also be our preferred approach for the isolated unit. If only we can get a high-power magnetics expert to chime in...

Thoughts?

Thanks,
Valery.

 

[klapauzius]

When looking for off-the-shelf components, it seems there are a bunch of companies that offer high power units for industrial and research applications that are isolated. I got quoted $9k for a 15 kW unit (500 V @ 30 amp). Still a lot of money, but cheaper than the Brusas.

My understanding from what Valery said is that the isolation is the thing that makes this so expensive and complex. But if you got their 12 kW non-isolated charger to charge the LEAF, maybe that is not necessary? Or is it seriously compromising safety?

 

[Cor]

When looking for off-the-shelf components, it seems there are a bunch of companies that offer high power units for industrial and research applications that are isolated. I got quoted $9k for a 15 kW unit (500 V @ 30 amp). Still a lot of money, but cheaper than the Brusas.
My understanding from what Valery said is that the isolation is the thing that makes this so expensive and complex. But if you got their 12 kW non-isolated charger to charge the LEAF, maybe that is not necessary? Or is it seriously compromising safety?

Probably the Leaf will not allow charging to start without the isolation (it actually measures it, apparently from what Gary said)
Valery has the right hint: use lower power units for more manageable magnetics.
For self-build and complete kits (Which is what EMW is promoting/selling) this is difficult to manage,
but it is super-easy if you can find the right surplus supplier of supplies.
I have a 1500W 48V 30 Amp power supply sitting on my desk that I need to trace out the way to
- control the output beyond the designed voltage limits via opto-coupler
- isolate the DC side from the chassis
With that, using 8 of these in series will give a portable supply of about 1 cubic foot and isolated voltage control for
- no output (zero volts)
- 240 to 440 V DC
- 12kW if powered from 208 or 240V.
In theory it can be powered from 110V also, but who has 50 Amps at 110V?
Cost will be no more than 10% of commercial available units
while the work to create the power section of the charger is limited to opening and making a modification to 8 supplies,
then wire them in series and mount them together in a shape that you like, you can make a charger
that is only 2.5 inch (63mm) tall as long as you have a space that is weather protected and
at least 5 inch wide and about 15 inch long (including connectors) and has space for 8 of those units with airflow, for example a 20 x 30" layer as a "double bottom" of an existing space or a 40 x 15" sidewall or so.
I plan on adding a couple of these supplies to my EV to allow using the full capacity of the J1772 chargers,
while currently I can only charge at roughly 2.5 kW, limited by the transformer in the old-style charger that I have now.
That will prepare my EV for the JuiceBox kit that I get at the end of this month.
I have 16 of these supplies sitting at home, which should be enough to build 2 full capacity DC Fast Chargers.
I wish I had more time to experiment, work and family keep me busy - hope to find some time to experiment with
these supplies soon.

 

[klapauzius]

Probably the Leaf will not allow charging to start without the isolation (it actually measures it, apparently from what Gary said)

Yes, that is what I recall having read somewhere on this forum. But Gary said a bit earlier in this thread that they did QC with a non-isolated unit (presumably the 12 kW kit that Valery mentioned??)??

I think I dont understand quite yet why the isolation is necessary...Apparently many conversion or DIY EVs are charged with non-isolated chargers?

 

[JeremyW]

When looking for off-the-shelf components, it seems there are a bunch of companies that offer high power units for industrial and research applications that are isolated. I got quoted $9k for a 15 kW unit (500 V @ 30 amp). Still a lot of money, but cheaper than the Brusas.

Be careful that it has power factor correction. Some do not, which makes the input current requirements much higher. I worked for a company that made a few models that didn't have PFC. :|

 

[JeremyW]

Probably the Leaf will not allow charging to start without the isolation (it actually measures it, apparently from what Gary said)

I've seen a non-isolated CHAdeMO charger charge my car with my own eyes. It does work.

 

[klapauzius]

Probably the Leaf will not allow charging to start without the isolation (it actually measures it, apparently from what Gary said)

I've seen a non-isolated CHAdeMO charger charge my car with my own eyes. It does work.

Now, that would put a "cheap" solution into reach.

If someone more knowledgeable could explain WHY the Leaf wants an isolated power source? I am sure there are good reasons for it.

But maybe those have to do more with making the car safe to use for the average person with no technical knowledge?

Edit: looking for an answer I found this:

http://www.diyelectriccar.com/forums/showthread.php/evdl-ev-charger-isolation-4692.html" onclick="window.open(this.href);return false;

The sentiment there was that it mainly is a liability issue for commercial products.
Like to hear what the more professionally involved here think?

 

[Cor]

Great news - the 48V 30A power supplies are already isolated from their chassis out of the box.
Only the 12V standby output and their other control signaling is referenced to the chassis ground, but since my design
is to isolate that that (using opto-couplers) anyway, this means that the entire high voltage DC output will be floating.
The spec of these supplies says it is isolated for 1500V so I am guessing that under 500V of series string there
should be no problem. This starts to look promising.
Now only verify that I can control them over a large range of DC output with the mods that I plan to make to the
voltage feedback loop and then I can start to see if I can hookup an AVR-CAN. I also ordered a couple loose controllers,
some blank TQFP64 boards and two CAN interface chips (the same as on the AVR-CAN) just in case I will succeed in
running some program in the controller that will not only receive CAN bus msgs but also make this a stand-alone charger.
We'll see.

 

[QueenBee]

Probably the Leaf will not allow charging to start without the isolation (it actually measures it, apparently from what Gary said)

I've seen a non-isolated CHAdeMO charger charge my car with my own eyes. It does work.

If someone more knowledgeable could explain WHY the Leaf wants an isolated power source? I am sure there are good reasons for it.

But maybe those have to do more with making the car safe to use for the average person with no technical knowledge?

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;

 

[poweredbysun]

Links on modifying ATX power supplies for a quick charger:


I have a few isolated PC ATX power supplies, one person's circuit diagram of them here:
http://www.pavouk.org/hw/en_atxps.html" onclick="window.open(this.href);return false;

These can be modified to output 4-16 volts dc, one person's method here:
http://boginjr.com/electronics/lv/atx-mod/" onclick="window.open(this.href);return false;

In the comments at the link above, the capacitors blow up over 16 volts, so they can be replaced
with higher voltage capacitors to get 4-24 volts out.

One method of stacking ATX power supplies is here:
http://w5jgv.com/tower_of_power/index.htm" onclick="window.open(this.href);return false;

Or they can be removed from the cases, and re-chassied as shown here:
http://www.instructables.com/id/Two-ATX-PSU-One-juiced-24-V-DC-PSU/" onclick="window.open(this.href);return false;

20 Amps x 360 Volts (nominal) = 7.2 kW from the stacked ATX power supply above.
So, a higher watt ATX power supply might be better.

ON semiconductor manufacturer has schematics and power graphs for their
second generation "green" power supply, so more efficiency and power factoring
and maybe little or no fan cooling can be had with ATX power supplies:
http://www.onsemi.com/pub_link/Collateral/TND313-D.PDF" onclick="window.open(this.href);return false;

Toroids can be wound, as shown in this video on youtube:
http://www.youtube.com/watch?v=wAH12a8-C1s&list=PL9A279EF261FE4A15" onclick="window.open(this.href);return false;

Wire for the toroid can be taken from old motors, such as in this youtube video:
http://www.youtube.com/watch?v=NrsoCKzkQaw" onclick="window.open(this.href);return false;

To keep costs within parameters, I am thinking the coils could be designed to use only
components that are available in bulk. This will take some effort, but could result in a power
supply with only a small number of custom parts. This would enable almost
anyone, anywhere, to manufacture it cheaply.

Maybe a time domain reflectometer can be used to measure the
length of wire in a coil. Multiply that by the average length of a turn to
determine the turns ratio without having to unwind to count the number of turns. Not sure
if this will work, or not. Search for time domain reflectometer on ebay...

Here is a link on modifying an ATX power supply to 13.8 volts. This is meant
to point out here that the number of turns can be modified to get a higher voltage
out of the same power supply. So, one could maybe take the voltage higher than
24 volts with this type of modification, cutting the number of power supplies needed.
http://www.qrp4u.de/docs/en/powersupply/" onclick="window.open(this.href);return false;

My purpose working with these ATX power supplies is to help make an open sourced
power supply which is isolated and puts out 12kw at 0-500 VDC, variable in a tenth of a second.
It would be nice to have EV to home power and the capability of charging another
ev on the road from the motive battery pack. This power supply is needed, so that
the option to send power both ways is there. Converting from ac to dc, dc to dc and
dc to ac is needed. So, even the Andromeda is only one third of the way there...

There is plenty of information available on ATX power supplies, so I figure this is a
useful starting point. There are only 2 ic's in this power supply, there is a single
layer circuit board and all the components are soldered through the board. These
are relatively easy to modify compared to surface mounted components with multiple
ic's and multilayer circuit boards.

Like Cor and others have said, stacked power supplies should do quick charging safely.
These could be recycling old power supplies for a new life and have environmental benefits.
And they seem like they could meet the requirements of this project.

Just a reminder that everything over 60 volts is definitely lethal, so this is dangerous.
Sorry about going on here, again.
Jim