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

[valerun]

Gary - what do you think is the tolerance in output current that the car expects? Say, if the car asks for 40A, how far can we be off that and still not fault out? We are designing current measurement circuits now and it would reduce cost quite a bit and make our boards much more universal if we can tolerate 5-10% error on the current measurement. Pls let me know what you think. If you are interested, I can give more details on where this trade-off is coming from.

 

[garygid]

One wonders how accurately the car measures current.
Perhaps Ingineer knows.

In our somewhat limited experience, when trying to
supply 30 amps, the car seems to have several tolerances.
It appears to tolerate rather wide variances initially, and short term.

Variations in the 2011 LEAF firmware versions apparently relaxed
some of the initial compliance-time constraints. The original
pre-April 2011 firmware appears to require noticeably
faster compliance.

It appears that more latitude is given for short term variations,
like noise, and the longer-term averages might have constraints
that we have not yet discovered.

Once one has an experimental system working, with good logging,
some of these questions can be investigated fairly easily, but
various family matters have stalled our investigations.
Until then, one probably wants a 1% sensor, to aid the collection
of useful experimental information.

However, with any fuel delivery system, does one really want
to have a 10% (+/- 5%) uncertainty in the delivery?

We have been trying to stay within plus or minus one amp.

As far as we know, the car does not send out information
about how far off it thinks the delivery rate is.

We do not even know if the QC is able to negotiate
a lower rate after charging starts, to load balance,
for example.

 

[valerun]

ok guys here's a quick (but important) update on the isolated charger.

We have just placed an order for the first batch of power and control PCBs for our isolation stage.

First 3 units of this high-power isolation stage will be available for ordering week of November 25th!

Quick specs:
* Input: 120-400VDC
* Output power: 12kW
* Efficiency: 94% at max power
* Cooling: Air
* Output voltage: up to 480VDC. Fixed nominal transfer ratio of 1:1.2 (inpututput). Actual transfer ratio depends on the load and can go down to 1:1 at rated load.
* Control: by a simple on/off TTL signal you provide. Fine output voltage control to be provided by the DC source you use to feed the isolation stage. One of our 12kW non-isolated chargers is a good option.
* Measurements: input & output currents and output voltage measurements are available as fully opto isolated analog signals. You will need to incorporate these into the control logic for your DC source in order to implement the charge protocols of your choice
* Internal protections implemented inside the unit so it's not as easy to blow up (thermal, overcurrent and overvoltage).
* Size: 10x10x8" machined enclosure, not environmentally protected
* Weight: ~20lbs

Initially, these will NOT be available as kits, only fully assembled boxes.

Exact pricing still TBD based on final part sourcing but will likely be right under $2,000 for the fully assembled and tested isolation stage.

Needless to say, these are what I would call 'early adopter' units but I think this is what you guys are, right? ;-) As mentioned above, you will have to connect the output voltage & current signals to your control stages yourself.

A couple of weeks later, we will release a firmware update to our non-isolated 12kW chargers that will make those control connections for you.

So, do we have the first 3 takers?

Let us know.

Thanks,
Valery.

 

[thorx]

Quick specs:
* Input: 120-400VDC

AC?

 

[TonyWilliams]

Quick specs:
* Input: 120-400VDC

AC?

I sure hope so... but not sure why not 480vac, vice 400vac (Euro specification).

 

[philipscoggins]

Valerun, would it be possible to post a short YouTube phone video to show the unit, how to connect it to the car & starting to charge?

 

[thorx]

Valerun, would it be possible to post a short YouTube phone video to show the unit, how to connect it to the car & starting to charge?

I don't think where there yet. this is still in development stage and requires something to control the powersupply.
Somthing that does the dance with the car.

 

[garygid]

From this description...

Fine output voltage control to be provided by the DC source you use
to feed the isolation stage. One of our 12kW non-isolated chargers is a good option.

it sounds like Valery is suggesting using this as stage #3, after the AC to DC input
stage #1 (perhaps with Power Factor Correction), and the stage #2 buck-regulator.

However, he says this Iso-stage needs at least 120v DC input, so the minimum output,
unless this stage is switched off, would be around 140v DC. To achieve the near-zero
output voltage that mini-QC appears to need, perhaps he intends switching off
this stage?

Perhaps this Iso-stage would be better used as stage #2 of three, with the
more-controllable buck-regulator as the final output stage #3?

 

[philipscoggins]

Valerun, would it be possible to post a short YouTube phone video to show the unit, how to connect it to the car & starting to charge?

I don't think where there yet. this is still in development stage and requires something to control the powersupply.
Somthing that does the dance with the car.

I thought the offer of 3 fully assembled boxes meant us followers might be able to see some action.

 

[valerun]

Valerun, would it be possible to post a short YouTube phone video to show the unit, how to connect it to the car & starting to charge?

I don't think where there yet. this is still in development stage and requires something to control the powersupply.
Somthing that does the dance with the car.

I thought the offer of 3 fully assembled boxes meant us followers might be able to see some action.

Yes will post a video of this stage used to charge one of our cars this week. Will be a video of our bench version (i.e. not packaged into a nice box but largely same design).

However, as thorx mentioned, at this point fully automated control is not quite there yet. So in that video we will be terminating the charge manually based on voltage reading on battery. And of course, no QC comms yet as we depend on Gary for that.

Gary - yes you can use this stage as an interim between the PFC and buck stages in our 12kW supply. This would however require MAJOR surgery on the 12kW supply if it's already assembled and IMO not worth it. You will have to break the HV ground between the two stages which is not a fun task... What you could do is get a PFC 12kW kit with TWO of those power PCBs and populate PFC portion on one of them and the buck portion on the second one. Then you could insert the isolation stage in between. Perhaps this is the easiest way to use the isolation stage, yes.

By now I think everyone understands that this is a DC to DC stage, right? It needs a separate AC->DC front end. Such as the PFC stage in our 12kW charger etc.

PS. Gary - yes, the output voltage pulldown is executed by turning off the stage and turning on the discharge relay. This will be managed by the control stage internal to the isolation stage based on the simple TTL commands provided by outside circuitry (i.e. a QC controller).

 

[hbleaf]

I've have some experience bringing Chademo chargers to market. Initially the safety checks tend to be tricky. The specs are listed in the Chademo specification but your charger will be operating in voltage mode and has to ramp and deramp quickly w little ripple. Also your current leakage detector must work or the test will fail! Boards like those from Bender can perform this at great cost but a simple solution in analog can also do it, but beware of patents :shock: even open source products are bound by law.

Once past the checks (5 secs ) go into current mode and follow the requests from vehicle CAN interface. Again the chademo spec lists the ripple current offset from request required. Its not that tight but best to rely on current shunts for accuracy and low cost without having to recalibrate every unit. Also Chademo has current ramp and deramp requirments listed in spec.

There is a circuit topology recommended by Chademo diverge from this at ones peril, can be done but tricky to meet every requirement with less balanced power circuits.

Also a fair amount of relay (contactor) orchestration is required to switch modes properly. For instance an AC disconnect is a safety required circuit and is current detector controlled, (ie must be in loop that breaks/make circuit).

Have fun and don't mess with non-isolated power circuits they can definitely kill

Steve
2011 Leaf

 

[garygid]

The results of our investigations of the QC process might
be incomplete, wrong, or misleading, and they do not attempt
to cover the specs and requirements of any existing standards.

As such, we might need to release our observations
for private non-commercial use only.

Most likely, any commercial interests should obtain
the appropriate applicable standards.

Use these observations entirely at your own risk.
We assume no liability whatsoever.

 

[jclemens]

Of course any help/insight from experience in working with this technology is greatly appreciated as long as no violations of Non-disclosure agreements, or imposing user agreements occur.

 

[garygid]

jc...
How is the Jolomo logging adapter doing, if at all?

Sadly, my 3D Printers await attention, however the
FlashForge Dual-Head Creator is closest to working.
Then, I could use it to make parts for the triangular
"dancing" Kossel Legacy 3D printer.

First, I need to heat the heads to see if I can get
the old plastic cleaned out, and new plastic fed
through, and then get the exterior of the heads
cleaned up. Unknown how they got so much
plastic-melt on the outside, where it would be
impossible to remove the heads.

 

[jclemens]

jc...
How is the Jolomo logging adapter doing, if at all?

Sadly, my 3D Printers await attention, however the
FlashForge Dual-Head Creator is closest to working.
Then, I could use it to make parts for the triangular
"dancing" Kossel Legacy 3D printer.

First, I need to heat the heads to see if I can get
the old plastic cleaned out, and new plastic fed
through, and then get the exterior of the heads
cleaned up. Unknown how they got so much
plastic-melt on the outside, where it would be
impossible to remove the heads.

Yes, affordable 3d printers are very needy things and take up a lot of time.

The plugs for this project are not completely stalled, I have some concepts, but it is finding the time to get it done which is the challenge. The only reason I have any time to do this stuff at all, is because I don't have kids (yet).
A single part can take 6 hours, and generally, I like to be around when it is first printing out, but I am gaining more confidence in my printer that I can leave it unsupervised. I have recently solved my warping issue with increased bed temperature, a chamber (plastic bags) and elmer's all purpose glue stick. Previously I had been using hairspray, but it gets gooey at higher temperatures and doesn't work.

 

[garygid]

jc...
Are "you" expecting a boy or a girl?

When using ABS, said to produce harmful fumes,
what do you do for ventilation?

To make this more thread-related, a good QC socket (married
to a QC Plug that would plug into the vehicle's QC port),
would allow us to minitor, and log the control signals, the
CAN communication, and even the HV voltage and current.

That Logging Adapter would be convenient for trouble
shooting and verifying expected operation of any QC
vehicle with any QC device. A great information
gathering tool for anybody working with the QC type
technology.

 

[tbleakne]

Gary - yes you can use this stage as an interim between the PFC and buck stages in our 12kW supply. This would however require MAJOR surgery on the 12kW supply if it's already assembled and IMO not worth it. You will have to break the HV ground between the two stages which is not a fun task... What you could do is get a PFC 12kW kit with TWO of those power PCBs and populate PFC portion on one of them and the buck portion on the second one. Then you could insert the isolation stage in between. Perhaps this is the easiest way to use the isolation stage, yes.

By now I think everyone understands that this is a DC to DC stage, right? It needs a separate AC->DC front end. Such as the PFC stage in our 12kW charger etc.

My understanding is that isolation can be achieved by a transformer whose secondary is isolated from its primary. I would think this could be provided most simply as an input transformer feeding a full-wave rectifier feeding the PFC. I would appreciate clarification of the necessity of this new DC to DC stage. Perhaps the PFC stage must go before isolation for some reason? Thanks.

 

[jclemens]

jc...
Are "you" expecting a boy or a girl?

When using ABS, said to produce harmful fumes,
what do you do for ventilation?

To make this more thread-related, a good QC socket (married
to a QC Plug that would plug into the vehicle's QC port),
would allow us to minitor, and log the control signals, the
CAN communication, and even the HV voltage and current.

That Logging Adapter would be convenient for trouble
shooting and verifying expected operation of any QC
vehicle with any QC device. A great information
gathering tool for anybody working with the QC type
technology.

Not expecting at all right now I hope :shock:

The fumes from the abs plastic I am using right now are not too bad, either that or I have become desensitized...

I am building a 1ft long QC extension cord with 2awg 600v welding cable and cat5e Ethernet cable... eventually.

 

[valerun]

Gary - yes you can use this stage as an interim between the PFC and buck stages in our 12kW supply. This would however require MAJOR surgery on the 12kW supply if it's already assembled and IMO not worth it. You will have to break the HV ground between the two stages which is not a fun task... What you could do is get a PFC 12kW kit with TWO of those power PCBs and populate PFC portion on one of them and the buck portion on the second one. Then you could insert the isolation stage in between. Perhaps this is the easiest way to use the isolation stage, yes.

By now I think everyone understands that this is a DC to DC stage, right? It needs a separate AC->DC front end. Such as the PFC stage in our 12kW charger etc.

My understanding is that isolation can be achieved by a transformer whose secondary is isolated from its primary. I would think this could be provided most simply as an input transformer feeding a full-wave rectifier feeding the PFC. I would appreciate clarification of the necessity of this new DC to DC stage. Perhaps the PFC stage must go before isolation for some reason? Thanks.

You are correct. However, a 20kW line frequency transformer weighs about 200lbs. It also costs ~$2,000 if bought from US distributors in quantity of one (can get down to $600 if buying 100 units from China but that's another story).

For stationary applications, might be ok. But the focus here is mobile, lightweight, so 20lbs is better than 200lbs.

Hope this helps.

 

[garygid]

I am building a 1ft long QC extension cord with
2awg 600v welding cable and cat5e Ethernet cable... eventually.

The one-foot length sort of leaves the heavy QC Plug
hanging in space. A couple of feet might be better?

If making an adapter...
I was hoping for something more like a 5" rigid device, with
a 2" plug-in barrel part to plug into the car, and a 3" extension
part that would hold the 2" deep socket of the QC plug.

The adapter might have room for a small PCB on the top, with N LEDs
showing, probably doing the ADC, and possibly a DB9 connector?

But, perhaps more general, an in-line QC socket that one could
use to easily make an 8-foot QC extension cord, to reach the
"next parking space over". That would really be VERY useful.

Then, a (variation of the present) Jolomo plug, along with the in-line
Jolomo socket would be a useful combination to make an adapter.

So, I now vote for an in-line socket as the next project, with
the only difficult part being the female receptacles for the
2 high voltage/current Power Pins. Receptacles for the 7
control pins should be relatively easy.

-----
In any case, if the stork visits, let us know!