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

[pchilds]

As Cor mentioned, In series operation a failure of one unit could result in high voltage reverse polarity applied to the outputs. There absolutely must be some investigation done and possibly modification to harden the system. Applying high-current reverse DC to the output would most likely result in the large electrolytic filters exploding and/or venting. Even a momentary reversal at low current could result in destruction of the output sensing and feedback circuits. When you are dealing with this much power you must not cut corners and "rig" it.

-Phil

A high power diode across each supply will keep the reverse voltage to under 1 volt. If these power supplies have a fault output, you could OR them together to shutdown all supplies if any fail.

 

[Cor]

Since typical server power supplies (esp the hot-plug ones) also have a Kill input, it is simply a matter of feeding the
combined Fail outputs into all the supply's Kill input to shutdown *now* as soon as one reports a failure.
As always - this theory has to be proven in reality and I also need to look at how to OR the outputs together and fan-in
(how many inputs can be fed from one Fail output) to see if some additional logic is needed, levels inverted and so on.
But I do plan to put a couple in series and then test them (charging my EV pack) just to see & validate.
I understand about the protecting diode, but 30+ Amp diodes need heatsinks and isolation and before you know it, that whole protection circuit is a project in itself and more expensive than the stack of server supplies... So I am trying to keep it simple.
That is also why I have not taken action on adding a buck converter from Valery - I do not have that money to spend and my expectation is that with just the supplies themselves and an isolated voltage control input, you can do what is needed for QC.

 

[Ingineer]

Cor's idea is sound. If the kill input can cease output on all remaining supplies as fast as a malfunctioning supply can die after asserting it's fail output, then in theory this will stop any reverse current. I'd probably hang a smaller diode across the output, just for momentary protection. If the diode is overloaded, it will likely fail short anyway still protecting the supply. (Hopefully long enough for the others to shut down)

-Phil

 

[TonyWilliams]

Anyway, one simple question. Do we have specifications for the CHAdeMO pins? Im no asking for guessing, but actual hard data? If so, that may be a contribution that I can provide.

See page for of this datasheet
http://www.dyden.co.jp/topics/data/pdf/evkyusoku17p.pdf

It gives the diameter and tolerance of the male pins.
The lengths we had to figure out on our own based on simply measuring the pins on publicly accessible stations.

What material & alloy did you build the pins from? Are they plated? Thermally protected (that's actually part of the CHAdeMO standard)?

 

[jclemens]

Anyway, one simple question. Do we have specifications for the CHAdeMO pins? Im no asking for guessing, but actual hard data? If so, that may be a contribution that I can provide.

See page for of this datasheet
http://www.dyden.co.jp/topics/data/pdf/evkyusoku17p.pdf

It gives the diameter and tolerance of the male pins.
The lengths we had to figure out on our own based on simply measuring the pins on publicly accessible stations.

What material & alloy did you build the pins from? Are they plated? Thermally protected (that's actually part of the CHAdeMO standard)?

Gary made the pins on my recommendation of using Copper rod, (difficult to machine) and then get them electroplated in silver.
so, yes they are plated.
What do you mean by thermally protected? I thought the inlet on the car has temperature sensors.

 

[Cor]

Gary made the pins on my recommendation of using Copper rod, (difficult to machine) and then get them electroplated in silver. so, yes they are plated.

For easier machining, use soft steel, then plate on a thick layer of copper for better conductivity and a thinner silver layer for protection.
For the female pin insert, I presume it is a rectangular piece of spring steel with thin slits cut/stamped to create the fingers, slightly bent across the center of all the fingers to make them push inward and then the sheet is rolled up into a cylinder
so it can be inserted into the female pin, after being plated with copper and silver also.

 

[valerun]

If anyone is considering using a bunch of 48V power supplies in series to make a QC, why would you then add another buck (or boost) stage? Why not just control the existing PWM circuit in the bank of power supplies? Probably as simple as adding an optoisolator (you might not even need that depending on the power supply design).

These enterprise-class power supplies are usually very well engineered and have good efficiencies, so it seems silly to add something external, thus adding loss, when you could just control the existing circuit. In addition, you'd be dealing with high voltages and currents in your buck stage, so any failures could be catastrophic. (For you, your LEAF, or your home!)

As Cor mentioned, In series operation a failure of one unit could result in high voltage reverse polarity applied to the outputs. There absolutely must be some investigation done and possibly modification to harden the system. Applying high-current reverse DC to the output would most likely result in the large electrolytic filters exploding and/or venting. Even a momentary reversal at low current could result in destruction of the output sensing and feedback circuits. When you are dealing with this much power you must not cut corners and "rig" it.

-Phil

Yes, controlling directly would be best solution. However, a couple of problems:
1. no-one seems to have schematics for those so we'd have to reverse-engineer the units to understand how they are controlled
2. even if we are successful at that, we might not be successful at getting the timing specs that we need for voltage rise / fall speeds
3. With 8 supplies, you would actually need 8 optos and associated circuitry. Of course, still less than building a whole new power stage but does entail a bit more engineering.
4. One will still need a control stage for sensors, running comms, executing commands etc. So all we're saving would be the actual buck power stage which is not that difficult to build once the layouts / driver circuits are all designed.

Also, the added benefit of adding a universal buck stage after the set is ability to go all the way down to zero volts output, making it a universal power supply. Not as interesting for this particular application, I would presume, but is quite interesting for others.

On a series connection - yes, every supply will have to have a reverse diode connected to the outputs. Then a control board will have to have an ability to sense a drop in input voltage and either (1) adjust its power draw accordingly, or (2) shut down entirely. (1) and (2) can be combined - say, a reduction in draw on a single-supply failure and complete shutdown on multiple. This way there is some built in redundancy and ability to 'limp-charge' at, say, 70% of the rate until a replacement supply can be swapped.

Valery.

 

[valerun]

not sure if you guys 'dig' this kind of stuff but here are some pics of the prototype isolation transformer we just built from 2 Ferroxcube T140 cores I mentioned earlier.

The idea is to test the single-module half-bridge isolation stage (a simple 1:1 into a resistive load) - hopefully we can squeeze this in sometime next week reusing some of the power PCBs we have here. Still would love to find a magnetics expert ;-)

 

[poweredbysun]

not sure if you guys 'dig' this kind of stuff but here are some pics of the prototype isolation transformer we just built from 2 Ferroxcube T140 cores I mentioned earlier. The idea is to test the single-module half-bridge isolation stage (a simple 1:1 into a resistive load) - hopefully we can squeeze this in sometime next week reusing some of the power PCBs we have here. Still would love to find a magnetics expert ;-)

Very pretty!
Thank you for the glasses in the picture so we get an idea of scale.
Those are large cores, but small compared to 10 power supplies.
Cor's solution is probably the least expensive one, recycling power supplies.
This is certainly the most elegant solution.
We will run out of used power supplies, someday, if everyone wants one of these.
Jim

 

[klapauzius]

Yes, depending on cost, I'd rather pay extra to have an integrated solution than an improvised one.

However at price points of $20k for a professionally assembled and built QC (e.g. the ORCA), the server power supply (saw the 3 kW HP supplies for $24 plus $35 shipping on ebay) seems also attractive.

I am very curious to see if there will be an isolated power supply kit offered and what its price point will be.

 

[valerun]

Yes, depending on cost, I'd rather pay extra to have an integrated solution than an improvised one.

However at price points of $20k for a professionally assembled and built QC (e.g. the ORCA), the server power supply (saw the 3 kW HP supplies for $24 plus $35 shipping on ebay) seems also attractive.

I am very curious to see if there will be an isolated power supply kit offered and what its price point will be.

If we are successful at achieving 15-20kW throughput, an integrated PFC kit with isolation will be priced at below $3,000 (not including the QC power connector which is a big variable at the moment). Perhaps significantly below depending on what we discover as additional requirements for making an isolated stage safe and adequately controllable for QC purposes.

 

[Ingineer]

not sure if you guys 'dig' this kind of stuff but here are some pics of the prototype isolation transformer we just built from 2 Ferroxcube T140 cores I mentioned earlier.

The idea is to test the single-module half-bridge isolation stage (a simple 1:1 into a resistive load) - hopefully we can squeeze this in sometime next week reusing some of the power PCBs we have here. Still would love to find a magnetics expert ;-)

I think you're going to find out that it's very difficult to design a high-power isolated design that's also reasonably efficient.

-Phil

 

[valerun]

not sure if you guys 'dig' this kind of stuff but here are some pics of the prototype isolation transformer we just built from 2 Ferroxcube T140 cores I mentioned earlier.

The idea is to test the single-module half-bridge isolation stage (a simple 1:1 into a resistive load) - hopefully we can squeeze this in sometime next week reusing some of the power PCBs we have here. Still would love to find a magnetics expert ;-)

I think you're going to find out that it's very difficult to design a high-power isolated design that's also reasonably efficient.

-Phil

Yes, very well may be. Fun is in trying, though.

High power high efficiency isolated designs are very possible. The question is how difficult it is to get there. Earlier this year, I spent some time with Slobodan Cuk (of Cuk converter topology fame, also a founder of TeslaCo, a power conversion company) - he has demonstrated 97% efficient designs at over 50 W/in^3. Of course, no hope of that getting to open source anytime soon...

 

[TonyWilliams]

Yes, depending on cost, I'd rather pay extra to have an integrated solution than an improvised one.

However at price points of $20k for a professionally assembled and built QC (e.g. the ORCA), the server power supply (saw the 3 kW HP supplies for $24 plus $35 shipping on ebay) seems also attractive.

I am very curious to see if there will be an isolated power supply kit offered and what its price point will be.

It looks like the Brusa chargers are down to about $1600 - $1700 each now. Three would make 10kW, and I don't recommend more than 10kW on typical 50 amp circuits found "in the wild".

http://insideevs.com/brusa-permanently-reduces-prices-for-on-board-battery-chargers/" onclick="window.open(this.href);return false;

 

[klapauzius]

It looks like the Brusa chargers are down to about $1600 - $1700 each now. Three would make 10kW, and I don't recommend more than 10kW on typical 50 amp circuits found "in the wild".

http://insideevs.com/brusa-permanently-reduces-prices-for-on-board-battery-chargers/" onclick="window.open(this.href);return false;

I think I'd even pass at a cost of $500/kW. While I would love to have 10 kW onboard charging capability, this would increase actual utility not by that much for me (especially since QC chargers seem to finally appear in decent numbers around here) . At least not enough to justify $5000+ cost.

On the other hand, a 12kw - 15 kW QC in my garage for less than $3k and being open source would also add some fun for the money (i.e. understanding how these things work + being able to tweak it to my hearts desire).

 

[valerun]

supplies are here. pics below. interestignly enough, in the batch of 15, 2 of the supplies were 2kW and apparently newer in construction (judging by the type of caps used, etc).

who's got the pinout?

 

[Cor]

who's got the pinout?

I posted it here before: http://www.rcgroups.com/forums/showthread.php?t=1621433" onclick="window.open(this.href);return false;
The second file (FH1500.pdf) has the datasheet with the pinout.
Connect PS On and PS Kill to ground (V12SB Return) to start the supply
Mine will only run on 240VAC, not on 110.

 

[Cor]

Valery,
THe 2kW version looks different than the construction that I see in my DPS-1500AB.
The pics show that the labels on yours have rev 4 which is the same as mine.
I am guessing that the 2kW version is a different (functionally compatible) DPS-2000AB or some similar number?

 

[valerun]

who's got the pinout?

I posted it here before: http://www.rcgroups.com/forums/showthread.php?t=1621433" onclick="window.open(this.href);return false;
The second file (FH1500.pdf) has the datasheet with the pinout.
Connect PS On and PS Kill to ground (V12SB Return) to start the supply
Mine will only run on 240VAC, not on 110.

Awesome! Thanks. Have you powered up yours yet?

 

[valerun]

Yes, depending on cost, I'd rather pay extra to have an integrated solution than an improvised one.

However at price points of $20k for a professionally assembled and built QC (e.g. the ORCA), the server power supply (saw the 3 kW HP supplies for $24 plus $35 shipping on ebay) seems also attractive.

I am very curious to see if there will be an isolated power supply kit offered and what its price point will be.

It looks like the Brusa chargers are down to about $1600 - $1700 each now. Three would make 10kW, and I don't recommend more than 10kW on typical 50 amp circuits found "in the wild".

http://insideevs.com/brusa-permanently-reduces-prices-for-on-board-battery-chargers/" onclick="window.open(this.href);return false;

I just chatted with Victor of metricmind (the authorized distributor of these in US) and he said his pricing of ~$2,500 per air-cooled unit already reflects this drop and would be about the same as if someone tries to import one of these directly. Apparently, duties / shipping / customs clearing etc add quite a bit. So still not quite $1,600 per supply unless you have some other source.