As was discussed in my "almost the CHAdeMO Spec" thread, I'm quite interested in (legally) cracking CHAdeMO for us to build our own chargers. There's a bit of legal muck surrounding CHAdeMO, due to its closed nature. I've decided to go ahead and start "the" thread leading to our reverse engineering of this spec. First, the ground rule: if you know/have the spec but are under an NDA to not talk about it, please do not post here.
Ok with the lawyers happy (I hope), lets have some fun with chargers! And yes, no matter how you slice it, a CHAdeMO EVSE is a charger.
The standard can be broken down into two parts, the analog side, and the digital or CAN bus side. Fortunately, the analog side is published right on the CHAdeMO website. I posted a more clear flowchart then what was published to make it really clear as to whats going on. I thought it was alright, but some thought it was so good that I must be looking at the standard!
I wasn't; I just took what was on the website, nothing more. I don't have access to the standard. Anyways, here is is:
And here's a schematic, this is directly from the CHAdeMO interface.pdf available at chademo.com.
As you can see, the analog side is fairly simple. It's those dang CAN messages that we need to figure out. I know there's a few sniffing the QC port, so I hope this thread will allow you to come out of the woodwork.
I have made a Google code site for the project, available at http://code.google.com/p/open-chademo/
. I will be updating it over the weekend.
Now, as far as generating the high power DC (and keeping it within 2% tolerance) this is sometimes done in one big switching mode unit, or is done modularity with separate smaller supplies. The hard part about this is that you need isolation, and that means running things through a transformer. Transformer size is proportional to switching frequency, so something in the high audible range or higher (I've heard 22 kHz is used, and I can clearly hear most of them), although the new Andromeda unit uses an even higher frequency to reduce size even further.
One very important warning: You can cause a fault condition if you muck around with this port and don't play by the car's rules. That being said Ingineer has done a lot of "experimentation" and has confirmed that most codes can be cleared with a 12v battery reset. However
, there is just enough knowledge in this thread to be extremely dangerous! You have been warned. Also, high voltage kills. This is serious, high power stuff and is meant to be mostly an academic exercise. It is not cost effective to build one of these for yourself at the moment. If you want a single phase and/or low power unit unit, talk to Ingineer about modifying a commercial unit for you.