openinverter forum

So since Touran has no built-in AC charger at all I created various hacky ChaDeMo chargers to still be able to charge it at home. On my upcoming road trip I will do some home charging where there are no 3-phase outlets. So that meant I had to create a 1-phase version as well. Power path is simple, rectifier -> booster -> cap -> output.
Let me walk you through this electric mayhem.

Ingredients

• Metal enclosure that has to be lurking about in your basement (don't buy new)
• Heat sink (must also be left over from a previous project - scrapped audio amplifier in my case)
• Fan (who doesn't have multiple 80mm fans in a box of fans?)
• Rev2 or 3 inverter brain board
• Rev2 gate driver - half populated
• About 50A IGBT brick (half bridge)
• Current sensor (here: remainder of the good old EMW charger)
• inductor (boost inductor from EMW charger)
• Some elcaps and a precharge resistor, discharge resistor
• elcaps (here: 2x680µF in series, so 340µF)
• IC sockets (that are hot-glued to the Anderson connector to carry the ChaDeMo control signals)
• Switch mode 12V power supply

Update: the IC sockets were bullshit, replaced them with a separate 7 pole connector left over from, guess what, the EMW charger.

Operation:

1. Plug in ChaDeMo (best do this first, as the output goes live as soon as you plug in - who needs an output relay )
2. Plug in mains, hit start
3. The cars battery relay is closed
4. 4s later the precharge relay is closed - this is boost mode so no use precharging to grid voltage, we must precharge to battery voltage
5. The configured max charge current is transmitted via ChaDeMo
6. The current command from ChaDeMo is obeyed

To my surprise the PI regulator makes a good effort to do some power factor correction. It boosts strongly in the "valley" and boosts just half that at the peak. According to my cheapo power meter the power factor is 0.9. I took it up to 3kW (7A average) with not much heat generated.
I couldn't be bothered to fire up the display, but one of the buttons acts as start. Stop button would be neat, actually...

If you're interested I can upload the software to github. Works the same as the inverter software. Web interface, CAN mapping and all that.
But strong disclaimer: this charger is a mayhem, it offers multiple chances to be electrocuted - don't do this at home.

How about a version based on the Gen 2 Prius half bride and inductor?

Wow! That is really good PF. And the handle looks good also.

Code here: https://github.com/jsphuebner/stm32-charger
I have stripped out parameters quite a lot.

SciroccoEV wrote: ↑Tue May 12, 2020 8:32 pm How about a version based on the Gen 2 Prius half bride and inductor?

Do it I don't need that much current in a 1-phase charger. It will be structurally the same.

Oh boy. You do know I'm just going to have to build this:)

Oh that is wicked!
Was gonna build a spare of my present EVSE in the coming months but with the 40kWh pack in the car now, the stock 3.6kW unit onboard is fairly impotent. This would be a crackin' workaround.

Do you have a CAD layout for the precise placement of the vent holes as shown on your enclosure?

I do, but thats proprietary air vortex plus technology

Ported the code to the inverter software today, for charge mode. Now Polo obtains a 0.92 power factor

Any chance of build instructions for a newbie ?

This is very nice. I see this porting super easy into an incar version 3kw AC charger with CAN control. Well It would done be if you just leave out chademo plug/socket parts, replace with relays+contactor setup, throw it in the car and leave the AC plug section on the outside. Only thinking working pronciple here, simplified.

Am I onto something here?

I would recommend anyone building one of these have an understanding of the electrical regulations in your country.

And have an understanding of electric power circuits.

If something happens to you or to an installation due to the use of something like this you are going to have quite a few people asking difficult questions and possibly getting fined.

I believe there should be a disclaimer with things like this so people understand this is purely meant as educational and that you have to work out if it is LEGAL to build and operate one of these yourself.

I agree. In my country a private person does not get asked of PF consistency of devices on his house.
Bussinesses do need a PF counter and they can get into trouble if this is too low.

tom91 wrote: ↑Sat May 16, 2020 9:40 am I believe there should be a disclaimer with things like this so people understand this is purely meant as educational and that you have to work out if it is LEGAL to build and operate one of these yourself.

This is true of almost everything discussed on this forum. IMO we do need a disclaimer (footer on every page?) and I've raised that with Johannes in the past.

It's important to understand that as we grow the proportion of non electrical engineers increases and we must change to accomodate that

tom91 wrote: ↑Sat May 16, 2020 9:40 am I believe there should be a disclaimer with things like this so people understand this is purely meant as educational and that you have to work out if it is LEGAL to build and operate one of these yourself.

I was hoping this would be obvious:

this charger is a mayhem, it offers multiple chances to be electrocuted - don't do this at home.

zippy500 wrote: ↑Wed May 13, 2020 8:22 pm Any chance of build instructions for a newbie ?

See above: if you need build instructions you probably shouldn't do it. I consider working with grid voltages far more dangerous than working with battery voltage because you just need to touch ONE part to have a hellofatime.

The source code itself will remain the only documentation, might add the pinout to the readme however.

EDIT: filled out readme.md https://github.com/jsphuebner/stm32-charger

Getting very curious on how the output voltage could be varied to suit different packs.
Could the web interface be made to carry out these adjustments.

Just pondering the notion. But that's how projects usually start !!

Stephen

Stephen Darbey wrote: ↑Thu May 21, 2020 12:38 pm Getting very curious on how the output voltage could be varied to suit different packs.
Could the web interface be made to carry out these adjustments.

You'll need to read the source code for an answer

johu wrote: ↑Mon May 18, 2020 5:40 pm The source code itself will remain the only documentation

Stranger things have happened Kevin.

Regards
Stephen

Given the restrictive nature of the licensensing of this design and the onerous requirements to use only available parts it has taken some ingenuity and legal wrangling with Johannes's high powered lawyers to get the project started. A scrap 15kw 3 phase vfd is providing most of the parts along with the inductor and buck/boost module from a gen 2 prius inverter.

I'm still unsure if this will the the poor or rich mans version so stay tuned and I will reveal as much as the air tight nda I had to sign will allow.

Its been fun knowing you Damien .

Looks like youve got some 16kW there. I recommend you add one centrifugal blower aimed at cooling fins in from the front. Also i found out Prius inductor doesnt need a lot of cooling, but i still added one fan in the back to scoop air over it.

Here is how i did it.
There is a large alu finned cooler under there. I bolt my IGBT and rectifier there. Caps are 2nd hand from a medical laser device which has strict standards so they should work in my application for some time. Of course Prius inductor bolts to the casing and is directly inside 120mm fan airflow. From the side you may notice additional 12V going directly to the battery. I didnt trust 2A supply to hold under load with heavy contactor and the powerfull fan, so i use additional power which is turned on by a small relay on the EMW board.
This is a 3phase charger and can take power from any L2 EVSE.

Notice Weimos D1 connected to EMW board. I never leave home without my Wifi friend .

Also see the 16A autofuse which brings the N line to capacitor center tap. This allows me to charge from single phase in case of emergency. I connect 310Vdc rectified and center tap doubles it to some 620Vdc which can effectively buck down to my battery. This was a simple measure and doesnt let me to use full 3kW potential from a single phase, but is a good alternative if there is no 3phase available.

Can we call it the infinitely resourceful Mr Damian McGuire version?

p.s. Can we now call the land-yacht the land-feather now that doesn't contain the calb cells (please don't do any high current testing... I don't think your cats want to explode!)

Great stuff Damien.

I have to say when Johannes started this thread I was thrilled, only to discover that disclaimers started appearing around every corner. To me it took a bit of the fun out of it, particularly as I was only interested in the single phase charging. ( Three phase not an option for me ) Fully understand the lethal risks and also legal reasons, but really,! Single phase and 'Poor mans charger' has to be allowed development as part of the overall and ultimate goal.
Thanks Damien and Arber. You have just restored my optimism for building a DIY charger. Long live the Rebel in you.

Stephen

Well thank you, we live to serve...

Now if you have no other option at home than single phase AC than you would want to use Johannes boost charging mode. That way you could get better PF and use more of your fuse.

My setup is primarily 3phase and made for fast charging . You need to know that inductor efficiency is proportional to load on it.

As mentioned elsewhere I overvolted the IGBT brick in poor mans charger. Since I don't have a spare one handy I thought lets just replace it with a discrete IGBT and diode. I wouldn't say this came out too well: Anyone got a 1 phase charger left over? Just need to make it chademo compatible in some way.

update:
To my surprise the bridge rectifier has survived and the logic board seems fine as well.
Should I decide to repair this with a new IGBT brick I should be aware that it won't be cooled so well: Some of the heatsink has been turned into plasma

Well... i may soon have 3 of singlephase chargers. I am most satisfied with Tesla charger and will be installing it in my pug. This will leave me with 3x liquid cooled 3kW Eltek chargers.
They are CAN controlled and could be programmed.
I have them directly connected to DC by 50A anderson connector. AC can also be directly connected via normal schuko cable, but charger wont start if there is no CAN command.

If you want i could remake one into air cooled charger. It is eqally robust as it is IP67. It just needs to remove 200W of heat for 3kW of charging.

I need to return from our urlaub in Croatia to pull them out... if you can wait?

Sounds good, especially the air cooled option. Would like to test it in late August because we go on a longer trip in September and I want to be able to charge single phase. As long as I'm home I'll just charge 3-phase.
Enjoy Urlaub, just pop me a message when you're back or so.