144Vdc EV Charger

the original post of this thread shows an isolated topology. take it easy... its there.

also, the original post if you look at the picture of the schematic the input is PFC stage switch driving a transformer and could be synchronous rectification output if you changed the diodes for mosfets on the right hand side near the output. so its not that far away from what you want. i just made it this way with the diodes cause its unidirectional and thus easier. is it the best most absolute perfected design? no. but the software is 90% done for this one.. and the design is done too (except for the magnetics) and there is value in having stuff done. you can always make a revision 2 with whatever small mods you want like your synchronous rectification on the output stage rather than diodes but then you have to do the softare for it and validate that software against random error. i want to try the unidirectional one first.. its for my own use because i have it at 144Vdc output. for 400V output its small change so i might make it so its easy to spin the design for any voltage you want (within reason). i'm expecting this design to clock in at 96-98% efficiency.

the original post is also for unidirection only. the topology changes for bi-directional. why? because if you know for sure you're making unidirectional you chose the topology that leads to the higher power density with the higher efficiency. that's the open source design i posted here (though it still needs some work). for bi-directional you have to make changes to the topology to support bi-directional flow and the efficiency is impacted by that necessary choice.

the bi-directional one, which i have the complete schematic design for today , is not being planned for construction yet and has not been posted. it has PFC (different topology), isolation, synchronous rectification and heavy filtering for both low and high frequency EMI, supprts 1-phase or 3-phase etc etc. the software is non-existent at this time. i'm expecting this design to clock in at 92 to 94% efficiency for the cost target i have. i'm not sure if i'll get to this anytime soon.. perhaps others will finish it first.

I would love to add a few of them to my wifes LEAF if you make the 400vdc version.

Otherwise, I would love to see a trace layout that supports an increased current version (lower turn count magnetics) for folks running 116.4vdc peak pack voltages (Zero, Polaris, Aricmoto, Victory, etc.)

there was a time when i had a handy spreadsheet (that i spent forever making) that was used also by magnetics manufacturing plant here in canada. could calculate up a design using any core material, supermendour, metglass, ferrite.. any geometry. it was good. quick. sadly, i don't know what happened to it. i think i left it on my old computer and when i pitched the computer it went with it. i'm sort of dreading making that spreadsheet again.... but its worth it. magnetics design is super interesting.

as for power levels.. for residential setting, we're talking 240V, 50A, maybe 60A max. so, somewhere around 10kW. graphine battery might like a 100A charger though..

my plan is to stay around 5-6kw for this first unidirectional charger. i want to prove it out like that and then i can put two in parallel and work on load sharing algorithm and have a 10kW charger which i think is more than enough.

HighHopes said:

i think i left it on my old computer and when i pitched the computer it went with it.

Click to expand...

Stuff like that is one reason I keep all the harddisks from dead systems (even the ones where the harddisk died; sometimes I can still get data off of it if the need arises).

huh... forgot all about this thread. Random Wednesday, good time for an update!

The design was completed. All the math, simulations and then schematic, bill of materials, PCB fab, assembly and test completed.
It did work well in forward direction. In reverse direction (towards the utility) the gain curve was not as expected but it still basically worked just not over the entire battery voltage range.

There was a lot learned here but the best thing that came out of it was a MathCAD file that can design the entire converter including the CLLC magnetics given any input and output. Unfortunately the transformer is custom design every time because it always requires a specific leakage inductance (the nature of the topology) so i do not have a way around that. It cost $50 for a transformer that could manage 3kW.

The original design had two boards to make debug easier and reduce costs if a redesign was necessary. board one was a universal voltage AC to DC boost PFC stage, bi-directional. the second board was DC to DC converter isolated resonant CLLC topology, bi-directional.