The power boards have finally shipped! Should arrive on Monday.
In other news, I spent quite a lot of time improving the logic board.
Replaced the 1A 5V buck with a new one that can do 2.5A average / 3.7A peak which is much better, although slightly more expensive LM5164 -> LTC7103, The input to the 5v buck now has a transient filter which clamps overvoltage spikes and smooths out the noisy input to put less stress on the part.
Added another two 5v->10v chargepumps so now there is room for 3 in parallel, allowing for up to 120mA on the 10v rail. Added a bunch more capacitance as well to reduce droop when the fets were switching at 60khz.
Added 220R CAN termination resistor which I forgot before.
Added 10k pulldowns on the ADC inputs to stop runaway devices when throttles become unplugged.
I managed to squeeze in the holes for the shield on the interboard connector, as it seems to be impossible to get hold of them without the shield (apart from buying ones with shields and taking them off). Which should make it easier to get assembled.
Added a feed through from the USB 5v to allow the logic side of the board to be powered by just plugging in USB. This means you can change settings, etc without needing external power. It is protected by a polyfuse and a 100V 3A schottky to stop it blowing USB ports up.
Added USBLC6-2SC6 to the USB connector to protect from ESD.
Finally got the silicone wire guard the right size and casting properly in the 3d printed mold.
Added a loop next to the connector to allow fitting a cable tie or something for strain relief.
Looking nice. Keep up good work!
I had issues with 3.3v dropping to much on my controller as I am also powering esp32 that can chew up up to 700mA when actively transmitting over wifi. Then replaced to another LDO and it's been stable.
I have had USB power tied with the 5v rail from day one of prototyping and had never had issues. Seems like a diode between the USB and the rest of the circuit is all that's needed. Very convenient to program and test virgin boards. Not sure why this is not standard on all VESC.
Yeah I had it connected at the start also, but removed it after connecting my power supply the wrong way round one time and it blew the diode up! Hence the polyfuse and slightly overkill diode current rating.
Don't think I have had any problems on 3.3v so far, got the STM32, IMU, BLE on there, but probably not much more than 200mA with it all going. Its just a 600mA LDO which I have used on all my boards from the beginning. (Don't understand why the official ones use bucks for everything, just more inductors to fall off in shocks or vibration)
The VESC 6 / 75/300 have a real problem of blowing up the STM32 if you put the sensor wires together with the phase wires. I don't understand why they have 0 protection for esd or any other transients. Especially given how many nice exposed io pins there are and how cheap tvs diodes are.
I will probably add some current limiting resistors on the IO before it gets to the tvs as well.
Very nice! Shouldn't the CAN termination resistor be 120ohm?
Yea the ESP32 draws a lot of current, but not really that much during transmitting. When starting wifi, it draws a huge current for a short time. It is recommended to use a capacitor on the 3.3V side close to the board. I used the ESP32 on the A200S, and the ESP32 sometimes gets stuck when starting up wifi.
Really looking forward to those power boards!
Well yes its supposed to be 120ohm... but I looked at vesc 6 schematic also and it has 220ohm?! My guess is so that if you have a bunch of vescs on the bus it doesn't have a problem with the resistance going too low.
Yup. It won't matter anyway, as you don't really have long cable lengths in a typical vesc application.
Power boards arrived, built one up to make sure everything fits. Now need to assembly a new logic board to run it.
Looks good, I am looking forward to see it run! Hope all goes well.
Beautiful, I am looking forward to either buying or building one of these.
Tested the power board today without a heatsink. From 25C it managed to do 200A for 60s before thermal throttling down to 100A continuous.
Motor is a TP Power 5860.
Looks great! How does that energy-wasting work, it seems you just have a motor spinning freely?
Its foc openloop. Which drives current in the d axis. So it makes loads of heat but doesn't produce any torque. Which is perfect for this type of testing as you don't need a load. Just a motor with low enough resistance that it doesn't heat up too much. (Hence the fan)
Alright, makes sense, thanks.
100A phase current continuous without any cooling or big mass is very impressive
Have you tried how much current it can drive continuous without the copper bus bars?
The bus bars are only on the battery side, just to give more surface area in contact with the heatsink really. The copper on the board is so thick it doesn't really need them.
The phase connections are just on the pcb tracks and no bus bars there, so this test won't really show any difference with or without them anyway. I am doing proper dyno testing at the weekend with two at 12s, should be able to get some good logs from that.
Also fun that this 100A cont was even without any heatsink, so if I replicate Benjamins setup for testing the 75/300, by clamping it to a big aluminium plate, I should see what it can really do.
when you plan to start sell a test boards for beta/ first users? I am very interested to participate. What is expected price?
Price will be £399. Pre-order discount still to be decided, but likely to be about 5-10%.
Hi All - I've got two A200s V2 units that I am looking to sell, unfortunately they didn't work for my application. One unit has never been powered, the other was only used on a test bench.
Looking to sell for $300 USD + Paypal fees. They are located in Gainesville FL USA, and can be shipped immediately.
I can be reached quickest via email, email@example.com
No the firmware is not compatible between the versions. I will add the firmware to github after release.
wow those power pcbs look cute.
What are they ? normal fr4 with 4 layer ? or something fancy
8layer fr4 tg180, 3/4/4/4/4/4/4/3 oz, 3mm thick.
Want some FR4 with your copper there?!
Now avaliable for preorder.
Have you tried to use thinner copper layers or less layers? 4 oz @ 8 layers is pretty expensive. How much current would be possible with a cheaper PCB?
I used to use 2oz 4 layer boards, but they don't really have low enough resistance or spread out the heat very well. The boards are not too expensive when you order at larger quantities like 100+ boards. The performance increase by going for such boards is huge. Well worth the extra expense in my experience.
Congrats! Have been watching this project for a bit and glad it's ready for preorder. Do you have more information about the preorder? Are the boards assembled and ready to be shipped, or are you getting enough orders together to make a bulk order at the fab?
Also, does the open source project on Altium represent the current state of the board, with all modifications you made during testing? Has anyone made one for themselves yet?
I have 100 power boards already and the mechanical bits (heatsinks, cases, bolts, etc). The preorder is so I can get a large order in for the logic boards to get the cost down to a sensible level. Plan is currently to put the order in by the end of the week, just doing the usual too and fro with the pcb fab at the moment. One of the main things I did over lockdown was acquire all the assembly kit I need to do the power boards here, as that lets me order the mosfets to order.
The altium project is the current state of the board, I update it everytime I make any changes. Although I have seen a few people making forks and removing all attribution which is a bit disheartening when you spend so much time on something. For now I changed the license on the project, but it doesn't stop the likes of flipsky and maker-x just rebranding it.
Thank you for your hard work on this project. I will put in an order and look forward to receiving it when it's ready. I'd also like to have a go at making one or several myself, and am very grateful for your willingness to open source your work. I know of no other comparable VESC design which is equally open. Your commitment to making the design available is laudable.
I'm sorry there are folks forking the project without attribution. I think people in the community can recognize quality, and hopefully reward the designers of new boards with their business.