Cheap FOCer 3 (Open-source, Low-cost, VESC 6 based ESC) (In Development)


New Features and Improvements vs CFOC2:

  • 16S safe operation
  • Estimated 120A motor operation
  • USB-C connector
  • Phase filters
  • DRVless design
  • Easy Bluetooth module addon
  • Further improvements to electrical stability from lessons learned in my more powerful designs
  • 1A 5V auxiliary output

The intent is to refresh the CFOC design so that it can actually be made by DIYers again in this chip shortage. I also intend to actually make these things with full heatsink/enclosure and sell them at the most affordable price that I possibly can. There’s not a hard ETA right now.

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Only got as far as performing basic power supply functions check, programming it, and seeing if it boots up. So far so good but got a long way to go to see how it does. A lot of new things to test on this baby.

One thing I’m going to change is adding more caps. Shorter ones but slightly fatter and more of them like in the pic below.

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АААА THE DICK STAYED!

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Yes I’m still here

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Beautiful! I can’t wait.

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Omg! Yes! Best Easter egg ever :joy:

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You beautiful bastard

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Out of curiosity, where the ‘‘lack of caps’’ and longer leads part of the issue with cfoc2 sometimes being unhappy on aggressive launches?

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Awesome!!!

Holy crap, that looks a lot more complex than CFOC2. Removing the DRV really bumped up the component count. Can’t wait to see how it works!

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This is very cool, I want to test it

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Nah. Most likely gate drive thing.

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I’m hoping DRV removal will improve reliability as well. I was mostly satisfied with V2 apart from the oddball generic drv fault that popped up when doing hard launching or trying to throttle against the hill. Though it may seem to be rooted somewhere in FOC sensorless mode as the V2’s ran a lot better once I connected the sensors. Can’t wait for this to be out to do a long needed upgrade.
@shaman Are there any estimates on how much this unit will cost assembly wise?

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It was $40ish per unit when doing 10 units from JLCPCB. Plus the cost of the caps, FETs, and cables. I maxed out JLCPCB’s service which included having them do the connectors. One could save a little bit more by doing all the though-hole stuff yourself.

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after the Raiden Zescs died out I was waiting for your DRV-less design to come to action, just hoping for those screw terminals for power and motor phase connectors, I just love it, it’s so easy to fix cable lengths and switch vescs between builds when you have those setup :green_heart:

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o.O

Wow can’t wait to see this in the field haha

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Unfortunately JLCPCB doesn’t seem to have the terminals that would work here.

Can you eli5 how a drv’less design is different from the usual one, no specific really just more of a curiosity on my behalf, ie what is used instead

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The DRV chips we use are MOSFET gate drivers with some extras, their job is to take digital signaling and use it to switch on and off the gates of a MOSFET quickly and efficiently. Basically fet gates need fairly small amounts of energy to switch on or off, but pumped into them quickly to minimise the time spent transitioning between off, half on, and on.

A normal logic out from a microcontroller can’t do that so you either use an integrated package like the DRVs or build a set of drivers yourself. You need 6 drivers per motor (3 phases and a circuit for high and low on each. I think this requires 6 but I might be missing a way to do it with 3) that each take up a bit of board space and add complexity to the layout. DRVs also have extra features like handling low power internal supplies like the 5v used by the processor, and they have current measurement circuits to accurately gauge motor current

(Apologies if you know this already and were looking for a more detailed explanation of how to implement a gate driver or something)

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Gotyah, thanks

Alright so I started taking a look at the gate drive waveforms and current sense quality. The gate driver I’m using is just barely strong enough to turn off the MOSFETs in a reasonable time. Not ideal but it’s something I can work with by adding some “help” to boost the drive strength. I’d like to use this gate driver since it’s well stocked right now.

The current sense signals are a bit noisy and I think I found why. Has to do with the switching frequency of the primary buck converter. I can adjust the switching frequency of the buck converter to be higher and also add some key capacitors in places to help squash the noise.

So far there’s nothing detrimental. Stuff I can deal with one way or another.

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