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

My own testing has been going well! But still waiting on more feedback from testers

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Looking forward to it! I have a Little Focer v3 in my OneWheel XR, am about to buy a second one for another build and also want a Cheap FOCer 3 for a OneWheel Pint I’m going to convert. :slight_smile:

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Yeah I think it will work well for that!

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Same thoughts here. I’m getting excited

Sign me up for some early access units! It is looking sweet, I might have to retire my CFOC 2s.

Excitement is sky rocketing here. Checking in every day for news.

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Ordering as soon as released. I’m using the Cheap Focer for a wind turbine application. The focer spins up the turbine, and from there it’s a pure regenerative braking application, where the generated power is controlled by applying a negative force/current.

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that sounds super cool, how much power do you get with this setup?

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I have tried to make the electronics myself with rectifying and buck converter stages, but mosfets and diodes burned at 350W. Then I realized that I could actually simplify everything by using a FOC motor controller with regenerative braking. Electronics are much simpler, already existing (and tested with CFOCER), and conversion much more efficient, and therefore doesn’t generate as much heat to be dissipated. So far, I have only used the FOCER2 in a test setup, so unfortunately, I cannot tell yet how much power I get, but maybe it’s according to spec with 120A.

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I a turbine setup, you would normally just rectify the 3 phases you get from the generator (motor), and put it straight into a battery. The problem here is that you have no control of the speed of the rotating wings, and these will in many cases run too slow. “My wings” are designed with a tip-speed-ratio of 7, meaning that the speed of the wing tips should be around 7 times the speed of the wind. This is where the wings produce the optimum lift (power). CFOCER and VESC allows you to do this in a very simple and efficient way.

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This sounds interesting. So you’re doing AC to DC with your turbine and a CFOC2?

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This is really cool, I’m interested to see how far you can push regenerative braking.

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I’m not an absolute expert here, but I believe that if current travels in the reverse direction due to a braking force, CFOC2/CFOC3 is acting as an “Active Rectifier”, which is more efficient than a passive rectifier with diodes. Also you can control the regenerated power, which you cannot with passive rectification (unless you add something like a buck/boost converter). So a lot of excitement here about the CFOC3 release.

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I’m new to the forum but really interested in building one of these when the design is done. Do you mind sharing how you’re sourcing the STM microcontroller with the chip shortage? Last I looked, all of the main suppliers were completely out of stock. Seems they’re available on Ebay but there’s gotta be a better place to source them. Flipsky, trampa, and many other manufacturers have VESCs in stock so the chips have to be available somewhere.

They have been available at LCSC lately STM32F405RGT6 STMicroelectronics | C15742 - LCSC Electronics

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Wow thank you, I didn’t check LCSC. Is it worth building a CFOC2 at this point, or is it best to wait for the DRVless CFOC3 considering how far along it appears?

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The DRV is unavailable, so it is better to wait

edit: I checked again and the DRV is available on LCSC: DRV8301DCAR Texas Instruments | C98969 - LCSC Electronics
So if you are pressed for time you could make a Cheap Focer 2, but I still think it would be better to wait for the 3. There are lots of improvements

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This is always the worst part of it…

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I attempted to build it at JLC a couple of days ago and all the parts were available with the exception of the 2512 R001 resistors and the Schottky diodes, both were easily replaced.

That being said, by the time I found the caps, etc., on LCSC and shipping for both, the total came to ~$400AUD (~$270USD) which I felt was a little steep for 5 of them, especially considering I’ll almost certainly F at least 1 of them.

I understand the v3 is designed with the chip shortage in mind, so I assume it will end up being a fair bit cheaper than that, so I decided to wait for v3.

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