Put together another prototype since I pretty much trashed the first one doing all kinds of surgery to it.
Works decent but need to tune the gate drive a bit more. Mosfet turnoff is just a tad too aggressive.
While I could do all of these bodges to the rest of the prototypes, I think I need to go ahead do another run. I’d rather not give beta testers anything too janky.
Tuned the gate drive stuff a bit better and now get appropriate overshoot. There’s always gunna be some amount of it and that’s why you spec MOSFETs with a voltage rating about 25% above your operating voltage. These MOSFETs are 100V rated.
In the turnoff waveform, you see a spike up to about 68V which is an 8V spike. That’s just fine imo. I like anything less than +10V for up to the max rated motor phase current.
I did up 100A with success. I don’t want to go higher until I have round 2 of these prototypes. But things are looking really good!
I have no idea why, but I’m definitely gonna have to build a couple of these.
MUST. FIND. MAGIC. SMOKE.
The next round of prototypes are done and about to ship to me. Then I can continue progress.
FYI, another secret project of mine that uses similar architecture and components just passed a road test at 140A motor current with a 16S battery on my ebike. I expect similar performance for the CFOC3
Just a matter of gate drive tuning now. Was hitting some good milestones on the bench. Tweaking Rgs and Cgs values to get those good rise/fall times. Stability is priority!
MOSFETs exhibit slight ringing on the gates during turnoff. Not used to seeing this specific occurrence. Might have something to do with the older SGT architecture of the MOSFETs. It’s not beyond control but just interesting to me.
Hey, this thing looks exactly like something we would need right now!
Looks awesome!
I have two questions: Is it going to have support for uart to bluetooth? Pwm input at the same time?
Everything is going to be controlled via vesc tool?
So it’s like most VESC based controllers. It has the same features as as your typical VESC but without built in bluetooth. You’ll have to add your own BT module
Hey there, can you already tell me what FET’s and Fet driver you are using for the cheap focer 3? I want to redesign the version two because I need a little more power. Or do you guys have any recommendations for 20s >100A controllers?
There is a list here
I have the Little FOCer for this kind of thing.
Test unit did up to 140A on the bench with 16S battery. It’s now time to toss this unit on something for field testing. If that goes well, then I’ll crank out some more test units for other testers!
Just did a test ride on my ebike. 16S, 120A motor, and 60A battery. No issues. Will crank up to 140A for round 2
Using a Kranked Motor ?
No but that would be cool. My ebike has a MXUS 3K Turbo hub motor
Going to Ben Walker in Switzerland tomorrow and bring him his Kranked Kit.
He is also working on other bikes and ordered a lightning-rods motor
I think he has also a https://www.revx.cz/
If you are looking for someone testing he can do it.
In Champery they have steep trails.
He can do 5000 ft uphill on full power.
Yeah I’ll have to see if the CFOC3 fits for his rig!
Not sure if anyone has asked but do we have a confirmed size for these? They look pretty big
Maybe not the right topic but Shaman have you ever worked on very low power BLDC systems, 5W or less? I’m trying to work out which if any approach would work for a project. It seems there’s a decent market for highly integrated ICs with FETs onboard for computer cooling fans so that’s easy enough but they have some power limits, and I can’t easily find gate drivers suitable for such low power. The gate drivers seem to start at higher voltages.
Any experience with small stuff like that? I can’t seem to find any existing projects other than this smart knob so I can copy their homework
