FOC'ing around (weak brakes and cutout)

Hey all,

With the release of vesc tool and 3.28 I decided to try FOC. setup was a bit buggy as i got failed detections and the “r is 0” bug, but i was eventually able to get everything setup. I copied my current limits from bldc on 2.18, but had a couple issues in my first ride. Here’s my setup…

10s4p Samsung 25R Each VESC (dual Ollin 4.12 setup): motor max: 70 motor min: -70 battery max: 40 battery min: -8 FOC sensored

The problem:

  1. The brakes are noticeably weaker than bldc while startup is about the same strength. There is a slight delay when accelerating and braking as well but i chalked this up to FOC limitations. I’ve already decreased ramp up time to .1s

  2. When i blast the throttle from standstill (unloaded) or quickly speed up going uphill (or I assume anytime I’m drawing a lot of current), The Vescs cutout and the wheels stop spinning until i let go and throttle again. The behavior is as if I’m getting over current, which i may very well be, but not sure why this happens in FOC and not BLDC. Haven’t checked error codes yet, but I’m assuming over current, will update later.

The board otherwise works fine with smooth startup and no issues running at 50k erpm. Any input is appreciated!


FOC is sensitive to sudden acceleration, mine cuts out at 0-100% throttle momentarily, It some times lose pole detection, also momentary, but sensored shouldn’t do that but if its over current u can increase absolute max up to 150a safely, though I only goes 140a. accelerating ramping u can just kill it with 0s, but I saw people complaining even after that. I haven’t try so…

Sensored shouldn’t have much to do with it given that it moves over to sensorless at about 3mph (7000eRPM). If I am getting over current faults I’ll check tonight to see how much current I’m drawing.

If the full throttle cutouts are something i “just have to live with” then I’ll probably switch back to BLDC.

I will miss the quietness and battery efficency though, I ended up with like 4-5% more battery at the end of my 3.7 mile ride.

Strangely my case was opposite to you XD I had over current in BLDC in braking and Switched to FOC, Efficiency only noticeable over 10miles I think, I get 3 miles more over BLDC

I have similar issue, but only cuts out when braking. Even if i brake and try to push the board with my feet, the vesc resets.

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Getting abs over current fault?

Will check when I get home :slight_smile: If I am, any ideas what might be causing it?

Honestly I’ve encountered that on every vesc, about 6 diff ones now. I can’t pin down the problem. I replaced everything from the fets, the shunts and caps, resistors and the issue always shows up again

Have you tried the FOCBOX? When we were blasting the throttle at the Raptor 2 event, it didn’t seem to fault.

Focbox on raptor is supposedly running some tweaked firmware. And yah happened on focbox too

When you get OC faults, what’s the current reported for you?

Over 130 filtered, actual is normal I have 4inches between batt and vesc, I’ve tried everything imaginable lol

if it’s about 130A then we should be able to just set the abs max higher and it should be fine right?

If battery is full, focbox with bms does give brake cut outs at the beginning of the ride - fault code over voltage

Probably, I actually looked for that yesterday but I don’t think the extended bldc tool has that option… Also it might fix the error but not the cause

Sure it does, it’s Absolute Max in the currents tab

@Sebike easily fixable by increasing max input voltage, not sure why Enertion would mess with this setting though.

@scepterr Here it is on both windows

Wierd guess 4am tweaking isn’t smart lol

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Let me know if upping the max, gets rid of the error. I’m going through and doubling all the caps in the vesc lol


Fault : FAULT_CODE_ABS_OVER_CURRENT Current : 280.5 Current filtered : 125.2 Voltage : 28.19 Duty : 0.705 RPM : 13659.7 Tacho : 365 Cycles running : 1176 TIM duty : 5918 TIM val samp : 2 TIM current samp : 4200 TIM top : 8400 Comm step : 0 Temperature : 38.06


Fault : FAULT_CODE_ABS_OVER_CURRENT Current : 329.6 Current filtered : 128.3 Voltage : 28.04 Duty : 0.932 RPM : 13752.8 Tacho : 368 Cycles running : 1186 TIM duty : 7830 TIM val samp : 2 TIM current samp : 4200 TIM top : 8400 Comm step : 0 Temperature : 33.40


This is full throttle on the bench from dead stop with the wheels/belt attached

LIES! @trampa

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