I have a VESC 6 MK IV with 5.02 firmware and recently upgraded the battery from 10s to 13s (above spec, I know). Near the top speed that I expected for this battery (30 km/h), the VESC keeps cutting out (see plot). The dark green trace often rises to 31 km/h and then the current drops to 0 without throttle change or a fault. Is there is a setting I forgot to change? ERPM at 35k is far below the 81k limit.
Hi!
I have a similar Issue. I also updated my Trampa Mountainboard to a new Batterie. After this i run trough the Motor Wizard and configured it new. Everything looked fine.
On the frist round my board not drive faster tham 10mph.
I tryed to change some settings but without any result.
i made several testround, what i have figured out was, the board keeps at 10mph doesn't matter if im going uphill or downhill.
It could go much faster downhill but it keeps at 10 mph.
Maybe this Issue is connected to your Issue.
I think it is actually a speed-dependent oscillation for me, which I had asked about last year and seemed to get better with less observer gain. Now the problem came up again because speed is higher. I'll try adjusting Ki/Kp/observer gains and see if it helps.
Writes: Firefly blog
Weird, I just logged into the forum to post a similar question for a very similar problem.
In my case I'm running an ebike motor, 36volts, 10s battery. I can only get to about 23-25mph on the bike then suddently the VESC cuts the power. If I shut off the throttle and wait 1-2 seconds (slowing down) then throttle up again it will run until it hits the speed limit again.
I've tried increasing the max erpm way above what it needs to be, I've checked all my current limits etc. Its all fine.
I just can't figure out why its suddenly cutting out. It doesn't even gradually decay, it just shuts off. The RED LED flashes on the VESC at the same time.
Hi!!
Maybe overcurrent fault on the BMS?
Easy fix, set battery max current lower on VESC in 5A increments until cutoff doesnt happen
I had BMS switched off (do you mean the internal battery BMS?), I have switched off DRV8301 OC mode and set slow ABS Current limit to False to test out:
Hi!!
Reducing the integral gain Ki to 12 from 24 helps with my oscillations. Ki=6 is worse again. See graphs. These are from test rides on a smooth and level surface w/o wind. Subjectively, even at the best settings I've found, there is still a yo-yo feel when the battery is nearly full. As the battery discharges, it gradually goes away. The 28.87 km/h test had about 1/3 the oscillation power as the 29.74 km/h test, both at Ki=12.
The hard limits of bart and tobias are probably something else. Logging the data (Developer tab on phone app), and then plotting it using the desktop app helps figure out what's going on.
Writes: Firefly blog
Performance has been smoother with an RPM limit enabled that is slightly below what the VESC can do at 95% duty cycle. Maybe there is a feedback process at battery-limited speed that causes oscillation: With max. duty cyle, if current randomly rises, battery voltage drops due to impedance. Then the motor slows down (because of Kv), causing current to drop and voltage to rise. With higher voltage, current rises again, completing the cycle.
To avoid this feedback and operate in the smoother RPM-limit mode, it might be worth adding code that automatically maintains an RPM limit (conf->l_max_erpm) slightly below what the instantaneous battery voltage supports.
Writes: Firefly blog