This thread is not about the behavior at 0 rpm. We know that we need to increase the motor max amps drastically to reach high watts at 0.so please stay to the topic about the acceleration boost.
So it seems that the problem doesn’t exist in Foc mode. That brings me back to my theory that this behavior is caused by wrong calculations. Maybe somebody can test with the same bat and motor settings on bldc and foc and tell us the difference.
@devin, please note that this diagram is a generic diagram and not a real world motor diagram. Also, it doesn’t state any load, which in the real world is constantly changing.
In the real world when the motor powers a skateboard we have wind resistance which increases with the square of the speed. So we need 1) power to accelerate (pretty constant in this case) plus 2) power to overcome increasing wind resistance.
Okay. Let’s consider the control scheme for a moment.
Which one is best for natural acceleration? Speed Torque Power
Before we agree on which one the controller should use, we can’t really discuss the way to go about achieving that.
I don’t have to prove anything and I am using VESCs since their existence in May 2015. Believe me, I did logging extensively. I am out of this now. @devin, and please get a VESC yourself and do those tests. You comments are increasingly annoying.
That is right. But you can clearly feel the boost in bldc and if you can’t feel it in Foc then that would be enough for me.
I had these boosts in BLDC mode (control: current no rev w brakes) only, if the max motor current and the max battery current were too far away from each other, especially when motor max was set too high.
Agreed. But in this case with the data shown in the video we are talking about a changing load and a changing duty cycle. So the graph is not fully applicable.
But let’s not high jack this thread.
Can you give examples of motor max and battery max when you had the boost?
Because in the video above, neither motor max nor battery max seem to be limiting. The actual currents are far below any limits. Does the VESC have any hard coded default limits that are superseding the settings?
It was something around 60A motor, 20A battery side. But I think there are more variables to be taken into account since there are many factors influencing. Remote/receiver/control mode/app config etc.
Are Median Filters enabled? Is that behavior different having them on/off?
yes @devin
However I also have this acceleration boost when coasting (maybe 10% throttle) at 25kmh and then applying throttle very lightly (maybe 20% or 30%). In this case I’m far away from any amp limits and your theory does not apply for this case.
So devin please: do not high jack this threat with your theory. It might be true or not. But @Ackmaniac is after something else here and doing a great job!
I will refrain from posting any further here. @Devin, please do the same so others can speak up as well!
This whole topic was already discussed with Benjamin Vedder a year ago on ES. This was his statement before he adjusted some specs on SW, FW and also on HW 4.10-12. Nevertheless, under some circumstances it might be still there.
The power burst that you are feeling is caused by the current measurement problem that I have tried to solve recently. What happens is that at a certain duty cycle (around 80%) one of the shunts will get noise coupled which causes an offset so that too hich current is measured for one commutation cycle and the current backoff kicks in. After this noise disappears the backoff will go back and you feel the kick that you described. With the recent firmwares I have been working on the sample synchronization and some other things to make it better in software, but a hardware solution would be better (by the way, this would not be a problem using three shunts, but using two is more tricky).