You seem to be really good at math. Are you decent at scripting? Would you be willing to build a javascript calculator to help us get the right settings into the VESC based on these attributes you describe?
Also i street test everything i build, so the only danger is to myself as far as this particular things goes.
I can totally script the heck out of this, I am just gonna need somebody to send up a feature list, or I am going to have to read this thread from top to bottom to see what is going on. We can get this programmed up in Angular and it would be secks.
BTW, this thread, is pretty epic. Thanks for continuing to hash it out boys!
I have to admit that i stopped reading this really interesting topic after about 50 posts because it got way to nerdy for me
So is there a working way to get rid of the unpredictable acceleration bursts in the the area close to max rpm without damaging the components in low rpm / full throttle situations?
My Setup:
VESC
2,2 kW 6355 190 KV (description says 80A max)
5000 mAh 10S 20C (100A continuous / 150A 10-second burst)
Hardware car fuse 40A continuous / 60A 10-second burst
This is where it gets not nerdy and I say as a rider thereâs no danger of unpredictable acceleration bursts. When u drive It often is a not perfectly smooth acceleration curve especially if ur driving a stick! U get used to it and id rather call it an acceleration profile.
Getting more torque at low speeds is what this is about I believe. The possibility to increase the battery amp limit
With hub motors Iâve it set to 70 and would like more. I notice the difference coming from the default 60. If u can set ur battery max to whatever the max u want to pull from the battery thatâs fine and makes sense but itâs possible to set the motor max to 200, just because thatâs all the bldc program allows. then Iâll bet 200 rocks. Whoâs going to do it. ?
Actually i am developing a new mode to control the power. And for that i needed to calculate how the actual power is calculated. So to answer your question how it would feel like with motor current set to 200 you can see it in the second picture. First picture is for 70 A motor current.
Both pictures show how how much watt would be produced at 70 % throttle.
So you see that you would reach max power at 0,85 Duty Cycle with 70 A Motor current and with 200 A you would reach it already at 0,3 duty cycle. So the board would feel more powerful but you have less control with the throttle.
So to summarize it.
With Max batterie Current you define the max power.
And with Max Motor Current you define how much power will be created by the throttle. This counts the most at low speeds an also defines how much control you have at higher speeds.
I made a interesting video to show the issues i see with current control.
My settings are:
Motor Max 80 A
Batt max 35 A
So it is 1400 Watts max in theory (35 A * 40 Volts = 1400 Watt).
For the video i added a stoper to my throttle so that the throttle will always give 50%.
As you can see it nearly reaches max power even at 50% throttle position.
I created another power control mode which lets you control the Watts by the throttle and not the current that goes to the motor. That means i can control the power in % at any speed.
See this video and have a look at the Watts. It is the same rack and the same throttle setting (50 %from start on) as in the previous video.
At duty cycles below 0.50 i use curent. otherwise the power would come in too hard. So donât be confused that it doesnât give 700 Watts from start on.
So you see in the graph the way i power the Motor with this new mode. You see the calculations of curent control and watt control and in the last colum on the right the watts it will use.
I know it is a bit hard to understand but it feels great. Gives you much more control at higher speeds.
The motor max limit and battery max limit should be IMO thought in this way:
Motor max is used to protect motor from excessive I^2*R losses.
Battery max limits the max input electric power, but should not necessarily be set as the max amount the batteries can supply, as this can be a pretty darn high amount of power at higher RPMs, as @Ackmaniac shows in his test table.
So even though we operate at constant current, because the AC voltage rises, and the current stays the same the overall power also increases and therefore provides uneven acceleration.
My controller doesnât exhibit this problem as it is speed (duty cycle) controlled compared to the VESCâs torque control. All my controller does is ramping up of the duty cycle to the accelerators linear trigger movement. AKA RC car remote, neutral position 0% duty, halfway pulled 50% duty and all the way pulled 100% duty.