Try to understand the vesc

since my last esc bruned, i will probably see if Trampa can make me fly, so i am trying to read as much as i can about vesc and how to use it, i had sucess with my set up but i think i can make it for efficient for 2019

i think i understood the basic, but not all about current control and the value to choose, so if you have the anwsers it will be nice:

  • can we use current control on a efoil?
  • brust at 150A, is it battery current or motor?

i understood that with duty control, 50% will given 1/2 of the voltage and 1/2 the rpm but with current control, if the motor has max out its torque and therefore its rpm at 80% of the throttle, amp will still go up (to the set limit) if i keep 100% throttle?
in that case am i “wasting amp” on the least 20% of the trigger? ( can i use the erpm limit to reduce that knowing the desire rpm needed?)

i have all the logic of a petrol engine in my head from mapping car’s ecu, it is pretty hard for me to switch on the electrical mode (torque, power, rpm…)

thank you

Sure, current control at electric motors is like power/acceleration control. So you get a smooth ramping.

First, 150A battery is only possible if you also have 150A motor. 150A motor means a lot of torque, 150A battery means a lot of power.
So what the ESC does: takes the battery power and transforms it. Power = Volt * Amps and power keeps (roughly) the same. So the voltage will get lower or keeps the same (makes sense since it is a PWM dutycycle ~0-95-99%) so the amps will rise or be at least the same (on the motor side, ==> motor amps >= battery amps).

Thats the theory, in practices I would just connect a HM-10 BLE module and start with max 70A Motor and 70A Battery and watch the temperature and then go up (you can set the limits easily by an android phone) till you have the desired power/speed.

Well, what current control does: variing the dutycycle till you have the current limit. So 2 examples:

  • your motor turning slowly and you hit the throttle to 50% => controller ramps up the dutycycle to maybe 30% first till you reach 50% of the max amp => motor starts spinning faster and amps are dropping => controller steps up the duty cycle to 45% till you are again at 50% of max amp. this is all done with a PID controller and that fast that you dont notice/feel anything.
  • you dont have your prop mounted and hit the throttle to 10% => esc ramps up to 100% duty but still reaches only 3% of max amps…well the PID would advise to increase the dutycycle but you already got 100% and dont max up the throttle limit of 10% of max amps…so it just keeps there pulling only the 3%.

So to answer your question: example 2) No the ESC cant increase the amps if the motor already maxed out at RPM (cant work as a step up converter).

if you configure your limits from the low end side and then adjust the throttle curves you should be on the safe side not wasting anything of your trigger travel.
erpm limit is just a safety function (e.g. if you dont want your kids to ride to fast…or not wanting to go fullspeed reverse)

theoretically yes!
in reality I would first try BLDC, especially if you are tuning your limits. FOC is a bit more demanding for the ESCs and therefore personally I would first try to find the working settings with the more robust and forgiving BLDC and then later on switch to the more efficient and quieter FOC.

Hope that helps.

thank you, i was missing the PID duty control over the current control, OK

regarding the amp : my motor is given for 130A and i recorded (if correct) pic over 200A on hard start, that my worry

i worried also about heat:

  • is it possible to calculate the heat of the fets during 100A application?

i have water cooling plate , pump and peltier module (about 100W) to similate heat on a watercooling system

on the last review Mr Vedder said if we manage to keep the box below 50°c the fets will be below 80°c with a 80A application

Are you planning on running the Trampa VESC at 12S?

Yes vesc v6.4 , probably 12s or 10s
And 18650 so voltage drop fast to 3.8-3.6/ cell

do you think it works?

i read the mobile apps, the vesc 6.4 is using the 3.39-40(?) and it is only working with android 7 or higher, BT 4.0, the module sold by trampa and the vesc tool modile apps

no ios…

edit: after looking i find this:
FW 3.40? so it sould be running