ferret wrote:PWM (Pulse Width Modulation) is the way the controller sends electricity from the battery to the motor. For example, when the controller is running %50 PWM, the battery is connected to the motor %50 of the time. This is roughly equivalent to giving the motor %50 of the voltage for %100 of the time, which will make the bike run at %50 max speed (assuming negligible aerodynamic resistance ).
Controller Continuous Phase Current Limit=110A
Controller Peak Phase Current limit=280A
BMS Battery Current Limit = 60A cont. / 120A peak
Controller Battery Current Limit = Configurable
Let's assume that the Controller Battery Current Limit is configured higher than the BMS limit so the BMS limit will be activated before the controller limit is activated.
If you are running at 25% PWM and the motor phases are drawing 100A, the actual battery current will be 100 X 25%=25 Amps. No limiting is in effect.
Then a you start climbing a slow steep hill. Running at 20% PWM, the motor now needs to draw 300A. The phase current will be limited to 280 amps by the controller and the battery current will be 280 X 20% =56 Amps.
After the hill you ride at high speed, say %80 PWM. The motor needs 180 Amps which means that the controller will need to draw 180 X %80 = 144 Amps from the battery. Since it is limited to draw only 120 battery Amps, the actual phase current will be 150 Amps (150 X %80 = 120).
Earlier I tried to give a generic example to explain the principles without resorting to complex formulas and now another example using the data from your hardware. I think you better ask more specific questions, like what you want to know about your hardware or about principles you want to understand better.
Thanks for the explanation. So the PWM is based on the kelly controller programming- more specifically the motor current and battery current limits? The controller just comes up with this %PWM based on hill/flat/downhill power requirements? I still dont know how that relates to battery current/phase current
Specifically I want to know the optimal kelly controller programming settings for my battery, controller, motor combination
I've had a read of the kelly programming reference
https://endless-sphere.com/forums/viewt ... 16&t=18916
So from what I can gather according to KEB type demo and my controller battery numbers, I just need to set max limits and downhill/flat will follow suit?
•Peak Phase Current: 280A
•Continuous Phase: 110A
battery 60a/120a discharge
leave the max motor current to 100% and just change the max battery current to 70%?
70% of 280A = 196a phase?
motor accepts max of 90a (or there abouts 7000w peak at 72v)
leaving 100% motor current 280a phase from controller?
This feels like the wrong forum for me (too advanced) I'd really like to learn here, I threw myself in the deep and and paying the price now haha
Is there any reference material / electronics course I should have read/done before posting & tackling this project? I suppose I will just email Kelly/QS motors for end user/consumer advice?