Now with 75V under load it still makes up to 112kph.
With the SVMC72150 without field weakening the same motor made 103kph with 82V under load.
But with the 7-none setting, the battery current drops now after 90kph. Before I had 250A battery current until 100kph.
Now I have around 160A @110kph, same as with the sabvoton with 50A fw setting.
The Far-Driver documentation around field weakening won’t even mention WeakResponse and makes it seem like Field Weakening is entirely controlled by the current limit is Ratios in Speed.
KoMoto controller which clearly uses Fardriver software makes this very contradictory statement:
“WeakRSP - Magnetic field weakening
Reducing this number will effectively reduce the maximum motor RPM. The lower the number the higher level of magnet weakening is used. Set to zero by default values available 0-6 plus disable. We would suggest using 0 as a preferred setting. “
“Reducing the number” which I interpret as 6, 5,4,3,2,1,0 effectively reduces motor RPM, which should mean less FW is used.
“The lower the number” which again I interpret as going from 6,5,4,3,2,1,0 the higher level of magnetic weakening is used”
Im not very familiar with Fardriver but I didn’t see anywhere you can tell it which magnet type you use. In Votol its there “surface mount or v-type”. In fardriver is AN0 surface mount AN16 embedded, with 15 levels in between to cover various types.
Perhaps the Sabvoton with 0 FW stops a little earlier for some reason.
Or perhaps the Fardriver actually adds a tiny bit if FW at the end right when the “weak” appears in the app.
But doing no load tests its very clear WeakResponse7 is essentially FW:none, because it will not run away even with no rpm or current limits. But as soon as you choose anything from 0-6 unloaded it will go fast and seemingly no limit.
On the road i tested WeakResponse 7 (my normal mode) and i can reach that with about 40a DC and 45a phase, and when i set weakresponse 6, with current limit 100a DC and 200a phase, my DC amp seemed to level off at 80a and phase at about 90a and the rpm was about 10% faster.
The fact it didn’t go to 100a DC or 200a phase, or hit any current limit in the ratios in speed table, tells me WeakResponse 6 would be the lowest setting. Unfortunately my bike is not stable at higher speeds to try 5.4.3.2.1.0.
What seems off is that it takes 100% more current to go 10% faster. But my Kv is very high being able to go about 74kph with weakresponse 7. Going about 81 kph with WeakResponse 6. I was expecting more like 40% more power needed, 20% for the added drag, 10% for lower torque. 10% field weakening.
Theres so many settings that in theory would affect the way the controller knows how to add FW current. And there is WeakCharacter, fast middle slow, which I can only assume are some PID settings for FW algorithm, how fast it adds FW current. (Not to be confused with the master PID settings for the current loop.)
It would be easier for me to test if my motor was much lower Kv, so that i needed FW just ro go 50kph. But that might make all weak response levels take it to the moon and require the ratios in speed table to reel it back in.
But maybe weakresponse isn’t really FW level but different algorithms on how to add FW current. Or how soon to start adding it.
For performance it would need to use max DC amps and just as back emf starting pushing that down, it would add just enough FW to allow amps back to peak.