larsb said:
Why would you do it? As far as i know you'll get lower torque and efficiency and get speed, which you don't need at low speed.. ?
Yes if we talk about motors which have surface mounted magnets than this is the case. you trade efficiency to get higher RPM and you should only use it if you ran out of RPM (and then not until 70-80% of top speed).
But those QS midmotors have an IPM rotor (magnets are covered in steel laminations), so it will be able to produce the so called reluctance torque additionally to the magnet torque if you apply flux weaken current.
This means on IPM motors you could gain speed and torque with field weakening current, not just speed.
here is a thread about that:
https://endless-sphere.com/forums/viewtopic.php?f=6&t=95100
and here is a test about hyundai HSG IPM motor:
http://build-its-inprogress.blogspot.com/2017/11/stall-torque-test-stand.html
Regarding the graph from the stall torque tests, it works like this:
On the left we see 100% nomal phase current (orange curve) which was adjusted to 100% D-axis current on right (blue curve). The sum (vector) of the phase current stayed the same.
I believe on surface manget motors the torque would just get lower and lower from left to right down to 0Nm on the far right (where D-axis current will only make heat).
at around 170A Q-axis current + 0A D-axis current you get out about 36Nm at 0RPM -> 170A total phase current
at around 115A Q-axis current + 125A D-axis current (in the middle) you get out about 56Nm at 0RPM -> sqrt(115² +125²) = 170A total phase current
edited: i confused Q and D
conclusion:
you would get about 50% more torque out of this hyundai HSG IMP motor if you drive it with 50/50% D+Q current.
at least thats how it should be as far as i understood the whole thing... please correct me if i am wrong!
This is APT AE96600 flux weakening screen.
evdrive9.png
Seems you can do pretty much what you want
You should find out what those settings stand for and then try it out.
@ bionicon
you mentioned that you have set 150A field weakening on sabvoton. Did you notice more torque at take off, or just more speed?