tecnologic wrote: ↑
Dec 30 2018 12:22pm
The flux path i was discussing there was the one from the V grove rotor not the qs3000w u posted up front. For the qs3000w u are right there is not much reluctance torque possible, it will only come by the magnets saturating the stator iron (5-10% max).
The pictured rotor with the V-groove magnets is QS3000W midmotor!
So unfortunately it really doesn't have much potential for additional reluctance torque due to the high magnet coverage, or with other words those very thin steel sections between the magnet poles don't allow it.
tecnologic wrote: ↑
Dec 30 2018 5:36pm
For IPMs and SPMs its the same id <0 lowers the Kv so reduces magnetic torque. But reluctance torque is added for IPMs.
if magnetic torque will be reduced it will lower kT
will be increased. typo?
toolman2 wrote: ↑
Dec 30 2018 10:25am
On the second point, when field weakening is applied you don't get those damaging or regen causing voltages out of the motor ( it reduces the back emf of the motor to be able to add further rpms
) -but that's all going well, let us ponder what might happen at 250% base speed and you get a fault condition..
-so for ultimate reliability, your right.
Oh you will get those damaging regen because of the too high voltage from the motor!
It is right that as long as throttle or field weakening current is applied to the motor, the kV and effective BEMF voltage will be lower, but imagine what happens if you now release the throttle at this moment.
Due to the body diodes in the FET's, any voltage on motor side which is higher than battery voltage will lead to a current flow into the battery, and if you look at the circuit diagram of a Mosfet power stage, you will see the diodes do the same as a 3-phase rectifier.
I have seen regen current on Adaptto if (1/kV)x RPM starts getting higher as battery voltage, and also on Nucular controller which does even things like -1000W of regen each time a release the throttle (RPM was about 20-30% higher as base speed, or as kV x battery voltage would allow).
So you won't be able to get 200% more base speed as long as the controller has Mosfet with body diodes. Thats whishful thinking, but not possible or better call it not that practical to have regenerative braking each time you release the throttle.
On bigger controllers which have IGBT's instead of FET's, things are probably different because IGBT's don't have body diodes, but also FET's can come without...