Variable field motor-- moving stator? [VIDEO]

[xenodius]

http://www.youtube.com/watch?v=6_41btVawMc

Can anyone explain what exactly is going on here? Why would this be a good thing? Wouldn't moving the stator like that reduce overall flux? It seems to increase RPM's though... similar effect to flux weakening?

Thoughts?

 

[major]

It is field (or flux) weakening. Just axial displacement to accomplish it. Less flux thru the armature coils so less generated voltage per rev, so higher RPM per volt, but less torque per amp.

 

[xenodius]

The finer points of motor theory are a weak point for me- Thankyou for confirmation. Kind of cool

 

[spinningmagnets]

It would be hard to retro-fit onto an existing E-bike hub-motor. However, it is interesting...a motor could be wound for a lower kV and have lots of torque from a stop. Then when it gets to going faster and it's drawing fewer amps during stable cruise speeds, you pull the stator out some to increase the kV and top-speed while still using the same battery voltage.