Wednesday, October 12, 2011

Short note: Electric motors for hybrid or electric aircraft

The Joby Motors seems to have good enough KV-values for running slow turning props (especially JM2S and JM2):

Electric Lazair uses these motors. Standard windings are available for up to 700 volt system!


008klm said...

700 volts?

008klm said...

700 volts? batteries?

Unknown said...

Yes, 700 volts.
Super easy: 189 * 3.7V LiPo or LiFePo cells in series.

This is how they are arranged in Toyota Prius or any other hybrid or electric car or electric airplane like Yuneek or Pipistrel. For example Toyota Prius has around 300 volt system.

Example electric plane - Electric Lazair has 16S system, which means 16*3.7 volts = 59.2 volt system voltage.

The Joby motors which are used on the Electric Lazair, are available with different windings and amount of poles and up to 700 volt system voltage windigs are offered according to their web site. Any motor manufacturer that does motors for this kind of applications plans for very high voltage because that way the losses are least bad and the wire size can be minimized and the heat issue associated with high amps gets mitigated as the amps are traded to volts.

For comparison, typically bigger RC planes are run with 6S-12S systems. Especially EDF jets need lots of volts to rotate the fan adequately fast enough.

LiPo and LiFePo systems have absolutely nothing to do with 12V car and airplane lead-acid batteries, except of course the same laws of physics apply.