In article ,
says...
On Wed, 27 Aug 2003 23:13:24 -0400, Ned Simmons
wrote:

In article ,
says...

I wonder if a brushless DC motor would commutate without external
excitation. Something has to supply the electronics that makes it
brushless.


Every brushless motor I've worked with has had a PM
armature--no excitation required. Else why would it be
called brushless?

Separate issues. No field excitation is required because it's PM.

I thought that's what I said?


Though I've never tried it, I'd expect one would make a
very good 3-phase generator. They certainly do a good job
of pumping up the bus voltage on the servo amp when
delivering negative torque to an overhauling load.

I agree, but it may be necessary to substitute diodes for the internal
elex.

I assume you're talking about substituting diodes for the
output stage of the amp here. Obviously if you're using the
motor as a generator, there's no need to actively commutate
the motor windings, but you do need to rectify the motor's
output if you want DC.

Ned Simmons