On Wed, 25 Jan 2017 23:22:29 -0500 Stephen Dubovsky <[email protected]> wrote:
> On Wed, Jan 25, 2017 at 10:25 PM, Jon Elson <[email protected]> wrote: > > > Field weakening is not possible on permanent magnet > > brushless motors. > > > > > It actually is. Apply current in the D axis will oppose and reduce the net > flux in the gap. Move a coil in between two N poles permanent magnets > facing each other and you will get no voltage as the field is zero at the > center. You risk demagnetizing the magnets at high temp. You also risk a > fault in the drive shutting off all the fets/igbts while running near top > speed, loosing the field weakening, back emf goes to full strength, and > rectified voltage back through the bridge becomes MUCH higher than the DC > bus can handle. Did not try that but have blown up many inverters for other reasons. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
