On Wed, Jan 25, 2017 at 11:22 PM, 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.
We tried to do this for some fault detection research. We set the winding currents so that the motor didn't move, but just heated itself. No failures. There is enough change in the magnets with heat that we could detect the changes, but they went right back to normal when the temperature went back down. We were hoping to get some degradation in the magnets over time, but it never happened. It was disappointing and reassuring at the same time. I suppose we should have gone higher with the current, because we never had any winding failures either. The drive was made for a lot more current than the motors could take. ------------------------------------------------------------------------------ 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
