John Kasunich wrote: > Is this for a permanent magnet AC servomotor, or just an induction > motor? It seems like for a servomotor you'd need a current loop, which > implies current feedback, which implies A/D converters. Or is it > possible to get decent performance from such a motor with an open-loop > drive? > > Apparently you can get away with this. My brushless drive only has commutation signals from the motor, and no current loop. (It does have current limiting.) It seems to work surprisingly well with a lot of motors. So, it is driving only 2 of the 3 motor terminals at any one time, with a PWM applied voltage proportional to the value EMC is feeding to the PWM comtroller. The only problem I seem to have is some motors wound specifically for sinusoidal drive waveforms hum at certain speeds. I am assuming this is the mismatch between my six-step drive and the motor's expected wave, effectively causing a velocity ripple.
Jon ------------------------------------------------------------------------------ Check out the new SourceForge.net Marketplace. It is the best place to buy or sell services for just about anything Open Source. http://p.sf.net/sfu/Xq1LFB _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
