On Wed, Apr 18, 2012 at 12:18 AM, Denny Esterline wr= ote: > Ok, I've got dents in my wall and lumps on my forehead. It's time to tap > the collective wisdom of the list. > > I'm building a system to control a sensored NEMA23 size brushless motor > based on a dsPIC33F128MC804. > I've got the motor spinning and I'm working out my control loops (speed a= nd > position). > Earlier, when I was doing simple bench testing, the motor > was noticeably smoother in one direction > than the other. Now that I have the gearbox and a load connected to it, > it's _much_ worse. > Clockwise, it's smooth as silk and moves my load at about 1.5 Amps. > Counter-clockwise it's noticeably > noisier and draws upwards of 7 Amps. The load is very close to the same i= n > both directions. > > I'm completely at a loss for why it would behave differently depending on > direction of rotation. It sounds like your hall sensors are out of phase (rotated) with respect to the magnetic fields. Another way of saying this is that your hall sensors are lagging in one direction and leading in the other. The same symptoms occur if you try to run a brushed DC motor with advanced timing, in the opposite direction. --=20 Martin K. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .