Yes the ppmc.0.pwm.00-03.freq 50000 After playing some time I've come up with this it responds from 2 rpm to 14 rpm when you set s this give and accual spindle speed from about 35 to 75 rpm But there is no to little control if load is applied to the spindle As soon as any p,I,g are added then it unstable surging up and down
-----Original Message----- From: Jon Elson [mailto:[email protected]] Sent: Tuesday, July 10, 2012 11:59 PM To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] Spindle hooked to dc servo amp Gene Heskett wrote: > On Tuesday 10 July 2012 23:59:04 Kasey Matejcek did opine: > > >> It set to 1000 >> setp ppmc.0.pwm.03.scale 1000 >> >> when you watch ppmc.0.pwm.03.value it changes from 1000 to -1000 and >> back and forth it goes when I set s 50 rpm then after some time >> ppmc.0.pwm.03.value goes to like 50 after some time but it still >> surges up and down and so does the number if left long enough >> ppmc.0.pwm.03.value goes to 0 or some really small number when the >> rpm is set lower than 100rpm but really never get stable above 100 >> rpm it just keeps surging up and down >> > > One other question might be in order here, just to remove the > possibility of a hidden low frequency pole in the feedback loop, what > are you using for an interface between the pwmgen output, and the > spindle motors own controller? > He is using my PWM servo amplifiers, these are 4-quadrant PWM amps with no smoothing or control loops in them. Motor voltage = DC supply * PWM duty cycle. So, I don't think that is it. I have done this on my minimill, but without the closed-loop part. It is not a stiff speed control, but it is free from instability, of course. Hmmm, but there IS one other possibility. If you command 100% duty cycle of the PWM, the bootstrap capacitors that create the gate bias for the high-side transistors will run down. Then, the motor may surge about like Kasey describes. So, that's why in the univpwm_motion.hal file it has : setp ppmc.0.pwm.03.max-dc 0.95 which sets it to 95 % duty cycle. You could as a test change that to 0.9 and see if it makes any difference. But, usually 95% is plenty of headroom, even 99% should work. In the partial file given by Kasey I did not see a frequency setting, as in setp ppmc.0.pwm.00-03.freq 50000 for 50 KHz. If there is no such line in the file, I have no idea what PWM frequency has been set, and that could cause a big problem. But, if the X and Z axes work, that probably is not the problem. This frequency is common to all axes on a UPC board. Jon ---------------------------------------------------------------------------- -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
