My understanding is that you would just set the speed with the vfd and assume that will be close enough. Then you would use the encoder to measure the actual speed and phase lock to it for the purpose of driving the Z axis when ridgid tapping.
If you wanted to control the speed more precisely, you could measure it, use the difference between it and the actual as an error to be zeroed with a PID or other control. You would increase the target frequency fed to the vfd to do the correction. Ken [EMAIL PROTECTED] Mark Kenny Products Company, LLC 55 Main Street Voice: (203)426-7166 Newtown, CT 06470 Fax: (203)426-9138 http://www.MarkKenny.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Anders Wallin Sent: Monday, December 11, 2006 3:41 PM To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] DIY closed-loop VFD ? hmm, answering my own post here... > A DIY way of closing the loop would be the following: > -Control the VFD using its 0-10V analog input (use the 4th DAC on the > m5i20 card) + direction input. > -Fit an encoder to either the motor shaft or the spindle > -close loop in EMC using PID there might be a flaw in this logic since the analog VFD input controls the output freqeuency, not the voltage/current. When the motor is loaded I would assume that we need more voltage/current through it, not just an increased frequency. On the other hand the V/f drive will increase voltage along with frequency... still not sure if this will work or not ?? AW ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
