On Thursday 01 May 2014 13:42:08 Curtis Dutton did opine: > Ok this makes sense. Thanks all for your explanations. I guess I just > wasn't sure what was reasonable behavior and what wasnt. > > So if the motor is rated for 36v, and the drive is rated for 80 volts > max. How much voltage can I get away with delivering to the drives > without damaging equipment? > > > Thanks, > Curtis
I, as an electronics type, would look at it from the motors rated currant viewpoint regardless of the family of motor. The motor more than likely has permanent magnet fields, and allowing more currant than about 1.25x the nameplate rating (based on my reading on the subject but I don't have an URL's to offer) gets you into a magnetic territory where the field magnets can be damaged by reducing their magnetic strength, and its an instant and permanent effect. The same effect applies to steppers, usually at currants above 1.25x nameplate. Applying an 80 volt supply to a 32 volt rated motor seems like it would be, if not currant limited in the driver, playing with fire. I would have to assume they said that assuming a condition where it could spin freely, letting its counter EMF control the current and therefore the resultant magnetic field. This isn't normally a concern with steppers because the 10 to 30x over voltage is just normal standard operating voltage for them. The drivers chopper limits on the currant are many times more important to the long term health of the motors. I see no reason not to apply much the same thinking to PM field servo motors. Any difference is in where the magnets are, the steppers magnet is the rotor, where a brushed servo has the magnet in its stator. But its still the strongest magnet we know how to build in production quantities. Now, in servo's I'll have to plead the big dummy because in brushless, hall effect commutated motors (BLDC?), it seem like a 3rd phase of drive to what is basically a 3 phase wound stepper motor frame assembly, meaning the rotor is the PM, would this not also apply? Or do they have something even more complex for the "BLDC" format? I am not using them, so I've not spent a lot of time researching how they are built. My understanding is quite incomplete for those, and is not clarified a bit by having so many available mappings in the BLDC driver. I suspect the reason for that boils down to a profound lack of a standard way of marking the motors leads as to phase & polarity, making the builder try every combination until he hits the right one that just happens to be correct for the wire hookup sequence he used? Is there a URL to read that would help me understand that Jon? > On Thu, May 1, 2014 at 10:44 AM, Jon Elson <el...@pico-systems.com> wrote: > > On 05/01/2014 06:22 AM, andy pugh wrote: > > > On 30 April 2014 19:37, Curtis Dutton <curtd...@gmail.com> wrote: > > >> The motor is a 130W motor > > >> 1.5mm at around 12000mm/min. > > > > > > That seems like a very small motor, and a very fast travel. > > > > > > Is it possible that the motor is simply running out of steam? > > > > Generally when the drive runs out of available voltage > > the following error very suddenly grows without bound. > > So, you can be at 500mm/min with error of .01mm, > > and then at 550mm/min the error rises continuously > > because full voltage applied to the motor is only > > giving you 520mm/min, to give an example. > > > > So, having the following error increase only a modest bit > > at higher speeds may indicate the drive just has a > > constant time lag in the internal loop. Or, it may > > be a torque limit, where the 130 W motor is nearly > > maxed out on current driving the axis at 12 m/min. > > Those conditions might cause a bounded error > > that increases roughly proportionally to velocity. > > > > Jon > > > > > > ---------------------------------------------------------------------- > > -------- "Accelerate Dev Cycles with Automated Cross-Browser Testing - > > For FREE Instantly run your Selenium tests across 300+ browser/OS > > combos. Get unparalleled scalability from the best Selenium testing > > platform available. Simple to use. Nothing to install. Get started > > now for free." http://p.sf.net/sfu/SauceLabs > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------ > ------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For > FREE Instantly run your Selenium tests across 300+ browser/OS combos. > Get unparalleled scalability from the best Selenium testing platform > available. Simple to use. Nothing to install. Get started now for > free." > http://p.sf.net/sfu/SauceLabs > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS ------------------------------------------------------------------------------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE Instantly run your Selenium tests across 300+ browser/OS combos. Get unparalleled scalability from the best Selenium testing platform available. Simple to use. Nothing to install. Get started now for free." http://p.sf.net/sfu/SauceLabs _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
