Motor torque depends on current. Then increasing acceleration torque will also increase but how much depends on the inertia, there rotational inertia and the mass moved. It is also possible there are some viscous load which depend on speed of motion or rotational load. I assume current will increase but how much I have no idea.
Electric motor generate a back EMF which depend on rotational speed so there is less voltage left to increase current/torque at high speed and more available voltage left to decrease speed. Here http://en.wikipedia.org/wiki/Brushed_DC_electric_motor#Torque_and_speed_of_a_DC_motor the voltage balance and torque equations a little bit more than half way down in the document is incredibly good knowledge if working with servo motors. It is also useful to think about this equations then working with other types of electric motors. The equations are actually so important i think it would be a good idea to include them in the Linuxcnc manual maybe in the integrator chapter and I could provide some help if I have enough time. Regargs Nicklas Karlsson On Sun, 19 Apr 2015 05:55:31 -0400 Gene Heskett <[email protected]> wrote: > On Sunday 19 April 2015 02:58:14 Karlsson & Wang wrote: > > Increase in speed should almost certainly be 48/28 faster. I think > > this is true for acceleration to. Then you just have to hope for the > > electric motor to tolerate the higher voltage and for the mechanics to > > tolerate higher speed/acceleration. > > Humm, I would have to assume that since the motor currents would not be > similarly increased, that the accels, wouldn't be enhanced by anywhere > near that same ratio. > > The motors ultimate torque shouldn't change, just the speed at which the > torque falls off due to inductance? > > At present I do not believe the applied accels are modulated in the TP to > be slower at the higher motor speeds where torque is falling off, so we > need to use an accel it can handle in spite of the falloff. This costs > us time at the lower speeds where there is generally plenty of torque. > > IMO, the accel should be applied with something that looks like a t=rc > time constant mapping, but that would not be optimum for the needed > decel since that would start a new t=rc curve, a fast slowing at an rpm > point where the torque is not available. > > Experimentally I have found I can move the existing setup at 22 ipm in > the range where table weights are well balanced if I use really slow > accels like 2 seconds or more to top speed. But for anything like > decent accel settings, I'll stall at 10 ipm or less so I generally use > sub 10 ipm moves now. One of the reasons for kicking the motor voltage > up closer to the limits of the drivers, 50 volts in the case of the > 2M542 driver. > > > Nicklas Karlsson > > Thanks Nicklas. At least I have a starting point now for how much faster > I can go. I got the new psu mounted with cooling arranged yesterday, > but not hooked up yet. > > Cheers, Gene Heskett > -- > "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> > > ------------------------------------------------------------------------------ > BPM Camp - Free Virtual Workshop May 6th at 10am PDT/1PM EDT > Develop your own process in accordance with the BPMN 2 standard > Learn Process modeling best practices with Bonita BPM through live exercises > http://www.bonitasoft.com/be-part-of-it/events/bpm-camp-virtual- event?utm_ > source=Sourceforge_BPM_Camp_5_6_15&utm_medium=email&utm_campaign=VA_SF > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ BPM Camp - Free Virtual Workshop May 6th at 10am PDT/1PM EDT Develop your own process in accordance with the BPMN 2 standard Learn Process modeling best practices with Bonita BPM through live exercises http://www.bonitasoft.com/be-part-of-it/events/bpm-camp-virtual- event?utm_ source=Sourceforge_BPM_Camp_5_6_15&utm_medium=email&utm_campaign=VA_SF _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
