On Wed, Jul 9, 2014 at 12:23 PM, Claude Froidevaux <men...@bluewin.ch> wrote:
> > to get en estimate of needed voltage: > > get the speed you need in rad/s (1t/s --> 6.28 rad/s) > multiply by the torque in Nm > > this will give you the output power of motor at max speed. > > then, as you know the current inside the motor, you can deduce minimal > needed voltage to get the same power (plus additional waste) > > for example: > > stepper: > 4Nm, 4.2A > > need 1000rpm (5 m/min with 5mm leadscrew) > > power @ max speed and max torque: 1000/60*2*pi * 4 = 104 W > > P = U *I --> 104 / 4.2 = 25 --> we need at least 25V, but this is > without taking any loss in accout (resistance, drive, sinus factor, > ...). Doubling this value will get you something that shall do the > tricks! (so 50V needed at least) > > this is a really rough calculation, but it help a lot to know what is > needed. > Sorry if I am making a simple mistake (I plead lack of sleep today) but isn't 4 * 2 pi 1000/60 equal to 419? More importantly, as you indicate that formula is flawed, because usually the max torque requirement is usually at low speeds, when you accelerate the axis. Of course the stepper motors lose torque at max speed, so the above formula is just a ballpark estimate; true V estimate should take into account the motor's Back-EMF (kV) characteristics, I believe. ------------------------------------------------------------------------------ Open source business process management suite built on Java and Eclipse Turn processes into business applications with Bonita BPM Community Edition Quickly connect people, data, and systems into organized workflows Winner of BOSSIE, CODIE, OW2 and Gartner awards http://p.sf.net/sfu/Bonitasoft _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
