On 8/6/2013 12:42 PM, Sven Wesley wrote: > 2013/8/6 Stephen Dubovsky<[email protected]> > > >> >> It does fix it. The feedback will cause the control loop to shift the >> commanded position away so that you ARE on the upslope of the torque >> curve. Its fundamentally how servos work. You need to develop >> Q(quadrature) current(flux) to get torque. The D(direct) current doesn't >> do any work. Technically, once you have feedback in a stepper system you >> can fully servo it and not require any 'holding current' if the application >> doesn't currently demand it. The fixed current most stepper drivers use is >> only because they don't know where they are in the DQ frame. So they >> provide a ton of D and shaft error shifts the angle to produce some Q. >> >> >> > If that's the case a closed loop stepper system is still interesting. > However, I've had a shorter mail discussion with Zapp about their products > and the given arguments and statements out rule them totally as a provider > for me. He started a debate about how bad it is to build a machine and a > retrofit is much better - without knowing a thing about my engineering > skills, profession or previous experience in machine construction (please > find a machine which is suitable for a five axis retrofit). > Right now I'm leaning towards servo's after all. > >
Sven, To really do it right and not guess, you really need to do some engineering on the motor size you need. Especially if you are making a new machine design and not replacing something that has already been running with a certain size motor. Here is some free motor sizing software that seems to be quite accurate. A number of Servo drive companies use this software and they brand label it.. http://visualsizer.com/ It is entirely free. I have used the Visual Sizer XP for years and it is really good but takes some effort to figure out how to run it even though it is very graphical. Mariss /Freimanis/ - the Gecko drive guy has stated a couple of times that the max power you can get out of a normal bipolar stepper motor/drive is about 200 watts. Keep in mind that all of the the Gecko drives run at 80 volts or less. Some other companies like Parker sell high voltage stepper drives that can deliver 200 volts or more to the motor so I think they may be able to get more than 200 watts of power out of a stepper motor due to the higher voltage which leads to higher torque at speed which equates to more power. Dave ------------------------------------------------------------------------------ Get 100% visibility into Java/.NET code with AppDynamics Lite! It's a free troubleshooting tool designed for production. Get down to code-level detail for bottlenecks, with <2% overhead. Download for free and get started troubleshooting in minutes. http://pubads.g.doubleclick.net/gampad/clk?id=48897031&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
