| Author |
Message |
Raghu
Joined: 22 Jun 2002
Posts: 19
|
 09 Feb 2003 4:26 Stepper Motor acceleartion |
|
|
|
I am using a 2.75Nm rated ( Pull out torque ) bipolar stepper motor. This has a winding resistance of 2.3 Ohms per phase; Rated current of 2 Amps / Phase. and Inductance of 14mH/Phase.
I am using the L297 + L298 combination driver as a bipolar chopper for driving the motor in full step mode. The supply is at 12V / 10 A rating.
I am unable to achieve the quoted torque if I increase the clock frequency beyond 500Hz and the motor just stalls. ( the motor data sheet shows the torque drooping only after 1000 Steps/ sec) . The load is just frictional and not inertial.
I currently use a clock source that can be varied between 100 to 1500 Hz but not ramping it . I am told that if I apply the clock with a ramp from 0 Hz to 1000 Hz in a time of say 0.5 Sec, then the stepper will support 2.75 NM at 1000 Hz.
Kinldy advise if my information on ramping the frequency is correct.
( If so I can then use the 555 clock source as a VCO and ramp the frequency )
Thanks.
Raghunathan
|
|
| Back to top |
|
 |
solvarg
Joined: 15 Feb 2002
Posts: 129
Location: Sweden
|
| 09 Feb 2003 13:55 Re:Stepper Motor acceleartion |
|
|
|
I doŽnt know if it helps you but I have found this URL very usefull
http://home.earthlink.net/~rustle/stepper/Tutorials/CurTutor.htm
Regards
|
|
| Back to top |
|
|
Raghu
Joined: 22 Jun 2002
Posts: 19
|
| 09 Feb 2003 15:50 |
|
|
|
Dear Solvarg,
Thanks for the link. It IS useful.
Bye
Raghu
|
|
| Back to top |
|
|
mdamdam
Joined: 12 Apr 2002
Posts: 55
Location: the old Europa
|
| 09 Feb 2003 18:13 |
|
|
|
You motor seems to be made for constant I driver.
Also it is important to build a trapezoidal curve of speed and make some tests ( depend of the charge ) .
Otherwise you will have the same problem for stopping it.
M
|
|
| Back to top |
|
|
Raghu
Joined: 22 Jun 2002
Posts: 19
|
| 10 Feb 2003 2:46 |
|
|
|
Yes. I had already switched over to a trapezoidal profile for the clock frequency for starting-running -stopping. Performance is better and close to the data sheets.
Raghu
|
|
| Back to top |
|
|
bunalmis
Joined: 03 Jan 2003
Posts: 246
Helped: 4
Location: Turkey
|
| 10 Feb 2003 17:47 Re: Stepper Motor acceleartion |
|
|
|
| You must increase the L298 voltage. 12V too low.
|
|
| Back to top |
|
|
mgajo
Joined: 15 May 2001
Posts: 344
|
| 10 Feb 2003 18:36 |
|
|
|
You can't get 2.75Nm with L298
 bye
|
|
| Back to top |
|
|
cbsirio
Joined: 05 Jan 2003
Posts: 72
|
| 11 Feb 2003 0:32 |
|
|
|
Hi,
when you are using stepper motors, you have to pay attention to several points:
1) look at Voltage: a stepper motor function as a dynamo, and it is speed-related : more is the speed, more is the "dynamo" effect. In this way the torque decrease, so you have to get a more high voltage.
2) have a look to acceleration: you can't go without ramping to the maximum speed!
3) look at half-step/full-step : it also influence the torque.
HTH Sirio
|
|
| Back to top |
|
|
lollobrigido
Joined: 13 Dec 2002
Posts: 146
Helped: 1
|
| 17 Feb 2003 14:45 |
|
|
|
your acceleration ramp depends upon the mass to move.
However for non too small stepper motors, 0-1000 hz in .5 s is a too higer acceleration, try in 1 sec.
If you want much more torque and a finest step, use the microstep method.
Lollo
|
|
| Back to top |
|
|
hobbymat
Joined: 16 Feb 2003
Posts: 35
|
| 14 Mar 2003 0:25 |
|
|
|
Try to increase your supply voltage to 36 volts (about the practical maximum for L298). More voltage means more maximum speed to your stepper.
Another thing to consider is that a stepper alone can't usually rotate very fast, as it needs something as a load to damp the resonant vibrations. A little friction on the shaft or mechanism won't do any harm - on the contrary.
And of course, the acceleration must be related to the voltage used and the inertia of the system. And remember to use a very even pulse stream, as an uneven stream of pulses is seen as a quickly varying speed command by the stepper, which it may or may not be able to obey.
I think that you'd better use two L6203 drivers instead of one L298. The former is a FET based driver that runs cool and can deliver more current than the latter. Usually the reliable maximum current for L298 is about 1.5 amps, with more current it usually fries to death, regardless of the heatsink. Besides, it's slowly becoming an obsolete component.
BTW: I think your motor's rated torque is 2.7 Ncm, not 2.7 Nm...
Happy stepping,
Hobbie
|
|
| Back to top |
|
|
nebisman
Joined: 13 Apr 2002
Posts: 285
Helped: 1
|
| 15 Mar 2003 15:38 |
|
|
|
dear friends,..
I need information about stepper motor dynamic models and software for simulate it. Please an advice or link related
thanks in advance
|
|
| Back to top |
|
|
nostrada
Joined: 04 May 2001
Posts: 40
|
| 15 Mar 2003 16:41 |
|
|
|
| the voltage is too low
|
|
| Back to top |
|
|
