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how can i design stepping motor acceleration profile?

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alphi

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mtd2003 stepper printer

I use bipolar PM stepping motor for small printer,and I need to accelerate motor from stand to 1000PPS speed,But how can I to design first step time and acceleration profile? (stepping motor datasheet have PULL-IN and PULL-OUT Torque data.)
anyone can help me?
 

Tohu

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I can't understand what exactly you want to now.How you can run the motor, how you can drive the motor or something else. If you talk only for a profil, the ramp, this is depend from the motor and your application., of course and from driving schem. If you using a current mode control, then you have more wide range for the ramp, if you have not a current mode, then ramp can't be very speepness, but this is depent and from needing torque.
 

alphi

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I use MCU+MTD2003 to drive bipolar steeping motor,2-2 PHASE. My printer motor's working process is stand~acceleration(12 step)~continue speed~deceleration(12 step)~stop.
now, I need to know how to calculate first step time of acceleration and ramp.
 

alphi

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same motor and same torque with speed,good acceleration can work and bad acceleration profile cannot work.anyone can tell me how to calculation it?
 

Tohu

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sorry, i don't can help to you, first i don't understand what is exactly the problem, if your driver is a good then you can use all available speed and acceleration up to maximum given from the producer. Sometimes all system have a critical speed, and to this speed you can have the resonance and noise.
When you talk about ramp i think about acceleration, step per/second/second, for example:
if you need to accelerate the motor from 50 to 500 rpm for 2 seconds, and the mottor is 1.8°
step per revolution is : step = 360/1.8 = 200
50 rpm is a 50*200/60 ≈ 167 step per second
500 rpm is a 500*200/60 ≈ 1666 step per second
acceleration = (1666-166)/2 ≈ 750 step/second/second

the maximum acceleration if not given from producer can calculate, but this is not very easy, because you must have electromagnetic parametre of the motor. if you not have these parameters, is more easy to determine it experimentally.
 

Eumel

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It's not so easy to calculate start frequency and acceleration. It depends on mass to be accelerated, motor power and friction of the mechanical drive. Also resonance can be a problem.

I would suggest the try and error method.

First try out the maximal start frequency (the frequency at which the motor starts and runs uniformly without losing steps). To ensure safe start use a start frequency a little lower then the one found out.

Then find out the fastes (linear) acceleration for the system. Start with higher values because of possible resonance effects at lower acceleration rates. Step to lower rates until your stepper accelerates without losing steps.

Greetings from Germany

Eumel
 

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