step motor speed using a microcontroller

[georgz]

Hi i want to buy **broken link removed** motor.
I would like to know the maximum speed it can reach using a microcontroller. Can anyone tell?? Also i want to drive it using a L298N IC. Is it possible?

 

[alexan_e]

No one can answer your question because what you are asking is a specification of the motor, the mcu is not going to limit the speed of the motor , the limiting factor will be the max rotation speed of the motor and the provided motor datasheet doesn't include that info.

Alex

 

[georgz]

I also checked the datasheet and couldnt find the answer. There is no way to find out?

Anyway, alexan_e ευχαριστώ!

 

[FvM]

Meaningful step motor datasheets have a torque versus speed characteristic, valid for a specific drive method, e.g. full step, constant current of xx A, maximum motor voltage of yy V supplied by the bridge driver. The characteristic is for constant speed, acceleration and deceleration ramps have to be applied in addition.

Torque versus speed means, that maximum speed is mainly a matter of required torque. But there's nevertheless an absolute maximum speed (depending on the motor voltage) due to the EMF of the step motor. Bipolar step motors, that are usually operated with constant current PWM bridges and respective high supply voltages can achieve at least several thousand steps/s.

 

[georgz]

Several thousand steps might not be enough... I want to make something like a propeller clock and i think i need at least 50 rounds per second. Right?
Using a step motor i know the position of the motor without using any sensors.

 

[FvM]

Using a step motor for a propeller clock doesn't sound reasonable. You won't know the position without a sensor, you'll need at least an index sensor. Having an index sensor makes a simple DC motor, or possibly a BLDC or PMSM the better choice. Inertia will enforce an almost constant rotational speed, independent of the drive method.

 

[georgz]

Hey thank you i'll find a brushless motor! Could you suggest a sensor to detect the position?

 

[FvM]

Most people are using standard transmissive photointerrupters. They are availabe in a large variability of shapes. Or use separate IR LED and a phototransistor. It should be shielded against enviromental light.

 

[georgz]

The first think i thought was to use IR led transmitter and reciever but i thought it would be too slow for that kind of application. I'll give it a try and use the IR led and the phototransistor.

One last question: the way to shield the phototransistor is by using a heat-shrink tube or i could buy one already shielded???
The ir led transmitter and the phototransistor reciever are going to be as close as possible.

 

[FvM]

Phototransistors aren't slow. they have us response times. A standard photointerrupter with an U shaped case will have a sufficient shielding for most cases.

 

[georgz]

Today i bought a tsop31230 IR recieved. I hope it's fast enough. Thank you!

TSOP31230 Vishay Semiconductors Infrarot-Receiver