How to calculate the speed of a stepper motor ?

[Navya]

Stepper motor doubt

in the data sheet of the stepper motor it is specified that
step angle is 15
5 rpm @ 200pps
unipolar
torque is 60 N/cm

Can anyone tell me how to calculate the speed of the motor ?

 

[manish12]

Re: Stepper motor doubt

5 rpm @ 200pps

 

[FvM]

Re: Stepper motor doubt

The motor seems to have a 100:1 gear, provided a pulse in "200 pps" means a full step. You get 200*(15/360) rps = 200*(15/360)*60 rpm = 500 rpm at the motor shaft or 5 rpm with the gear.

 

[Navya]

Stepper motor doubt

Can you please explain to me how u got the gear ratio ? and i need to know the delay as i read speed=stepangle/delay [rad/sec]
How can we determine it is full step from 200pps?
And what is meant by gear ratio of a stepper motor?

 

[manish12]

Re: Stepper motor doubt

means a full step

unipolar

this is for same motor ?

 

[FvM]

Re: Stepper motor doubt

I don't know if your stepper motor has a gear, you should now better. Without a gear, the data don't make sense. However, if it has a gear, the reduction ration is normally printed on the case or at least in the data sheet.

I have written my calculation, the reduction ratio is 500:5 = 100 to my opinion.

Stepangle and speed of motors is usually not given in rad respectively rad/s.

 

[manish12]

Re: Stepper motor doubt

this may be help full for you !

STEP MODES

Stepper motor "step modes" include Full, Half and Microstep. The type of step mode output of any motor is dependent on the design of the driver.

FULL STEP

Standard (hybrid) stepping motors have 200 rotor teeth, or 200 full steps per revolution of the motor shaft. Dividing the 200 steps into the 360º's rotation equals a 1.8º full step angle. Normally, full step mode is achieved by energizing both windings while reversing the current alternately. Essentially one digital input from the driver is equivalent to one step.

HALF STEP

Half step simply means that the motor is rotating at 400 steps per revolution. In this mode, one winding is energized and then two windings are energized alternately, causing the rotor to rotate at half the distance, or 0.9º's. (The same effect can be achieved by operating in full step mode with a 400 step per revolution motor). Half stepping is a more practical solution however, in industrial applications. Although it provides slightly less torque, half step mode reduces the amount "jumpiness" inherent in running in a full step mode.

15 step angle how? if 200pps

it should be 1.8 = 360 /200 and , so for 1 revolution you need 200 feed and between that there is some delay , which define the actual rpm of motor .

and this delay adjusted according to your requirement .

for optimum the delay = 1ms

for 1 revolution complete dalay = 200ms

so , 1 r in 200ms therefor 5 r in a 1000ms = 5rps , 5*60 =300rpm

thank you !

 

[FvM]

Re: Stepper motor doubt

Hello manish12,

apart from all useful information you gave, if a motor is specified to have 15° step-angle, it's most likely not a hybrid motor, but there are other types as well. Be sure that I have used a lot of stepper motors with 15 or 7.5° step angle in various designs.

Regards,
Frank

 

[manish12]

Re: Stepper motor doubt

360/15 = 24 teeth stepper motor with 6/5 wire i think !

but , rotor jumping is greater here than 1.8 .

i always prefer 4 winding 6/5 wire stepper motor . simple to design driver ckt as compare to unipolar.

 

[Navya]

Re: Stepper motor doubt

Hi all,

Thanks for your valuable opinions.
I got only one sheet as datasheet for the stepper motor which i selected. From which i got only few info.
Please find the attachment
please explain whatever you understand from this

Thanks,
navya

 

[FvM]

Re: Stepper motor doubt

Hello,

the motor is exactly as expected, including the 100:1 (or 1:100 as the manufacturer prefers to write) gear reduction ratio, that I already calculated. Also voltage and coil resistance is given, unipolar circuit had been already statet (what manish12 designates a "4 winding 6/5 wire stepper motor").

The only information not explicitely given in the datasheet is the maximum operation frequency. But implicitely, it's clear that with suggested 200 pps (pulses per second = Hz) nominal torque values can be achieved. With this motor type and unipolar constant voltage drive, you could expect fast decrease of torque above 200 Hz (may be 350 or 400 Hz can be achieved with low torque). Also not explicitely stated, but expectable for a gear motor with effectively no inertia seen by the motor, is to have 200 Hz as start-stop-frequency, not needing speed ramps.

There has been apparently doubt how to calculate rotation speed for this motor. However, as the datasheet confirms, the formula is simply given by the 5 rpm@200 pps expression. Required step frequency is intended revolutions per minute multiply by 40 Hz, usual up to maximum of 5 rpm or 200 Hz, respectively a minimum step-to-step delay of 5 ms.

Regards,
Frank

 

[Navya]

Re: Stepper motor doubt

Why 40hz was multiplied? Is it standard?
How did u reach a delay of 5ms?

 

[FvM]

Re: Stepper motor doubt

simply 5 rpm@200 Hz = 1 rpm@40 Hz, also 1/200 Hz = 5 ms

 

[Navya]

Re: Stepper motor doubt

Hi Frank,
Thanks a lot for your help.
One last question.
Can this controller MM908E626(stepper motor driver with hbridge inbuilt) drive this unipolar motor ?
can the vsup of the microcontroller be directly given to the stepper motor supply?