Clarify the Stepper motor doubt

[samson.bunty1986]

Hi all,

Am driving bipolar stepper motor using DRV8821 driver..Without chopping, the motor current waveforms are good without any noise...But, if i chopped the current to 1A or 1.2A my current waveforms has much high frequency noise..

can anyone clarify about this???

 

[shortbus=]

Its not "noise" it is the chopped voltage output from the chopper/PWM. Should be around 20kHz, or the upper audio range.

 

[samson.bunty1986]

Will this effect the efficiency of the motor???

 

[shortbus=]

No, at ~20kHz the motor won't even know its happening. That is the beauty of "chopping", the voltage is not affected only the amperage.