DRV8711: Voltage across stepper motor coil

Ali Rasouli

Part Number: DRV8711

I measure 2.6VDC across the coil of my stepper motor when VM = 24 VDC. Why is the voltage across coil so low eventhough VM is 24 vdc.

over 1 year ago

0 Ryan Kehr over 1 year ago

TI__Guru 55565 points

Hello,

In a stepper motor driver, current is always being regulated using PWM control. As you issue pulses on the STEP input, current will increase or decrease depending on where you are at in the indexer table. Because of the PWM control, you will see lower voltage than VM across the windings.

There are some great videos on stepper motors you can watch below:

https://www.ti.com/video/series/stepper-motors.html

Regards,

Ryan

0 Ali Rasouli over 1 year ago in reply to Ryan Kehr

Prodigy 30 points

Thanks Ryan for your reply. I watched the videos on stepper motors as well.

How can I know if my motor is getting enough juice. In order for us to get the required torque, we need 24VDC at 4.1 amps, and I want to make sure the motor is getting the speced power.

Thanks

Ali

0 Ryan Kehr over 1 year ago in reply to Ali Rasouli

TI__Guru 55565 points

Ali,

Do you have a current probe in your lab? With a current probe, you should be able to see your rated current at full scale and adjust VREF and internal registers according to get there.

Regards,

Ryan

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DRV8711: Voltage across stepper motor coil