DRV8711: Distorted current waveform

Jason Maxwell

Part Number: DRV8711
Other Parts Discussed in Thread: DRV8461

Hello,

I have a customer whose application is a stepper motor drive, and he says that he is getting a distorted current waveform whenever the motor goes above 100-150 RPM. The waveform is pasted below. What could be causing this? Is it device specific?

Thanks!

Jason Maxwell

6 months ago

+1 Murugavel4637 6 months ago

TI__Mastermind 21345 points

Hi Jason,

This is not device specific. This is because of insufficient VM voltage to overcome the back EMF generated by the stepper at those speeds resulting in phase currents not reaching target value for proper current regulation and wave shaping. This is expected behavior of stepper drives. You may find several e2e posts on this topic. Here's an example with one of our integrated stepper drivers DRV8461, https://e2e.ti.com/support/motor-drivers-group/motor-drivers---internal/f/motor-drivers---internal-forum/1311084/drv8461-waveform-analysis/4983598?tisearch=e2e-sitesearch&keymatch=DRV8711%2525252525252520current%2525252525252520waveform#4983598.

Customer may be able to improve the waveform either by increasing the VM voltage, reducing the IFS or reducing the RPM if both VM and IFS cannot be changed.

Regards, Murugavel

+1 Jason Maxwell 6 months ago in reply to Murugavel4637

TI__Prodigy 295 points

Hi Murugavel,

Thank you for this answer. It was very helpful for me to see. I'll let you know if there are any follow-up questions from the customer.

Best,

Jason Maxwell

Motor drivers

Motor drivers forum

DRV8711: Distorted current waveform