DRV8306EVM: Motor speed drops significantly with small change in load

Sadashiva Kamath

Part Number: DRV8306EVM
Other Parts Discussed in Thread: DRV8308, DRV8306

Hi,

I'm using DRV8306-EVM to evaluate scroll compressor. I observed that there is significant SPEED drop (approx. 90 rpm) when there is small change in load. Hall Sensor: 102.5Hz to 96.51Hz. i.e., from Motor speed 1,537.5 rpm to 1,447.65 rpm

Please let me know is there any VDS, IDRIVE or any other parameter can be tuned? Is User having any control on closed-loop parameters?

Also, I have attached scope capture of a) Motor phase winding current (CH #1, Yellow) and b) Hall Sensors input (Ch #3, Pink).

Is Hall sensor voltage swing is good?

JP1 is OPEN & JP2 is short. HPWR = 5V given from external source

over 5 years ago

0 Adam Sidelsky over 5 years ago

TI__Guru 65170 points

Sadashiva,

Is this the same issue as your DRV8308 thread but using the DRV8306 instead?

DRV8306 is open-loop only, you will need to use FGOUT and the MCU to close the loop so that your MCU can increase the PWM input to account for the speed drop under load.

Regards,

-Adam

0 Sadashiva Kamath over 5 years ago in reply to Adam Sidelsky

Expert 1175 points

Thanks for prompt response.

Yes, this is the same issue as your DRV8308 thread but using the DRV8306 instead.

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DRV8306EVM: Motor speed drops significantly with small change in load