DRV10970: Large delay when switching direction at very low speed

Oleg Zinovev

Part Number:

The same problems arise as with Nahuel, but the difference is that we need to change the direction of the motor when it moves very slowly.

His solution:

" turning the PWM off, waiting 1ms, changing direction, waiting 1ms and then turning the PWM on again" ,works only for one direction :(

Any idea why the driver is so asymmetrical?

over 6 years ago

0 Sanmesh Udhayakumar over 6 years ago

TI__Expert 6065 points

Hey Oleg,

1) If this is a 30 deg hall placement motor instead of 0 deg, this could be the root of the assymetry.
a) Which commutation mode do you use?
b) Try using the CMTMOD = 0 for Sinusoidal operation mode with 0° Hall placement to help with the assymetry problem when spinning in both directions.
c) Play around with the DAA pin setting. I would try to set it high to minize the angle offset as well, as this too can cause assymetry

2) Can you specify what happens in the case in which the switching direction doesn't work?

Sincerely,
Sanmesh U.

0 Sanmesh Udhayakumar over 6 years ago in reply to Sanmesh Udhayakumar

TI__Expert 6065 points

Any follow up Oleg?

0 Oleg Zinovev over 6 years ago in reply to Sanmesh Udhayakumar

Prodigy 160 points

So far we are testing your suggestions. There are some problems that make it difficult to respond quickly.

0 Sanmesh Udhayakumar over 6 years ago in reply to Oleg Zinovev

TI__Expert 6065 points

Ok no worries. Just let me know when you are able to follow up further

0 Avish Gupta over 6 years ago

Intellectual 470 points

Hi Oleg,

Go through the following post

Sanmesh Udhayakumar said:

Part Number: DRV10970

I have verified on bench that when changing FR pin, regardless of the times you toggle FR pin, the device always enters brkmod, waits until motor stops, waits Cretry time, then starts the motor according to FR pin direction. Since the motor always goes back to zero speed before restarting when toggling FR pin, I dont think you can use FR pin to modulate speed. You will have to use the pwm pin method to get low speed I believe.

Please Refer e2e.ti.com/.../2900326

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DRV10970: Large delay when switching direction at very low speed