Start up and thermal question of DRV10983

Hi Nagasawa-san,

Please my comments to your questions below.

I want to suggest DRV10983 to customer. And I have question.

(1) Customer system needs are 2000rpm in 100ms after a start, is it possible?

[KS] How does this speed translate to electrical Hz ?   

(2) Is there concern that motor spin in the reverse direction in a startup?

[KS] There are two options available for motor startup : Align and IPD. When Align is used there is chance the motor will spin backwards when DRV10983 is aligning motor to known position. IPD estimates position of motor by sensing variation in inductance and motor will not spin backwards in this mode, but for IPD to work, motor must have have some inductance variation.     

(3) The recommendation is Tj up to 105 ℃ in  data sheet, Is it operate at Ta = 105 ℃ on the following conditions?

◆Condition

Vin  6V～12V

Output current: 0.4A (Ave)  2A (Peak)

Ta:105℃

[KS] DRV10983 should be able to operate at 105 ℃ as long as PCB layout guidelines are followed as per datasheet and adequate copper is used on ground plane to dissipate heat.

Regards,

Krushal  

Kurushal-san

Thank you for quick response.

(1) Customer system needs are 2000rpm in 100ms after a start, is it possible?

[KS] How does this speed translate to electrical Hz ?   

⇒Sorry for lack of explanation. They want to use 12 pole motor.

And caluculating 36P of datasheet, start up Electrical Hz within 100ms is

2000rpm/(60second/min×1mechcycle/6ecycle)=200Hz

And Max speed of their system is 6000rpm.

Is this possible?

(2) Is there concern that motor spin in the reverse direction in a startup?

[KS] There are two options available for motor startup : Align and IPD. When Align is used there is chance the motor will spin backwards when DRV10983 is aligning motor to known position. IPD estimates position of motor by sensing variation in inductance and motor will not spin backwards in this mode, but for IPD to work, motor must have have some inductance variation.     

⇒I'm chaking their inductance spec.

Regards

Tomohiro  Nagasawa

Hi Nagasawa-san,

200 Hz in 100 ms is difficult for any driver, you are looking at acceleration of 2000 Hz/sec. Normally for any motor, acceleration is limited by inertia, other torque like friction, damping  and current limit of driver.  When DRV10983 transition in close loop, there is option of having fastest acceleration possible and in this mode acceleration is based on current limit used.

I missed one point the from earlier post -

◆Condition

Vin  6V～12V

Minimum operating voltage for DRV10983 is 8 V, so I would recommend DRV10975 which has same set of features and fits well for this operating range.

Regards,

Krushal 

Krushal-san

Thank you for kind reply.

How long does it take in the shortest until I reach 2000rpm only as a guide?

If you need detail condition, please send e-mail below.

nagasawa_tomohiro@tte.toyotsu.net

Regards

Tomohiro Nagasawa