DRV8301-RM48-KIT Low Speed Running Problem

Zhaoqin Guo

Prodigy 40 points

Other Parts Discussed in Thread: RM48L952, DRV8301, LVSERVOMTR

I am using the 8301-RM48 motor kit.

When I run Project "RM48L952_foc_encoder_speed" for speed control of the motor.

When I set the reference speed to be "0.05", which is "172rpm", the motor is still running properly.

But if the reference speed is set to be "0.04", which is "138rpm", the motor just stops.

Is there anything I can do to make the motor run at a low speed, say "10-20 rpm"?

over 10 years ago

0 Milan Rajne over 10 years ago

TI__Expert 8885 points

Guo,

It is recommended that you ask this query to herclues e2e forum:

http://e2e.ti.com/support/microcontrollers/hercules/f/default.aspx

As per my understanding, typically this happens becuase QEP.Theta does not get updated during consecutive ISR due to low speed. Going with higher PPR encoder would be one way to achive lower speed operation or changing the speed feedback algorithm from edge count mode to Capture count mode should help.

Best Regards

Milan

0 Zhaoqin Guo over 10 years ago in reply to Milan Rajne

Prodigy 40 points

Milan,

Thanks for your suggestion.

I tried to run the same motor using InstaSPIN-FOC, it can run at lower speed by using sensorless control. So I think you are right, the problem is the encoder which does not working properly at low speed.

Best regards

Zhaoqin

0 ChrisClearman over 10 years ago in reply to Zhaoqin Guo

TI__Guru** 118000 points

Zhaoqin Guo said:
I tried to run the same motor using InstaSPIN-FOC, it can run at lower speed by using sensorless control.

Try InstaSPIN-MOTION and watch what it can do in sensored velocity or position control with an encoder!

0 Zhaoqin Guo over 9 years ago in reply to ChrisClearman

Prodigy 40 points

Hi, Chris,

I tried to run the motor using InstaSpin-Motion, when I set a very low speed as target, (5rpm), the motor can run, although the performance is not good.

Can we conclude that actually the encoder works at low speed?

So the problem comes back to the program of "RM48L952_foc_encoder_speed".

Best regards

Zhaoqin

0 ChrisClearman over 9 years ago in reply to Zhaoqin Guo

TI__Guru** 118000 points

You must be making a mistake. InstaSPIN-MOTION on the DRV8301 with the Teknic LVSERVOMTR works incredibly well. With the encoder feedback (proj_lab12 or _13 for position) you will see excellent performance at 5 RPM and much, much, much slower.

I can't comment on the Hercules project, you will need to address this on the Hercules forum I'm afraid.

0 Zhaoqin Guo over 9 years ago in reply to ChrisClearman

Prodigy 40 points

Thanks. Chris. Will look into it.

0 Eli_jia over 8 years ago in reply to Milan Rajne

Intellectual 530 points

Hi Milan,

When I use capture count mode, I found the speed response becomes slow, and the motor running discontinuously. The encoder has 2500ppr and I want the motor run at 1 rpm. Do you have any advice? Thanks!

0 Nicholas Oborny over 8 years ago in reply to Eli_jia

TI__Mastermind 21305 points

Hi Eli_jia,

Which kit are you using? I recommended you take your question to the corresponding controller's forum for the best response.

0 Eli_jia over 8 years ago in reply to Nicholas Oborny

Intellectual 530 points

Hi Nicholas,

I use HVMotorCtrl+PfcKit_v2.1 with F2833x, Thanks!

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DRV8301-RM48-KIT Low Speed Running Problem