TMS320F28054M: Rs calibration problem when motor stops at mechanical endstop position

Qiang Guo

Part Number: TMS320F28054M

Hi TI and Adam,

Rs re-calibration can only be done when the motor is able to rotate freely at both directions during the re-calibration. (if i understand correctly)

This can create a problem when my motor has loads on it and tends on stop at my mechanical endstop position, at this position my motor can only move freely at one direction not another.

If my motor can't move at one direction during the Rs- re calibration, the Rs re-calibration can't be done, which will cause a bigger problem when it proceeds to SPINTAC Position plan.

How do I fix this problem without increase my motor startup time?

I have two plans to solve this problem but both of them are taking too much startup time for my motor to move

1: do the re-calibration twice if it fails at first time, which would double my startup time from 6sec to 12sec

2: use velocity plan to move my motor to a position where my motor is able to move freely at both direction before Rs-recalibration,

Any suggestions to solve this problem effectively?

over 8 years ago

0 Yanming Luo over 8 years ago

TI__Guru** 115500 points

In InstaSPIN-motion, uses recalibrating the Rs value of the motor to ensure that both the encoder and the motor are aligned on a zero degree electrical angle, which supposes the motor free stops and can use recalibrating to lock the rotor.
In your case, it's better to use absolute encoder, or incremental encoder with U/V/W hall signal, or using IPD to get the rotor initial position without locking the rotor by motor rotate.

0 Qiang Guo over 8 years ago in reply to Yanming Luo

Expert 1695 points

Hi Yanming,

I check the lab21 about IPD, it only shows a check mark on F2806X, not with F2805X, I am using f28054M, I am not sure whether I can use lab21 with F28054M. Please confirm that, thanks!

0 Yanming Luo over 8 years ago in reply to Qiang Guo

TI__Guru** 115500 points

The reference can be used on F28054M, but it's for PM with obvious saliency ratio (IPM), no for all PMSMs.

0 Adam D. Reynolds over 8 years ago

Guru 12800 points

I agree with Yanming's comments. The only other thought I had was you could try to manually step the motor in both directions prior to doing an alignment to ensure that it is free to move.

0 Qiang Guo over 8 years ago in reply to Yanming Luo

Expert 1695 points

Instead of using FAST, can I use QEP with IPD?

0 Adam D. Reynolds over 8 years ago in reply to Qiang Guo

Guru 12800 points

You should be able to combine the labs together.

You will need to determine the best method of aligning the motor and encoder for your application. Maybe it is using FAST while looking for an index line, maybe it is using the hardstop itself as a home mechanism.

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TMS320F28054M: Rs calibration problem when motor stops at mechanical endstop position