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AM263P4: Speed Calcultion Problem with ENCODER

Burak Yeniaydin
Prodigy 220 points
Part Number: AM263P4
Other Parts Discussed in Thread: LVSERVOMTR

Tool/software:

Hello,

I am using AM263P LP, BOOSTXL 3phGANINV and LVSERVOMTR (Teknic M-2310P-LN-04K) with encoder config.

After running the motor at high speeds and then stopping it, the measured speed takes a long time to reach zero, even though the motor shaft is stopped. During this time, the speed estimation remains high value. If I attempt to restart the motor before the speed reaches zero, the control can become unstable, and the motor may suddenly spin at a very high speed.

When I replace SPDCALC_run with SPDFR_run, this issue disappears completely. As shown first image I attached from the UMC documentation, the code uses SPDCALC_run for encoder.


However, according to the .h file, SPDCALC_run appears to be written for sensorless speed estimation.

Why is SPDCALC_run considered suitable for encoder use?
Is it unreasonable or incorrect to use SPDFR_run instead of SPDCALC_run when working with an encoder?

Regards,
Burak

  • +1
    TI__Expert 4020 points

    Hello Burak,

    Recently, we came to know about this during one of our implementations. The delay you're noticing with the encoder is due to the integral component of the SPDCALC_run()-PI controller holding residual error even after the motor has stopped. While SPDCALC_run() works reasonably in sensorless contexts (where the angle is noisy and needs smoothing), you can use SPDFR_run() for direct position feedback from encoder which comes with a low-pass filter to smooth high-frequency noise filtering. This is planned to be documented for the next release.

    Best Regards,

    Masoud