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TMS320F28035: HFI Library - HFI loses angle under load

Chris Jablonski1
Prodigy 20 points
Part Number: TMS320F28035

Hi, 

I am evaluating the HFI library and have my system functioning with some issues. I am basing the code off of the HVPM_Enhanced_Sensorless project. One issue is that the HFI algorithm goes unstable under load. Below is a plot of the encoder angle (YELLOW), the HFI angle (MAGENTA) and the phase current (CYAN) under "normal" HFI operation.

Once load is applied the HFI angle becomes corrupted and eventually (as load increases) the angle is lost the algorithm becomes unstable.

Questions:

1) Is this an indication that the motor saliency is disappearing under load?

2) Are there any suggestions or tuning tips to help deal with this situation?

Thanks,

Chris

  • 0
    TI__Guru** 114200 points

    1. As you know, the HFI algorithm is only applied to control salient pole PMSMs, such as IPM motor has a high saliency ratio. And the HFI is only used during startup and low speed. In most IPMs, the saliency ratio will be reduced when the torque current increases, so you should inject a higher current if the load is very heavy.
    2. You may try to increase the injection voltage and tune the coefficient of HPF. Please make sure that the dc bus voltage is enough to provide the injection voltage and torque current during the motor is running with a heavy load.