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TMS320F28334: HVACI_Sensorless_F2833x Estimated speed and Estimated Angle

Part Number: TMS320F28334

Hello

I am running my AC induction motor using HVACI_Sensorless_F2833x project. 

I have two questions to ask 

1)                When I run the motor without load the rotor speed given by ACI_SE(Speed estimation macro) is true. I have verified this using tachometer. 

but when the load is applied to motor the estimated speed given by macro is inappropriate. The estimated speed is not same as actual rotor speed.

Instead of giving actual rotor speed the estimated speed is same as the estimated speed when motor running without load.

example:

Case 1: Motor is running without load (Speed reference = 500 RPM)

-  estimated speed = actual rotor speed (Verified using tachometer) = 500 RPM

Case 2: Motor is running with load

- estimated speed = 500 RPM ≠ actual rotor speed (0 < rotor speed < 500 RPM)

Is this right scenario or estimated should be the actual rotor speed?

What can be Cause for this scenario?

2)      The Elec theta we get from encoder is same as estimated theta flux? Are both the same thing or two different quantities?

I have this question because we are not using Elec theta from encoder in feedback for park/Inverse park input.

Please address my issue/doubts with technical elaboration.

Thanks in advance.

Regards.

  • Did you set the right motor parameter for running the sensorless-FOC?

    What's the difference between the estimated speed and the measured speed? If the error is very small and a constant value, that's could be normal.

  • Hi Yanming,

    Thanks for the reply.

    Yes, the motor parameter is right. Now what can be the other causes for this scenario?

    The difference between estimated and actual speed is very less when motor is running without any load.

    But when we run the motor with load or stall the motor with load the actual speed is let's say 0 RPM but yet estimated speed is shown 500RPM.

    I hope you've gone through my second question also. If not I am asking it again here:

    2) The Elec theta we get from encoder is same as estimated theta flux? Are both the same thing or two different quantities?

    I have this question because we are not using Elec theta from encoder in feedback for park/Inverse park input.

    Thanks in advance.

    regards.

  • But when we run the motor with load or stall the motor with load the actual speed is let's say 0 RPM but yet estimated speed is shown 500RPM.

    Did you set the right flux current? You may take a look at the application note, and try to change the flux current (id).

    2) The Elec theta we get from encoder is same as estimated theta flux? Are both the same thing or two different quantities?

    I have this question because we are not using Elec theta from encoder in feedback for park/Inverse park input.

    If you calculated the angle correctly with encoder, the angles from the encoder and estimator could be the same.