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PGA411-Q1: Modelling of tracking loop for controller gain determination

user6207351
Prodigy 20 points
Part Number: PGA411-Q1

There are a few documents describing the AFE and PI control loop.  What seems to be missing in detail is the way the error is calculated and fed into the PI controller. What is documented in PGA411-Q1 Resolver Sensor Interface.pdf does not work when implemented verbatim.

I would like to model the tracking loop in Simulink so I can pass through real speed/angle data to access the angle error and stability. My questions are:

1) In the Analogue Application Journal; System Modeling in Matlab Simulink for PLL-based resolver-to-digital converters, a model is described of the PGA411-Q1.  Is this model available for download?

2) Could you please explain how the analogue error signal gets demodulated and how this becomes a 16bit representation of error?

3) Although the tracking loop runs at a high update rate, am I right in thinking the update of the error is based on the excitation frequency?

  • 0
    TI__Expert 3435 points

    Hi,

    Thank you for contacting us. Please find the answers below:

    1. Currenty, the Matlab model is not available to customers. This cannot be downloaded from ti website.

    2. & 3. These are good questions, but unfortunately the block diagram in the datasheet is the only available informtaion to the customers. The tracking loop performance can be measured with a step response using a resolver simulator. Testing the PGA411 with the resolver simulator with the required test conditions is a better approach to find out if PGA411 is a correct fit for the application or not. 

    Best Regards

    Sharath.

  • 0 in reply to Sharath Vallamkonda
    TI__Expert 3435 points

    Hi,

    Is it possible for you to test the PGA411 for speed angle by connecting the actual motor? Is there any reason you want to use Matlab to run these tests? 

    Regards

    Sharath.

  • 0 in reply to Sharath Vallamkonda
    Prodigy 20 points

    Yes but there are limitations.  A dyno may not be able to produce the acceleration seen in the field. It cannot test the tracking loop to find it's stability limits. A traction motor in a vehicle may experience high accelerations when driving over a speed bump and this could also cause driveline excitation which may not be reproducible on a dyno.

    Previous resolvers I have used were calibrated offline (Simulink model) to ensure the best compromise between phase lag and stability. It is also useful for testing fault conditions and other noise factors such as a high frequency torsional mode of the shaft.

    Thank you.