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TIEVM-VIENNARECT: Input Voltage Calibration of a 3-Phase Vienna Converter.

Vignesh M
Prodigy 75 points
Part Number: TIEVM-VIENNARECT

Tool/software:

Hi,

I am using a 3-phase Vienna converter (TIEVM-VIENNARECT).

The issue is that when I apply an input of 120 Vacrms, 3-phase, 50 Hz, the input voltage displayed in Code Composer Studio is around 116 VAC.

Using DMM, I have measured the input applied to board is 120.2Vacrms.

How can I calibrate this issue?

Regards,
Vignesh

  • 0
    TI__Mastermind 42195 points

    Check the input voltage reference is correctly supplied. Most EVMs have the option of 3v0 or 3.3V. You're off by about that much, so it could be the issue. Please note that all signals will be off by the same 1.1 scale factor, so check others too.

    Finally, if it is just one signal or you are confident that the VREF is good then go and check the scale factor. I believe that HW should have it correctly configured.

    This error is likely to come from two pieces, 1 the signal at the PIN is not scaled correctly by the HW circuits, check with DMM at device pin. 2 The scale factor applied in the code is not correct, Adjust the scale factor.

    Regards,
    Cody 

  • 0
    Prodigy 75 points

    Hi Watkins,

    Thanks for your reply!

    What is the scale factor?

    The ADC used is 12-bit, so the scale factor is 0.000244.

    I have checked the hardware, and everything looks fine.

    Could you please explain with code?

    Regards,
    Vignesh

  • 0 in reply to Vignesh M
    TI__Mastermind 42195 points

    You have a signal entering the device which is 0 to lets say 3V. you are likely not interested in only sensing a 3V signals. Perhaps a Voltage input of +/-170V, or a current. These are not 3 volt signals, therefore you will need to develop circuitry to scale your signal to 3V. Then once it is sampled the MCU will need to apply a scale factor to understand what the input actually corresponds to. Either of these, HW or SW, could be wrong in your implementation. As i mentioned before there may be some clues to what is going wrong depending on if only one signal is off, or multiple.

    No I will not explain with code.

    Regards,
    Cody