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TIDM-HV-1PH-DCAC: Problems on loop calculation

Green Deng
Expert 4490 points
Part Number: TIDM-HV-1PH-DCAC
Other Parts Discussed in Thread: POWERSUITE

Dear team:

According to the above figure, the feedback of voltage loop is only related to the load, and independent of the effective value of the output voltage.

However, when my customer uses PowerSuite to calculate the loop, he finds that the loop model of the corresponding voltage outer loop is inconsistent when inputting different AC voltage effective values.

Vout=110Vrms

Vout=220Vrns

Why is the calculation result different from the model description?

Best regards,

Green

  • 0
    TI__Genius 11955 points

    I see that the low frequency gain is different. However, the power stage (plant) gain curve crosses the 0-dB line at the same freq of 200Hz for both figures. Also at that point the the phase is the same as about 75 deg.

    Shamim

  • 0 in reply to Shamim Choudhury
    TI__Expert 4490 points

    Hi Shamim:

    Yes, the low-frequency gain has indeed changed. After the customer changed the output voltage from 220vrms to 110vrms, the low-frequency gain of power stage changed.

    He doesn't understand why it changes, because theoretically, the gain curve of the power stage has nothing to do with the amplitude of the output AC voltage.

  • +1
    TI__Genius 11955 points

    If you look at the current loop model the gain will change if the voltage across the inductor is changed.

    So, with Vout change while maintaining the same DC bus, the voltage voltage across output inductor will also change That will change the current loop gain.