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TIDM-02002: Does the result after running SFRA include the frequency response characteristics of GH and H?

Green Deng
Expert 4490 points
Part Number: TIDM-02002
Other Parts Discussed in Thread: SFRA

Dear team:

if(CLLLC_clearTrip == 1)
{
CLLLC_HAL_clearPWMTripFlags(CLLLC_PRIM_LEG1_PWM_BASE);
CLLLC_HAL_clearPWMTripFlags(CLLLC_PRIM_LEG2_PWM_BASE);
CLLLC_HAL_clearPWMTripFlags(CLLLC_SEC_LEG1_PWM_BASE);
CLLLC_HAL_clearPWMTripFlags(CLLLC_SEC_LEG2_PWM_BASE);

#if CLLLC_TEST_SETUP == CLLLC_TEST_SETUP_EMULATED_BATTERY
CLLLC_closeGiLoop = 1;
#endif

CLLLC_clearTrip = 0;
}

if(CLLLC_closeGiLoop == 1)
{
#if CLLLC_SFRA_TYPE == CLLLC_SFRA_CURRENT
CLLLC_giError = (CLLLC_SFRA_INJECT(CLLLC_iSecRefSlewed_pu) -
CLLLC_iSecSensed_pu);
#else
CLLLC_giError = (CLLLC_iSecRefSlewed_pu - CLLLC_iSecSensed_pu);
#endif

Under the above conditions, run the SFRA GUI to analyze the response characteristics of the frequency sweep loop, and save the data in .CSV after the run is complete.

Questions:

1, Does the .CSV data saved under the above conditions only contain the response characteristics of the open loop transfer function (GH), or both the open loop transfer function (GH) and the response characteristics of the plant (H)?

2, If the above data only contains the response characteristics of the open loop transfer function (GH), I want to get the response characteristics of the plant (H), is it necessary to close the current loop (make CLLLC_closeGiLoop = 0) and let the program run at a fixed switching frequency? Then use the SFRA GUI to perform a frequency sweep test.

Best regards

  • 0
    TI__Mastermind 43730 points

    Please follow the UG, in Lab 2 data will be collected for GH and H but as the loop is not closed GH data is not relevant or incorrect. In Lab 3 and Lab4 when the loop is closed it will measure both GH and H and store that in CSV file. 

  • 0
    Prodigy 170 points

    Hi Manish，

     I got a problem.

    In Lab 2，the SFRA injects small signal on the “CLLLC_pwmPeriodRef_pu” and collects the isense or vsense,so we can get the data of H;

    in Lab3 and Lab4 when the loop is closed，the SFRA injects small signal on the vref or Iref and collects the isense or vsense,so we can get the data of GH.But how did the data for H come together?

  • 0 in reply to Aiden zhang
    TI__Mastermind 43730 points

    Aiden, 

    Even though we are injecting on the reference, we do know the duty/control effort similar to the open loop case and also the feedback, we can compute the plant response from those two variables alone. For the GH we need to look at controller reference and feedback. 

    All the information is available to compute both plant and GH in closed loop as well.