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SFRA measurement

Neeraja K
Prodigy 40 points
Other Parts Discussed in Thread: SFRA

While doing, SFRA when I am forcing the output value as below,

VIENNA_dutyPU_DC = 0.8f;

VIENNA_duty4PU = VIENNA_SFRA_INJECT(VIENNA_dutyPU_DC);


var1.Ref =1;

VIENNA_SFRA_COLLECT((float32_t *)&VIENNA_duty4PU,
(float32_t *)&var1.Ref);

I am getting the following response. 

I made var1.Ref = 0.5. Then  also similar response as above.

======================================================================================

But, when I force as shown in code below , which forces output as a factor of duty I am getting below response, which is correct.

var1.Ref = VIENNA_duty4PU;

VIENNA_SFRA_COLLECT((float32_t *)&VIENNA_duty4PU,
(float32_t *)&var1.Ref);

What could be the issue in the first method ?.

  • 0
    TI__Intellectual 1490 points

    Can you mention how much noise injection amplitude provided and what are SFRA configurations? Input argument to this function: SFRA_F32_config()?

    What frequency at which SFRA inject/collect and SFRA_F32_runBackgroundTask functions are called?

    Regards,

    Shashank

  • 0 in reply to Shashank Madineni
    TI__Intellectual 1490 points

    Neeraja,

    SFRA collect has two input arguments [ Compensator output / Plant input and Plant output].

    In first case, you are providing controller output/ plant input as (0.8+ noise) and plant output as "1". => which leads to plant transfer function k/noise and that will impact plant transfer function.

    In second case, you are providing controller output/ plant input as (0.8+ noise) and plant output as "controller output". => which leads to plant transfer function k. 

    So, both plots are correct as per my understanding!

    Regards,

    Shashank