Is it possible to use the Frequency Response Estimation Block in order to measure a real plant?

Hello,

I am trying to obtain the Frequency Response of a Buck Converter using the Frequency Response Estimator Block (FRE) from Simulink Control Design Library.

I am using the following hardware:

1. C2000 Digital Power Buck Converter BoosterPackfrom Texas Instruments: https://www.ti.com/tool/BOOSTXL-BUCKCONV
2. TMS320F280049C LaunchPad from Texas Instruments: https://www.ti.com/tool/LAUNCHXL-F280049C

I have used the Simulink Embedded Coder Support Package for Texas Instruments C2000 Processors in order to create two simulink files:

1. target.slx: Configure and generate code for the Buck converter and load it to the controller (target)
2. host.slx: Graphical User Interface run on host computer which communicates with target via CAN interface

First I have tried to integrate the Frequency Response Estimation Block first on target.slx ( the generation gives no error but I cannot import the frequency response data to matlab/visualize it). What am I doing wrong here?

Then I tried to use it in host.slx (here the problem is with sending the sinusoidal perturbed duty cycle from the FRE block from the GUI(host) to DSP(target) accurately (via CAN interface) and sending the ADC measurement of the output voltage from DSP(target) to GUI(host) - these signals vary very fast and cannot be accurately sent.).

Is there a way to use this block in order to obtain the Frequency Response of a real Buck Converter?

Answer 1

[Brahmadev]

Hi @Evelyn Lovasz,

When using the 'Frequency Response Estimator' block for an unstable plant, online estimation works in a closed-loop configuration, provided that the closed loop is internally stable. Using the approach mentioned in the following example in target.slx should allow estimation of frequency response. Alternatively, offline estimation can be done after recieving the data.

https://www.mathworks.com/help/slcontrol/ug/online-estimation-of-frequency-responses-of-nonlinear-plant.html

You can refer to the following MathWorks documentation for more information:

https://www.mathworks.com/help/slcontrol/online-frequency-response-estimation.html

Hope this helps in resolving your query!