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CCS/LAUNCHXL-F28379D: 3Ph PWM Rectifier

hossein khaligh
Intellectual 425 points
Part Number: LAUNCHXL-F28379D


Tool/software: Code Composer Studio

Hi,

What is the "Vdc_ref" and "Vdc_measure " polarity sign  in a 3Ph PWM Rectifier?

I want built a 2 loop controller for a 3-ph PWM rectifier. inner loop is line Current and outer loop is Vdc.

for outer loop should I calculate Vdc_ref - Vdc_measure or  Vdc_measure - Vdc_ref?

in my test setup positive polarity of current sensor is from grid to DC link

  • 0
    TI__Genius 11945 points

    In your case you should calculate (Vdc_ref - Vdc_measure).

    This way voltage loop will regulate the output (Vdc_measure) to follow the reference voltage (Vdc_ref).

    Shamim

  • 0 in reply to Shamim Choudhury
    Intellectual 425 points
    Hi
    but some articles calculated Vdc_measure - Vdc_ref. for example in matlab simulink.
    it confused me!!
    sorry! what is your references?
    also, I tested Vdc_measure - Vdc_ref and received a correct response. But some times it doesn't work!
    what is wrong?
  • 0 in reply to hossein khaligh
    Intellectual 425 points
    I do these process to create a close loop PWM rectifier:
    1-connecting three phase power to PWM rectifier and charging DC link(With pre-charge resistor)
    2-running CCS. at the first I Close inner loop(current) then increase id_ref to increase Vdc
    3- closing outer loop(voltage loop).
    in step 2 for first time that i close inner loop my IGBT drivers show fault but when I repeat this for 2 or 3 time it become true and is run.
    also, I can not run step 3 without step 2. I must run step 2 then run step 3. if I don't do this, my IGBT drivers show fault.

    ???
  • 0 in reply to hossein khaligh
    TI__Genius 11945 points
    In step 2 the IGBT driver fault could be because of high current caused by closing the loop for the first time. This may not happen when you run the complete system (both current and voltage loop) and start with a soft-start routine. So for now ignore this IGBT driver issue and verify how closely your current loop tracks your reference current. If this tracking looks good then you add the voltage loop as you did in step 3.

    Yes, you cannot run step 3 without step 2. The inner current loop must be closed when you add the voltage loop (step 3).

    Shamim