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TIDA-01606: DC-Link Capacitor Calculation

Alejandro Martinez
Prodigy 10 points
Part Number: TIDA-01606

Hello!

I'm using TIDA-01606 as a reference for a three-phase inverter design. What I'd like to know is how did you calculate the required capacitance for the dc-bus (which is shown as a split capacitor in the general diagram). From the image of the assembled kit, it looks like it takes eight electrolytic capacitors. So, can you please indicate how did you design that specific part of the input circuit?

Thanks in advance.
Regards

A. Martinez

  • +1
    TI__Intellectual 2100 points

    Dear Martinez,

    there is a split capacitor in the general diagram because there is a middle point that is required in order to create the "third level".

    The capacitance has been selected in order to have a reasonable energy storage in the DC bus. Currently, there are equivalent 240uF. This capacitance has been selected by applying the sequent formula:

    C=(Power*Delta T)/(0.5*Vinitial*Vinital-Vfinal*Vfinal)

    Capacitance has been calculated for a voltage sag that last for 1 ms and with the aim of do not have a variation in the DC bus voltage higher than 100 V.

    Best Regards

    Riccardo

  • 0 in reply to Riccardo Ruffo
    Prodigy 10 points

    Thanks a lot for your answer Riccardo, it really helped to clarify things!

  • 0 in reply to Riccardo Ruffo
    Intellectual 810 points

    Dear Riccardo,

    For  this formula  C=(Power*Delta T)/(0.5*Vinitial*Vinital-Vfinal*Vfinal)

    Power = Rated inverter power

    Delta T = Time considered to withstand sag

    Vinitial = Voltage in DC bus before Sag

    Vfinal = Minimum voltage in DC Bus after sag happened

    Please let know if these are correct

    And one more doubt C=(Power*Delta T)/(0.5*(Vinitial*Vinital-Vfinal*Vfinal)) is this is correct?

    With Regards

    Saravana