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PMP40766: iTHD measurement

Sahil Gupta
Prodigy 80 points
Part Number: PMP40766

Tool/software:

Hi , 

Can you guide me how is iTHD measurement done. 

Reason I ask - iTHD in real life in case of EV charger is function of Isc/Il, where Isc is short circuit current at input, Il is maximum demand current over a period of time(6 months, 12 months). {based on IEEE519 standard)

Hence asking in TI reference design , how was iTHD measured.

Thanks, 

  • 0
    Prodigy 80 points

    Also if you can help explain me the implementation of CC loop, CV loop in brief(top level) done in this design- that will be great too!

    Thanks a lot

  • 0 in reply to Sahil Gupta
    TI__Mastermind 27135 points

    Hi Sahil,

    1. The iTHD was measured using an AC power analyzer capable of measuring up to the 50th harmonic. The test data is collected using an isolated AC supply with only the PMP40766 board connected (no other loads connect to the AC output). 

    2. The CC loop is implemented using U7A as its error amplifier and the CC loop is implemented using U7B as its error amplifier. The CV set point is determined by the resistor divider R63, R64, R62 and R65 along with the internal 2.5V reference. The CC loop set point is set by the voltage at pin 5 (the CC loop reference voltage), the current sense amplifier gain and current sense resistance. The output of each error amplifier is OR'd together using D10. The loop with the lowest error "wins" and controls the regulation point.

    Best Regards,

    Ben Lough

  • 0 in reply to Benjamin Lough
    Prodigy 80 points

    Thanks Ben this helps me.