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F28035 for PV inverter

Felix Zhang
Intellectual 645 points

Hi all,

I'm thinking to implement a PV inverter based on the F28035 including MPPT, PLL, islanding etc, is it possible to work well if I use set the carrier frequency to such as 170KHz? anyone has such experience? If possible, I even want to implement the PLC (power line communication) to the single chip, is that possible? any suggest? thanks a lot in advance!

regards,

Felix

  • 0
    TI__Mastermind 43730 points

    You neeed to tell more about the system to suggest a device for you,

     

    What type of topology is it?

     

    Single Phase? Three Phase?

     

    Single stage (both MPPT and inverter in single stage) or dual stage (MPPT boost separate from inverter),

     

    you want to use 170 Khz for the inverter? What power level is your inverter?

  • 0 in reply to Manish Bhardwaj
    Intellectual 645 points

    Hi Manish,

    It will be interleaved flyback converter and DC/AC inverter dual stage for single phase AC output.

    now I'm considering about 110kHz, about 200w. Flyback will be in DCM, s/w should include MPPT, PLL etc.

    This will also use PLC to communicate with other module or a host. Thanks for your answer!

    regards,

    Felix

  • 0 in reply to Felix Zhang
    TI__Mastermind 43730 points

    110Khz is for DC-DC, what switching frequency are you using for DC-AC ? Are you actively controlling DC-AC in closed loop ?

    I woudl suggest making a table of the cycles you are using in your system

    MPPT is very slow only 10-20Hz, typically,you can ignore this for mips calculations.

    PLL needs to run at 20Khz, PLL Cycles / (CPU Frequency/ 20Khz) = % CPU utilization by PLL

    closed loop control of DC-DC at 100Khz  , Control Loop Cycles/ (CPU Frequency / 100Khz) = % CPU Utilization by PLL, 

    PLC would take up the entire CPU utilization, no mips would be left to do any control loop operation. An option could be to use CLA (the mips calculations explained above apply).

    Another factor could be the number of ADC's being used in your system, depends heavily on the style of system you have and what all you are sensing.

    Also do you want PLC to be compliant to talk to the utility or just for local  communication between solar nodes?

    F2806x in my view would be better fit for PLC + control for solar application than F2803x. on F2803x you would run out of RAM as PLC consumes a lot of RAM space. 

    On F2806x you can dedicate the control task to CLA and the C28x can be used for control of power stage, However a lot still depends on the system requirements 

    regards

    Manish Bhardwaj

     

  • 0 in reply to Manish Bhardwaj
    Intellectual 645 points

    Hi Manish,

    thank you very much, it helps me a lot!

    Best regards,

    Felix