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TIDA-01606: How to properly control the current?

Gavin Chen
Prodigy 50 points
Part Number: TIDA-01606

Tool/software:


Hi,
Excuse me, there is a sentence in Lab7,
"Set the AC input voltage to 230 VRMS with appropriate current limit."
How to do appropriate current control?
Thanks,

  • +1
    TI__Expert 7855 points

    Gavin,

    that current limit is referring to the AC power source current limit as a mean of protection for your test in case something goes wrong.

    Just as you would set a current limit on any lab power supply, depending on how much load you expect to draw off the output voltage rail.

    In the lab 7, the example only tests at 200W off the 800VDC output.  

    Iline current limit = Total Power / (Vphase 3 * efficiency) = 200W /(230V*3*0.9)

    Iline current limit = 0.32 A

    That means, you should set your ac power supply current limit say ~0.5 A.  There is no reason to have the current limit set to 10A if you're expected to test only 200W.

    -Kelvin

  • 0 in reply to Kelvin Le THS
    Prodigy 50 points

    Hi Kelvin,
    Does this mean that I can't set iline trip limint too high in main.sysconf? (Currently set to 50)
    I want to explain the problem I encountered.
    We use a generator in Lab7 to do AC->DC conversion. Because its frequency is not fixed, the frequency range is set to 5Hz~330Hz.
    Before testing, TINV_BOARD_PROTECTION_IINV_A/B/C, but we set these to 0 (because fault_iInvA_overCurrent or B or C is also overcurrent) first turn off.
    So far, only once in the middle of the test did the PFC successfully start and briefly reach 400V DC (AC is only 47~53V L-L) and then it was fault_iGridA_overCurrent (A/B or C) overcurrent,
    So I was wondering, is there any way to limit the current to the minimum range before starting the pfc? And then relax it?

    Thanks,

  • 0 in reply to Kelvin Le THS
    Prodigy 50 points

    Hi Kelvin,
    I just understood what you meant. You mean limiting the input current on the AC power supply?
    But I am using a generator now, and the current is uncontrollable...
    Today, in order to verify whether the igrid is really overcurrent, we set TINV_BOARD_PROTECTION_IGRID_A/B/C to 0, and then it was troublesome!
    Yes, the mosfet on the board burned out XD

  • 0 in reply to Kelvin Le THS
    Prodigy 50 points

    Hi Kelvin,
    Excuse me, how is this 0.835 calculated?
    #define TINV_VREF_DEFAULT ((float32_t)0.835)
    Because we have another scenario of 800V DC in -> 220V AC (L-L) out, when 0.835 is set, the output voltage is too high.
    Currently, I halve this value and then slowly increase the voltage to 220V AC.
    thanks