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TIDA-01606: TIDA-01606 current control loop

Part Number: TIDA-01606

Hello my friends, I'm trying to understand the software for TIDA-01606 bidirectional inverter/PFC but i have something that i didn't understand.

Why in the current loop they use Grid current instead of inverter current?

 // In function TINV_readCurrentAndVoltageSignals() Line: 404 (in tinv.h)
TINV_iInv_A_sensed_pu = TINV_iGrid_A_sensed_pu;
TINV_iInv_B_sensed_pu = TINV_iGrid_B_sensed_pu;
TINV_iInv_C_sensed_pu = TINV_iGrid_C_sensed_pu;
.
.
.
//Then, the abc2dq0 in function TINV_runTransformOnSensedSignals()
//Line: 578 (in tinv.h)
ABC_DQ0_POS_run(&TINV_iInv_dq0_pos,
TINV_iInv_A_sensed_pu,
TINV_iInv_B_sensed_pu,
TINV_iInv_C_sensed_pu,
TINV_sine, TINV_cosine);
.
.
.
//Current loop in function TINV_runCurrentLoop() Line: 631 (in tinv.h)
TINV_gi_id_out =
TINV_GI_RUN(&TINV_gi_id, TINV_idRef_pu, TINV_iInv_dq0_pos.d);

TINV_gi_iq_out =
TINV_GI_RUN(&TINV_gi_iq, TINV_iqRef_pu, TINV_iInv_dq0_pos.q);

All the researches that I read and MATLAB simulation models deal with inverter current not grid current. Can anyone explain this to me?

Thank you in advance

  • Dear Ahmed,

    Thanks for your interest in the sequent reference design. As can be seen from the schematic of the board, the currents can be measured from both the grid and the inverter sides.

    Control loops of the current can be closed by using both the currents:

    • Inverter current feedback is when you are closing the current loops from the inverter current;
    • Grid current feedback is when you are closing the current loops from the grid.

    Here, a list of info related to these two control strategies:

    Inverter current feedback:

    • very common in industry because it allows you to also use the current measurement for protection of the half-bridge. This solution is cheaper.
    • Controlling the power plant is easier. You do not have to add any damping effects.

    Grid current feedback: 2

    • if you really want to keep under control the current that is flowing in the grid this can be a solution (like implemented in the reference design).
    • Sometimes the capacitors of the PFC will collect external current ripples (typically inductors towards the grid are small). These currents can be removed by using this measurement technique.
    • You do not have to compensate the reactive capacitive current with the inverter. It is done automatically. In this way, you have a direct control of the real P and Q pushed in the grid.

    I hope I have fully answered your questions.

    Best regards

    Riccardo

  • Thank you very much. This answers my queries.