TMS320F28377D: -

what do you mean by distorted waveform? The waveforms shown above seem to be similar.

Best regards,

Pawan

Sorry for not posting enough information about the errors.

1. the code for sensing is just same as the above. use ADC for sensing grid voltage and then normalize it.

2. next use ABC to DQ0 transform => run SPLL => transform DQ0 to ABC "here is done by using the ti's library"

3. delay 10 seconds for proper PLL operation and after that update the CMPA values to the gate signals so that sine wave can be generated.

During the 1-step, (which is sensing and normalizing), the result was good as I expected. as the figure below.

This result was achieved using the CCS's graph tool using the below code.

    if(Result_idx<BUF_LENGTH){
        CHECK[Result_idx] = VA_pu;
        CHECK2[Result_idx] =duty_A;
        CHECK3[Result_idx] =cmpValueA;
        Result_idx++;
    }

so I think that the sensing and the normalizing doesn't seems to be a problem.

Next, to see if the transformation and the spll is malfunctioning, I looked at the theta value of the spll.

    // Initialize SPLL
    duty_A = 0.5f;
    duty_B = 0.5f;
    duty_C = 0.5f;
    sine_VAL =  0.0f;
    cosine_VAL = 1.0f;
    delta_t = 1.0f / ISR_FREQUENCY;
    SPLL_3PH_SRF_init (RAMP_FREQUENCY, delta_t, &grid_SPLL);

the SPLL is initilized with this values and the theta in the figure is just from this code.

// Update the angle from SPLL
    angleSPLL_radians = grid_SPLL.theta[1];
    sine_VAL = sinf(angleSPLL_radians);
    cosine_VAL = cosf(angleSPLL_radians);

From this sequence, I think the output of the phase voltage should follow the sine wave. but the result of it is somehow distorted.

the blue (CH.2) is the sensed grid voltage (220Vrms, 60Hz) and the yellow(CH.1) is the phase voltage I genereated using the inverter and the posted code.

is there any advice to achieve the pll operation with the grid-tied inverter?

THANK for reading the posted question.

Thank you for the clarification. What are the updates done to the code compared to the TIDA-01606 example? Can you also try with 50Hz grid signal and see if this issue reoccurs?

I can't generate 50Hz, because the grid voltage is fixed to 60Hz. 

Compared to TIDA-01606, 

static inline void TINV_runISR1_lab4(void)
{

    TINV_readCurrentAndVoltageSignals();

    TINV_runTransformOnSensedSignals();

    if(TINV_clearPWMTrip == 1)
    {
       TINV_clearPWMTrip = 0;
       TINV_closeGiLoop = 1;
       TINV_HAL_enableGateRST();
       TINV_HAL_clearPWMTripFlags(TINV_Q1_Q3_A_PWM_BASE);
       TINV_HAL_clearPWMTripFlags(TINV_Q2_Q4_A_PWM_BASE);
       TINV_HAL_clearPWMTripFlags(TINV_Q1_Q3_B_PWM_BASE);
       TINV_HAL_clearPWMTripFlags(TINV_Q2_Q4_B_PWM_BASE);
       TINV_HAL_clearPWMTripFlags(TINV_Q1_Q3_C_PWM_BASE);
       TINV_HAL_clearPWMTripFlags(TINV_Q2_Q4_C_PWM_BASE);
    }

    TINV_runCurrentLoop();

    DQ0_ABC_run(&TINV_vInv_dq0,
                TINV_vdInv_pu, TINV_vqInv_pu, TINV_vzInv_pu,
                TINV_sine, TINV_cosine);

    TINV_duty_A_pu = TINV_vInv_dq0.a;
    TINV_duty_B_pu = TINV_vInv_dq0.b;
    TINV_duty_C_pu = TINV_vInv_dq0.c;

    if(TINV_closeGiLoop == 1)
    {
        TINV_HAL_updatePWMDuty(TINV_duty_A_pu, TINV_duty_B_pu, TINV_duty_C_pu);
    }
    else
    {
        TINV_deadBand = TINV_deadBandMin;
        TINV_HAL_updatePWMDuty(0.5, 0.5, 0.5);
        TINV_HAL_updatePWMDeadBand(TINV_deadBand);
    }

    TINV_runSPLL(TINV_vGrid_dq0_pos.d,
                TINV_vGrid_dq0_neg.d,
                TINV_vGrid_dq0_pos.q,
                TINV_vGrid_dq0_neg.q);

    TINV_sine = sinf(TINV_angleSPLL_radians);
    TINV_cosine = cosf(TINV_angleSPLL_radians);

    if(TINV_startPowerStage == 1)
    {
        if(TINV_vGrid_A_sensed_pu > 0.0f && TINV_vGrid_A_sensed_prev_pu < 0.0f)
        {
            TINV_startPowerStage = 0;
            TINV_closeGiLoop = 1;
            TINV_clearPWMTrip = 1;
        }
    }

The code above is the code I usually use. which is LAB4.

Since I;m not using the current loop control, the current control loop is excluded.

However, the format is same which is 

the ABC to DQ0 transformation, and SPLL (the TIDA-01606 uses use either DDSRF or SPLL) , then DQ0 to ABC transformation.

Thanks