UM1561 datasheet(25/39 Pages) STMICROELECTRONICS

25 / 39 page

UM1561

Implementation of digital phase locked loop

Doc ID 023556 Rev 1

25/39

static s16 Delta_Theta=0;

static u16 freq_monitor_time=0;

mul_q15_q15_q31(Input_Integration,SAMPLING_TIME,&Delta_Theta_tmp);

Delta_Theta = (s16)(Delta_Theta_tmp>>16);

Theta=Theta+Delta_Theta;//

Theta_time++;

if(zero_detect==50)

{

VqFiltered_min=65500;

VqFiltered_max=0;

Theta_time=0;

zero_detect=0;

}

VqFiltered_prec = (u16)(Grid_Volt_q_d.qV_Quadrature + 0x8000);

VqFiltered = (u16)(((s32)(((s32)VqFiltered<<8) - (s32)VqFiltered) +

(s32)(VqFiltered_prec))>>8);

if(VqFiltered>VqFiltered_max) VqFiltered_max=VqFiltered;

else if(VqFiltered<VqFiltered_min) VqFiltered_min=VqFiltered;

VqFiltered_mean=(u16)((VqFiltered_max+VqFiltered_min)>>1);

where:

●

Theta=Theta+Delta_Theta;//

is (Grid angle estimation: Theta changes value

linearly each switching period between -32768 to 32768).

The anti-islanding protection is based on grid voltage and frequency monitoring. The “Vq”

DC-component, used for the first, is made up of an offset value (32768) plus a DC-value

function of the AC Vrms value (for example Vac=265 Vrms -> Vq=39080 or Vac=186 V ->

Vq=37150).

//265V max & 186V min

if((VqFiltered_mean>=39080 || VqFiltered_mean<=37150) &&

State_Control==GRID_INSERTION && MPPT_EN==TRUE && zero_detect>5 &&

Vacprot==TRUE)

{

GPIO_ResetBits(GPIOA, GPIO_Pin_1);

State_Control = STOP_WITH_DELAY;

Diagnostic_Control=GRID_VOLTAGE_OUT_OF_RANGE;

}

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