Home Forums General Phase-angle VS Burst-fire

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  • imnull
    Participant
    Post count: 4
    #4806 |

    Hello,

    As I understand this PID control unit is regulate power by Burst-Fire (On-Off) principle.

    Is it possible to regulate a thyristor by Phase-Angle using this PID unit?

    Thanx.

    rocketscream
    Keymaster
    Post count: 65

    Hi,

    Unfortunately currently not implemented on the unit.

    imnull
    Participant
    Post count: 4

    Thanks. Any idea on when it could potentially happen?

    LulaNord
    Participant
    Post count: 1

    Hi…as per my knowledge hase angle control varies the effective voltage by connecting the
    load to the line only during some fraction of each half cycle,
    starting at an adjustable point in each half cycle, and ending at the
    next current zero crossing.Burst control varies the effective average voltage (over a longer
    time) by connecting the load to an integer number of complete half
    cycles in a burst, and then disconnecting the load from the line for
    some other integer number of full half cycles. Some systems use
    integer full cycles, rather than full half cycles, to prevent any net
    DC in the burst waveform. Burst mode has more low frequency ripple
    than phase control, but makes less radio frequency and harmonic noise,
    because all on switching is done very near the zero voltage points in
    the line voltage wave and all switch off points are at zero current
    points in the load current wave.

    imnull
    Participant
    Post count: 4

    I have not got your point.. unfortunately. if you need please follow the link to understand how thing are working
    http://www.bristolwatch.com/ele2/zero_crossing.htm
    OR

    Dimming 230V AC with Arduino

    What I would like is to osPID to be able to control phase angle burst firing control units.

    As I understand there should be changes to existing code in order to control burst firing.. (currently use a potentiometer to control the power = gate voltage).

    Please find below a code to control burst firing on the unit we create. Will it be possible to integrate the code with osPID system, so the system could control burst firing control units as well?

    #define triacPulse A0

    boolean enable = false;
    int timer1_counter;
    int counter = 0;
    int counter_hold = 0;
    int counter_half_period = 0;
    int ctrl_value = 0;
    int ctrl_value1 = 0;
    int ctrl_value2 = 0;
    float tickPerCtrlUnit;
    float ctrl_value_x; // intermediate variable used for calculations
    int control_duration = 5;

    void set_timer1_interrupt() //initializes timer1
    {
    // initialize timer1
    noInterrupts(); // disable all interrupts
    TCCR1A = 0;
    TCCR1B = 0;

    // Set timer1_counter to the correct value for our interrupt interval
    //timer1_counter = 64886; // preload timer 65536-16MHz/256/100Hz
    //timer1_counter = 64286; // preload timer 65536-16MHz/256/50Hz
    timer1_counter = 65071; //17143; //34286; // preload timer 65536-16MHz/256/2Hz
    // 65071 for TCNT1 and prescaler 1 give us 255 timer interrupts for 1 half period (16.67 mS)
    TCNT1 = timer1_counter; // preload timer
    TCCR1B |= (1 << CS10); // prescaler = 1
    TIMSK1 |= (1 << TOIE1); // enable timer overflow interrupt
    interrupts(); // enable all interrupts
    }

    ISR(TIMER1_OVF_vect) // interrupt service routine (to be taken automatically
    // from Arduino libraries
    {
    TCNT1 = timer1_counter;
    digitalWrite(8, (digitalRead(8) ^ 1)); // just for test purposes now
    counter = counter + 1;

    if (enable)
    {
    if (counter == ctrl_value1)
    {
    digitalWrite(triacPulse, HIGH);
    }
    if (counter == ctrl_value2)
    {
    digitalWrite(triacPulse, LOW);
    }
    }
    else
    {
    digitalWrite(triacPulse, LOW);
    }

    }

    // the setup function runs once when you press reset or power the board
    void setup() {
    // initialize digital pin 13 as an output.
    pinMode(7, INPUT);
    pinMode(9, OUTPUT);
    pinMode(0, OUTPUT);
    pinMode(1, OUTPUT);
    pinMode(10, OUTPUT);
    pinMode(A0, OUTPUT);
    pinMode(8, OUTPUT);
    pinMode(A6, INPUT);

    digitalWrite(9, LOW); // turn OFF everything

    // digitalWrite(7, HIGH);

    digitalWrite(10, LOW);
    digitalWrite(0, LOW);
    digitalWrite(1, LOW);
    digitalWrite(A0, LOW);
    attachInterrupt(4, acon, CHANGE);
    set_timer1_interrupt();
    Serial.begin(9600); // for test purposes

    // cli(); // disable global interrupts
    // sei();
    }

    // the loop function runs over and over again forever
    // for now, nothing important for actual functionality of the
    // device
    void loop() {
    if (counter_half_period / 10 == 0)
    {
    digitalWrite(9, (digitalRead(9) ^ 1)); // change D9 for test purposes
    }
    if (counter_half_period > 100) // also for test purposes
    {
    Serial.print(counter_hold);
    Serial.print(” “);
    Serial.print(ctrl_value);
    Serial.print(” “);
    Serial.print(ctrl_value_x);
    Serial.print(” “);
    Serial.print(tickPerCtrlUnit);
    Serial.print(” “);
    Serial.print(ctrl_value1);
    Serial.print(” “);
    Serial.println(ctrl_value2);
    counter_half_period = 0;
    }

    }

    // begin zero crossing interrupt routine
    void acon()
    {
    // noInterrupts(); // disable all interrupts

    counter_hold = counter;
    counter = -1; //initialization ov counter for the next half period calculations\
    tickPerCtrlUnit = counter_hold/255.0; //calculation of number of timer ticks peer unit of control
    digitalWrite(8, LOW);
    counter_half_period = counter_half_period + 1;
    ctrl_value = analogRead(A6)/4; //the result: integer range 0 … 255
    ctrl_value = 255 – ctrl_value; // 255 … 0 now: “0” -> min phase
    // “255” -> max phase

    if (ctrl_value >248)
    {
    enable = false; //disable TRIAC control pulse, because its duration is defined as 5 timer ticks
    } //so minimal phase corresponds approximately 6 timer ticks out of approx.255.
    else
    {
    enable = true;
    }

    ctrl_value_x = ctrl_value*tickPerCtrlUnit;

    if (ctrl_value < 20)
    {
    control_duration = 15;
    }
    else
    {
    control_duration = 5;
    }

    ctrl_value1 = (int)ctrl_value_x;
    ctrl_value2 = ctrl_value1 + control_duration;

    // ctrl_value1 = 255 – ctrl_value;
    // ctrl_value2 = ctrl_value1 + 5;

    // interrupts(); // enable all interrupts
    }

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