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How to code a dead band of 10us in Arduino?

Former Member

Hello all!

I am trying to run an H-bridge Inverter using Arduino. I am generating PWM pulses through Arduino and using IR2110, I am feeding those pulses to the switches. My problem is, I want to add dead band of 10us in programming it self. I want to generate 4 PWM signals A,B,C and D where A and B will have a deadband. C will be a complimentary wave of A and D will be  complimentary wave for B.
But I am not able to get this deadband by putting  " delaymicroseconds(10); " code.

 

Please help me out for this.

Thanks.

Palash

  • 0

    It isn't really feasible to implement dead band timing on a micro unless it has hardware support in a timer or motor driver peripheral. Many ARM based micros form ST and NXP  and other parts form Microchip and TI offer this feature but the Atmel based Arduino does not.

    You could consider using a driver chip like this:

    http://www.intersil.com/content/dam/Intersil/documents/isl7/isl78420.pdf

    with hardware dead band control (only up to 220nS - your 10uS is much longer than would normally be considered).

     

    It may be that you have outgrown the Arduino (the IR2110 isn't what I would call a beginner's part) and you should perhaps look at better equipped micros.

     

    MK

  • 0 in reply to michaelkellett

    Thanks a lot for your reply! Actually we are running out of time and that is why I thought Arduino Uno would be a nice option to deal with. Can you please suggest some tested circuits for ISL78420 IC so that I can try it? I have to complete my project in a month's time image

  • 0 in reply to michaelkellett

    Also, I wonder if 10us dead time is very much high or it is okay to deal with?

  • 0 in reply to Former Member

    You can't expect to just find a circuit and use it - if you think the ISL78420 might do you need to study the data sheet and any app notes. You can't use chips like this without designing pcbs and making them - so it's good to be very confident that your design will work before you start trying to make it.

     

    With regard to the dead time - think about why you need dead time ?

    You can only decide on the right amount by calculation or simulation. If you post the ciruit you are thinking of using and the specification that it must meet, it might be possible to advise you.

     

    MK

  • 0 in reply to michaelkellett

    Actually, I have done all that for IR2110 so I don't have much time for this. My IR2110 cards are running well so I need only to code a PWM with appropriate dead band. I though you might have worked on that chip and so asked you to share it. Anyways, I have tried to generate the dead band through a code. I will try it tomorrow and post the results here. Proteus is showing some promising results. Will post here if my inverter works fine image

  • 0

    Thank you all for the help!

    I have found the solution.

    Here is the code which generates PWM for 4 switches with deadband:

    ============================================================================

    double pi=3.14159;

    float t=0.0;

    double ws=314.159265;

    double wt=12566.37061;

    double s=0;

    double tri=0;

    int pwm=5;

    int pwm1=6;

    int pwm2=3;

    int pwm3=11;

     

     

    void setup()

    {

      pinMode(pwm,OUTPUT);

      pinMode(pwm1,OUTPUT);

      pinMode(pwm2,OUTPUT);

      pinMode(pwm3,OUTPUT);

    }

     

     

    void loop()

    {

      s=0.8*sin(ws*t);

      double k=8/(pi*pi);

      tri=k*(sin(wt*t)-((1/9)*sin(3*wt*t))+((1/25)*sin(5*wt*t)));

     

      if(s>tri)

      {

        delayMicroseconds(2.5);

        digitalWrite(6,LOW);

        digitalWrite(11,LOW);

        delayMicroseconds(2.5);

        digitalWrite(5,HIGH);

        digitalWrite(3,HIGH);

      }

      else

      {

        delayMicroseconds(2.5);

        digitalWrite(5,LOW);

        digitalWrite(3,LOW);

        delayMicroseconds(2.5);

        digitalWrite(6,HIGH);

        digitalWrite(11,HIGH);

         

    }

     

      //digitalwrite(5,~pwm);

      t=t+0.0031847;

    }

     

    And the output waveform of the inverter:

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    Any suggestions ?

     

    Thanks,

    Palash

  • 0 in reply to Former Member

    how i can change the tri frequency?

     

     

    i need tri frequency 5KHZ.  How i can change ?

     

    ///////

    double pi=3.14159;

    float t=0.0;

    double wt=31415.9265;

    double vcon=0;

    double s=0;

    double s1=0;

     

     

    double tri=0;

     

    int pwm=5;

     

    int pwm1=6;

     

    int pwm2=3;

     

    int pwm3=11;

    char d;

     

    void setup()

     

    {

      Serial.begin(9600);

     

      pinMode(pwm,OUTPUT);

     

      pinMode(pwm1,OUTPUT);

     

      pinMode(pwm2,OUTPUT);

     

      pinMode(pwm3,OUTPUT);

     

    }

    void loop()

     

    {

     

      vcon=0.8;

      s=vcon;

      s1=-s;

     

      double k=10/(pi*pi);

     

      tri=k*(sin(wt*t)-((1/9)*sin(3*wt*t))+((1/25)*sin(5*wt*t))-((1/49)*sin(7*wt*t))+((1/81)*sin(9*wt*t)));

     

     

      if(s>tri&s1>tri)

     

      {

        delayMicroseconds(3);

     

        digitalWrite(5,HIGH);   //1

     

        digitalWrite(3,HIGH);   //2

      

        delayMicroseconds(3);

     

        digitalWrite(6,LOW);  //not 1

     

        digitalWrite(11,LOW);  // not 2

     

     

     

      }

     

      else if(s>tri & s1<tri)

     

      {

     

        delayMicroseconds(3);

     

        digitalWrite(5,HIGH);

     

        digitalWrite(3,LOW);

     

        delayMicroseconds(3);

     

        digitalWrite(6,LOW);

     

        digitalWrite(11,HIGH);

     

    }

      else if (s<tri & s1>tri)

    {

        delayMicroseconds(3);

     

        digitalWrite(5,LOW);

     

        digitalWrite(3,HIGH);

     

        delayMicroseconds(3);

     

        digitalWrite(6,HIGH);

     

        digitalWrite(11,LOW);

      

      

      

    }

    else if (s<tri & s1<tri)

      {

        delayMicroseconds(3);

     

        digitalWrite(5,LOW);

     

        digitalWrite(3,LOW);

     

        delayMicroseconds(3);

     

        digitalWrite(6,HIGH);

     

        digitalWrite(11,HIGH);

       

      }

     

      t=t+0.00031787;

     

    }

     

    Thank,

    Perasak

  • 0 in reply to Former Member

    Look at this   tri=k*(sin(wt*t)-((1/9)*sin(3*wt*t))+((1/25)*sin(5*wt*t))-((1/49)*sin(7*wt*t))+((1/81)*sin(9*wt*t))); You need to calculate a sine wave at the correct frequency of 5Hz.

  • 0 in reply to clem57

    Hi all,  I'm new to Arduino and I have not used a H block before but understand how it operates.  What I don't understand is the dead band.  What is that used for? Thanks for replies. 

  • 0 in reply to dmaruska

    From memory, not a data sheet

     

     

     

    It is the transition time where both upper and lower drivers are off,

     

    without this there is a risk that a momentary shorting path will exist as an upper driver and a lower driver on the same side are transitioning together and provide a direct path from the + Rail to the – Rail (Not through the motor) for a brief time

     

    By having a dead band between turning off the currently conducting drivers and turning on the next pair, it allows the turning off pair to actually turn off before the new ones are on (There not instantaneous as much as we would like them to be)

     

     

     

    I hope I explained that ok

     

     

     

    Peter