code for dc -dc converter

emmanuelbabu · April 22, 2015, 3:45pm

Im working on a dc-dc buck boost converter, with 2 different switching elements for bidirectional operation:

#include <PID_v1.h>
#include <math.h>

float pwPin1 = 5;
float pwPin2 = 6;
float analogPin1 = 1;
float analogPin2 = 2;
float analogPin3 = 3;
float value1 = 0;
float value2 = 0;
float boostDuty = 0;
float buckDuty = 0;
int v1 = 0;

double Input1;
double Output1;
double Setpoint1;
double Input2;
double Output2;
double Setpoint2;

double aggKp1 = 1, aggKi1 = 0.5, aggKd1 = 1;              // settiing aggressive values of Kp Ki Kd for PID1
double consKp1 = 0.1, consKi1 = 0.05, consKd1 = 0.25;    // settiing aggressive values of Kp Ki Kd for PID1

double aggKp2 = 1, aggKi2 = 0.5, aggKd2 = 1;              // settiing aggressive values of Kp Ki Kd for PID2
double consKp2 = 0.1, consKi2 = 0.05, consKd2 = 0.25;    // settiing aggressive values of Kp Ki Kd for PID2

PID myPID1(&Input1, &Output1, &Setpoint1, consKp1, consKi1, consKd1, DIRECT);        //PID1
PID myPID2(&Input2, &Output2, &Setpoint2, consKp2, consKi2, consKd2, DIRECT);        //PID2

void setup()
{
  pinMode(pwPin1, OUTPUT);                                //set PWM 5 to output
  pinMode(pwPin2, OUTPUT);                                //set PWM 6 to output
  Input1 = analogRead(analogPin1);                               //take feedback of output in boost mode to PID1
  Input2 = analogRead(analogPin2);                               //take feedback of output in boost mode to PID2
  Setpoint1 = 777;                                        // set point for PID1
  Setpoint2 = 491;                                        // set point for PID2
  myPID1.SetMode(AUTOMATIC);                                // turn ON PID1
  myPID2.SetMode(AUTOMATIC);                                //turn on PID2
  TCCR0B = TCCR0B & B11111000 | B00000001;                  // set freq. of PWM to 62.5kHz
}

void loop()
{
  TCCR0B = TCCR0B & B11111000 | B00000001;
  Input1 = analogRead(analogPin1);
  Input2 = analogRead(analogPin2);
  v1 = analogRead(analogPin3);

  double gap1 = abs(Setpoint1 - Input1);                 //distance away from setpoint
  double gap2 = abs(Setpoint2 - Input2);                 //distance away from setpoint

  if (gap1 < 10)
  {
    myPID1.SetTunings(consKp1, consKi1, consKd1);
  }
  else
  {
    myPID1.SetTunings(aggKp1, aggKi1, aggKd1);
  }

  if (gap2 < 10)
  {
    myPID2.SetTunings(consKp2, consKi2, consKd2);
  }
  else
  {
    myPID2.SetTunings(aggKp2, aggKi2, aggKd2);
  }

  if (v1 <= 511 && v1 > 306)
  {
    do            // boost converter  fn.
    {
      Input1 = analogRead(analogPin1); //read A2
      boostDuty = 1 - (Input1 / 778);  //calculate boost  duty ratio
      myPID1.Compute();
      analogWrite(pwPin2, (boostDuty * 255 * Output1)); //write to D6

    }
    while (v1 > 306);

  }

  else
  {
    do   //buck converter fn.
    {
      Input2 = analogRead(analogPin2);
      value1 = Input2 / 4.01;
      buckDuty = value1 / 202;
      myPID2.Compute();
      analogWrite(pwPin1, buckDuty * Output2);
    }
    while (v1 < 511);
    
    v1 = analogRead(analogPin3);
    if (v1 = 0)
      analogWrite(pwPin1, 0);
  }
}

As per value of v1 the buck mode or boost mode gets selected.Im facing the following problems:

The buck mode does not seem to generate a PWM??
Ive used 2 seperate PID fns. ...can someone please check wether ive applied correctly? especially the output statement?
I based the duty ration of buck & boost fn on the basic voltage eqn. for buck and boost converter...is that fine...and ive multipled it with output1 & output 2 of PID??
The processor is heating up??why?
Is the if ..else statement used for selecting boost and buck function correct???

Ive attached the power circuit diagram for your reference..

Please help have a project submission.....

Thanks & regards
Emmanuel

system · April 22, 2015, 4:33pm

float pwPin1 = 5;
float pwPin2 = 6;
float analogPin1 = 1;
float analogPin2 = 2;
float analogPin3 = 3;

Pin numbers are NOT floating point values.

I quit reading at that point.

MarkT · April 22, 2015, 4:56pm

The S and D markings on your "switches" seem at odds with the diodes marked.

You have no high-side driver?

emmanuelbabu · April 23, 2015, 5:16am

hi MarkT/PaulS

Thanks for the reply...

I havent shown the driver but ive considered the same...its a TLP250 opto -driver....ill correct the S..D foul up...

The value to pins are integers??

could you please help me out with the following points:
"

The buck mode does not seem to generate a PWM??
Ive used 2 seperate PID fns. ...can someone please check wether ive applied correctly? especially the output statement?
I based the duty ration of buck & boost fn on the basic voltage eqn. for buck and boost converter...is that fine...and ive multipled it with output1 & output 2 of PID??
The processor is heating up??why?
Is the if ..else statement used for selecting boost and buck function correct???
"

Emmanuel

nickgammon · April 23, 2015, 5:23am

Please edit your post, select the code, and put it between [code] ... [/code] tags.

You can do that by hitting the "Code" button above the posting area (It looks like a scroll with < > inside it).

How to use this forum

  v1 = analogRead(analogPin3);
    if (v1 = 0)
      analogWrite(pwPin1, 0);

do            // boost converter  fn.
    {
      Input1 = analogRead(analogPin1); //read A2
      boostDuty = 1 - (Input1 / 778);  //calculate boost  duty ratio
      myPID1.Compute();
      analogWrite(pwPin2, (boostDuty * 255 * Output1)); //write to D6
    }
    while (v1 > 306);

Where does v1 change in that loop?

system · April 23, 2015, 6:50am

float pwPin1 = 5;

Input pins can float, but that doesn't mean . . .

nickgammon · April 23, 2015, 6:54am

float pwPin1 = 5;

You could also consider making it const. Is the number 5 going to change?

anon57585045 · April 23, 2015, 7:12am

Please post a complete schematic, including the Arduino connections and optoisolators. You will need it to get a good grade on the project, anyway...

Then maybe we can tell you why it is heating up. Or it will dawn on you as soon as you look at it.

emmanuelbabu · April 23, 2015, 7:37am

Please edit your post, select the code, and put it between [code] ... [/code] tags.

You can do that by hitting the "Code" button above the posting area (It looks like a scroll with < > inside it).

How to use this forum
  v1 = analogRead(analogPin3);
    if (v1 = 0)
      analogWrite(pwPin1, 0);
Gammon Forum : Electronics : Microprocessors : Arduino programming traps, tips and style guide
do            // boost converter  fn.
    {
      Input1 = analogRead(analogPin1); //read A2
      boostDuty = 1 - (Input1 / 778);  //calculate boost  duty ratio
      myPID1.Compute();
      analogWrite(pwPin2, (boostDuty * 255 * Output1)); //write to D6
    }
    while (v1 > 306);
Where does v1 change in that loop?

v1 is from analog pin 3, it is connected to a supercapacitor which discharges from 2.5V to 1.5V...

emmanuelbabu · April 23, 2015, 7:41am

AWOL:
float pwPin1 = 5;
Input pins can float, but that doesn't mean . . .

i think i got the syntax wrong...what i meant was "PWM pin no. 5 is a float value and variable name im using for pin no.5 is pwPin1 ..."?????

nickgammon · April 23, 2015, 7:49am

v1 is from analog pin 3, it is connected to a supercapacitor which discharges from 2.5V to 1.5V...

Now answer my question:

Where does v1 change in that loop?

emmanuelbabu · April 23, 2015, 7:53am

aarg:
Please post a complete schematic, including the Arduino connections and optoisolators. You will need it to get a good grade on the project, anyway...

Then maybe we can tell you why it is heating up. Or it will dawn on you as soon as you look at it.

ok...will do best i can to put it online...

emmanuelbabu · April 23, 2015, 7:55am

Ok...v1 is not updated in that loop....right?i.e i havent called the analogRead there...?correct?

emmanuelbabu · April 23, 2015, 7:56am

no. 5 does not change...its not a constant...but it referes to PWM pin 5....cud you pl tell me th correct declaration.???

nickgammon · April 23, 2015, 8:07am

 const byte pwPin1 = 5;

emmanuelbabu · April 23, 2015, 8:16am

ok...thanks ...could you pl have a look at the PID part input and out put of PID..?

emmanuelbabu · April 23, 2015, 3:12pm

# include <math.h>
#include <PID_v1.h>

const byte pwPin1 = 5;
const byte pwPin2 = 6;
int analogPin2 = 3;
int analogPin1 = 0;
float v1 = 0;
float boostDuty = 0;
float buckDuty = 0;

double Input1;
double Output1;
double Setpoint1;

double aggKp1 = 2, aggKi1 = 1, aggKd1 = 2;              // settiing aggressive values of Kp Ki Kd for PID1
double consKp1 = 0.1, consKi1 = 0.05, consKd1 = 0.25;    // settiing conservative values of Kp Ki Kd for PID1

PID myPID1(&Input1, &Output1, &Setpoint1, consKp1, consKi1, consKd1, DIRECT);        //PID1

void setup()
{
  pinMode(pwPin1, OUTPUT);
  pinMode(pwPin2, OUTPUT);
  Setpoint1 = 778;                                        // set point for PID1
  myPID1.SetMode(AUTOMATIC);                                // turn ON PID1
  TCCR0B = TCCR0B & B11111000 | B00000001;
}

void loop()
{
  TCCR0B = TCCR0B & B11111000 | B00000001;
  Input1 = analogRead(analogPin1);
  v1 = analogRead(analogPin2);
  double gap1 = abs(Setpoint1 - Input1);                 //distance away from setpoint

  if (gap1 < 10)
  {
    myPID1.SetTunings(consKp1, consKi1, consKd1);
  }
  else
  {
    myPID1.SetTunings(aggKp1, aggKi1, aggKd1);
  }


  do
    {
      v1 = analogRead(analogPin2);
      Input1 = boostDuty;
      myPID1.Compute();
      boostDuty = 1 - (v1 / 778);  //calculate boost  duty ratio
      analogWrite(pwPin2, (Output1*boostDuty)); //write to D6
      if ( boostDuty > 0.603 || boostDuty < 0.3421) {
        analogWrite(pwPin2, (boostDuty = 0));
      }

    }
    while (v1 > 307);
  }

Ive implemented a PID from the example, the PID does not seem to be responding, can some one please check the if there is any syntax error in the implementation??

Emmanuel

system · April 23, 2015, 4:37pm

what i meant was "PWM pin no. 5 is a float value

No. PWM pins are either on or off, just like any other digital pin. The difference is that they are off and on with quite short intervals between the changes. The duty cycle, another int value, defines the ratio of on to off and off to on intervals, but the intervals are ints. There is nothing about a PWM pin that involves a float - not the pin number, not the value written to a PWM pin, and not the value read from a PWM pin.

emmanuelbabu · April 26, 2015, 10:00am

PaulS:
No. PWM pins are either on or off, just like any other digital pin. The difference is that they are off and on with quite short intervals between the changes. The duty cycle, another int value, defines the ratio of on to off and off to on intervals, but the intervals are ints. There is nothing about a PWM pin that involves a float - not the pin number, not the value written to a PWM pin, and not the value read from a PWM pin.

thanks paulS..

do you have an example code for implemention a PID function with autotune??

i have to implement that in the code...ive been searching for an example code which uses the required syntax on arduino.cc,...but couldnt get any??

Emmanuel

emmanuelbabu · April 26, 2015, 10:02am

Hi!

does anyone have an example code for implemention a PID function with Autotune??

i have to implement that in the code for my project...ive been searching for an example code which uses the required syntax on arduino.cc,...but couldnt get any??

Topic		Replies	Views
PID controller General Guidance	17	6196	May 5, 2021
Unstable duty ratio PWM on pin 5 & 6 @ 62.5kHz Programming	12	4227	May 5, 2021
Duty cycle not updating General Guidance	21	3079	May 5, 2021
Dc/DC Converter project - Arduino switches by itself when connected to circuit Motors, Mechanics, Power and CNC	21	7176	May 6, 2021
Arduino PID Library News	123	146966	May 6, 2021

code for dc -dc converter

Related topics