BUCK circuit with voltage closed loop

Working conditions: The input voltage must be greater than 28V, and the resistor outside the enable pin can also be changed to achieve adjustment.
Actual circuit: To change the value of the input and output capacitors, it is best to take a larger value, and the inductor should also use a relatively large value to reduce voltage ripple.
Circuit composition: Use EG3112 as the driver chip and LM358 as the op amp of the sampling circuit.
The code part only gives the PID part. If you need other parts, you can contact
the PID module code:
//Define PID variable structure
struct _pid{
    float SetSpeed; //Define set value
    float ActualSpeed; //Define actual value
    float err; //Define deviation value
    float err_last; //Define last deviation value
    float Kp, Ki, Kd; //Define proportional, integral and differential coefficients
    float voltage; //Define voltage value (variable for controlling actuator)
    float integral; //Define integral value
}pid;
 
//Initialize variables
void PID_Init(float Kp,float Ki,float Kd,float speed)
{
    pid.SetSpeed=speed; //Set value
    pid.ActualSpeed=0.0; //Sampling value
    pid.err=0.0; //Error
    pid.err_last=0.0; //Last error
    pid.voltage=0.0; //Output value
    pid.integral=0.0; //Cumulative integral value
    pid.Kp=Kp;
    pid.Ki=Ki;
    pid.Kd=Kd;
}
 
//Position PID algorithm
 
int PID_realize(float ActualSpeed)
{
pid.ActualSpeed=ActualSpeed; //Input actual value
    pid.err=pid.SetSpeed-pid.ActualSpeed; //Calculate error
    pid.integral+=pid.err; //Integral value
    pid.voltage=pid.Kp*pid.err+pid.Ki*pid.integral+pid.Kd*(pid.err-pid.err_last);
    pid.err_last=pid.err; //Assign the last error
    return pid.voltage; 
  }