pid_con.c

大型申请专利项目温控电加热PID调节部分源程序

/*====================================================================================================
   其中包含了读温度的子程序
=====================================================================================================*/
#include<at89x52.h>
#include <string.h>
#include <stdio.h>

#define uint  unsigned int
#define uchar unsigned char
#define PID_CAL_TIME 3 //执行pid运算的时间常数
extern uchar xdata pid_control_time;//执行pid运算的时间变量
extern uint ad_convert(uchar four_in_one);
extern uint  xdata set_temper1,set_temper2;		/*设定温度*/
extern uint  xdata	kp1,kp2,		/*比例常数*/
					ki1,ki2,		/*积分常数*/
					kd1,kd2,		/*微分常数*/
					kz1,kz2;		/* 自定义常数*/


uint PIDCalc( struct PID *pp, uint NextPoint );
void PIDInit (struct PID *pp);
uint read_temperature (uchar sel_tunnel) ;
void PID_control(void);

uchar xdata temper1_ready,temper2_ready;
int   xdata	heat1_time,heat2_time;			/*每个时间片内的加热时间*//*heat*_time的初始值设为100*/
/*====================================================================================================
    PID Function
    
    The PID (比例、积分、微分) function is used in mainly
    control applications. PIDCalc performs one iteration of the PID
    algorithm.

    While the PID function works, main is just a dummy program showing
    a typical usage.
=====================================================================================================*/

xdata struct PID {

        uint  SetPoint;           //  设定目标 Desired Value

        uint  Proportion;         //  比例常数 Proportional Const
        uint  Integral;           //  积分常数 Integral Const
        uint  Derivative;         //  微分常数 Derivative Const

        uint  LastError;          //  Error[-1]
        uint  PrevError;          //  Error[-2]
        int  SumError;           //  Sums of Errors

}PID;

/*====================================================================================================
   PID计算部分
=====================================================================================================*/

uint PIDCalc( struct PID *pp, uint NextPoint )
{
    int  dError,
            Error;

        Error = pp->SetPoint -  NextPoint;          // 偏差
        pp->SumError += Error;                      // 积分
        dError = pp->LastError - pp->PrevError;     // 当前微分
        pp->PrevError = pp->LastError;
        pp->LastError = Error;
        return (pp->Proportion * Error              // 比例项
            +   pp->Integral * pp->SumError         // 积分项
            +   pp->Derivative * dError             // 微分项
        );
}

/*====================================================================================================
   Initialize PID Structure
=====================================================================================================*/

void PIDInit (struct PID *pp)
{
    memset ( pp,0,sizeof(PID));
}

/*====================================================================================================
    进行温度值的采样,输出值为温度值的10倍
=====================================================================================================*/

uint read_temperature (uchar sel_tunnel)                      
{
    uchar i;
    uint ad_data,ad_sum,ad_max,ad_min;
    uint temperature;
    ad_sum=0;
    ad_max=0;
    ad_min=4096;
    for(i=0;i<7;i++)
    	{
    	 ad_data=ad_convert(sel_tunnel-1);
    	 ad_sum+=ad_data;
    	 if(ad_max<ad_data)
    	 	ad_max=ad_data;
    	 if(ad_min>ad_data)
    	 	ad_min=ad_data;	
    	}
    ad_sum-=ad_max;
    ad_sum-=ad_min;
    ad_data=ad_sum/5;
    temperature=((float)ad_data-2458)*1000/3276;	/*temperature的单位为0.1摄氏度*/
    return(temperature);	
}

void PID_control(void)
{
   xdata  struct PID  PID_T1,PID_T2;			  //  PID Control Structure
    uint xdata  temper1,temper2;			  //  PID Feedback (Input),当前的温度值
	if(pid_control_time>=PID_CAL_TIME)
	{
		pid_control_time=0;
	    PIDInit ( &PID_T1 );				  //  Initialize Structure
	    PIDInit ( &PID_T2 );    	          //  Initialize Structure

	
	    PID_T1.Proportion = kp1;              //  Set PID Coefficients
	    PID_T1.Integral   = ki1;				
	    PID_T1.Derivative = kd1;
	    PID_T1.SetPoint   = set_temper1;      //  Set PID Setpoint
		PID_T2.Proportion = kp2;              //  Set PID Coefficients
	    PID_T2.Integral   = ki2;
	    PID_T2.Derivative = kd2;
	    PID_T2.SetPoint   = set_temper2;      //  Set PID Setpoint

	
                               
        temper1 = read_temperature(1);    //  Read Input
        temper2 = read_temperature(2);        
        
        //temper1=380;
        //temper2=380;
        heat1_time = PIDCalc ( &PID_T1,temper1 );      //  Perform PID Interation
        if(heat1_time<=0)
        	heat1_time=0;
        heat2_time = PIDCalc ( &PID_T2,temper2 );
        if(heat2_time<=0)
        	heat2_time=0;        
		}
}