热电阻PT10 PT100 Cu50 Cu100电阻转温度程序

ID:54731 · 发表于 2015-1-27 12:46

热电阻PT10 PT100 Cu50 Cu100电阻转温度程序
/*******************************************************************************
*函数描述:PT10&PT100 Cu50&Cu100 热阻转温度
*输入变量:R 热阻阻值
      type热电阻类型 0 PT10
                              1 PT100
                              2 Cu50
                              3 Cu100
*返回变量:float T 温度
*******************************************************************************/
float RtoT(float R, uchar type)
{
      uchar R0;  // 热电阻0度时阻值
      float T, tmp, min, mid, max;
      float x, y, z;
      float d = 3.9083/1e3, b = -5.775/1e7, c = -4.183/1e12;

      if(type <= 1)
      {
            if(type == 0)
            {
                     R0 = 10; min = 1.852; mid = 10; max = 39.049;  // Pt10
            }
            else
      {
                     R0 = 100; min = 18.52; mid = 100; max = 390.49; // Pt100
         }
            if(R>=mid && R<=max)
            {
                     y = sqrt(d*d - 4*b*(1-R/R0));
                     T = (y-d) / (2*b);  // 得出温度
            }
            else if(R<mid && R>=min)
            {
                     x = 0; y = -100; z = -201;
                     tmp = R0*(1 + d*y + b*y*y + c*(y-100)*y*y*y);
                     while(fabs(tmp-R)>=0.007)
                     {
                              if(R > tmp)
                              {
                                    x = x; z = y;
                                    y = (x+y)/2;
                              }
                              else
                              {
                                    x = y; z = z;
                                    y = (y+z)/2;
                              }
                              tmp = R0*(1 + d*y + b*y*y + c*(y-100)*y*y*y);
                     }
                     T = y;  // 得出温度
            }
      }
      else
      {
            if(type == 2)  // Cu50
                     R0 = 50;
            else          // Cu100
                     R0 = 100;

            x = 150; y = 50; z = -50;
            tmp = R0*(1 + 4.289/1e3*y - 2.133/1e7*y*y + 1.233/1e9*y*y*y);
            while(fabs(tmp-R)>=0.007)
            {
                     if(R > tmp)
                     {
                              x = x; z = y;
                              y = (x+y)/2;
                     }
                     else
                     {
                              x = y; z = z;
                              y = (y+z)/2;
                     }
                     tmp = R0*(1 + 4.28899/1e3*y - 2.133/1e7*y*y + 1.233/1e9*y*y*y);
            }
            T = y;
      }

      return T;
}