变频恒压供水系统设计毕业论文 - 图文

长春工业大学人文信息学院毕业设计（论文）

if(!P3_5)//再一次判断P3.5 是否按下 {

while(!P3_5);//等待P3。5 为高电平 number++;//通道号显示加一 if(number>8)number=1;//八通道 } } }

PID控制子程序 ： #include #include #include struct _pid {

int pv; /*integer that contains the process value*/ int sp; /*integer that contains the set point*/ float integral; float pgain; float igain; float dgain; int deadband; int last_error; };

struct _pid warm,*pid;

int process_point, set_point,dead_band;

float p_gain, i_gain, d_gain, integral_val,new_integ;;

/*------------------------------------------------------------------------ pid_init

DESCRIPTION This function initializes the pointers in the _pid

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长春工业大学人文信息学院毕业设计（论文）

structure

to the process variable and the setpoint. *pv and *sp are integer pointers.

------------------------------------------------------------------------*/ void pid_init(struct _pid *warm, int process_point, int set_point) {

struct _pid *pid; pid = warm;

pid->pv = process_point; pid->sp = set_point; }

/*------------------------------------------------------------------------ pid_tune

DESCRIPTION Sets the proportional gain (p_gain), integral gain (i_gain),

derivitive gain (d_gain), and the dead band (dead_band) of a pid control structure _pid.

------------------------------------------------------------------------*/ void pid_tune(struct _pid *pid, float p_gain, float i_gain, float d_gain, int dead_band) {

pid->pgain = p_gain; pid->igain = i_gain; pid->dgain = d_gain; pid->deadband = dead_band; pid->integral= integral_val;

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长春工业大学人文信息学院毕业设计（论文）

pid->last_error=0; }

/*------------------------------------------------------------------------ pid_setinteg

DESCRIPTION Set a new value for the integral term of the pid equation.

This is useful for setting the initial output of the pid controller at start up.

------------------------------------------------------------------------*/ void pid_setinteg(struct _pid *pid,float new_integ) {

pid->integral = new_integ; pid->last_error = 0; }

/*------------------------------------------------------------------------ pid_bumpless

DESCRIPTION Bumpless transfer algorithim. When suddenly changing setpoints, or when restarting the PID equation after an extended pause, the derivative of the equation can cause

a bump in the controller output. This function will help smooth out that bump. The process value in *pv should be the updated just before this function is used.

------------------------------------------------------------------------*/ void pid_bumpless(struct _pid *pid) {

pid->last_error = (pid->sp)-(pid->pv); }

/*------------------------------------------------------------------------ pid_calc

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长春工业大学人文信息学院毕业设计（论文）

DESCRIPTION Performs PID calculations for the _pid structure *a. This function uses the positional form of the pid equation, and incorporates an integral

windup prevention algorithim. Rectangular integration is used, so this function must be

repeated on a consistent time basis for accurate control. RETURN VALUE The new output value for the pid loop. USAGE #include \ float pid_calc(struct _pid *pid) { int err;

float pterm, dterm, result, ferror; err = (pid->sp) - (pid->pv); if (abs(err) > pid->deadband) {

ferror = (float) err; /*do integer to float conversion only once*/ pterm = pid->pgain * ferror; if (pterm > 100 || pterm < -100) { pid->integral = 0.0; } else {

pid->integral += pid->igain * ferror; if (pid->integral > 100.0) {

pid->integral = 100.0; }

else if (pid->integral < 0.0) pid->integral = 0.0; }

dterm = ((float)(err - pid->last_error)) * pid->dgain;

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