【文章內(nèi)容簡介】
urate mathematical models, control theory is difficult to use other technologies, the system controller structure and parameters must rely on experience and onsite missioning to determine, when applied PID control technique is more convenient. That is, when we do not fully understand a system and the controlled object, or can not be an effective means of measurement to obtain system parameters, the most suitable PID control technology. PID control, in practice there are PI and PD control. PID controller is the error according to the system, using proportional, integral, differential calculation of the volume control to control. Proportion (P) controlProportional control is the most simple control method. The controller39。s output and the input error signal proportional. When only a proportional control system output when there is steadystate error (Steadystate error). Integral (I) control In integral control, the controller39。s output and the input error signal proportional to the integral. An automatic control system into the steady state if there is steadystate error, claimed that this control system is called a steadystate error or poor system (System with Steadystate Error). In order to eliminate steady state error, the controller must introduce the integral term. Integral term of the error depends on the time integral, as time increases, integral term will increase. Thus, even if the error is very small, integral term will increase over time to increase its promotion of the controller output increases to further reduce the steadystate error, until zero. Therefore, the ratio of + integral (PI) controller allows the system to enter steady state of no steady state error.Differential (D) control In the differential control, the controller output and differential input error signal (ie, rate of change of error) is proportional to. Automatic control system to overe the errors in the adjustment process of oscillation or even instability may occur. The reason is because of greater inertia ponents (links), or a lag (delay) ponent, can inhibit the role of error, the changes always lag behind changes in the error. The solution is to change the role of inhibition of error, ahead, that is close to zero in the error and suppress the role of error should be zero. This means that the controller only the introduction of the ratio item is often not enough, th