中央空调中一类不确定性模型的MFAC研究

Study on one kind of model with uncertainty based on MFAC in central air-conditioning

中央空调运行过程中设备老化、非线性和外部因素等原因造成一阶惯性加滞后模型的不确定性,从而导致原来控制参数失效.针对此种情况运用无模型自适应控制(Model Free Adaptive Control,MFAC)方法,研究由于不确定性而造成过程增益、时间常数和滞后时间变化——单参数变化、二参数变化和三参数变化时,对MFAC性能的影响.通过MATLAB仿真,分析模型参数变化对调节时间和超调量的影响以及与PID控制效果的比较,结果表明MFAC具有很好的稳定性和抗干扰性以及对时延变化的不敏感,故可使用MFAC解决中央空调系统中时延变化较大而导致控制性能变差的问题.同时该结果也表明对于具有不确定性的一阶惯性加滞后系统,过程增益、时间常数不确定性很大时使用MFAC效果亦不理想.

The fact that the aging equipments, nonlinearity and other external factors combine to make one-order plus delay-time process model uncertain in central air-conditioning, makes the initial control parameters uneffective. Aimed at one-order plus delay-time process model with uncertainty in central air-conditioning, the MFAC（Model Free Adaptive Control） is introduced in studing the control characters. At one parameter, two parameters or three parameters of the model’s process gain, the time constant and delay time would change because of the uncertainty and The control effects also change. The changes on the overshoot and settling time are simulated and compared with PID, which show that MFAC are the characters of good stability and anti-interference and is insensitive to the change of delay-time. Therefore, MFAC proves to be suitable for solving the problem of control failure caused by changing delay time. The study results also show the MFAC method may have no good effect on one-order plus delay-time process model with big uncertainty on process gain and time constant parameters.