基于频域分析的高阶加时滞模型辨识方法

Identification Method of High Order Model with Time Delay Based on Frequency Domain Analysis

工业生产中含有时滞环节的高阶过程对象,由于控制器结构复杂,采用直接设计控制器和传统模型降阶的方法实现起来比较困难,同时噪声会对控制器产生干扰,可能导致这些方法得不到满意的结果。针对这一问题,提出了一种高阶加时滞模型的频域辨识方法,通过对控制回路中过程对象的输入和输出信号进行频谱分析和拉普拉斯变换,得出过程对象在重要频率段上的频率响应特性,采用最小二乘法从幅值和相位两方面拟合成一个一阶或二阶加纯滞后传递函数,最终获得对象模型。通过MATLAB仿真结果验证了所提方法的有效性和精确性。

For the high-order process objects with time delay in industrial production, it is difficult to implement the direct design of the controller and the traditional model order reduction method due to the complex structure of the controller. In addition, the interference of noise to the controller generate unsatisfactory results. In order to solve this problem, this paper proposed a frequency domain identification method of high order plus time delay model, through the process plant in the control circuit of input and output signal frequency spectrum analysis and Laplace transformation, it was concluded that the frequency of the process plant on important frequency could response characteristics, and the least square method is used in both amplitude and phase fitting a first or second order plus pure lag transfer function, finally the plant model is obtained. At last, MATLAB simulation results verified the effectiveness and accuracy of the proposed method.