Research On Identification And Control Algorithm Of Solar Fresh Air System

Solar fresh air system is a new type of cleaning system that can improve the indoor living environment in winter.This system not only overcomes the shortcomings of traditional heating methods such as high energy consumption and serious pollution,but also solves the problem of poor indoor air quality.The research on its modeling and control issues is of great significance for improving the thermal utilization rate of the entire system,reducing building thermal energy consumption,and achieving building micro energy consumption.In order to establish a mathematical model of the solar fresh air system,this paper analyzes the operating mechanism of the controlled object in the system,determines the structural form of the system model,obtains the parameter information of the system model through system identification methods,and establishes a mathematical model that can characterize the input and output characteristics of the solar fresh air system.In order to achieve stable control of solar fresh air systems,a fresh air controller is designed based on fuzzy sliding mode control algorithm.The main content of this article are as follows:(1)Researched the structure and operating principle of solar fresh air system,analyzed the operating modes of the system and determined the corresponding operating conditions for different operating modes.According to the system characteristics,regard the heat exchange equipment at the end of the system as the control object of the fresh air system.(2)The mathematical model of the controlled object of the fresh air system was established.Firstly,by analyzing the operating principle of the controlled object,the structural form of the system model was preliminarily determined.Secondly,using the system parameter identification method to establish the mathematical model of the fresh air system: adopting the disturbance rejection identification method based on forgetting factors to overcome the impact of colored noise signals in the identification data on identification accuracy;using a one-dimensional time-delay search strategy to identify unknown time-delay parameters in the system model;by establishing an auxiliary model of the controlled object,a complete identification vector was constructed.Finally,combining the above three methods,the parameters of the solar fresh air system model were identified based on system operation data,and a more accurate system model was established.After verification,the introduction of forgetting factor enhances the identification algorithm’s ability to track colored noise signals and improves the identification accuracy,the identification algorithm used in this paper can accurately estimate the system parameters under the interference of different initial values and different levels of white noise.(3)A fuzzy sliding mode controller for solar fresh air was designed.In order to suppress sliding mode chattering and improve the control performance of the system,a variable power function approach rate was adopted and a fuzzy controller was used for adjusting the weight parameters in the approach rate.The characteristics of the power function in the approach rate function were utilized to reduce the switching gain when the system state approaches the sliding mode surface and improve the approach speed when the system state is away from the sliding mode surface.The Lyapunov stability criterion was utilized to verify the stability of the established solar fresh air fuzzy sliding mode control system.The comparative analysis of MATLAB simulation were conducted.Compared with PID control algorithm,the control algorithm used in this paper has the characteristics of no overshoot,fast response speed,and strong anti-interference ability.Compared with conventional fuzzy sliding mode control algorithms,the control algorithm used in this paper can effectively shorten control time and suppress sliding mode chattering.