Design Of A Fuzzy Fractional Order PID Controller For Temperature In A Air-Conditioning Room And Its Performance Analysis

With the development of science and technology and the increasing requirements of comfortable degree for the human’s living and working environment, the central air-conditioning systems (CACSs) are widely used in the realm of architecture. However, a CACS offers a comfortable living and working environment to people while it also brings the issue of energy consumption. On the basis of ensuring the requirements of comfortable degree, how to minimize the energy consumption of CACSs to the most degree is a most fundamental problem for the air-conditioning technicians, which makes us pay more attention to the energy-saving control technology on CACSs. For the indoor temperature plants with the characteristics of large time delay and inertia, how to design the reasonable controllers that can regulate the controlled temperature parameters to reach the set value quickly and accurately is the ultimate goal of the control technology of air-conditioning parameters.Based on the theories of fractional PID and fuzzy control, a fuzzy fractional order PID controller for indoor temperature is proposed in this paper by synthesizing the algorithms of fractional order PID control and fuzzy control. The numerical simulations and configurations are executed for the proposed controller and its corresponding control system by Matlab software, and the control performance indexes and the parameters of the proposed controller are analysised and tuned, respectively. The results show that the proposed controller is feasible in theory and achieves the desired control goals. The main research results are as follows.1. Based on the transfer function and block diagram, the input and output characteristics for the air-condition rooms with indoor temperature, air handling units, measuring sensors, controllers, and actuators are mathematically analysised. Meanwhile, the transfer function expressions of the above ones are given.2. On the basis of the requirements of air-conditioning process for the indoor temperature control, the design principle and steps for a fuzzy fractional order PID controller with indoor temperature and the tuning method on control parameters using the fuzzy rules are proposed by synthesizing the algorithms of fractional order PID control and fuzzy control, respectively. The numerical simulations for the proposed controller are executed under refrigeration and heating modes. The results indicate that the proposed controller is feasible and the control performance indexes of the corresponding control system meet the desired requirements.3. For the same controlled plant with indoor temperature, an expert PID controller is applied to it, respectively. A permance comparsion of the proposed controller with an expert PID controller and fuzzy fractional order PID controller for the same controlled plant is carried out. The simulation results show that the fuzzy fractional order PID controller is superior in the performance indexes such as overshoot, control accuracy, regulation time, etc.