基于限幅模糊PID算法的蓄热性能检测仪密闭绝热双腔体温度控制研究

Temperature Control System of Closed Adiabatic Dual Cavity in Floor Thermal Storage Efficiency Detector Based on Limiting Fuzzy PID Algorithm

【目的】地采暖地板蓄热性能检测仪采用密闭绝热双腔体结构,对试件进行检测时要求上腔体在900 s内达到设定温度为T_0的初始检测条件,温度误差小于±0.25℃,均匀度小于±0.20℃。针对检测腔体对初始温度的特殊要求,提出一种限幅模糊PID算法,以实现对密闭绝热双腔体腔内温度的快速、精准控制。【方法】首先建立限幅带,设Δe>0,且Δe∈N,当测量值与设定值的偏差ε≤|Δe|时,输出增量由PID算法给出;当ε>Δe或者ε<-Δe时,输出增量由模糊推理给出控制输出量。算法中将温度实际值与设定值的误差以及误差变化率划分为若干个论域中的模糊值,并且建立相应的模糊规则,对于任意一个实时温度采样值,控制系统能够自动求出与目标值的偏差,通过模糊算法给出相应的输出量,从而达到上腔体温度快速调节的目的。【结果】1)限幅模糊PID算法在820 s时,上腔体温度达到稳定状态,与原设计相比提前350 s; 2)温度精度达到±0.15℃; 3)腔体内温度均匀度为±0.15℃。【结论】基于限幅模糊PID算法的地采暖地板蓄热性能检测密闭绝热双腔体温度控制系统,可实现通过调节下腔体温度达到对上腔体温度快速、准确调节的目的,为检测初始条件的设定提供可靠保障,提高了整个设备的可靠性,保证了检测结果的准确性。

【Objective】 Closed adiabatic dual cavity structure is used in thermal storage efficiency detector of floor, and the initial set testing condition temperature T 0 which error is less than ± 0.25 ℃, uniformity is less than ± 0.20 ℃ in upper cavity should be realized within 900 s before testing the thermal storage efficiency. Aiming at the special requirements of initial temperature to upper cavity, this paper presents a limiting amplitude fuzzy PID algorithm which could quickly and accuracy get set temperature in closed adiabatic dual cavity.【Method】 Firstly, limiting band should be established,set Δ e 〉0 and Δ e ∈ N. When the deviation of measured value between the set value accord with ε ≤ ｜ Δ e ｜, the output is given by the PID algorithm. And when ε 〉 Δe or ε 〈- Δe, the output is given by fuzzy inference. The deviation, deviation rate of temperature and output are divided into different fuzzy values, and then fuzzy rules are established. For any real-time temperature sampling value, controller can automatically determine the deviation of target value, and output is given by fuzzy algorithm, to achieve the purpose of temperature adjustment in upper cavity rapidly.【Result】 In this paper, the improved fuzzy PID algorithm and the original control algorithm are tested experimentally. The experimental result show that： 1）the upper cavity temperature becomes a steady state at 820 s, 350 s earlier than the original design; 2）accuracy of temperature up to ± 0.15 ℃; 3）uniformity of the upper cavity temperature is ± 0.15 ℃, and all above design meet the design requirements.【Conclusion】 This paper presents a limiting amplitude fuzzy PID algorithm for temperature control in closed adiabatic dual cavity, which achieves a preferable control effect that temperature of upper chamber could regulate by adjusting the lower chamber temperature quickly and accuracy on floor thermal storage efficiency detector. That provides reliable guarantee for setting of initial conditions, improves the reliability of whole device and ensuring the accuracy of testing result .