Abstract: [Objective] Closed adiabatic dual cavity structure is used in thermal storage efficiency detector of floor, and the initial set testing condition temperature T₀ 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 Δe >0 and Δe∈N. When the deviation of measured value between the set value accord with ε ≤|Δe|, 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.

Key words: fuzzy PID algorithm, closed adiabatic dual cavity, thermal storage efficiency detection, temperature control