电子膨胀阀的分段式变增益PID控制研究--以环境试验箱为案例

Research on Segmented Variable Gain PID Control of EEV--Taking Environmental Test Chambers as an Example

以蒸发器出口过热度为控制对象的传统电子膨胀阀PID调节策略,难以兼顾制冷系统降温和稳态工况。本文对电子膨胀阀采用过热度和间室温度偏差双反馈的分段式变增益PID控制方案进行分析和研究,并与传统的定增益PID控制方案进行对比验证。试验结果表明:环境试验箱采用变增益PID控制方案,降温速率平均提高11.8%~49.3%,超调时间平均缩短7.1%~57.7%,恒温期间间室温度波动度降至0.1℃,并且在-40、-20、0、20℃不同间室温度下均有良好的变工况适应性。

The electronic expansion valve is regulated by considering the superheat at the outlet of the evaporator as the control object.However,the traditional proportion integration differentiation(PID)control strategy fails to simultaneously consider the dynamic pull-down and steady-state performance of the refrigeration system.In this study,a segmented variable-gain PID scheme involving double feedback of the superheat and compartment temperature deviation is analyzed and compared with the traditional constant-gain PID scheme with single feedback.The results of the environmental test chamber demonstrate that at a constant temperature,the variable-gain PID scheme increased the pull-down rate by 11.8%-49.3%,decreased the overshoot time by 7.1%-57.7%,and reduced the temperature fluctuation to 0.1℃.This method also adapted well to variable working conditions at compartment temperatures of-40℃,-20℃,0℃,and 20℃.