基于最小稳定过热度的制冷系统变负荷优化控制

摘要

This paper analyzed the stability mechanism of variable capacity cooling system having a variable compressor and electronic expansion, and identified the minimum stable superheat of the evaporator outlet corresponding with the system cooling capacity through experiments, then verified the minimum stable superheat through the step changing of compressor frequency. Through coordination control compressor frequency with electronic expansion valve opening based on the minimum stable superheat, the experiments were carried out under varying load. Compared with fixed superheat, the results demonstrate that the controller can adapt the changes of running condition and cold load, has the characteristics of good tracking ability without overshoot, high control precision and remarkable effect about COP.%通过对采用变频压缩机和电子膨胀阀的变容量制冷系统稳定性的机理分析与实验研究辨识得到了与制冷量相匹配的蒸发器最小稳定过热度,并通过对压缩机频率阶跃变化下制冷系统的特性分析对最小稳定过热度进行了验证.采用基于最小稳定过热度的压缩机频率和电子膨胀阀开度协调控制方法,在制冷系统变负荷工况下进行了试验.结果表明,该方法很好的适应了制冷系统变工况的控制要求,相比常规的定过热度控制,具有跟踪性能良好、动态控制精度高,并能有效的提高制冷系统的变负荷运行时的性能系数(COP).