中文摘要：

针对可在不同环境温度下制取高温热水的复叠式空气源热泵系统，运用二级压缩比大致相等的原则确定最优中间温度从而控制中间冷凝压力的方法。采用适用性较好的比例一积分一微分（ProportionIntegrationDifferentiation，PID）算法，利用可编程逻辑控制器（ProgrammableLogicController，PLC）进行核心控制，通过实验验证了在不同的室外环境温度条件下，面对负荷的变化，该系统控制快速、平稳且精确，实现了对复叠式空气源热泵系统的优化控制。

英文摘要：

For the cascade air-source heat pump operated under different environment temperature, the proper control of intermediate pressure is important. In this paper the principle that two stage compression ratio is approximately equal is used to determine the interme-diate pressure at the optimal middle temperature. The proposed method and control strategy were implemented by highly applicable Propor tion Integration Differentiation （PID） algorithm and Programmable Logic Controller（PLC）. A test was conducted, and it showed that the control method was sensitive, stable and accurate with various outside conditions and indoor loads.