Abstract:

Modern heat pumps operate over increasingly wide ranges of temperatures, heat loads, compressor and fan speeds, making robustness of feedback controllers an increasingly critical issue. This paper presents results of a model-based analysis of process gain variation, and identifies a relatively simple approach for scheduling compensator gains for a conventional heat pump feedback architecture. The approach is effective at addressing process gain variation caused by widely ranging values of compressor and fan speeds. To address potential loss of feedback control robustness caused by plant uncertainty that is unmeasured, typically due to heat pump installation and application variability, the theory of unfalsified control is studied. An unfalsified control algorithm is designed for one feedback loop that is particularly susceptible to unmeasured plant uncertainty, and shown to be functional in a nonlinear simulation. Several potential issues associated with maturing unfalsified control theory into a practical technology for application to production heat pumps are discussed.