Integrated Optimization of High-Speed Motor Drive and Compressor System: A Case Study

Climate change and decarbonization challenges are forcing the HVAC &R industry to transition to low Global Warming Potential (GWP) and natural refrigerants. Despite the environmental benefits, low-GWP refrigerants often yield to trade-offs in system performance, flammability and volumetric capacity. Compressors need to be optimized to adapt working chambers and displacement volume requirements to the thermophysical properties of the refrigerants. In addition, to meet capacity targets under full- and part-load conditions, variable-speed operation also plays an important role especially during heating conditions. This paper describes an integrated optimization approach that couples the optimization of both compressor geometry and electrical motor for residential heat pump applications with emphasis on colder climates. The modelling framework includes a generalized semi-empirical compressor model as well as a multi-objective electric driver optimization toolbox (EDOT). The two sub-models were trained and validated with an R410A scroll compressor dataset and a detailed Method-of-Moments (MoMs) engine, respectively. A case study of a scroll compressor using Minneapolis weather data and low-GWP replacements has been considered to demonstrate the utilization of the modelling framework and the design trade-offs. The new-designed compressor was found to be 30% smaller in volume than the original design while maintaining a comparable performance.