A Trajectory-based Bumpless Switching Control of Multi-Evaporator Air-Conditioning Systems

Multiple-evaporator/vapor compression cooling systems are used for air conditioning in multi-zone buildings with a refrigerant supplied to each individual zone-evaporator from a central compressor/condenser unit. Such systems, incorporating controlled electronic expansion valves associated to each evaporator and a variable-speed compressor, allow the overall system to be able to operate in different modes in order to achieve cooling requirements and energy efficiency. Switching between the different modes associated with the cooling demands might give rise to switching transients. Such transients are likely to negatively impact the control performance and consequently the energy efficiency of the overall system. In this paper, a novel technique is proposed for dealing with such transients when switching between control modes in a multiple-evaporator/vapor compression cooling system in order to ensure that the control performance undergoes no degradation. The proposed approach is purely a “data-driven” technique using only the plant input/output measurements available in real-time. A simulated experiment with a two-evaporator/vapor compression cooling system shows that the proposed algorithm can achieve a quite satisfactory overall performance under mode switching.