Decoupling control of a cascaded heat pump system for multi-temperature transport

Multi-temperature transport systems enable the simultaneous transport of goods with different temperature requirements. Currently, most existing systems are limited to either cooling or heating the compartments, restricting their use to specific goods and ambient temperature conditions. Therefore, this work proposes a novel system architecture featuring three temperature-controlled compartments, utilizing two cascaded vapor compression heat pumps to enable energy-efficient combined cooling and heating of the compartments. However, the control of multi-temperature transport systems is known to be challenging, especially due to the coupled dynamics that can cause unwanted temperature deviations in the compartments, potentially leading to damage or loss of goods. To address this issue, we present a control strategy based on feedback linearization to decouple the system, allowing for individual temperature control of each compartment. The robustness of this control concept against unknown disturbances and parameter uncertainties of the model is investigated. Simulation results demonstrate the performance and effectiveness of the decoupling control concept, achieving a 15% reduction in temperature deviations compared with a conventional control scheme without decoupling.