"Operation Strategies of Heat Pump Systems in High-Performance Electric Vehicles"

"The energy consumption of a thermal management system cannot be neglected and is a significant contributor compared to the total energy consumption of a battery electric vehicle. Using a heat pump as part of the thermal management system, can heat and reduce energy consumption at low ambient temperatures. A state-of-the-art heat pump system consists of numerous actuators such as fans, pumps, electrical heater, compressor, and valves. An existing challenge remains to develop efficient operational strategies for these components with the corresponding interactions in dynamic boundary conditions. A physical model of the system can be used to optimize the control method and consequently, helps to save energy. The objective of this investigation is to obtain an operating strategy, which efficiently distributes the electric power between the heat pump compressor and the electric heater. In this context, the influence of an optimized, model-based control of the compressor speed on the efficiency of the overall system is analyzed in a Model-in-the-Loop simulation. This operational strategy development is based on a holistic model of a high-performance electric vehicle heat pump system using the object-oriented language Modelica. In particular, the characteristics of a high-performance vehicle heat pump system are addressed by modeling the actuators, such as expansion valves and compressor. The validation of this model is performed by using experimental data reflecting the steady-state and dynamic behavior of the system. In summary, a system operating strategy improvement can be achieved by the dynamic system model, controllers designed for the system and the associated analyses. The results show an energy savings potential and an improvement in the overall COP of 15% at an ambient temperature of -10?C compared to a non-optimized operational strategy of the heat pump system. "