Control Strategy Design for the Thermal Management System of an Electric Heavy Quadricycle

Electric vehicle thermal management system is essential for electric vehicles to guarantee cabin thermal comfort and battery appropriate operating temperature. As a matter of fact, in such systems, high- and low-temperature driving conditions can severely affect system performance, in terms of overall efficiency and driving range. In this context, an effective thermal management solution both for cabin thermal comfort and battery heating/cooling is investigated in this paper.A key innovation is the deep integration of the HVAC and battery heating/cooling circuits. Primarily, in winter scenario, the heat generated by the powertrain during operation is used to warm the cabin, thereby mitigating the necessity for additional electric cabin heating. This way, despite the inclusion of an extra heat exchanger, a consistent amount of heat can be recovered and the use of the battery energy for electrical heating activation is significantly reduced, as already presented by the authors in a previous study. Furthermore, the HVAC sub-system is designed so as to streamline hot or fresh air to the battery for heating or cooling purposes, respectively, resulting in a comprehensive and integrated solution that enhances overall energy efficiency, with minimum penalizations in cabin comfort.This evaluation employs a 1-D model of the HVAC and battery heating/cooling integrated circuit and a 0-D model to interface it with the vehicle powertrain. A second order electrical equivalent circuit model is employed for the battery, to better capture transient behavior and heat generation, with all the parameters in the model being temperature-and SoC-dependent. Different control strategies are proposed for the management of the thermal system and various driving conditions, including scenarios during summer and winter with different speed profiles, are taken into account to assess their performance.It is important to note that while this integrated approach introduces a degree of complexity, the benefits in terms of energy efficiency are shown to be substantial if the system control logic is designed properly. This multi-faceted analysis contributes valuable insights to the ongoing discourse on optimizing electric powertrains for enhanced performance and efficiency under diverse operating conditions.The analysis carried out allows to effectively determine the influence of the HVAC sub-system on the battery state of charge, and then in terms of driving range, i.e. for the Helsinki driving cycle, the deactivation of the cabin heating allows the increase of about the 30% the driving time. It has been also highlighted how the different control strategy can influence the average battery temperature and as a consequence its internal resistance especially during winter scenario. Due to the high thermal load required during the summer driving conditions, the control strategy seems to be less effective.