Advances in design, modeling and control of thermal management systems for electrified powertrains 2019-01-1397
While hybrid electric vehicles (HEVs) bring opportunities of improving fuel economy to tackle
energy and environmental issues, due to added heat source components and distinct driving
modes, they introduce complexities to the associated thermal management systems (TMSs).
Previous studies have shown that a TMS has a significant impact on the energy consumption
of an HEV. An efficient TMS demands a holistic and strategic approach to synthesize design,
modeling and control aspects; however, in spite of earlier efforts on this topic, this strategy has
not been established yet. This paper thus aims to provide a comprehensive analysis of the
state of the art of TMSs and to identify opportunities for future research. Starting from an
observation, the temperature levels of main components in an HEV, various TMS architectures
found in literature were reviewed. Given a TMS topology, component models are required to facilitate controller design, which were analyzed with different levels of abstraction, ranging from first order thermodynamics models to finite element models. Subsequently, relevant control algorithms developed were compared, from rule-based and proportional-integral-derivative (PID) controllers typically for systems with mechanical actuators, to optimal control methods particularly for systems with electrified actuators. It can be observed that TMSs utilizing waste heat recovery technologies and exchanging heat efficiently through proper arrangement of cooling circuits achieved better performance than TMSs without these features. Furthermore, compared with conventional controllers, optimal controllers based on control-oriented models demonstrated remarkable energy consumption reduction. More importantly, in terms of fuel efficiency improvement, an integrated energy and thermal management system outperformed its separated counterpart. It is therefore concluded that, in order to achieve optimal performance, a TMS needs to be incorporated into the high-level energy management system (EMS) of an HEV, where a multi-objective optimization problem is solved, taking into account of topology, technology, size and control optimization.