###### Abstract  
The performance and efficiency of green energy sources in electric vehicles (EVs) are significantly affected by operation temperatures. To maintain the optimal temperatures of a hybrid energy system (HES), an innovative hybrid thermal management system (IHTMS) was designed. The IHTMS contains a coolant pump, a heat exchanger, a proportional valve for hybrid flow rates, five coolant pipes, and three electromagnetic valves to form two mode-switch coolant loops. A Matlab/Simulink-based simulator of the IHTMS was constructed by formulating a set of first-ordered dynamics of temperatures of coolant pipes and energy bodies using the theories of [PERSON]'s law of cooling and the lumped-parameter technique. Parameters were majorly derived by measured performance maps and data from the experimental platform of the IHTMS. To properly manage the optimal temperatures, four control modes were designed for inner-loop form and outer-loop form. For the experimental platform to verify the simulator, two power supplies generated the waste heat of dual energy sources calculated by the driving cycle and vehicle dynamics. Simulation results show that the temperatures were controlled at their optimal ranges by proper mode/loop switch. With the inner-loop mechanism, the rise time of optimal temperature decreased 27.4%. The average simulation-experiment temperature error of the battery was 0.898 \({}^{\circ}\)C; the average simulation-experiment temperature error of the PEMFC was 4.839 \({}^{\circ}\)C. The IHTMS will be integrated to a real HES in the future. fuel; battery; electric vehicle; thermal management system; control strategy +
Footnote †: journal: Applied Sciences  
and lithium dendrite formation [2]. Similarly, for the proton exchange membrane fuel cells (PEMFCs), to protect the systems, several issues are required to be concerned: keeping 60-80 \({}^{\circ}\)C operation temperature, thickness of membrane, humidity of membrane and reaction gas pressures [3]. From the above, the improvement of these concerns, especially for the temperature control (thermal management), the cooling system will enhance the charge/discharge efficiency, and extend the life cycle of the energy sources so that the green vehicle performance will be raised. Meanwhile, the concept of \"hybridization\", which was proposed recently, has been successfully employed to several vehicles such as EVs and HEVs. For example, a three-power-source hybrid powertrain was developed, and a proposed optimal control of integrated energy management/mode switch timing led to significant energy and CO\({}_{2}\) reduction [4]. For dual in-wheel motors (IWMs) designs for EVs, the global search method (GSM) was used for optimal control strategies and motor sizing selection [5]. For the comparison of control strategies of hydrogen fuel cell vehicles, the equivalent consumption minimization strategy (ECMS), peaking power source strategy and fuzzy logic control strategy (FLCS) were used to compensate the inherent drawbacks of lower power density and less power response of fuel cells [6]. It proved that the ECMS increased the operation efficiency, reduces the cost and it decreased the fuel consumption. In this research, an emulated fuel cell/battery hybrid power system was developed while the hybrid thermal control technique was designed. To efficiently analyze the thermal effect for green energy source prior to experiments, system modeling and numerical simulation are necessary. To minimize aging by adopting the optimal charging strategy, the battery model was built so that the operation conditions (temperature, aging, state-of-charge) were input and the optimal fast charging was selected [7]. A thermal model of full-size-scale cylindrical battery pack cooled by channeled liquid flow was developed [8]. For another study, the charging and discharging C-rate (2 C, 1 C or 0.5 C) were given for simulation and experimental verification. The study reviewed the factors (i.e., high C-rate charge/discharge, aging, etc.)