The complex coupling relationship in the cooling branch of direct-cooled battery thermal management systems leads to increased difficulty in controlling the temperature of the occupant compartment and the battery of electric vehicles as well as high energy consumption under high-temperature conditions in summer. In order to solve these problems, this study designed a secondary throttle (ST) orifice opening control at the refrigerant outlet of the battery branch and proposes a new cooling control strategy based on a deep reinforcement learning (RL) algorithm to control the compressor speed (N_compressor) and ST orifice opening. We also compared the performance of the RL control strategy and the proportion integration differentiation (PID) control under two different working conditions. The results show that the RL control strategy could better control the passenger compartment and battery cold plate at 22 °C and 20 °C, the system superheating was also more stable, and the compressor energy consumption (W_compressor) was 0.33 kW h⁻¹ and 0.38 kW h⁻¹ under a uniform climbing condition and NEDC condition, which were 5.7% and 7.3% lower than those of the PID control strategy, respectively.

Proton exchange membrane fuel cells (PEMFCs) have the advantages of long operation cycles, high energy efficiency, and no pollution of reaction products. Temperature is an important factor to ensure the operation of fuel cell systems. Too high temperature will cause irreversible damage to the proton exchange membrane, and too low temperature will greatly reduce the power generation efficiency of fuel cells. Therefore, the effective thermal management temperature control can ensure the stable operation of the system under steady state and dynamic variable load. It can also improve the reaction efficiency of the fuel cell system and prolong the life of the fuel cell. This paper mainly summarized the cooling mode and control strategy of PEMFCs based on thermal management system. The application of different cooling methods is further discussed. The characteristics of traditional proportional-integral-derivative (PID) control, fuzzy PID control, predictive control, adaptive control, and other common thermal management control strategies were described in detail. The research status of scholars in various countries were analyzed, respectively, and the cooling effects of different strategies are compared. Through the review and research on the temperature control of PEMFCs, it is found that the stable operation of the stack is inseparable from the coordination of reasonable cooling mode and control strategy.