Adaptive Hybrid Thermostat Control Strategy for Series Hybrid Electric Vehicles

For series hybrid electric vehicles (SHEV), rule-based strategies are realistic and powerful in real-time applications. However, the previous rule-based strategy cannot strike a balance between the best fuel economy and the best battery performance while maintaining the advantages of real-time applications. In order to obtain higher efficiency and reduce battery consumption, we have developed an adaptive hybrid thermostat strategy. On the basis of maintaining the load leveling of the thermostat strategy, the threshold-changing mechanism is added to realize the adaptive adjustment of the engine starting power under different SOC conditions, so as to achieve the goal of prolonging the battery life. In addition, the more fuel-efficient emergency handling rules designed to further reduce comprehensive fuel consumption. Finally, the effective battery power obtained through the battery aging model is introduced in the comparison of the test results, which scientifically verifies the effectiveness of the strategy. The results show that the proposed strategy strikes a balance between better fuel economy and healthier battery operation. Specifically, compared with the thermostat strategy with better economic performance, the proposed strategy provides 6.39% fuel economy increase in FTP-75×3 and 48.76% battery life optimization in WLTC×4. Compared with the power follower strategy which is more conducive to battery operation, it provides 15.67% fuel economy growth in CLTC×4 and 38.97% battery life optimization in FTP-75×3.