Mode transition coordination control for parallel hybrid electric vehicle based on switched system

Hybrid electric vehicles equipped with several different power sources can change operation mode to deal with different operating conditions to improve fuel economy and reduce exhaust emissions. Due to the significant difference in the characteristics of the power sources and the discontinuity in the dynamics of the clutch, noticeable torque fluctuations occur during mode transition, which may result in system shock and an uncomfortable riding sensation. Based on the idea of a switched system, we proposed a three-stage control strategy to facilitate a smooth transition from electric mode to hybrid driving mode. In this coordination control strategy, a fuzzy-proportional-integral mixed controller was used to manipulate engine speed and an adaptive sliding mode controller was applied to control the electric motor torque for compensating for torque disturbances. Furthermore, the proposed control strategy was validated on hardware-in-the-loop simulation platform. The results demonstrate the effectiveness of the proposed coordination control strategy to allow improved vehicle drivability.