HEV mode transition strategy based on fuzzy sliding mode control

Hybrid electric vehicles are one of the most practicable technologies in the automobile industry to conserve resources and to protect the environment. Mode transitions between different modes are critical to improve fuel economy and driving performances. Due to the response delay of the engine and the engagement of the clutch, smooth transitions are sometimes difficult to achieve. Fuzzy sliding mode control based on the gain of the switching term is adopted in this paper to reduce the jerk and frictional losses during mode transition by controlling the ISG torque. The main focus of the controller is to make the engine clutch speed follow the motor clutch speed. Thus, the speed difference between the two sides of the clutch can be reduced smoothly. The joint simulation results show that fuzzy sliding mode control can achieve smaller vehicle jerk and less clutch frictional losses compared with conventional methods.