Control strategy for all the mode-switches of hybrid electric vehicle

This article focuses on the mode-switch control of a new type of full hybrid electric vehicle with a torque-limiting clutch and an overrunning clutch. The working mode regions of hybrid electric vehicle are divided according to the characteristics of the engine and motor. The target-required torque of the power source in each working mode is determined by a rule-based control strategy for optimal system efficiency. To reduce the torque fluctuation and improve the ride comfort of the vehicle, the coordinated torque control strategy has been proposed during the mode-switch process. The fuzzy control strategy of the oil pressure loaded on the torque-limiting clutch has been put forward. To improve the ride comfort during the mode-switch, the motor has been used for compensation of the rest of the vehicle-required torque according to the clutch-transmitted torque and the output torque of the engine. The dynamic model of the system in each mode-switch has also been established. The simulation has been conducted using MATLAB/Simulink platform for all the mode-switches. Furthermore, the experiment of the motor-assisted engine starting process with the proposed control strategy has been carried out. The result of the experiment is consistent with that of the simulation, and the control strategy proposed in this article is effective for the mode-switch control.