Dynamic modelling and systematic control during the mode transition for a multi-mode hybrid electric vehicle

Abstract

A smooth mode transition is critical for the driveability of hybrid electric vehicles and is difficult to achieve owing to transient intervention of torques from the engine, the electric machine and the transmission. This paper presents a systematic control strategy during transition from the motor-only mode to the compound driving mode of a multi-mode hybrid electric vehicle using one electric machine. The proposed strategy divides the mode transition process into four consecutive operating phases and employs a fuzzy gain-scheduling proportional–integral–derivative controller as feedback to adapt various non-linearities. Dynamic modelling of the vehicle system emphasizing the dynamics of the engine, the transmission, the clutches and the drive axle is conducted for validation simulation. Simulation results show that the mode transition controlled by the designed fuzzy gain-scheduling proportional–integral–derivative controller is completed in 700 ms with the vehicle jerk below 3.5 m/s3 and where the produced clutch frictional losses are only 56 J. The performance is better than those controlled by a conventional proportional–integral–derivative controller. A sensitivity study shows the proposed controller has good adaptability to disturbances caused by the changing road conditions, the uncertainties in engine system and the noise from clutch actuation.