Torque Coordination Control During Mode Transition For A Single-motor Hybrid Electric System

For a single-motor parallel hybrid electric vehicle,the traction motor needs to accomplish the task of driving the vehicle and starting the engine simultaneously during mode transition.A model reference controller(MRC)is proposed in this thesis in order to guarantee the stability of the mode transition.In this control system,the whole mode transition process is divided into two stages.In the first stage,the engine is started through the slipping frictional torque of P2 disconnected clutch.The second stage begins when the engine speed and motor speed difference reaches a threshold.In this stage,using the characteristic of the clutch frictional torque which is only related to the direction of the speed difference between frictional plates to reduce the engine angular acceleration,the synchronization of angular speed and angular acceleration between engine and motor is accomplished rapidly.As the result,the P2 clutch can be locked smoothly.The control system of this stage is an over-actuated system with 3 inputs and 2 outputs.The 3 inputs are the motor torque,the engine torque and the clutch torque.And the 2 outputs are the angular speeds of the different shafts of the clutch.The reference model chosen in this thesis is the dynamics of the output shaft of motor-only driving mode.By reducing the error between the plant and the reference model,a smooth and low-jerk mode transition is achieved.The control quality is tested through Matlab/Simulink simulation and real-time hardware-in-loop simulation.The impact of the threshold is also provided.