Research on Coordinated Control of Engine and Motor in Hybrid Vehicles for Improving the Economic Performance

The coordinated torque management strategy of the P2.5 hybrid system is based on the engine torque management, engine speed management, the catalyst heat time control and the motor torque control. The specific contents are as below:1)The engine torque control. The intake pressure control, the idle speed control and the reserved torque control are included.2)The engine speed control. The engine speed control is to control the engine speed towards a requested target engine speed from the automatic gearbox.3)The catalyst heat time control. The transition of the stage mainly depends on the model temperature of catalytic converter. When the catalytic converter model temperature is greater than the threshold value, the catalytic converter will exit the heating stage and enter the second stage, and the engine starts to output power with the car.4)The motor charge torque control. When the catalytic converter heating is in the parking condition, the motor is requested to generate electricity to impose a certain load on the engine to accelerate the heating speed of the catalytic converter. In the driving condition, the engine load is maintained stable by the motor assist.The vehicle results are conducted and show that the emission management control can be decreased the fuel consumption by 26.15% compared to the traditional vehicles.