Research On Energy Management Control Strategy Of Range-extended Electric Vehicle

The range-extended electric vehicle with motor direct drive and two power sources of engine and battery is considered as an ideal transition model from fuel vehicle to pure electric vehicle.As the key technology of vehicle development,the energy management control strategy of range-extended electric vehicle involves the power distribution of engine and battery,which directly affects the fuel consumption,emission,power and other performance of the vehicle.Through in-depth study of the energy management control strategy,the reasonable energy flow and mode switching between the two power sources can be achieved to reach the best control effect.This paper takes a range-extended light truck as the target vehicle to study the energy management control strategy.Based on the forward simulation model of the whole vehicle built with Simulink,This paper focuses on analysis and comparison of the two common rule-based control strategy and the Equivalent Consumption Minimum Strategy is designed.The rapid control prototype test system is built to verify the Strategy in real time.The main contents of the research work are as follows:(1)According to the configuration characteristics of the range-extended electric vehicle,the parameters of the main components are calculated,and based on the component's parameters obtained from bench test,the forward simulation model of the range-extended electric vehicle is built under the MATLAB / Simulink environment,which mainly includes the component(traction motor,battery,engine,generator,vehicle)model,driver model and controller model.(2)Aiming at the problem of battery life decay,a semi empirical battery capacity decay Simulink model is established to characterize the battery life decay degree with effective ampere hour flux.Two control strategies commonly used in Engineering:single point thermostat control and engine multi-point control are established by Stateflow.The two control strategies are simulated and analyzed with the comprehensive fuel consumption per 100 km and the percentage of battery capacity attenuation as evaluation indexes.The simulation results show that under the control of single point thermostat,the fuel consumption is lower because the engine always works at the highest efficiency point,but the battery life is more serious than that under the engine multi-point control because of the frequent charging and discharging of large current.(3)The adaptive Equivalent Consumption Minimum Strategy is designed.Based on the configuration of the range-extended electric vehicle,the value of the equivalent factor is studied and adaptive control is added to improve the self adaptability of the strategy.The fuel consumption is set as the objective function of the system,and the power distribution ratio of the engine and battery is determined by solving the instantaneous optimal control.The simulation results show that the SOC fluctuates smoothly and the fuel consumption is close to the single point thermostat control,but the battery life is greatly improved compared with the two rule-based control strategy.(4)Using Veri Stand software and NI PXI hardware,a rapid control prototype test system is built.The simulation model is compiled by RTW tool and downloaded to the lower computer of the rapid control prototype.The upper computer monitoring interface is designed in Veri Stand,and the energy management control strategy is verified under the mode of manual throttle and cycle condition.