Research On Energy Management Strategy For TTR-based Plug-in Hybrid Electric Vehicle

Through-the-road(TTR)hybrid electric vehicle is a new hybrid configuration which combines output-power through driving road and has the advantage of multi drive mode.Under the control of reasonable energy management strategy,it could meet the requirements of both dynamic and economic performance and thus has a broader development perspective.Taking TTR hybrid electric vehicle as the main research object,the main work completed in this paper includes parameter matching of power elements,design of rule-based energy management strategy and simulation analysis of vehicle's performance via simulation model.The control effect of the energy management strategy in real bus environment is evaluated by simulation tools of CANoe and through the hardware-in-loop(HIL)platform,online control effect is also verified.The specific contents of this paper include the following aspects.1.Parameter matching of power elements of TTR hybrid electric vehicles.The structure of the vehicle is determined according to the prototype.And the matching results can meet the index of climbing performance and acceleration performance.Besides,by summing up the matching calculation process,a simple motor-parameter-matching software is developed and could greatly reduce computational effort.2.Establishing vehicle model.Firstly,the vehicle is modeled both by AVL CRUISE and MATLAB/Simulink.The former is used to verify the calculation results and ensure they are reasonable and reliable.The latter including driver model,engine model,motor model,BSG motor,transmission system model,power battery model and vehicle dynamic model,which is the basis of design energy management strategy and simulation analysis.3.Rule-based energy management strategy.The energy management strategy consists of two parts including power calculation and power distribution.Driving power is calculated according to maximum driving force at the wheel and braking power is calculated according to output characteristics of vehicle braking system.Before defining the dynamic distribution relationship,vehicle's driving mode is divided into six types which including start mode,motor priority mode,engine priority mode,motor disable mode,high-speed mode and braking mode.The shift schedule of CVT gearbox is determined according to demand power and velocity.The rule-based strategy refers to both the optimal-working-curve control strategy and the equal-fuel-consumption-area control strategy and could balance the dynamic performance and economic performance of the vehicle.4.Simulation and analysis.The energy management strategy is simulated and verified in Simulink environment.The results show that the strategy is reasonable and effective.The vehicle could follow the target driving cycle which proves vehicle's good dynamic performance and the equivalent fuel consumption is about 7.367L/100 km which proves vehicle's good economic performance.By switching the driving mode,SOC curve is decreased at first and then remain stable.Based on CANoe software,the energy management strategy is analyzed under bus environment and is proved to be reasonable.Error between vehicle's velocity data recorded under real bus environment and that under simulink environment is small and the correlation coefficient of the two results is 0.99.Based on real vehicle control units,the energy management strategy is tested by hardware-in-loop platform.The test results based on real pedal signal show that the vehicle could achieve acceleration and braking functions in accordance with the driver's intent.And the test results based on drving-cycle are very similar to the simulation results and the equivalent fuel consumption is about 7.732L/100 km,which shows that the energy management strategy is effective and energy-efficiency and has the potential to be used in real control hardware.