Research On Energy Management Strategy Based On Dual-mode Power-split Hybrid Electric Vehicle

Power-split hybrid electric vehicles(HEV)have great potential for fuel economy because of combining the advantages of Serial HEVs and Parallel HEVs.However,due to its complicated structural characteristics of power-split hybrid vehicles,the energy management strategy has a direct impact on vehicle dynamics and fuel economy.In this paper,a dual-mode power-split hybrid vehicle model is taken as the research object.The structure of the powertrain is analyzed and then the vehicle model is established.Based on this,two kinds of energy management strategies are developed,i.e.,a rule-based strategy and an equivalent consumption minimization strategy(ECMS).Then,both strategies are simulated and verified.First,the logic threshold control strategy based on engine optimal rules is developed.The engine speed is divided into three sections according to the brake specific fuel consumption(BSFC),i.e.,low,medium and high sections.Two motors are used to regulate and compensate the engine speed and torque combined with the optimal operation curve of the engine respectively,to ensure the engine operating near the optimal operation curve.Then the control strategy is developed in Simulink software environment and the vehicle model is established by using AMESim.So the strategy is verified by Simulink/AMESim cosimulations.In the ECMS strategy,an equivalent factor is proposed which is calculated from the perspective of power flow based on the equilibrium relationship between power consumption and compensation of the battery.Thus,the reference value of equivalent factor is determined,and adjusted combined with the actual driving condition and based on SOC feedback.In addition,the equivalent factor is adjusted in real-time by using a PI controller.Finally,a hardware-in-the-loop(HIL)simulation platform based on PT-LABCAR is developed to verify the proposed ECMS control strategy.Comparing with simulation results of rule-based control strategy,the results show that the design of equivalent factor proposed in ECMS strategy is effective in maintaining the battery SOC at the target value,and have better fuel economy meanwhile.