Research On Nonlinear Control Strategy Of Hybrid Energy Source System For Electric Vehicle Based On Passivity-Based Control

In recent years,energy shortages and environmental pollution issues have forced people to carry out research on new energy vehicles actively,especially electric vehicles.In order to meet the requirements of driving range and dynamic performance,this paper combines the batteries with high energy density but low power density and short service life with the supercapacitor with high power density,high current charging and discharging speed but low energy density to form a hybrid energy source,which can fully exert the characteristics of the two energy sources and realize the complementary advantages between them.To make up for the lack of single energy source as the power source of the electric vehicles.This article mainly focuses on the nonlinear control strategy of the bi-directional DC/DC converter and the energy management strategy of the hybrid energy sources for electric vehicles.In electric vehicles,the stability of the DC bus voltage affects the working performance of the vehicle’s motor directly,so it is very important to control the DC bus voltage.In this paper,maintaining the stability of the DC bus voltage as the main control objectives,the system’s Brayton-Moser(BM)model and Port-Controlled Hamiltonian(PCH)model are constructed to study the nonlinear control strategy of the bi-directional DC/DC converter.In this paper,the passivity-based control in nonlinear control is selected as the emphases for research,and three passivity-based control strategies are analyzed including Power Shaping Passivity-Based Control(PS-PBC),Sliding Mode Control Passivity-Based Control(SMC-PBC)and Interconnection and Damping Assignment Passivity-Based Control(IDA-PBC).By Matlab/Simulink simulation,the effectiveness of passivity-based controllers is verified,and compares the control effects of the three passivity-based controllers on the stability of the DC bus voltage.This paper analyzes the driving speed and power demand of electric vehicles under six typical cycling conditions,determines the FTP-75 condition as the basic condition of energy management strategy in this paper.In order to give full play to the characteristics of the two energy sources,the idea of primary and secondary energy sources is adopted.Taking the rated power of the battery and the state of charge of the supercapacitor as the logic threshold,arule-based energy management strategy is designed.Combining the energy management strategy with the nonlinear control strategy,the Matlab/Simulink simulation results verifies two strategies can achieve a reasonable distribution of load power between energy sources,and at the same time ensure the stability of the DC bus voltage under FTP-75 operating conditions.The experimental platform of the hybrid energy source system is built,and the relevant experimental verification of the controller designed in this paper was conducted.The experimental results are consistent with the simulation results,proving the effectiveness of the interconnection and damping assignment passivity-based controller and the rule-based energy management strategy.