Research On Hybrid Energy Storage System Of Electric Vehicle Based On Switching Boost Converter Network

Electric vehicles have become the mainstream direction of automobile development because of their energy saving and emission reduction.The hybrid energy storage system combines high-power-density supercapacitors and high-energy-density Li-batteries through a bidirectional DC-DC converter,which can meet the dual requirements of electric vehicles for energy density and power density of energy storage systems.Therefore,it is of great significance to study related issues such as the power converter topology,control method and power allocation strategy of the vehicle-mounted hybrid energy storage system.This article proposes an on-board hybrid energy storage system for electric vehicles based on a switching boost converter network in view of the problems existing in the on-board energy system of electric vehicles,and analyzes its working principle in detail.The proposed topology can allow the one-phase bridge arm of the inverter to work in a through state,and has the ability to resist electromagnetic interference.This topology provides a bidirectional energy flow path with high voltage gain,which is used for energy exchange between the Li-battery-SC hybrid energy system of electric vehicles and the AC side load.The working principle of the topology is verified by simulation.Secondly,this paper uses the state space averaging method to establish a small signal model of the topology working in boost and buck modes,and obtain the transfer function of the system.Based on the pole-zero diagram,the influence of the inductance,capacitance,parasitic resistance of the inductor,equivalent series resistance of the capacitor and the shoot-through duty cycle in the switching boost converter network on the output response characteristics of the system is analyzed,and simulation verification is carried out.Then,according to the operating conditions of the electric vehicle and the charging state of the energy storage system,a logic threshold-based energy management strategy is adopted to allocate power to the on-board hybrid energy system.The lithium battery is used as the main energy storage component of electric vehicles,and the super capacitor provides the peak power demand of the load and recovers the braking energy.Based on the energy management strategy,a system control block diagram with four controllers is designed to ensure that the battery output current and the super capacitor voltage remain stable,and the AC side current is stable.The voltage and current controllers are designed in the frequency domain according to the Bode plot,and the designed controller has good dynamic characteristics.The energy management strategy is verified through simulation.Finally,an experimental platform with ARM microprocessor and CPLD as the control core is designed and implemented,and the electrical feasibility of the topology and the applicability of the designed controller and control strategy are verified through experiments.