Research On Super Capacitor Hybrid Energy Storage System And Control Strategy Of Electric Vehicle

In recent years,the development of electric vehicles,especially pure electric vehicles,has become faster and faster.Most electric vehicles still use lithium batteries as the main source of power during the driving process of electric vehicles at present.However,the shortcomings of lithium batteries such as low power density inhibit the development of electric vehicles.As an energy storage device,lithium batteries need to withstand the impact of high-peak and high-frequency load currents,which greatly shortens the life of lithium batteries.The hybrid energy storage device of Super Capacitor(SC)and lithium battery can transfer the high frequency load fluctuations to the super capacitor,meeting the power demand of electric vehicles under different complex working conditions,and reducing the cost of lithium batteries.The power output burden increases the number of charge and discharge cycles.The Hybrid Energy Storage System(HESS)for electric vehicles containing super capacitors is of great practical significance to the extension of the driving range of electric vehicles,the improvement of energy utilization efficiency,and its reliability.This paper focuses on the research of the super capacitor-lithium battery hybrid energy storage system and control strategy for electric vehicles.The subject first analyzed the charging and discharging performance of super capacitors and lithium batteries and established mathematical models.In order to evaluate the life status of lithium batteries,a semi-empirical model of attenuation based on the Arrhenius model was cited on this basis to estimate the capacity attenuation of the battery.In order to effectively distribute the power given value obtained by the Power Split Strategy(PSS)of the hybrid energy storage system,a new bidirectional DC/DC converter was designed and a small signal model control was proposed.It improves the accuracy of power distribution control.In the parameter optimization of the hybrid energy storage system,the multi-objective optimization method is used to establish the objective function minimization equation,and the number of series and parallel connections of super capacitors and lithium battery cells is obtained,and the dynamic programming method is used to determine the working conditions 1and2 Perform power distribution.For the hybrid energy storage system,a rule-based and frequency-domain power allocation strategy is proposed,and the effectiveness,advantages and disadvantages of the strategy are analyzed.Finally,the overall simulation model of the electric vehicle HESS is designed to verify the power distribution control capability of the newly proposed bidirectional DC/DC converter,and at the same time,the different PSS of the electric vehicle under given operating conditions is simulated and verified.Simulations and experiments have verified that the HESS control strategy of electric vehicle super capacitors in this paper can efficiently distribute the power output of the two energy storage elements,reduce the number of high-current charging and discharging of the lithium battery pack,and inhibit the capacity degradation of the lithium battery.Extend the service life of lithium battery packs and the driving range of electric vehicles.The characteristics of large charge and discharge current and high power density of the super capacitor module improve the utilization rate of the feedback energy.Figure[54]table[10]reference[62]...