Research On Energy Management System Of Solar Electric Vehicle With Automatic Light Tracing Function

Energy crisis and environmental pollution restrict the development of traditional vehicles.Electric vehicles,as an effective way to solve this problem,have been developing rapidly in the world in recent years.Energy storage system is one of the key technologies of electric vehicles,and also the biggest bottleneck of the development of electric vehicles.Lithium battery is the most widely used energy storage element in electric vehicles,but limited to the current technical level,the performance of electric vehicles with lithium battery as a single energy source is difficult to meet the requirements of vehicle driving mileage and power performance.Solar energy is safe,clean,pollution-free and low cost in use.Super capacitor has the advantages of high power density,fast charge and discharge speed,long cycle life,etc.If solar energy is used to supplement the power of lithium battery and share the peak power of lithium battery by using super capacitor.So the composite energy source system composed of solar cells,lithium batteries and super capacitors is an effective way to improve the driving range of electric vehicles,improve the power performance and prolong the service life of lithium batteries.Aiming at the problems existing in the energy storage system of electric vehicles,this paper studies the key assembly matching,modeling,energy management strategy,performance and optimization of the energy management system of solar electric vehicles with automatic light tracing function.The main research contents and conclusions are as follows:(1)A solar electric vehicle configuration with solar cell / lithium battery / super capacitor as energy source is proposed.The structure of solar electric vehicle composite energy system with automatic light tracing function is determined.According to the vehicle parameters and performance indicators,the key components such as solar cell system,motor,lithium battery and super capacitor are matched.(2)A new automatic lighting tracing system for solar electric vehicles is proposed,including mechanical mechanism and its control scheme.Based on multi-sensor fusion,the position control of solar panel on the roof is carried out in two dimensions,and the angle of solar panel in vertical and horizontal plane is adjusted.The system can automatically turn off,open and adjust solar panels according to the information collected by various sensors,which solves the contradiction between the efficiency of solar energy conversion and the wind resistance of the whole vehicle,and can protect the solar panel.(3)Based on MATLAB / Simulink,a simulation platform of solar electric vehicle with automatic light tracing function is built.According to the vehicle driving dynamics equation,the vehicle dynamics simulation model is established;the solar cell mathematical model is built,which can simulate the output of the solar cell;according to the longitude and latitude position of the vehicle location and the sun’s altitude angle,azimuth angle and yaw angle at the current moment,using the simplified two-dimensional diagram of the mechanical mechanism of the solar automatic light tracing system,the rotation angles of the height angle adjusting motor axis and the azimuth angle adjusting motor axis of the solar automatic light tracing system in the two-dimensional position control of the solar panel are analyzed and calculated.Based on the second-order RC model,the mathematical model and efficiency model of lithium battery is built;based on the equivalent circuit model of super capacitor,the SOC calculation model and efficiency model of super capacitor is built;based on the efficiency characteristics of DC / DC converter,the DC /DC converter model is built.(4)The energy management strategy for the energy system of solar electric vehicle with automatic light tracing function is formulated.Based on the disturbance observation method,the maximum power point tracking model of solar cells is built,which makes the solar cells always output the maximum power under different environmental conditions,and verifies the effectiveness of the disturbance observation method;based on the second-order RC model of lithium-ion battery,the state of charge of lithium-ion battery is estimated by using the forgetting factor recursive least square method and unscented Kalman filter(UKF)algorithm.The accuracy of forgetting factor recursive least square method and UKF algorithm is verified.According to the different working modes of the system,the energy management strategy based on logical threshold value is developed for the solar electric vehicle composite energy system with automatic lighting function.Combined with the annual monthly average solar radiation intensity data of an area,the simulation is carried out under Worldwide Harmonized Light Vehicles Test Cycle(WLTC),New European Driving Cycle(NEDC)and Urban Dynamometer Driving Schedule(UDDS),which verifies that the solar electric vehicle with automatic light tracing function can effectively increase the driving range,and the super capacitor can realize the “peak clipping and valley filling” of the output power of the lithium battery,reduce the peak current of the lithium battery,and effectively extend the service life of the lithium battery.