Study On Hybird Power Energy Management System Of Micro Electric Vehicle

Electric vehicle has the advantages of energy saving, environmental protection, highefficiency etc. However, the current vehicle power battery cannot solve the dualrequirements of specific energy and power to the power supply system of electric vehicle.A single power supply of electric vehicle has a series of problems, such as battery energyloss, short battery life, brake energy recovery is not sufficient, etc. The reasonablecombination between power batteries and ultra-capacitors, which can effectively solveabove mentioned problems, the power and economy have been improved greatly.In this paper, about the hybrid power energy management system of Micro-EV, themain research contents are as follows:Through experimental to obtain the OCV-SOC characteristic curves and pulsedischarge voltage time response characteristic curves of LiFePO4power battery,established the improvement of the two order RC equivalent circuit model, combined withthe characteristic curves and based on forgetting factor RLS algorithm, designed theestimation algorithm of the online parameter of LiFePO4power battery equivalent circuitmodel. At the same time, combined the equivalent model parameters online estimationwith the LiFePO4power battery SOC estimation, designed the joint estimation algorithmof LiFePO4power battery and equivalent circuit model parameters and SOC estimation,suitable for application in practical working environment. Analysed the characteristic ofultra-capacitors and bi-directional DC/DC converter, and established the equivalent modelof ultra-capacitors and a bidirectional DC/DC converter.Designed the application structure of hybrid power system of electric vehicle, andanalyzed its working principle, combined with power distribution control objectives ofcomposite power supply and formulated its working modes; designed the main circuitstructure of composite power supply, gave a detailed analysis of the various workingmodes.According to the performance requirements of electric vehicle, combining the roaddriving cycle finished the performance calculation of vehicle on power systemrequirements, and chieved the reasonable matching of LiFePO4batteries andultra-capacitors hybrid power in their respective parameters.Based on logic threshold and fuzzy control theory, completed the hybird power energy management control strategy, through the second development of automobile simulationsoftware ADVISOR2002, a hybird power supply model of Mico-EV was built, so thatdone the road driving cycle simulation, comparative analysis of two kinds of controlstrategies.Finally, based on the Freescale microprocessor MC9S12DP512, used the relatedmodule, and carried on the corresponding extension of the peripheral circuit, to detect thevarious performance parameters of hybird power supply, fault diagnosis, alarm and CANcommunication function. According to the design of the hardware and control strategy,designed part of software the program flow chart.