| The state of battery used on electric vehicle is the important data of BatteryManagement System. The state of battery is described by the State of Charge or the State ofEnergy. SOC reflect the capacity state of the battery, and SOE reflect the energy state of thebattery.The battery pack is connected to the motor and provide energy for the motor. Theremaining energy of the battery pack is used to describe the ability of the motor and theability of the battery pack. Compared to SOC, SOE is suitable to demonstrate the dischargecapacity of the battery.This subject is from the important project named pure electric grade commercial busdeveloped which is belong to the high-tech electric car company in Jilin Province. Theresearch of the battery management system is an important technology in the project, BMS isused to achieve data, manage and protect the battery pack. The estimation of SOE ismeaningful to BMS, the battery pack can be protected in the process of charging anddischarging to overcharge and overdischarge. The SOE is an important data to achievebalance of battery pack and energy optimization, and predict the driving range.Currently there are many researches in the filed of SOC, and few researches in the filedof SOE, which lead to the differences of the definition of SOE. Generally, the current isstable in the discharge, and the remaining energy is calculated easily and accurately. Butthere is a complex condition in the pure electric vehicle, because of the great change ofcurrent and temperature. The great change of voltage leads to calculate the SOE difficultly.The researchers used a variety of methods on the estimation of SOC, which have differentresults. It is a key to select the appropriate filtering algorithm to estimate the SOE.There are three keys to get the accurate result. the calculation formula of the SOE.Firstly, establish the algorithm of the SOE. Secondly, establish a suitable battery mode.Thirdly, choose the method of the estimation of SOE. According to the analysis of theresearch on state of battery, this paper mainly makes four works. Main contents andconclusions of this paper are as follows: 1．Study the factors which affect the battery charge and discharge according to theexperiments. Get the relation between the ambient temperature, charge and discharge rate,SOH and the energy. Finally, establish the accurate calculation formula of the SOE.2．Analysis the commonly battery models, and consider computation, accuracy, andpractical scope of the model to select the appropriate battery model. Establish the expressionof the battery model through the experiments data, and simulating the accuracy and scope ofthe model by the different discharge conditions.3．The simulink model of the SOE estimation is established based on the unscentedkalman filter algorithm, and simulating the accuracy and scope of the model by the differentdischarge conditions. The Sage-Husa adaptive filtering algorithm is combined into the UKFto change the parameters to improve the estimation accuracy.4．The verification of the SOE based on AUKF is verified on the remote monitoring andcontrol system on pure electric vehicles. Remote Monitoring System has a lot of functions ofreceiving and sending battery voltage, current, temperature, and send the battery data to theSOE estimates model in the Matlab environment by the Configuration software. It canachieve the results of the SOE estiomation.The SOE estimation model is established by the UKF algorithm based on the newexpression of SOE and simplify the electrochemical model. Then compose the adaptivealgorithm with the UKF algorithm to change parameter. The SOE estimation model isestablished based on the AUKF algorithm is more accurately through the experiments andvehicle verification. |
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