| With the development of science and technology, due to the deterioration of the environment and energy problem, electric vehicle has gradually got people’s attention. It has become the most promising new energy industry. As the main power source of electric vehicle, power bat tery is the critical part. Its usage performance has a significant impact on the development of electric vehicle. In this paper, the life prediction of power battery based on the classification of the decline mode for electric vehicle is carried out, and the evaluation of the state of health and the prediction of remaining useful life of power battery under the condition of actual dynamics situation is further discussed.In this paper, we learn the decline mechanism of lithium ion batteries, verify the lithium ion battery charging and discharging experimental data of the National Aeronautics and Space Administration, and analyze the main internal and external factors that influence power battery capacity decline. The study aims at predicting the remaining useful life of power battery by evaluating the state of health. To achieve the accurate evaluation, we define the battery charge capacity as the power battery performance decline evaluating characterization, which is used to calculate current state’s power battery remaining capacity. The decline mode of power battery is established in this paper. On the basis of the concept of decline mode, we use K-means clustering method to obtain a series typical decline mode, use the maximum information coe fficient method(MIC) to complete decline mode classification of power battery and use the method of support vector machine(SVM) curve fitting to finish the performance evaluation of power battery under the condition of a specific decline mode. We apply the method of weighted Markov chain to forecast the future decline mode of power battery, and achieve the prediction of remaining useful life of power battery with the method of linear superposition. In order to verify the feasibility and validity of the proposed method, we carry out confirming study. The design of charge and discharge cycle test is based on the standard of electric vehicle power battery test procedures at home and abroad, and the investigation and analysis of electric vehicle actual using situation. According to the test, we obtain the capacity decline data of the whole life cycle of power battery, and then classify the measured data into eight different typical decline mode s. We evaluate the state of health and predict the remaining useful life of power battery under the condition of a specific decline mode which the data lays on. The predict results are close to the actual measurement results. The prediction is accurate and the error is small.This paper is based on the decline mode clustering and classification. We establish the new power battery life decline mode, achieve the more accurate prediction of the battery remaining useful life under the condition of actual variable situation. It has a perfect guidance to analyze the battery state of charge, monitor the battery state of health, and improve the battery management system. |
