| With the society development, the natural resources consuming and pollution problem are aggravating seriously. Electric vehicle has been focused more and more by people for its clean and high energy efficiency. The most widely used power source, Li-ion battery, still has the problem of bad performance at low temperature. At low temperature, battery resistance is increased seriously, battery capacity is decreased and charging process is limited. These problems make the electric vehicle developing hardly at alpine region. This paper studies the battery pack heating system to solve the problems.Firstly, battery performance tests are made at different temperature with three different material batteries, the influence on capacity, open circuit voltage and resistance with different temperature is obtained. The battery equivalent circuit model is built and the reason of battery performance decrease at low temperature is analyzed with electrochemical reaction.Secondly, the heating effects of different heating methods are analyzed. The electro thermal film heating method is selected as the final heating method with considering heating effect and feasibility. The battery pack and heating system are designed and manufactured.Finally, the battery heating effect is simulated by COMSOL. According to the simulation result, the heating strategy of partition heating power control is proposed to decrease the temperature difference. The heating tests are made at different temperature, the test result shows that, the proposed heating strategy has the well heating effect and the battery performance can be effectively increased. |
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