| Now,as an effective way to solve the current environmental and energy problems in China,electric vehicles have been vigorously promoted by the government.However,in the process of the promotion of electric vehicles,there are still a lot of technical problems,especially in the energy storage device of electric vehicles.At present,the energy storage devices used mainly in electric vehicles are lithium ion power batteries.It has been shown that with the decrease of temperature,the internal resistance of the lithium ion power battery increases exponentially,which leads to the speed of the capacity attenuation of the power battery.When the temperature is reduced to a certain value,the battery is difficult to charge and discharge.These problems have greatly hindered the promotion of electric vehicles in the north.The electric bus with semi-active composite energy storage system in the north area was used as the research object in the dissertation.The mathematical model and constraint conditions were established according to the kinetic formula.The mathematical model and constraint conditions were established according to the kinetic formula.Moreover,on the basis of the working conditions of urban roads in Harbin,a convex optimization was proposed,in which temperature was considered.The optimal allocation results were compared with the rule based power allocation method.Moreover,the energy efficiency and the power battery output were compared and analyzed.The results of simulation analysis shown that compared with the rule based power allocation method,the proposed method had improved the comprehensive energy efficiency by 2.42% and 1.45% respectively in summer and in winter.In summer and winter,the maximum change rate of battery power was reduced by 10.19% and 56.51%,respectively.The power variance of this method was 8.66 k W.Compared with the rule based power allocation strategy,the average power variance of the battery was reduced by 20.11% in winter. |
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