| Facing the increasingly serious environmental and energy problems, the international community pay close attention to electric vehicles, which have the advantage of low carbon and energy saving. Because of the uncertainty of EVs’ charging activities in time and space, free charging may lead to power consumption increase during the peak load of the power grid and system efficiency reduction. Therefore it has a prospective significance and practical value in improving the accept capacity of power system, reducing the adverse effect and promoting its technology fusion with Smart Grid, to research the charging load characteristic of electric vehicles and its impact to power system.The vehicular charger is mainly consist of active power factor correction (APFC) and DC/DC power conversion. In this paper, three kinds of control strategies of APFC are compared and the applicability of common DC/DC power conversion circuits is analyzed firstly. According to parameters of the vehicular charger in the laboratory, its simulation model is built up in PSCAD environment, in which the APFC average current control and the constant current-constant voltage charging mode are designed and realized. In order to obtain the OCV-SOC curve of power battery, the intermittent discharge method is used in testing on three group lithium battery. Then the OCV-SOC static model is established and its parameters are determined by the fitting tool of Matlab. On this basis, a battery model suitable for electric vehicle charging is built, and its accuracy is verified through comparison between simulation results and actual curves. Finally steady-state and voltage control experiment are conducted on the vehicular charging system in the laboratory. The experimental results show that the active power of charger is a constant power characteristic, and its reactive power has a linear relationship with voltage, which can be described by a static load model. |
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