With the popularity of electric vehicles, a large number of charging stations connected to the grid, will bring about tremendous influence on the power, voltage and current of grid. This paper briefly introduces several common types of charging mode, and analyzes the characteristics of them. According to statistics, a resistive model of charging stations, simulating the regional power grid with a IEEE34 node model, has been established to forecast the daily load curve, using Monte Carlo simulation. An analysis is performed for a power grid to demonstrate the impacts of the daily load curve considering different power of charging stations, which are under coordinated charging conditions, to indicate the harm of uncoordinated charging and put forward solutions.

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The large scale development of electric vehicle will have both benefits and potential stresses on power grid. It is shown that uncoordinated charging of EVs’ on the grid will produce series of problems, while intelligent charging can improve the operation of the power grid. In this study, based on several scenarios of charging modes, such as plug and charge, night charging and intelligent charging, the corresponding EV load models have been established. Therefore, an analysis is performed for the load characteristics of Shandong power grid to demonstrate the impacts of different EV charging scenarios. The results demonstrate that rational utilization of EVs’ load and energy storage property can help to decrease the maximum load of grid and the peak-valley difference, to stable load, and to raise the utilization of the power facilities.

An accurate mathematic model of permanent magnet synchronous motor (PMSM) is necessary for precise torque control and/or high efficiency drive control. This paper discusses the development model of PMSM by taking all losses and saturation into account. In the proposed model, all losses composing of the copper loss, core loss, mechanical loss and stray loss were analyzed to improve the torque equation. In addition, considering the influence of saturation level, the variations of the core loss resistance, direct-quadrature axis magnetic inductance and permanent magnet flux were discussed on support of the data analyzed by Ansoft. In order to verify the developed model, a start up simulation is performed in the mode of open-loop and the results confirm the validity of the model.

In order to propose reasonable method of harmonic suppression for EV charging station, three methods that are 6-pulse rectifier with APF, 12-pulse rectifier, PWM rectifiers are analyzed and compared. Firstly,the corresponding simulation model of charger and charging station are built based on the principle of EV charger and the main method of harmonic suppression. Then the harmonic content and power factor for different simulation model are researched. Meanwhile, the advantages and disadvantages of different simulation model are studied according to the results of simulation, the use of performance and economy. At last, the improvement measure and development direction for three methods are proposed.