The Resonance Phenomenon and Analysis of Electric Vehicle Charging Station

With the increasing number of the paralleled LCL chargers in charging station, many of them put up with the problems that some of the charging modules do not work. To solve the problem, a test is carried out in one chosen charging station, and the reason of the problems is analyzed, which is that a resonance occurs between LCL chargers and the grid, leading to a sudden change of reactive power. Then the mechanism of the resonance is analyzed based on the topology and control strategy of the LCL chargers. Finally a simulation model is built with Simulink to verify the correctness of the analyses above. The result shows that under the condition of grid-voltage containing some harmonics, the resonance may take place between paralleled LCL chargers and the grid, and the resonant frequency is decreasing while the number of the paralleled LCL chargers is increasing.