Üç faz çiftyönlü elektrikli araç şarj devresinin modellenmesi ve simülasyonu

The aim of this research is to investigate how an electric vehicle (EV) charger with controllers performs and affects the EV battery, integrated to the grid. At present, typical applications of EV chargers usually include only charging of the vehicle battery providing unidirectional power flow between the power grid and EV. The proposed three-phase grid connected EV charger system enables bidirectional power flow, sending unused energy in EV battery back to the electricity grid in the scope of V2G operation in addition to conventional charging of the battery. The EV charger circuit consists of two stages, one of which is three-phase AC/DC PWM converter and the other is synchronous DC/DC converter, between which a DC link capacitor having 800V rated bus voltage is inserted. Also, a Li-ion battery pack with the nominal voltage of 500V is used for the system. LCL filter is utilized for AC/DC part of the charger to attenuate line current ripples and the other components are selected based on the theoretical analysis performed as well. Two-loop control algorithms, of which design parameters are calculated using some detailed mathematical analysis, are implemented for both AC/DC converter and DC/DC one to achieve tight voltage & current regulations for the EV charger. Then the performance of the bidirectional EV charger circuit is evaluated via some simulation work in Matlab/Simulink based on closed-loop operation and harmonic contents for grid side. Simulation results are discussed to analyze the closed-loop performance of the EV charger system during various conditions and the developed theory regarding control system design is verified. Harmonics & THD values of line currents are also investigated for various battery voltage levels using the obtained results. In addition, loss analysis is performed to show that the bidirectional EV charger system can operate with high efficiency values.