Improving DC-Bus Voltage Regulation in Grid Fed EV Fast Charging Station Using MLI Based DVR

This article presents a T-type 5-level inverter based dynamic voltage restorer (DVR) as a power quality (PQ) solution to enhance DC-bus voltage regulation in grid fed electric vehicle fast charging stations (EVFCS). The designing of DVR connected EVFCS is carried out in this work. There is a noticeable impact of EV loading on EVFCS performance. To observe the effect of EVs loading on DC-bus, three Li-ion battery packs are used. The performance of closed loop current regulated buck converters is examined for various loading scenarios. Further, the impact of EVs loading on several EVFCS parameters, including DC-bus voltage, charging current, battery SOC and battery voltage is examined in simulation. A closed loop voltage controller based on the
$ \alpha \beta$
to
dq
transformation is constructed for 1-
$ \phi$
DVR in order to reduce the loading effect of EVs. This DVR maintains the rated DC-bus voltage (110 V), guaranteeing proper voltage regulation and the rated current of each battery under all three loading scenarios. Additionally, the DVR protects the point of common coupling (PCC) from voltage harmonics generated by EVFCS and maintains it within the IEEE 519 limit. Finally, to validate the simulation results, an experimental study is also carried out on reduced scale with a T-type 5-level DVR to observe the improved performance of EVFCS.