An isolated-boost-converter-based unidirectional three-phase off-board fast charger for electric vehicles

In this work, a novel three-phase unidirectional off-board Electric Vehicles (EVs) fast charger is proposed. Each phase of the proposed converter consists of a two-stage converter. The first stage is an AC-DC front-end converter with power factor correction (PFC) control. The front-end AC-DC converter is based on an isolated boost converter, which has a boosting capability and provides galvanic isolation. In this stage, parallel-in parallel-out isolated boost converter modules are employed in each phase. This enables sharing the current among modules to avoid implementing one module with a high current rating to meet the fast-charging requirements. The multimodule option provides fault-ride through capability for the proposed charger. The DC outputs of involved phases, that is, three isolated DC voltages, are fed to three cascaded DC-DC unidirectional buck converters. The charging terminals are used to charge the EV battery through a filter inductor with a charging current controller's aid. A detailed illustration of the suggested closed-loop controllers is presented to ensure a successful operation for the proposed architecture. A simulation case study for a 25-kW charger is presented. Finally, a 1-kW prototype is implemented for experimental validation.