Development of a three-phase interleaved converter based on SEPIC DC-DC converter operating in discontinuous conduction mode for ultra-fast electric vehicle charging stations

One of the main challenges that impact transportation systems electrification is their batteries' charging process. This work presents the development of a three-phase ultra-fast Electric Vehicle (EV) charger based on the SEPIC converter. Since SEPIC operating in Discontinuous Conduction Mode (DCM) is usually recommended for low-power applications, this work proposes a scheme for its employment in high-power EV chargers. This is achieved through three single-phase modules of interleaved SEPIC converters. The presented scheme ensures reducing the stresses on the semiconductor devices since the power is divided over the interleaved modules. The design addresses DCM operation in terms of both capacitor voltage and inductor current (DCVM and DICM, respectively). This paper examines the analysis of the proposed converter and the small-signal modelling. Also, the converter efficiency is assessed. A Constant Current (CC) charging approach is deployed for charging the EV battery. The validation of the designs is explored through simulation results using MATLAB/Simulink platform. A 4 kW experimental prototype for the interleaved SEPIC DC-DC converter is built to verify the claimed contributions with 92% efficiency.